Patent Publication Number: US-2022227640-A1

Title: Water distillation apparatus, method, and system

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation application of U.S. patent application Ser. No. 16/370,038, entitled: Water Distillation Apparatus, Method, and System, filed on Mar. 29, 2019, (Attorney Docket No. Z37) now U.S. Publication No. US-2020-0115254-A1, published on Apr. 16, 2020, which claims priority from U.S. Provisional Patent Application Ser. No. 62/745,748, filed on Oct. 15, 2018 and entitled Water Distillation Apparatus, Method and System (Attorney Docket No. Y45), which is hereby incorporated herein by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     The present invention relates to water distillation and more particularly, to a water vapor distillation apparatus, method, and system. 
     BACKGROUND INFORMATION 
     A dependable source of clean water eludes vast segments of humanity. For example, the Canadian International Development Agency reports that about 1.2 billion people lack access to safe drinking water. Published reports attribute millions and millions of deaths per year, mostly children, to water related diseases. Many water purification techniques are well known, including carbon filters, chlorination, pasteurization, and reverse osmosis. Many of these techniques are significantly affected by variations in the water quality and do not address a wide variety of common contaminants, such as bacteria, viruses, organics, arsenic, lead, mercury, and pesticides that may be found in water supplies in the developing world and elsewhere. Some of these systems require access to a supply of consumables, such as filters or chemicals. Moreover, some of these techniques are only well suited to centralized, large-scale water systems that require both a significant infrastructure and highly trained operators. The ability to produce reliable clean water without regard to the water source, on a smaller, decentralized scale, without the need for consumables and constant maintenance is very desirable, particularly in the developing world. 
     The use of vapor compression distillation to purify water is well known and may address many of these concerns. However, the poor financial resources, limited technical assets, and low population density that does not make it feasible to build centralized, large-scale water systems in much of the developing world, also limits the availability of adequate, affordable, and reliable power to operate vapor compression distillation systems, as well as hindering the ability to properly maintain such systems. In such circumstances, an improved vapor compression distillation system and associated components that increases efficiency and production capability, while decreasing the necessary power budget for system operation and the amount of system maintenance required may provide a solution. 
     SUMMARY 
     In accordance with an embodiment of the present disclosure, a water vapor distillation system for providing distillate at a controlled temperature is disclosed. The water vapor distillation system includes a water vapor distillation device configured to receive a volume of source water from a fluid source and produce distillate, the device comprising: a concentrate flow path comprising a concentrate output; a distillate flow path comprising a distillate output; at least one source proportioning valve; a first heat exchanger comprising at least a portion of the distillate flow path; a second heat exchanger including at least a portion of the concentrate flow path, wherein the first heat exchanger and the second heat exchanger in fluid flow communication with the fluid source; a distillate sensor assembly in communication with the distillate flow path and located downstream the first heat exchanger, the distillate sensor assembly configured to generate a distillate temperature measurement; and a controller configured to control the source proportioning valves, the controller configured to: receive the distillate temperature measurement; determine the difference between a first target temperature and the distillate temperature measurement; and split the source water from the fluid source between the first heat exchanger and the second heat exchanger based on the difference between the first target temperature and the distillate temperature measurement. 
     In accordance with an embodiment of the present disclosure, a water purification system for outputting distillate at a controlled temperature may comprise a distillation device in selective fluid communication with a fluid source via a set of source proportioning valves. The distillation device may having a concentrate output and distillate output respectively coupled to a concentrate flow path and a distillate flow path. The system may further comprise a first heat exchanger including a portion of the distillate flow path and a second heat exchanger including a portion of the concentrate flow path. A flow path from the fluid source may be in heat exchange relationship with each of the first and second heat exchanger. The system may further comprise a distillate sensor assembly in communication with the distillate flow path downstream of the portion of the distillate flow path included in the first heat exchanger. The distillate sensor assembly may be configured to generate a distillate temperature measurement. The system may further comprise a controller configured to govern operation of the source proportioning valves in a first operating mode to split incoming flow from the fluid source between the first and second heat exchanger based on a delta between a first target temperature and the distillate temperature measurement. 
     In some embodiments, the controller may be configured to determine a total source proportioning valve duty cycle which dictates the amount of incoming flow from the fluid source. In some embodiments, the system may further comprise a concentrate reservoir and a concentrate level sensor. The controller may be configured to determine the total source proportioning valve duty cycle based on a concentrate accumulation rate calculated from a level measurement output of the concentrate level sensor and a target concentrate accumulation rate. In some embodiments, the controller may be configured to govern operation of the source proportioning valves in a second operating mode to allocate the entire total source proportioning valve duty cycle to a source proportioning valve gating source flow to the second heat exchanger and open a source proportioning valve gating source flow to the first heat exchanger at added duty cycle which is no greater than a predefined limit. In some embodiments, the predefined limit may be selected from a list consisting of 5%, 2%, less than 2%, and zero. In some embodiments, the first operating mode may be a low temperature distillate production state and the second operating mode may be a hot temperature distillate production state. In some embodiments, the controller may be configured to open a source proportioning valve gating source flow to the first heat exchanger based upon a second target temperature and a delta between the second target temperature and the current concentrate temperature in the second operating state. In some embodiments, the second target temperature may be at least 65° C. hotter than the first target temperature. In some embodiments, the second target temperature may be at least 50° C. hotter than the first target temperature. In some embodiments, the second target temperature, may be greater than 95° C. and less than 100° C. In some embodiments, the second target temperature may be 96° C. In some embodiments, the second target temperature may be at least double the first target temperature. In some embodiments, the second target temperature may be at least 2.5 times the first target temperature. In some embodiments, the second target temperature may be at least 3.5 times the first target temperature. In some embodiments, the system may further comprise an evaporator level sensor disposed in an evaporator reservoir in fluid communication with an evaporator of the distillation device. The controller may be configured to, in the second mode, determine the total source proportioning valve duty cycle at least in part based on an evaporator level data signal indicative of a level of a water column in the evaporator reservoir. In some embodiments, the first target temperature may be at least 20° C., but no greater than 25° C. In some embodiments, the system may further comprise a source fluid temperature sensor. The controller may be configured to determine the first target temperature based at least in part on a source fluid temperature measurement received from the source fluid temperature sensor. In some embodiments, the system may further comprise a concentrate sensor assembly in communication with the concentrate flow path downstream of the portion of the concentrate flow path included in the second heat exchanger. The concentrate sensor assembly may be configured to generate a concentrate temperature measurement. In some embodiments, the controller is configured to open a source proportioning valve gating source flow to the second heat exchanger based at least in part upon a delta between a third target temperature and the concentrate temperature measurement. In some embodiments, the third target temperature may be a historic average of the concentrate temperature. In some embodiments, the controller may be configured to open a source proportioning valve gating source flow to the second heat exchanger based at least in part upon a minimum limit. In some embodiments, the minimum limit may be the greater of a predefined duty cycle or a predefined percentage of the combined duty cycle for all of the source proportioning valves. In some embodiments, the predefined duty cycle may be 5%. In some embodiments, the predefined percentage may be 10%. In some embodiments, the controller may be disposed in an electronics box in heat transfer relationship the flow path from the fluid source leading to the second heat exchange. In some embodiments, the controller may be configured to determine an electronics box cooling duty cycle command and open a source proportioning valve gating source flow to the second heat exchanger based at least in part upon a the electronics box cooling duty cycle command. In some embodiments, the electronics box cooling duty cycle may be determined based at least in part on a delta between a target electronics box temperature and an electronics box temperature measurement collected from an electronics box temperature sensor configured to measure temperature of the electronics box and in data communication with the controller. In some embodiments, the distillate sensor assembly may include redundant temperature sensors. In some embodiments, the distillate sensor assembly may include redundant temperature sensors and redundant conductivity sensors. In some embodiments, the first and second heat exchanger may be helical and formed by winding the heat exchangers around the exterior of the distillation device. 
     In accordance with an embodiment of the present disclosure a fluid distillation apparatus may comprise at least one controller and a source inlet in selective fluid communication with a fluid source via at least one valve. The fluid vapor distillation apparatus may further comprise an evaporator in fluid communication with the source inlet. The fluid vapor distillation apparatus may further comprise a steam chest coupled to the evaporator and in fluid communication with a compressor. The fluid vapor distillation apparatus may further comprise a concentrate reservoir attached to the steam chest via an inflow path. The concentrate reservoir may be disposed laterally to the steam chest such that at least a portion of the concentrate reservoir is at even height with the steam chest. The fluid vapor distillation apparatus may further comprise a condenser in fluid communication with an outlet of the compressor via a straight line flow path. The straight line flow path may include a condenser inlet having a fenestrated segment with a plurality of fenestrations. The fenestrations may establish a flow path from the condenser inlet to the condenser. The fluid vapor distillation apparatus may further comprise a product process stream reservoir coupled to the condenser by a product reservoir inlet. The product process stream reservoir may be disposed laterally to the condenser such that at least a portion of the product process stream reservoir is at even height with the condenser. 
     In some embodiments, the inflow path may include an obstruction. In some embodiments, the obstruction may include a plate. The plate may have a segment which extends into the concentrate reservoir at an angle substantially perpendicular to the inflow path. In some embodiments, the obstruction may extend into the concentrate reservoir and divide the concentrate reservoir into a first portion and a second, sheltered portion. In some embodiments, the fluid vapor distillation apparatus may further comprise a venting pathway extending from the concentrate reservoir to the steam chest. In some embodiments, the venting pathway may extend substantially parallel to and above the inflow path with respect to gravity. In some embodiments, the product reservoir inlet may be adjacent a product accumulation surface of the condenser. In some embodiments, the compressor may be driven by a motor mounted in a receiving well recessed into the side of the steam chest. In some embodiments, the compressor may include an impeller which rotates about an axis which passes through at least a portion of the steam chest and is off-center, but parallel with respect to a longitudinal axis of the steam chest. 
     In accordance with another embodiment of the present disclosure a water vapor distillation apparatus may comprise a sump and an evaporator having a first side in communication with the sump. The evaporator may have a second side in fluid communication with a steam chest. The water vapor distillation apparatus may further comprise a concentrate reservoir attached to the steam chest via an inflow path having a first portion and second portion. The second portion may be at least in part by an obstruction. The obstruction may extend into the concentrate reservoir in a direction transverse to the first portion and may divide the concentrate reservoir into an unsheltered section and a sheltered section. The water vapor distillation apparatus may further comprise a float assembly disposed in the sheltered section. The float assembly may be displaceable over a displacement range inclusive of points at even height with all steam chest liquid levels in an expected range of steam chest liquid levels. The water vapor distillation apparatus may further comprise a sensor configured monitor a position of the float assembly and output a data signal indicative of a liquid level in the steam chest based on the position of the float assembly. The water vapor distillation apparatus may further comprise a compressor having an inlet establishing fluid communication with the steam chest and an outlet establishing fluid communication with a condenser. 
     In some embodiments, the sensor may be an encoder. In some embodiments, the float assembly may include at least one magnet. In some embodiments, the sensor may be a hall effect sensor. In some embodiments, the float assembly may be attached to a pivot. In some embodiments, the float assembly may be displaceable about the pivot. In some embodiments, the obstruction may extend into the concentrate reservoir at an angle substantially perpendicular to the first portion of the inflow path. In some embodiments, the water vapor distillation apparatus may further comprise a venting pathway extending from the concentrate reservoir to the steam chest. In some embodiments, the venting pathway may extend parallel to and above the first portion of the inflow path. In some embodiments, the venting pathway may have a smaller cross-sectional area than that of the first portion of the inflow path. 
     In accordance with another embodiment of the present disclosure a water vapor distillation apparatus may comprise a sump having a source fluid input. The water vapor distillation apparatus may further comprise an evaporator having a first side in fluid communication with the source fluid input via the sump and a second side in fluid communication with a steam chest. The evaporator may be configured to transform source fluid from the source fluid input to low pressure vapor and concentrate as source fluid travels toward the steam chest. The water vapor distillation apparatus may further comprise a concentrate reservoir attached and disposed laterally to the steam chest. The concentrate reservoir may include a concentrate level sensor configured to monitor the level of concentrate in the steam chest and generate a data signal indicative of the level of concentrate. The water vapor distillation apparatus may further comprise a compressor having a low pressure vapor inlet establishing fluid communication with the steam chest and a high pressure vapor outlet establishing fluid communication with a condenser via a condenser inlet. The water vapor distillation apparatus may further comprise a condenser in heat transfer relationship with a plurality of exterior surfaces of the evaporator. The condenser may be configured to condense a high pressure vapor stream from the compressor by contacting the high pressure vapor stream with the plurality of exterior surfaces of the evaporator. The condenser may include a condensing portion and a condensate accumulation or storage portion. The water vapor distillation apparatus may further comprise an auxiliary condensate reservoir in fluid communication with the condensate accumulation portion. The auxiliary condensate reservoir may be attached to the condenser adjacent an accumulation surface of the accumulation portion, The auxiliary condensate reservoir may include a condensate level sensor configured monitor a level of condensate in the accumulation portion and generate a data signal indicative of a percentage which the accumulation portion is filled with condensate. 
     In some embodiments, the accumulation portion may have a volume less than ten liters. In some embodiments, the plurality of exterior surfaces may be exterior surfaces of a plurality of evaporator tubes included in the evaporator. In some embodiments, the plurality of exterior surfaces may be exterior surfaces of between 90-100 evaporator tubes included in the evaporator. In some embodiments, the plurality of exterior surfaces may be exterior surfaces of between 70-80 evaporator tubes included in the evaporator. In some embodiments, the condensate level sensor may include a float assembly attached to a pivot. In some embodiments, the float assembly may be displaceable about the pivot over a displacement range inclusive of points at even height with a range of levels defined by the accumulation portion. In some embodiments, the concentrate level sensor may include a float assembly disposed in a sheltered section of the concentrate reservoir separated from an unsheltered portion of the concentrate reservoir by a barrier. In some embodiments, the float assembly may be attached to a pivot and may be displaceable about the pivot over a displacement range inclusive of points at even height with all steam chest concentrate levels in an expected range of steam chest liquid levels. In some embodiments, the concentrate level sensor may be disposed within a sleeve which forms the barrier. 
     In accordance with another embodiment of the present disclosure, a concentrate level control system for a fluid vapor distillation apparatus may comprise a source fluid input in selective fluid communication with a source fluid reservoir via at least one input valve. The concentrate level control system may further comprise an evaporator in fluid communication with the source input and in fluid communication with a steam chest. The evaporator may be configured to transform source fluid from the source fluid input into a vapor stream and a concentrate stream as the source fluid travels toward the steam chest. The concentrate level control system may further comprise a concentrate reservoir attached and disposed lateral to the steam chest via an inflow path and including an outlet in selective communication with a concentrate destination via an outlet valve. The concentrate level control system may further comprise a concentrate level sensor configured to generate a data signal indicative of a concentrate level in the steam chest. The concentrate level control system may further comprise a controller configured to deliberately alter the concentrate level in a predetermined pattern by governing actuation of the at least one inlet valve via a fluid input control loop as well as analyzing the data signal. The controller may be further configured to actuate the outlet valve to a closed state when the data signal indicates the concentrate level is below a first threshold and actuate outlet valve to an open state when the concentrate level is above a second threshold. 
     In some embodiments, the predetermined pattern may create a sawtooth waveform when concentrate level is plotted over time. In some embodiments, wherein the period of the sawtooth waveform may be dependent at least in part upon a fluid input command from the fluid input control loop. In some embodiments, the fluid input command may be determined based on a predetermined target concentrate production rate. In some embodiments, the controller may be configured to operate in a plurality of operational states and the predetermined target concentrate production rate may be state specific. In some embodiments, the controller may analyze the data signal on a predetermined basis. In some embodiments, wherein the concentrate level may be assigned a predefined expected range and the first threshold may be less than or equal to 50% of a maximum level of the expected range. In some embodiments, the first threshold may be between 40% and 50% of the maximum level of the expected range. In some embodiments, the concentrate level may be assigned a predefined expected range and the second threshold may be greater than or equal to 50% of a maximum level of the expected range. In some embodiments, the second threshold may be between 50% and 60% of the maximum level of the expected range. In some embodiments, wherein the concentrate level may be assigned a predefined expected range and the first threshold may be less than or equal to 40% of a maximum level of the expected range. In some embodiments, the first threshold may be between 40% and 30% of the maximum level of the expected range. In some embodiments, the concentrate level may be assigned a predefined expected range and the second threshold may be greater than or equal to 45% of a maximum level of the expected range. In some embodiments, the second threshold may be between 45% and 55% of the maximum level of the expected range. In some embodiments, the concentrate level may be assigned a predefined expected range and the first and second thresholds may be defined as a percentage of a maximum level of the expected range. The second threshold may be between 4 and 20 percentage points greater than the first threshold. In some embodiments, the concentrate destination is a mixing can. 
     In accordance with another embodiment of the present disclosure a method for controlling a level of concentrate in a distillation device and verifying fluid flow within the distillation device may comprise inputting a source fluid to the distillation device though at least one inlet valve. The method may further comprise evaporating at least a portion of the source fluid to generate a vapor and a concentrate as the source fluid travels toward a steam chest. The method may further comprise collecting concentrate in a concentrate reservoir attached and disposed lateral to the steam chest via an inflow path. The method may further comprise providing a data signal indicative of a concentrate level in the steam chest from a concentrate level sensor disposed in the concentrate reservoir. The method may further comprise altering, with a controller, the concentrate level in a predetermined pattern by governing actuation of the at least one inlet valve via a fluid input control loop as well as analyzing the data signal and actuating an outlet valve of the concentrate reservoir to a closed state when the data signal indicates the concentrate level is below a first threshold and to an open state when the concentrate level is above a second threshold. 
     In some embodiments, altering the concentrate level may comprise altering the concentrate level to create a sawtooth waveform when concentrate level is plotted over time. In some embodiments, analyzing the data signal may comprise analyzing the data signal on a predetermined basis. In some embodiments, the method may further comprise assigning a predefined expected range to the concentrate level and setting the first threshold at less than or equal to 50% of a maximum level of the expected range. In some embodiments, setting the first threshold may comprise setting the threshold to between 40% and 50% of the maximum level of the expected range. In some embodiments, the method may further comprise assigning a predefined expected range of the concentrate level and setting the second threshold at greater than or equal to 50% of a maximum level of the expected range. In some embodiments, setting the second threshold comprising setting the second threshold between 50% and 60% of the maximum level of the expected range. In some embodiments, the method may further comprise assigning a predefined expected range to the concentrate level and setting the first threshold at less than or equal to 40% of a maximum level of the expected range. In some embodiments, setting the first threshold may comprise setting the threshold to between 40% and 30% of the maximum level of the expected range. In some embodiments, the method may further comprise assigning a predefined expected range of the concentrate level and setting the second threshold at greater than or equal to 45% of a maximum level of the expected range. In some embodiments, setting the second threshold comprising setting the second threshold between 45% and 55% of the maximum level of the expected range. In some embodiments, the method may further comprise assigning the concentrate level a predefined expected range and setting the first and second thresholds as a percentage of a maximum level of the expected range, the second threshold being between 4 and 20 percentage points greater than the first threshold. 
     In accordance with another embodiment of the present disclosure a temperature control system for controlling temperature of a product process stream of a distillation device to a request temperature may comprise a source fluid input in selective fluid communication with a source fluid reservoir via a set of fluid input valves. The system may further comprise an evaporator in fluid communication with the source input and in fluid communication with a compressor. The evaporator may be configured to transform source fluid from the source fluid input into a vapor stream and a concentrate stream as the source fluid travels toward the compressor. The system may further comprise a condenser in fluid communication with the compressor configured to transform pressurized vapor from the compressor into condensate. The system may further comprise a condensate flow path and a concentrate flow path including respective first and second heat exchangers. The first and second heat exchangers may each include a heat exchanging portion of a source fluid flow path from the source fluid reservoir. The heat exchanging portion may be downstream the source fluid input valves. The system may further comprise a condensate temperature sensor configured to generate a data signal indicative of a condensate temperature. The condensate temperature sensor may be disposed on the condensate flow path downstream the first heat exchanger. The system may further comprise a controller configured to actuate the set of input source valves based on a first control loop which governs a total open state time for all input source valves of the set of input source valves and a second control loop which receives the data signal and the requested temperature and divides the total open state time between all of the input source valves to adjust the condensate temperature to the requested temperature. 
     In some embodiments, the heat exchanging portions of the source fluid flow paths within the first and second heat exchanger may be disposed countercurrent to their respective condensate and concentrate flow paths. In some embodiments, the system may further comprise a destination device in fluid communication with the condensate flow path via a point of use valve. In some embodiments, the requested temperature may be generated by the destination device. In some embodiments, the destination device may be a medical system. In some embodiments, the medical system may be configured to mix at least one dialysate solution. In some embodiments, the destination device may be a dialysis machine. In some embodiments, the destination device may be a hemodialysis machine. In some embodiments, at least one of the first and second control loop may be a PID control loop. In some embodiments, the gain of at least one of the terms of the PID control loop may be zero. In some embodiments, a feed forward term may be combined with the output of the second control loop. In some embodiments, the feed forward term may be based off an estimated division of total open state time. In some embodiments, the system may further comprise a concentrate level sensor configured to output a concentrate level data signal indicative of a concentrate level within the distillation device. The first control loop may be configured to receive a target concentrate level and the current concentrate level data signal and as inputs to the first control loop. In some embodiments, the controller may be further configured to adjust a heater duty cycle based at least in part on the total open state time for all input source valves of the set of input source valves. In some embodiments, the controller may be configured to increase the heater duty cycle when the open state time for all of the input source valves of the set of input source valves is increased. 
     In accordance with another embodiment of the present disclosure a method for controlling the temperature of a product process stream of a distillation device to a requested temperature may comprise governing a flow of source fluid input to the distillation device by actuation, with a controller, a set of source fluid valves. The method may further comprise converting, in an evaporator, at least a portion of the source fluid input into a vapor and a concentrate. The method may further comprise condensing, in a condenser, the vapor into a condensate. The method may further comprise removing at least a portion of the condensate and the concentrate from the distillation device through respective condensate and concentrate flow paths. The method may further comprise exchanging heat, in a first heat exchanger, between the flow of source fluid and the condensate flow path and exchanging heat, in a second heat exchanger, between the flow of source fluid and the concentrate flow path. The method may further comprise providing a condensate temperature data signal to the controller from a temperature sensor on the condensate flow path located downstream the first heat exchanger. The method may further comprise determining, with a controller, a total open state time for the set of fluid input valves between set of fluid input valves based on a first control loop and dividing the total open state time between the set of fluid input valves based on a second control loop which receives the temperature data signal and a requested temperature. 
     In some embodiments, the method may further comprise flowing the condensate and concentrate through the condensate and concentrate flow paths in a direction countercurrent to the flow of the source fluid. In some embodiments, the method may further comprise providing the condensate to a destination device by actuating a point of use valve downstream the temperature sensor. In some embodiments, the requested temperature may be generated by the destination device. In some embodiments, the destination device may be a medical system. In some embodiments, the method may further comprise mixing a dialysate using the condensate. In some embodiments, the destination device may be a dialysis machine. In some embodiments, the destination device may be a hemodialysis machine. In some embodiments, at least one of the first and second control loop may be a PID control loop. In some embodiments, the method may further comprise setting at least one of the gains of the PID control loop to zero. In some embodiments, wherein the method may further comprise combining a feed forward term with the output of the second control loop. In some embodiments, the method may further comprise determining the feed forward term based off an estimated division of total open state time. In some embodiments, wherein the method further comprises inputting a current concentrate level provided by a concentrate level sensor and a target concentrate level to the first control loop. In some embodiments, the method may further comprise adjusting a heater duty cycle based at least in part on the total open state time for all input source valves of the set of input source valves. In some embodiments, adjusting the heater duty cycle may comprise increasing the heater duty cycle when the open state time for all of the input source valves of the set of input source valves is increased. 
     In accordance with another embodiment of the present disclosure a temperature control system for controlling the temperature of a product process stream of a distillation device to a requested temperature may comprise a first source fluid input and a second fluid source input in selective fluid communication with source fluid reservoirs respectively via a first set of fluid input valves and a second set of fluid input valves. The system may further comprise an evaporator in fluid communication with the first and second source fluid input and in fluid communication with a compressor. The evaporator may have a heating element to transform source fluid from the first and second source fluid inputs into a vapor stream and a concentrate stream as the source fluid travels toward the compressor. The system may further comprise a condenser in fluid communication with the compressor. The condenser may be configured to transform pressurized vapor from the compressor into condensate. The system may further comprise a condensate flow path and a concentrate flow path including respective first and second heat exchangers. The first and second heat exchangers may each include a heat exchanging portion of a source fluid flow path from the source fluid reservoirs, the heat exchanging portion being downstream the sets of source fluid input valves. The system may further comprise a condensate temperature sensor configured to generate a data signal indicative of a condensate temperature. The condensate temperature sensor may be disposed on the condensate flow path downstream the first heat exchanger. The system may further comprise a controller configured to actuate the first set of input source valves based on a first control loop which governs a total open state time for all input source valves of the first set of input source valves and a second control loop which receives the data signal and the requested temperature and divides the total open state time between all of the input source valves of the first set of input source valves to adjust the condensate temperature to the requested temperature. The controller may be configured to monitor at least one process variable and to actuate the second set of input source valves when one of the at least one process variable is outside of a predefined threshold. 
     In some embodiments the first set of fluid input valves may include at least one valve not included in the second set of fluid input valves. In some embodiments, one of the first and second source fluid inputs may be temperature controlled. In some embodiments, the second source fluid input may be temperature controlled. In some embodiments, the second source fluid input may be a hot fluid input. In some embodiments, the at least one process variable monitored by the controller may be a heating element duty cycle. In some embodiments, the at least one process variable monitored by the controller may be an output of the first control loop. In some embodiments, the at least one process variable may be a compressor speed. In some embodiments, the heat exchanging portion of the source fluid flow path may be a common flow path for fluid from the first and second source fluid input. 
     In accordance with another embodiment of the present disclosure a temperature controls system for controlling the temperature of a product process stream of a distillation device to a request temperature may comprise a source fluid input in selective fluid communication with a source fluid reservoir via a set of fluid input valves. The system may further comprise an evaporator in selective fluid communication with the source fluid input via a bypass valve and in fluid communication with a compressor. The evaporator may be configured to transform source fluid from the source fluid input into a vapor stream and a concentrate stream as the source fluid travels toward the compressor. The system may further comprise a condenser in fluid communication with the compressor configured to transform pressurized vapor from the compressor into condensate. The system may further comprise a condensate flow path and a concentrate flow path including respective first and second heat exchangers. The first and second heat exchangers may each include a heat exchanging portion of a source fluid flow path from the source fluid reservoir, the heat exchanging portion being downstream the source fluid input valves. The system may further comprise a condensate temperature sensor configured to generate a data signal indicative of a condensate temperature. The condensate temperature sensor may be disposed on the condensate flow path downstream the first heat exchanger. The system may further comprise a controller configured to actuate the set of input source valves based on a first control loop which governs a total open state time for all input source valves of the set of input source valves and a second control loop which receives the data signal and the requested temperature and divides the total open state time between all of the input source valves to adjust the condensate temperature to the requested temperature. The bypass valve may be disposed in the source fluid flow path downstream of the heat exchanging portion of the source fluid flow path. The bypass valve may have a divert valve state which directs fluid from the source reservoir to a drain destination. The controller may be configured to actuate the bypass valve to the divert valve state when the controller determines at least one process variable is outside of a predetermined threshold. 
     In some embodiments the at least one process variable may be a relationship between the condensate temperature and a source fluid temperature provided by a source fluid temperature sensor. In some embodiments, the at least one process variable may be a source fluid temperature sensed by a source fluid temperature sensor. In some embodiments, the at least one process variable may be defined at least in part by the condensate temperature and a source fluid temperature sensed by a source fluid temperature sensor. In some embodiments, the controller may alter the duty cycle of at least one of the input source valves when the bypass valve is in the divert valve state. In some embodiments, the controller may increase the duty cycle of at least one of the input source valves when the bypass valve is in the divert valve state. In some embodiments, the controller may alter the duty cycle of at least one of the input source valves to 90-100% when the bypass valve is in the divert valve state. In some embodiments, one of the at least one of the input source valves may be a valve controlling flow of source fluid through the heat exchanging portion of the first heat exchanger. 
     In accordance with another embodiment of the present disclosure a temperature controls system for controlling the temperature of a product process stream of a distillation system to a requested temperature may comprise a source fluid input in selective fluid communication with a source fluid reservoir via a set of fluid input valves. The system may further comprise a distillation device configured to generate a concentrate stream and a condensate stream. The system may further comprise a condensate flow path and a concentrate flow path including respective first and second heat exchangers. The first and second heat exchangers may each include a heat exchanging portion of a source fluid flow path from the source fluid reservoir, the heat exchanging portion being downstream the source fluid input valves. The system may further comprise a condensate temperature sensor configured to generate a data signal indicative of a condensate temperature. The condensate temperature sensor may be disposed on the condensate flow path downstream the first heat exchanger. The system may further comprise a point of use device in selective communication with the condensate flow path. The point of use device may have an outlet fluid path for output fluid generated by the point of use device. The output fluid path may have a third heat exchanger including a heat exchanging portion of a branch of the source fluid flow path. The system may further comprise a controller configured to actuate the set of input source valves based on a first control loop and a second control loop which govern the fluid of source fluid through the heat exchanging portions of the first and second heat exchangers and based on at least one process variable. The controller may actuate a branch valve to the branch of the source fluid flow path when the at least one process variable is outside a predetermined threshold. 
     In some embodiments, the at least one process variable may a relationship between the condensate temperature and a source fluid temperature provided by a source fluid temperature sensor. In some embodiments, the at least one process variable may a source fluid temperature sensed by a source fluid temperature sensor. In some embodiments, the at least one process variable may be defined at least in part by the condensate temperature and a source fluid temperature sensed by a source fluid temperature sensor. In some embodiments, the point of use device may be a medical device. In some embodiments, the point of use device is a dialysis machine. In some embodiments, the point of use device is a hemodialysis machine or a peritoneal dialysis machine. In some embodiments, the point of use device may be a dialysate admixing device. In some embodiments, the branch of the source fluid flow path may be disposed upstream of the heat exchanging portion of the source fluid flow path in the first and second heat exchangers. In some embodiments, the output fluid may be a dialysate effluent. 
     In accordance with another embodiment of the present disclosure a condensate accumulation rate control system for controlling a rate of condensate accumulation within a distillation device may comprise a source fluid input in selective fluid communication with a source fluid reservoir via a set of fluid input valves. The system may further comprise an evaporator in fluid communication with the source input and in fluid communication with a compressor having an impeller operatively coupled to an impeller motor. The evaporator may be configured to transform source fluid from the source fluid input into a vapor stream and a concentrate stream as the source fluid travels toward the compressor. The system may further comprise a condenser in heat transfer relationship with a plurality of exterior surfaces of the evaporator. The condenser may be configured to condense a high pressure vapor stream from the compressor by contacting the high pressure vapor stream with the plurality of exterior surfaces of the evaporator. The system may further comprise a condensate levels sensor configured to sense a current level of condensate in the condenser. The system may further comprise at least one controller configured to govern a rotation speed of the impeller by periodically generating an impeller motor command based on a last motor speed command, a motor speed goal, and a speed command increment limit. The motor speed goal may be calculated by a control loop which receives the current condensate level and a desired condensate level as control loop inputs. 
     In some embodiments, the speed command increment limit may be ≤10 rpm/sec. In some embodiments, wherein the speed command increment limit may be ≤5 rpm/sec. In some embodiments, the controller may be configured to compare the impeller motor command to a minimum command speed threshold and maximum command speed threshold and adjust the impeller motor command to a modified impeller motor command equal to the minimum command speed threshold when the impeller motor command is below the minimum command speed threshold and equal to the maximum command speed threshold when the impeller motor command is above the maximum command speed threshold. In some embodiments, the minimum command speed threshold is between 1500-2500 rpm. In some embodiments, the maximum command speed threshold is calculated each time the motor speed command is generated. In some embodiments, the maximum command speed threshold may be calculated based on at least one motor parameter. In some embodiments, the system may further comprise a motor temperature sensor configured to output a temperature data signal indicative of a temperature of the impeller motor and a power factor correction current monitoring circuit configured to output a PFC data signal indicative of a current power factor correction current, the maximum command speed threshold being calculated based on a the temperature data signal and the PFC data signal. In some embodiments, the maximum command speed may be capped a predetermined value. In some embodiments, wherein the predetermined value may be between 4500-6500 rpm. In some embodiments, the predetermined value may be 5000 rpm. In some embodiments, the predetermined value may be about 2.5 times larger than the minimum command speed threshold. 
     In accordance with another embodiment of the present disclosure a method for controlling a rate of condensate accumulation within a distillation device may comprise providing a source fluid input to the distillation device. The method may further comprise evaporating, in an evaporator, at least a portion of the source fluid input into a low pressure vapor. The method may further comprise compressing, via an impeller, the low pressure vapor into a high pressure vapor. The method may further comprise condensing, in a condenser, the high pressure vapor into a condensate and transferring heat from the high pressure vapor to the evaporator. The method may further comprise providing a level of condensate within the condenser sensed by a condensate level sensor to a controller. The method may further comprise calculating, with the controller, a motor speed goal based on the level of condensate and a desired condensate level. The method may further comprise governing, with a controller, a rotation speed of the impeller by periodically generating an impeller motor command based on a last motor speed command, a motor speed goal, an a speed command increment limit. 
     In some embodiments, the speed command increment limit is ≤10 rpm/sec. In some embodiments, the speed command increment limit is ≤5 rpm/sec. In some embodiments, the method may further comprise comparing, with the controller, the impeller motor command to a minimum command speed threshold and maximum command speed threshold and adjusting the impeller motor command to a modified impeller motor command equal to the minimum command speed threshold when the impeller motor command is below the minimum command speed threshold and equal to the maximum command speed threshold when the impeller motor command is above the maximum command speed threshold. In some embodiments, the minimum command speed threshold may be between 1500-2500 rpm. In some embodiments, the minimum command speed threshold may be 2000 rpm. In some embodiments, the method may further comprise calculating the maximum command speed threshold each time the motor speed command is generated. In some embodiments, calculating the maximum command speed threshold may comprise calculating the maximum command speed threshold based on at least one motor parameter. In some embodiments, the method may further comprise providing a temperature data signal indicative of a temperature of the motor from a motor temperature sensor to the controller and providing a power factor correction data signal indicative of a current power factor correction current from a monitoring circuit to the controller. In some embodiments, the method may further comprise calculating the maximum command speed threshold based on the temperature data signal and the power factor correction data signal. In some embodiments, the method may further comprise capping the maximum command speed threshold at a predetermined value. In some embodiments, the predetermined value may be between 4500-6500 rpm. In some embodiments, the predetermined value may be 5000 rpm. In some embodiments, the predetermined value may be or may be about 2.5 times larger than the minimum command speed threshold. 
     In accordance with an embodiment of the present disclosure a fluid vapor distillation apparatus having first and second separable sections may comprising; a source inlet in selective fluid communication with a fluid source via at least one valve. The apparatus may further comprise a sump downstream the source inlet. The apparatus may further comprise an evaporator having a plurality of tubes in fluid communication with the sump. The apparatus may further comprise a steam chest coupled to the evaporator and in fluid communication with a compressor. The apparatus may further comprise a condenser in fluid communication with an outlet of the compressor. The condenser may surround the plurality of tubes. The apparatus may further comprise a support plate rotatably coupled to a pivot and attached to the first section. The apparatus may further comprise a housing coupled to the second section via at least one mount. The first and second section may be held together in a first state via one or more fastener and disconnected from one another in the second state in which the first section rotatable about the pivot. 
     In some embodiments, the at least one mount may be an isolation mount. In some embodiments, the first section may include the sump, evaporator, and condenser. In some embodiments, the second section may include the steam chest and condenser. In some embodiments, the pivot may include a bias member. In some embodiments, the bias member may be in a relaxed state when the first and second section are in the first state and may be in a compressed state when the first and second section are in the second state. In some embodiments, the bias member may have a relaxed state and an energy storing state. The support plate may have a displacement path between a first position when the bias member is in the relax state and a second position when the bias member is in the energy storing state. In some embodiments, the displacement path may be a linear displacement path. In some embodiments, the displacement path may be parallel to an axis of the pivot. In some embodiments, the bias member may be a gas spring. 
     In accordance with another embodiment of the present disclosure a distillation device may comprise a source fluid input in selective fluid communication with a source fluid reservoir via a set of fluid input valves. The device may further comprise an evaporator in fluid communication with the source input and in fluid communication with a compressor. The evaporator may be configured to transform source fluid from the source fluid input into a vapor stream and a concentrate stream as the source fluid travels toward the compressor. The device may further comprise a condenser in fluid communication with the compressor configured to transform pressurized vapor from the compressor into condensate. The device may further comprise a condensate flow path and a concentrate flow path including respective first and second heat exchangers. The first and second heat exchangers may each include a heat exchanging portion of a source fluid flow path from the source fluid reservoir. The heat exchanging portion may be downstream the source fluid input valves. The device may further comprise a condensate temperature sensor configured to generate a data signal indicative of a condensate temperature. The condensate temperature sensor may be disposed on the condensate flow path downstream the first heat exchanger. The device may further comprise a controller configured to actuate the set of input source valves based on a first multimodal control loop which generates a number of provisional total open state commands for all input source valves of the set of input source valves. The controller may be configured to actuate the set of input source valves based on a slider which generates a single total open state command from the number of provisional commands. The controller may be configured to actuate the set of input source valves based on a second control loop which receives the data signal and a temperature set point and allocates the total open state command between all of the input source valves to adjust the condensate temperature to the temperature set point. 
     In some embodiments, the heat exchanging portions of the source fluid flow paths within the first and second heat exchanger may be disposed countercurrent to their respective condensate and concentrate flow paths. In some embodiments, the controller may be configured to operate in a plurality of operational states and the temperature set point may be dependent upon the state. In some embodiments, the device further comprises a destination device in fluid communication with the condensate flow path via a point of use valve. In some embodiments, the destination device may be a medical system. In some embodiments, the medical system may be configured to mix at least one dialysate solution. In some embodiments, the destination device may be a dialysis machine. In some embodiments, the destination device may be a hemodialysis machine. In some embodiments, at least one of the first multimodal controls loop and second control loop may include a PID control loop. In some embodiments, the gain of at least one of the terms of the PID control loop may be zero. In some embodiments, the number of provisional total open state commands may be adjusted by the output of at least one adjuster control loop. In some embodiments, the distillation device may further comprise a sump. The sump may be intermediate the source input and evaporator. One of the at least one adjuster control loop may be configured to produce an output based on a target sump temperature and current sump temperature measured by a sump temperature sensor configured to generate a data signal representative of a temperature of fluid in the sump. In some embodiments, one of the at least one adjuster control loop may be configured to produce an output based on a target vapor temperature and current vapor temperature measured by a vapor temperature sensor configured to generate a data signal representative of a temperature of the vapor stream. In some embodiments, the device may further comprise a concentrate level sensor configured to output a concentrate level data signal indicative of a concentrate level within the distillation device. The controller may be configured to determine a current blowdown rate from the concentrate level data signal. The first multimodal control loop may be configured to receive a target blowdown rate and the current blowdown rate data signal and as inputs. In some embodiments, at least one of the provisional total open state commands may be a first production temperature state command and at least one of the provisional total open state commands may be a second production temperature state command. In some embodiments, the device may further comprise an evaporator level sensor configured to output an evaporator data signal. The controller may be configured to generate at least one of the provisional total open state commands based at least in part on inputs of a target evaporator sensor level and the evaporator data signal. In some embodiments, the target evaporator sensor level and the evaporator data signal may be input into a derivative controller. In some embodiments, the derivative controller may be a PID controller having a D term gain at least one order of magnitude greater than the P and I term. 
     In accordance with another embodiment of the present disclosure, a water vapor distillation apparatus may comprise a sump having a source fluid input. The apparatus may further comprise an evaporator having a first side in fluid communication with the source fluid input via the sump and a second side in fluid communication with a steam chest. The evaporator may be configured to transform source fluid from the source fluid input to low pressure vapor and concentrate. There may be a non-uniform liquid level in the evaporator during operation. The apparatus may further comprise an evaporator reservoir disposed laterally to the evaporator and in fluid communication therewith via the sump. The evaporator reservoir may include a level sensor configured to monitor a level of a water column in the evaporator reservoir and generate a data signal indicative of the level of the water column. The apparatus may further comprise a compressor having a low pressure vapor inlet establishing fluid communication with the steam chest and a high pressure vapor outlet establishing fluid communication with a condenser via a condenser inlet. The apparatus may further comprise a condenser in heat transfer relationship with a plurality of exterior surfaces of the evaporator. The condenser may be configured to condense a high pressure vapor stream from the compressor by contacting the high pressure vapor stream with the plurality of exterior surfaces of the evaporator. The condenser may include a condensing portion and a condensate accumulation portion. The apparatus may further comprise a processor configured to actuate a set of input source valves to the source fluid input based in part on the data signal. 
     In some embodiments, the level sensor may include a displaceable member which is displacable over a displacement range which is smaller than the height of the evaporator reservoir. In some embodiments, the level sensor may include a displaceable member which is displaceable over a displacement range extending from a first end portion of the evaporator reservoir to at least a midpoint of the evaporator reservoir. The displacement range may be a distance less than 70% of the height of the evaporator reservoir. In some embodiments, the first end may be an end of the evaporator reservoir most distal to the sump. In some embodiments, the evaporator reservoir may be in communication with the steam chest via a venting pathway extending from a first end potion of the evaporator reservoir. In some embodiments, the venting pathway may extend from the evaporator reservoir to a concentrate reservoir attached and disposed laterally to the steam chest. In some embodiments, the height of the evaporator reservoir may be greater than the height of the evaporator. In some embodiments, the processor may be configured to determine a total open state time for the set of input source valves based in part on a target water column level and a current water column level determined via analysis of the data signal. In some embodiments, the processor may be configured to determine the total open state time for the set of input source valves based in part on the output of a PID controller which receives the target water column level and the current water column level as inputs. In some embodiments, a gain for at least one of a P term, I term, and D term of the PID controller may be zero. In some embodiments, a gain for a D term of the PID controller may be at least one order of magnitude greater than a gain for a P term and an I term of the PID controller. In some embodiments, a gain for a D term of the PID controller may be more than two orders of magnitude greater than a gain for a P term and an I term of the PID controller. In some embodiments, the processor may be configured to determine the total open state time based in part on a target blowdown rate and a current blowdown rate as indicated from a blowdown level data signal produced by a blowdown level sensor in a blowdown reservoir attached to the steam chest. In some embodiments, the processor may be configured to determine a total open state command in part based on the output of at least one adjuster control loop. In some embodiments, one of the at least one adjuster control loop may be configured to produce an output based on a target sump temperature and current sump temperature measured by a sump temperature sensor configured to generate a data signal representative of a temperature of fluid in the sump. In some embodiments, one of the at least one adjuster control loop may be configured to produce an output based on a target vapor temperature and current vapor temperature measured by a vapor temperature sensor configured to generate a data signal representative of a temperature of the vapor stream. In some embodiments, the controller may be configured to alter a total open state command for the set of input source valves in response to a change in the water column level indicated by the data signal. In some embodiments, the controller may be configured to alter a total open state command for the set of input source valves in proportion to a rate of change in the water column as indicated by the data signal. 
     In accordance with another embodiment of the present disclosure a method of controlling flow of a source fluid into a distillation device may comprise establishing a non-uniform liquid level in an evaporator of the distillation device. The method may further comprise sensing, with a first level sensor, a liquid column level in an evaporator reservoir in fluid communication with the evaporator and disposed at even height with the evaporator. The method may further comprise sensing, with a second level sensor, a concentrate level in a concentrate reservoir in fluid communication with the evaporator. The method may further comprise generating, with a processor, a source inlet valve open time command based at least in part on the concentrate level and a target concentrate accumulation rate as well as a delta between the liquid column level and a target liquid column level. The method may further comprise commanding a number of source inlet valves to open based on the source inlet valve open time command. 
     In some embodiments, sensing the liquid column level may comprise displacing a displaceable member over a displacement range which is smaller than a height of the evaporator reservoir. In some embodiments, sensing the liquid column level may comprise displacing a displaceable member over a displacement range extending from a first end portion of the evaporator reservoir to at least a midpoint of the evaporator reservoir. The displacement range may be a distance less than 70% of a height of the evaporator reservoir. In some embodiments, the first end may be an end of the evaporator reservoir most distal to a sump of the distillation device. In some embodiments, the method may further comprise venting the evaporator reservoir, via a venting pathway, into a steam chest of the distillation device disposed superiorly to the evaporator. In some embodiments, the venting pathway may extend from the evaporator reservoir to a concentrate reservoir attached and disposed laterally to the steam chest. In some embodiments, generating the source inlet valve open time command may comprise inputting the delta to a PID controller. In some embodiments, a gain for at least one of a P term, I term, and D term of the PID controller may be zero. In some embodiments, a gain for a D term of the PID controller may be at least one order of magnitude greater than a gain for a P term and an I term of the PID controller. In some embodiments, a gain for a D term of the PID controller may be more than two orders of magnitude greater than a gain for a P term and an I term of the PID controller. In some embodiments, generating the source inlet valve open time command may comprise determining a current concentrate accumulation rate from the concentrate level and calculating a delta between a target concentrate rate and a current concentrate accumulation rate. In some embodiments, generating the source inlet valve open time command may comprise generating an output of at least one adjuster control loop. In some embodiments, the method may further comprise sensing a current sump temperature with a sump temperature sensor and generating the output of at least one adjuster control loop comprises producing the output based on a target sump temperature and current sump temperature. In some embodiments, the method may further comprise sensing a temperature of a vapor stream in the distillation device with a vapor temperature sensor. In some embodiments, generating the output of at least one adjuster controller may comprise producing the output based on a target vapor temperature and current vapor temperature. In some embodiments, the method may further comprise altering the source inlet valve open time command in response to a change in the liquid column level. In some embodiments, the method may further comprise altering the source inlet valve open time command in proportion to a rate of change in the liquid column level. 
     In accordance with another embodiment of the present disclosure a fluid vapor distillation apparatus may comprise at least one controller. The apparatus may further comprise a source inlet in selective fluid communication with a fluid source via at least one valve. The apparatus may further comprise an evaporator in fluid communication with the source inlet. The apparatus may further comprise a steam chest coupled to the evaporator and in fluid communication with a compressor. An exterior surface of the steam chest may form a portion of an inlet flow path to the compressor and a portion of an outlet flow path to an outlet of the compressor. The apparatus may further comprise a concentrate reservoir. The concentrate reservoir may be attached to the steam chest via an inflow path and disposed laterally to the steam chest such that at least a portion of the concentrate reservoir is at even height with the steam chest. The apparatus may further comprise a condenser in fluid communication with the outlet of the compressor via a straight line flow path. The straight line flow path may include a condenser inlet fixedly attached to a sheet having a first face defining a portion of the steam chest and an opposing face defining a portion of the condenser. The apparatus may further comprise a product process stream reservoir coupled to the condenser by a product reservoir inlet, and disposed laterally to the condenser such that at least a portion of the product process stream reservoir is at even height with the condenser. 
     In some embodiments, the inflow path may include an obstruction. In some embodiments, the obstruction may include a wall which extends into the concentrate reservoir at an angle substantially perpendicular to the inflow path. In some embodiments, the obstruction may extend into the concentrate reservoir and divide the concentrate reservoir into a first portion and a second, sheltered portion. In some embodiments, the obstruction may include at least one vent port. In some embodiments, the product reservoir inlet may be adjacent a product accumulation surface of the condenser. In some embodiments, the compressor may be driven by a motor partially disposed within a receiving well recessed into the side of the steam chest. In some embodiments, the compressor may include an impeller which rotates about an axis which extends lateral to the steam chest and is parallel with respect to a longitudinal axis of the steam chest. 
     In accordance with another embodiment of the present disclosure, a distillation device may comprise a source fluid input in selective fluid communication with a source via a set of fluid input valves. The device may further comprise an evaporator in fluid communication with the source input and in fluid communication with a compressor having an impeller operatively coupled to an impeller motor. The evaporator may be configured to transform source fluid from the source fluid input into a vapor stream and a concentrate stream as the source fluid travels toward the compressor. The device may further comprise a condenser in heat transfer relationship with a plurality of exterior surfaces of the evaporator. The condenser may be configured to condense a high pressure vapor stream from the compressor by contacting the high pressure vapor stream with the plurality of exterior surfaces of the evaporator. The device may further comprise a concentrate level sensor configured to sense a current level of concentrate in a concentrate reservoir having an inflow path disposed above the evaporator and having a long axis which extends alongside the evaporator. The device may further comprise at least one controller configured to govern a rotation speed of the impeller in a low temperature distillate production state and a high temperature distillate production state by periodically generating an impeller motor command based on a low temperature distillate production nominal speed command in the low temperature distillate production state and a high temperature distillate production nominal speed command in the high temperature distillate production state. The low temperature distillate production nominal speed command may be a faster motor speed command than the high temperature distillate production nominal speed command. 
     In some embodiments, an adjustment may be made to the impeller motor command based on a data signal from the concentrate level sensor indicative of a level of concentrate in the concentrate reservoir. In some embodiments, the adjustment may be limited by an impeller motor command increment limit. In some embodiments, the impeller motor command increment limit may ≤10 rpm/sec. In some embodiments, the impeller motor command increment limit may be ≤5 rpm/sec. In some embodiments, the impeller motor command may be decremented when the data signal indicates that the level of concentrate in the concentrate reservoir is greater than a first threshold. In some embodiments, the first threshold may be defined as the concentrate level at which the concentrate reservoir is at a predefined fill value between 65-80% full. In some embodiments, the impeller motor command may be held to no greater than a previously commanded impeller motor command value when the data signal indicates that the level of concentrate in the concentrate reservoir is greater than a first threshold. In some embodiments, the first threshold may be defined as the concentrate level at which the concentrate reservoir is at a predefined fill value between 65-80% full. In some embodiments, the impeller motor command may be incremented when the data signal indicates that the level of concentrate in the concentrate reservoir is greater than a second threshold. In some embodiments, the high temperature distillate production nominal speed command may a calibrated value defined during manufacture. In some embodiments, the high temperature distillate production nominal speed command may be less than 80% of the low temperature distillate production nominal speed command and more than 45% of the low temperature distillate production nominal speed command. In some embodiments, the low temperature distillate production nominal speed command may be 4500 rpm. In some embodiments, the low temperature distillate production nominal speed command may be 5000 rpm. 
     In accordance with another embodiment of the present disclosure a method of controlling a compressor of a distillation device may comprise opening at least one fluid input valve to deliver source fluid into a sump of the distillation device from a fluid source. The method may further comprise transforming source fluid into a concentrate stream and vapor stream in an evaporator. The method may further comprise determining, with a processor, a state specific compressor speed command. The compressor speed command may be based on a low temperature distillate production nominal speed command in a low temperature distillate production state and based on a high temperature distillate production nominal speed command in a high temperature distillate production state. The low temperature distillate production nominal speed command may be a faster motor speed command than the high temperature distillate production nominal speed command. The method may further comprise generating, with the processor, a final command speed based on the compressor speed command. The method may further comprise commanding, with the processor, rotation of an impeller of the compressor at the final command speed. The method may further comprise compressing the vapor stream via the compressor. The method may further comprise condensing the vapor stream into a condensate and transferring heat to the evaporator as the vapor stream condenses. 
     In some embodiments, the method may further comprise sensing, with a level sensor, a level of concentrate in a concentrate reservoir in fluid communication with the evaporator. In some embodiments, generating the final command speed may comprise determining an adjustment to the compressor speed command based on the level of concentrate. In some embodiments, determining the adjustment may comprise decrementing the compressor speed command when the level of concentrate is greater than a first threshold. In some embodiments, the first threshold may be defined as the concentrate level at which the concentrate reservoir is at a predefined fill value between 65-80% full. In some embodiments, determining the adjustment may comprise holding the final command speed to no greater than a previously commanded final command speed when the level of concentrate is greater than the first threshold. In some embodiments, determining the adjustment may comprise decrementing the compressor speed command when the level of concentrate is greater than a second threshold. In some embodiments, generating the final command speed may comprise determining an adjustment to the compressor speed command. In some embodiments, the adjustment may bwe limited by an increment limit. In some embodiments, the increment limit may be ≤10 rpm/sec. In some embodiments, the increment limit may be ≤5 rpm/sec. In some embodiments, the high temperature distillate production nominal speed command may be a calibrated value defined during manufacture. In some embodiments, the high temperature distillate production nominal speed command may be less than 80% of the low temperature distillate production nominal speed command and more than 70% of the low temperature distillate production nominal speed command. In some embodiments, the low temperature distillate production nominal speed command may be 4500 rpm. 
     In accordance with another embodiment of the present disclosure a distillation device may comprise a sump in selective fluid communication with a source via a set of fluid input valves. The device may further comprise at least one heating element and a least one sump temperature sensor in the sump. The sump temperature sensor may be configured to generate a sump temperature data signal. The device may further comprise an evaporator having a first side in fluid communication with the sump and a second side in fluid communication with a compressor having an impeller operatively coupled to an impeller motor. The evaporator may be configured to transform source fluid from the source fluid input to a vapor stream and concentrate. The device may further comprise a condenser in heat transfer relationship with a plurality of exterior surfaces of the evaporator. The condenser may be configured to condense a high pressure vapor stream from the compressor by contacting the high pressure vapor stream with the plurality of exterior surfaces of the evaporator. The device may further comprise a concentrate level sensor configured to sense a current level of concentrate in a concentrate reservoir having an inflow path disposed above the evaporator and having a long axis which extends alongside the evaporator. The device may further comprise a vapor temperature sensor disposed in a flow path of the vapor stream and configured to generate a vapor temperature data signal. The device may further comprise at least one controller configured to determine a duty cycle command for the at least one heating element. The duty cycle command may be based at least in part upon a target temperature of the vapor stream, the vapor temperature data signal, the sump temperature data signal and a total source open command for the set of fluid input valves. 
     In some embodiments, the target temperature of the vapor stream may be 108° C. In some embodiments, the controller may be configured to adjust the duty cycle command to conform with at least one limit. In some embodiments, the limit may be a maximum power consumption limit. In some embodiments, the controller may be configured to adjust the duty cycle command based at least in part on a power consumption of the compressor. In some embodiments, the controller may be configured to calculate a limit for the duty cycle command by determining a power consumption of the compressor and subtracting the power consumption of the compressor from a predefined power value. In some embodiments, the predefined power value may be defined as a maximum total power for the system. In some embodiments, the duty cycle command may be limited to a predefined maximum duty cycle. In some embodiments, the predefined maximum duty cycle may not greater than a 90% duty cycle. In some embodiments, the target temperature of the vapor stream may be state specific. In some embodiments, the target temperature in a low temperature distillate production state may be higher than the target temperature in a high temperature distillate production state. In some embodiments, the target temperature of the vapor stream in a first state may be 108° C. and the target temperature of the vapor stream in a second state may be 104° C. In some embodiments, the target temperature in a first state may be 4° C. hotter than the target temperature in a second state. In some embodiments, the target temperature in a first state may be at least 95% of the target temperature in a second state, but less than the target temperature in the second state. In some embodiments, the controller may be configured to determine a feed forward term used to determine the duty cycle command based on the total source open command for the set of fluid input valves and at least one thermodynamic characteristic of the source fluid. In some embodiments, the thermodynamic characteristic may be a specific heat of the source fluid. In some embodiments, the target temperature of the vapor stream may be 111-112° C. 
     In accordance with an embodiment of the present disclosure a method of heating fluid in a distillation device may comprise opening at least one fluid input valve to deliver source fluid into a sump of the distillation device from a fluid source. The method may further comprise sensing a sump temperature of the source fluid in the sump via a temperature sensor. The method may further comprise sensing a vapor temperature of a vapor stream generated from the source fluid. The method may further comprise comparing, with a processor, the vapor temperature to a target vapor temperature. The method may further comprise inputting a delta between the vapor temperature and the target vapor temperature to a first controller and generating a first controller output. The method may further comprise providing an input based at least in part upon the first controller output and sump temperature to a second controller and generating a second controller output. The method may further comprise altering the second controller output into an altered second controller output based on a total open state time of the at least one fluid input valve. The method may further comprise commanding a duty cycle for a heating element in the sump based on the altered second controller output and at least one limit. 
     In some embodiments, the target vapor temperature may be in a range of 108° C.−112° C. In some embodiments, the at least one limit may include a maximum power consumption limit. In some embodiments, the at least one limit may include a limit based at least in part on a power consumption of a compressor in the distillation device. In some embodiments, the method may further comprise calculating a limit of the at least one limit by determining a power consumption of the compressor and subtracting the power consumption of the compressor from a predefined power value. In some embodiments, the predefined power value may be defined as a maximum total power for the system. In some embodiments, the at least one limit may include a predefined maximum duty cycle limit. In some embodiments, the predefined maximum duty cycle may not be greater than a 90% duty cycle. In some embodiments, the target vapor temperature of the vapor stream may be state specific. In some embodiments, target temperature in a low temperature distillate production state may be higher than the target temperature in a high temperature distillate production state. In some embodiments, the target temperature in a first state may be 4° C. hotter than the target temperature in a second state. In some embodiments, the target temperature in a first state may be at least 95% of the target temperature in a second state, but less than the target temperature in the second state. In some embodiments, the second controller output into an altered second controller output may comprise determining a feed forward term based on the total source open command of the at least one fluid input valve and at least one thermodynamic characteristic of the source fluid. In some embodiments, the thermodynamic characteristic may be a specific heat of the source fluid. 
     In accordance with an embodiment of the present disclosure, a water distillation device may comprise a sump in selective fluid communication with a fluid source via a set of source proportioning valves. The device may further comprise an evaporator in fluid communication with the sump. The device may further comprise a steam chest coupled to the evaporator and in fluid communication with a compressor. The device may further comprise a concentrate reservoir attached to the steam chest via an inflow path and having a concentrate level sensor configured to generate a concentrate level data signal indicative of fill percentage of the concentrate reservoir. The concentrate reservoir may be coupled to a concentrate flow path. The device may further comprise a condenser coupled to an outlet of the compressor and in fluid communication with a condensate flow path. The device may further comprise a first and second heat exchanger including a heat exchanging portion of a source fluid flow path from the fluid source. The heat exchanging portion of the first heat exchanger may be in heat exchange relationship with the condensate flow path and the heat exchanging portion of the second heat exchanger in heat exchange relationship the concentrate flow path. The heat exchanging portions of the source fluid flow path may be downstream the source proportioning valves. The device may further comprise at least one distillate sensor in communication with the condensate flow path at a point downstream the first heat exchanger. The device may further comprise a controller configured to determine a total open state time of the source proportioning valves based at least in part on the concentrate data signal and a target concentrate rate. The controller may be configured to allocate percentages of the total open state command to each of the source proportioning valves based on at least one distillate sensor data signal from the at least one distillate sensor. 
     In some embodiments, the condenser may include a condensing portion and a condensate accumulation portion. In some embodiments, the condenser may be in fluid communication with a condensate reservoir including a condensate level sensor configured to monitor a level of condensate in the condensate reservoir and generate a condensate data signal indicative of a fill percentage of the condensate accumulation portion. The condensate reservoir may be intermediate the condenser and concentrate flow path. In some embodiments, the controller may be configured to maintain a target fill percentage of the condensate accumulation portion based on the output of a PID control loop which uses as inputs the target fill percentage and a delta between the target fill percentage and the current fill percentage as indicated by the condensate data signal. In some embodiments, the target fill percentage may be equivalent to at least one liter and less than 2 liters. In some embodiments, the condenser may be in fluid communication with a condensate reservoir including a condensate level sensor configured to monitor a level of condensate in the condensate reservoir and generate a condensate data signal indicative of a fill percentage of the condensate reservoir. The condensate reservoir intermediate the condenser and concentrate flow path. In some embodiments, the at least one distillate sensor may include a temperature sensor. In some embodiments, the at least one distillate sensor data signal may be a temperature data signal indicative of a current condensate temperature after passing through the heat exchanger. In some embodiments, the controller may be configured to allocate the percentages of the total open state command to each of the source proportioning valves based on a control loop which uses a target condensate temperature and the current condensate temperature as inputs. In some embodiments, the target temperature may be at least 35° C., but no greater than 40° C. In some embodiments, the target temperature may be at least 20° C., but no greater than 30° C. In some embodiments, the target temperature may be at least 90° C., but less than 100° C. In some embodiments, the distillation device may further comprise a fluid source temperature sensor which generates a data signal indicative of the temperature of the source fluid and the target temperature may be determined by the controller based in part on the source temperature data signal. In some embodiments, the target temperature may be limited to a range of 20-25° C. 
     In accordance with another embodiment of the present disclosure, a distillation system may comprise a distillation device in selective fluid communication with a fluid source via a set of source proportioning valves. The distillation device may have a concentrate output coupled to a concentrate flow path and may have a condensate output coupled to a condensate flow path. The system may further comprise a first and second heat exchanger each including a heat exchanging portion of a source fluid flow path from the fluid source downstream of the source proportioning valves. The heat exchanging portion of the first heat exchanger may be in heat exchange relationship with the condensate flow path and the heat exchanging portion of the second heat exchanger may be in heat exchange relationship the concentrate flow path. There may be a dedicated source proportioning valve for each heat exchanger. The system may further comprise a condensate sensor assembly in communication with the condensate flow path at a point downstream of the first heat exchanger. The system may further comprise a controller configured to, in a first operating mode, split a commanded flow of source fluid from the fluid source between the source proportioning valves based on a delta between a first target temperature and a current concentrate temperature received by the controller from the condensate sensor assembly. In a second mode, the controller may be configured to allocate the entire commanded flow to the source proportioning valve dedicated to the second heat exchanger and open the source proportioning valve dedicated to the first heat exchanger at a duty cycle which may be no greater than a predefined limit. 
     In some embodiments, the predefined limit may be 5%. In some embodiments, the predefined limit may be 2%. In some embodiments, the predefined limit may be 0%. In some embodiments, the condensate sensor assembly may include redundant temperature sensors. In some embodiments, the first and second heat exchanger may be helical and formed by winding the heat exchanger around the exterior of the distillation device. In some embodiments, the first operating mode may be a low temperature distillate production state and the second operating mode may be a hot temperature distillate production state. In some embodiments, the first target temperature may be at least 35° C., but no greater than 40° C. In some embodiments, the first target temperature may be at least 20° C., but less than 25° C. In some embodiments, the controller may be configured to open the source proportioning valve dedicated to the first heat exchanger based upon a second target temperature and a delta between the second target temperature and the current concentrate temperature in the second operating mode. In some embodiments, the second target temperature may be at least 65° C. hotter than the first target temperature. In some embodiments, the second target temperature may be at least 50° C. hotter than the first target temperature. In some embodiments, the second target temperature may be greater than 95° C. and less than 100° C. in some embodiments, the second target temperature may be 96° C. In some embodiments, the second target temperature may be at least double the first target temperature. In some embodiments, the second target temperature may be at least 2.5 times the first target temperature. In some embodiments, the second target temperature may be at least 3.5 times the first target temperature. In some embodiments, the system may further comprise an evaporator level sensor disposed in an evaporator reservoir in fluid communication with an evaporator of the distillation device. The controller may be configured to, in the second operational state, determine the total flow command at least in part based on an evaporator level data signal indicative of a level of a water column in the evaporator reservoir. In some embodiments, the first target temperature may be at least 20° C., but no greater than 30° C. In some embodiments, the first target temperature is 25° C. 
     In accordance with another embodiment of the present disclosure a method of controlling and allocating a flow of source fluid into a distillation device may comprise sensing, with a concentrate level sensor, a concentrate level in a concentrate reservoir in fluid communication with an evaporator of the distillation device. The method may further comprise sensing a temperature of product fluid produced by the distillation device at a point downstream of a product heat exchanger which places product fluid in heat exchange relationship with incoming source fluid. The method may further comprise determining, with a processor, a concentrate accumulation rate based on the concentrate level. The method may further comprise calculating, with a processor, a first delta between the concentrate accumulation rate and a first target concentrate accumulation rate and a second delta between the concentrate accumulation rate and a second target concentrate accumulation rate. The method may further comprise determining, with a processor, a first provisional open state command and second provisional open state command for a first and second source inflow proportioning valve. The first provisional open state command may be based on the first delta and the second provisional open state command based on the second delta. The method may further comprise computing, with a processor, a final open state command from the provisional open state time commands. The method may further comprise dividing, with the processor in a first operational state, the final open state command between the first source inflow proportioning valve and second inflow proportioning valve. The first source inflow proportioning valve may lead to a product heat exchanger. The dividing may be based on a delta between a target product temperature and the temperature of the product fluid. The method may further comprise allocating, with the processor in a second operational state, an entirety of the final open state command to the second source inflow proportioning valve. The method may further comprise opening, via a command from the processor, the first source inflow proportioning valve at a duty cycle which is no greater than a predefined limit with the processor in the second operational state. 
     In some embodiments, the first target accumulation rate may be greater than the second target accumulation rate. In some embodiments, computing the final open state command may comprise inputting the first provisional open state command and second provisional open state command into a slider. In some embodiments, computing the final open state command may comprise generating a hybrid command from the first and second provisional source open state commands. In some embodiments, computing the final open state command may comprise determining a first state fraction and a second state fraction and multiplying the first provisional open state command by the first state fraction and multiplying the second provisional open state command by the second state fraction. In some embodiments, computing the final open state command comprises adjusting the command from predominately the first provisional open state command to predominately the second provisional open state command during a transition between the first operational state and the second operational state. In some embodiments, computing the final open state command may comprise adjusting the command from purely the first provisional open state command to purely the second provisional open state command during a transition between the first operational state and the second operational state. In some embodiments, the second operational state may be a hot distillate production state. In some embodiments, the dividing may comprise determining an open state command for the first source inflow proportioning valve based on a delta between a target product temperature and the temperature of the product fluid and determining an open state command for the second source inflow proportioning valve by subtracting the open state command from the first source inflow proportioning valve from the final open state command. In some embodiments, the predefined limit may be a limit of less than 5%. In some embodiments, the predefined limit may be a limit of less than 2%. In some embodiments, the predefined limit may be 0%. In some embodiments, the determining the second provisional open state command further may comprise sensing a level of a liquid column, with an evaporator level sensor, in an evaporator reservoir in fluid communication with the evaporator. The second provisional open state command may be based in part on a delta between the level of the liquid column and a target level of the liquid column. In some embodiments, the second provisional open state command may be based on a rate of change in the delta between the level of the liquid column and the target level of the liquid column. 
     In accordance with an embodiment of the present disclosure a medical system may comprise at least one concentrate fluid. The system may further comprise a distillation device having an evaporator, a condenser, and a purified product water heat exchanger having a source fluid flow path and a purified product water flow path in heat exchange relation with one another. The system may further comprise a medical treatment device the medical treatment device may include a treatment fluid preparation circuit in selective fluid communication, via a point of use valve, with the purified product water flow path. The medical treatment device may include a treatment device processor configured to command mixing of the at least one concentrate and purified water to generate a prescribed treatment fluid with the treatment fluid preparation circuit. The system may further comprise a communications link between the treatment device processor of the medical treatment device and a distillation device processor of the distillation device. The medical treatment device processor may be configured to transmit mode commands to the distillation device processor. The system may further comprise a sensor assembly in communication with the purified product water flow path. The system may further comprise a source valve intermediate a fluid source and the source fluid flow path. The distillation device processor may be configured to actuate the source valve based at least in part on the mode commands and data from the sensor assembly. 
     In some embodiments, the sensor assembly may include at least one temperature sensor and at least one conductivity sensor. In some embodiments, the distillation device processor may be configured to actuate the source valve based at least in part on the mode commands and temperature data from the sensor assembly. In some embodiments, the distillation device processor may be configured to actuate the source valve based at least in part on the mode commands and data from the sensor assembly and a target set point for purified water. In some embodiments, the target set point may be a temperature set point. In some embodiments, the target set point may be determined by the distillation device processor based on the mode commands. In some embodiments, the target set point may be based off a first mode command of the mode commands which may be in the range of 20-35° and a target set point based off a second mode command of the mode commands which may be greater than 90° C. 
     In some embodiments, the medical treatment device may be a dialysis machine. In some embodiments, the medical treatment device may be a hemodialysis device. In some embodiments, the treatment fluid may be a dialysis fluid. In some embodiments, the condenser may include a condensing section and a product storage section. The product storage portion may have a volume of at least one liter. In some embodiments, the distillation device processor may be further configured to govern operation of a compressor motor of the distillation device based at least in part on the mode commands. In some embodiments, the distillation device processor may be further configured to govern operation of a concentrate outlet valve of the distillation device based at least in part on the mode commands. 
     In accordance with an embodiment of the present disclosure a medical system may comprise a distillation device having and evaporator, a source inlet flow path to a source input in fluid communication with the evaporator, a condenser, a purified product water output flow path in fluid communication with the condenser. The system may further comprise a first and second filter in the source inlet flow path. The system may further comprise a plurality of pressure sensors including a first pressure sensor upstream the first filter and a second pressure sensor downstream the second filter. The system may further comprise a medical treatment device the medical treatment device including a treatment fluid preparation circuit in selective fluid communication, via a point of use valve, with the purified product water output flow path. The system may further comprise a communications link between a treatment device processor of the medical treatment device and a distillation device processor of the distillation device. The distillation device processor may be configured to conduct a first filter replacement check based on data from the plurality of pressure sensors and the treatment device processor may be configured to conduct a second filter replacement check and command the distillation device processor into a filter replacement mode, via the communications link, when either of the first or second filter replacement check fails. 
     In some embodiments, the second filter replacement check may include a check of a number of days elapsed since installation of the first and second filter against a limit. In some embodiments, the medical treatment device may include a graphical user interface. In some embodiments, the second filter replacement check may include a check of a user input on the graphical user interface against at least one predefined criteria. In some embodiments, the system may further comprise a sampling port disposed intermediate the first and second filter and the predefined criteria may be a water chemistry test strip criteria. In some embodiments, the water chemistry test strip criteria may be a chlorination level criterion. In some embodiments, the distillation device processor may be configured to command a flush of the first and second filter prior to at least one of the first filter replacement check or second filter replacement check. In some embodiments, the distillation device processor may be configured to conduct the first filter replacement check based on a filter output pressure data signal from the second pressure sensor. In some embodiments, the distillation device processor may be configured to indicate a failure of the first filter replacement check when the filter output pressure is below a threshold. In some embodiments, the distillation device processor may be configured to conduct the first filter replacement check based on a delta between a pressure upstream of the first and second filter as indicated by the first pressure sensor and a pressure downstream of the first and second filter as indicated by the second pressure sensor. In some embodiments, the distillation device processor may be configured to indicate a failure of the first filter replacement check when the delta is less than a threshold. 
     In accordance with another embodiment of the present disclosure A medical system may comprise a distillation device having a source water input and a fluid output flow path. The system may further comprise a medical treatment device including a plurality of fluid flow paths, a plurality of valves, at least one fluid pump, and a fluid inlet in selective fluid communication, via a point of use valve, with the fluid output flow path. The system may further comprise a communications link between the medical treatment device and distillation device. The system may further comprise a sensor assembly in communication with the fluid output flow path. The system may further comprise a treatment device processor configured to actuate the plurality of valves and the at least one fluid pump to pump a high temperature fluid through the plurality of fluid flow paths. The system may further comprise a distillation device processor configured to govern operation of the distillation device based on at least one data signal from the sensor assembly and a mode command sent over the communications link from a treatment device processor of the medical treatment device to produce and output the high temperature fluid to the fluid output flow path during a first period in which the point of use valve is commanded open by the distillation device processor and a second period in which the point of use valve is commanded closed by the distillation device processor and a valve to a flow path in fluid communication the fluid output flow path is commanded open. 
     In some embodiments, the source water input may be in fluid communication with a non-temperature controlled fluid source. In some embodiments, the medical treatment device may be a dialysis machine. In some embodiments, the medical treatment device may be a hemodialysis machine. In some embodiments, the plurality of fluid flow paths may include a first flow path and second flow path separated from one another by a semi-permeable membrane. In some embodiments, the plurality of fluid flow paths may be included in at least a blood pumping cassette and a dialysate pumping cassette. In some embodiments, the medical treatment device may include a fluid reservoir and the treatment device processor may be configured to send a signal to the distillation device processor to end the first period based on an amount high temperature fluid contained in the fluid reservoir. In some embodiments, the medical treatment device may include a heater. In some embodiments, the at least one data signal may include at least one temperature data signal. In some embodiments, the distillation device may include a compressor and the distillation device processor may be configured to govern operation of the compressor via a compressor speed command determined based in part on of the mode command. In some embodiments, the distillation device processor may be configured to govern operation of the distillation device based on the least one data signal and another mode command sent over the communications link from a treatment device processor to produce and output a medical treatment fluid component to the fluid output flow path. In some embodiments, the plurality of flow paths may comprise a medical treatment fluid mixing circuit and the treatment device processor may be configured to command operation of the at least one pump and plurality of valves to mix the medical treatment fluid component with at least one concentrate in fluid communication with the plurality of flow paths in accordance with a predetermined prescription. 
     In accordance with another embodiment of the present disclosure a water distillation apparatus may comprise a sump having a source fluid input. The apparatus may further comprise an evaporator in fluid communication with the source fluid input via the sump. The apparatus may further comprise a condenser including a condensing portion and a condensate accumulation portion. The apparatus may further comprise an auxiliary condensate reservoir in fluid communication with the condensate accumulation portion and attached to the condenser adjacent an accumulation surface of the accumulation portion. The auxiliary condensate reservoir may be fluidly coupled to a point of use device via a condensate flow path. The apparatus may further comprise a condensate level sensor configured to monitor a level of condensate in the accumulation portion and generate a data signal indicative of a fill level of the accumulation portion. The apparatus may further comprise a controller configured to govern operation of a diverting valve included in the condensate flow path based at least in part on the data signal and a target condensate level. The controller may further be configured to command the diverting valve to a closed state based on a derivative of the data signal. 
     In some embodiments, the accumulation portion may have a volume less than ten liters. In some embodiments, the condensate level sensor may include a float assembly attached to a pivot. The float assembly may be displaceable about the pivot over a displacement range inclusive of points at even height with a range of fill levels in the accumulation portion. In some embodiments, the condensate level sensor may include a float displaceable along a displacement axis over a displacement range inclusive of points at even height with a range of fill levels in the accumulation portion. In some embodiments, the condensate level sensor may include a float displaceable along a displacement path through a displacement range inclusive of points at even height with a range of fill levels in the accumulation portion. In some embodiments, the controller may be configured to command the diverting valve to a closed state based on the derivative of the data signal exceeding a predefined minimum threshold. In some embodiments, the controller may be configured to command the diverting valve to a closed state based on the derivative of the data signal having a negative value greater than a predefined magnitude. In some embodiments, the controller may be configured to command the diverting valve to a closed state based on the derivative of the data signal indicating the point of use device is consuming condensate from the distillation apparatus. In some embodiments, the apparatus may further comprise a heat exchanger including a portion of the condensate flow path and a portion of a source flow path coupled to a water source and the source fluid input. In some embodiments, the apparatus may further comprise a sensing assembly in communication with the condensate flow path downstream the portion of the condensate flow path included in the heat exchanger. The sensing assembly may be configured to output a temperature data signal. In some embodiments, the controller may be configured to command the diverting valve to a closed state based on a derivative of the temperature data signal. In some embodiments, the controller may be configured to command the diverting valve to a closed state based on a derivative of the temperatures data signal exceeding a predefined maximum threshold. In some embodiments, the controller may be configured to command the diverting valve to a closed state based on a derivative of the temperature data signal having a positive value greater than a predefined magnitude. In some embodiments, the controller may be configured to command the diverting valve to a closed state based on a derivative of the temperature data signal indicating the point of use device is consuming condensate from the distillation apparatus. In some embodiments, the controller may be configured to command the diverting valve to a closed state based on an integral of a derivative of the temperature data signal. In some embodiments, the controller may be configured to command the diverting valve to a closed state based on an integral of a derivative of the temperatures data signal exceeding a predefined maximum threshold. In some embodiments, the controller may be configured to command the diverting valve to a closed state based on an integral of a derivative of the temperature data signal having a positive value greater than a predefined magnitude. In some embodiments, the controller may be configured to command the diverting valve to a closed state based on an integral of a derivative of the temperature data signal indicating the point of use device is consuming condensate from the distillation apparatus. 
     In accordance with another embodiment of the present disclosure, a water distillation apparatus may comprise a sump having a source fluid input. The apparatus may further comprise an evaporator in fluid communication with the source fluid input via the sump. The apparatus may further comprise a condenser fluidly coupled to a point of use device via a condensate flow path. The apparatus may further comprise a condensate level sensor configured to generate a data signal indicative of a fill level of the condenser. The apparatus may further comprise a heat exchanger including a portion of the condensate flow path and a portion of a source flow path coupled to a water source and the source fluid input. The apparatus may further comprise a sensing assembly in communication with the condensate flow path downstream the portion of the condensate flow path included in the heat exchanger. The sensing assembly may be configured to output a sensor assembly data signal. The apparatus may further comprise a controller configured to govern operation of a diverting valve included in the condensate flow path based at least in part on the data signal and a target condensate level. The controller may further be configured to command the diverting valve to a closed state based on a derivative of the sensor assembly data signal. 
     In some embodiments, the controller may be configured to command the diverting valve to a closed state based on a derivative of the sensor assembly data signal. In some embodiments, the controller may be configured to command the diverting valve to a closed state based on a derivative of the sensor assembly data signal exceeding a predefined maximum threshold. In some embodiments, the controller may be configured to command the diverting valve to a closed state based on a derivative of the sensor assembly data signal having a positive value greater than a predefined magnitude. In some embodiments, the controller may be configured to command the diverting valve to a closed state based on a derivative of the sensor assembly data signal indicating the point of use device is consuming condensate from the distillation apparatus. In some embodiments, the controller may be configured to command the diverting valve to a closed state based on an integral calculated using the sensor assembly data signal. In some embodiments, the integral may be calculated from a derivative of the sensor assembly data signal. In some embodiments, the controller may be configured to command the diverting valve to a closed state based on the integral exceeding a predefined maximum threshold. In some embodiments, the controller may be configured to command the diverting valve to a closed state based on the integral having a positive value greater than a predefined magnitude. In some embodiments, the controller may be configured to command the diverting valve to a closed state based on the integral indicating the point of use device is consuming condensate from the distillation apparatus. In some embodiments, the sensor assembly data signal may be a temperature data signal. 
     In accordance with another embodiment of the present disclosure a water purification system for outputting a process stream at a controlled temperature may comprise a distillation device in selective fluid communication with a fluid source via a set of source proportioning valves. The distillation device may have a concentrate output and distillate output respectively coupled to a concentrate flow path and a distillate flow path. The system may further comprise a first heat exchanger including a portion of the distillate flow path and a second heat exchanger including a portion of the concentrate flow path. A flow path from the fluid source may be in heat exchange relationship with each of the first and second heat exchanger. The system may further comprise a distillate sensor assembly in communication with the distillate flow path downstream of the portion of the distillate flow path included in the first heat exchanger and configured to generate a distillate temperature measurement. The system may further comprise a controller configured to actuate the set of input source valves based on a first multimodal control loop which generates a number of provisional total open state commands for the source proportioning valves, a slider which generates a single total open state command from the number of provisional commands, a second control loop which receives the distillate temperature measurement, a first target temperature, and a second target temperature, and allocates the single total open state command between all of the input source valves to adjust the condensate temperature to a temperature set point. 
     In some embodiments, the system may further comprise an electronics box in thermal communication with the source fluid flow path. In some embodiments, the second control loop may allocate the total open state command at least in part by generating provisional allocating commands based at least in part on the first target temperature and second target temperature and inputting the provisional allocating commands into a second slider. In some embodiments, the controller may be configured to operate in a plurality of operational states and the temperature set point is dependent upon the state. In some embodiments, the controller may be configured to transition between a first state of the plurality of operational states and a second state of the plurality of operational states. In some embodiments, at least one of the first multimodal controls loop and second control loop may include one or more PID control loop. In some embodiments, the one ore more PID control loop may include a feed forward term which alters the output of the one or more PID loop. In some embodiments, the number of provisional total open state commands may be adjusted by the output of at least one adjuster control loop. In some embodiments, one of the at least one adjuster control loop may be configured to produce an output based at least in part on a concentrate temperature. In some embodiments, at least one of the number of provisional total open state commands may be adjusted by a feed forward term. In some embodiments, at least one of the provisional total open state commands may be altered based on a pre-allocated source duty cycle command determined based at least in part on a concentrate temperature sensed by a concentrate sensor assembly in communication with the concentrate flow path downstream of the portion of the concentrate flow path included in the second heat exchanger. In some embodiments, the second control loop may be configured to generate its output based in part on a target electronics temperature and a current electronics temperature measured by an electronics temperature sensor. In some embodiments, the temperature set point may be adjusted by the controller based at least in part on a source fluid temperature data signal generated by a source fluid temperature sensor. 
     In accordance with another embodiment of the present disclosure a water purification system for outputting a process stream at a controlled temperature may comprise a distillation device in selective fluid communication with a fluid source via a set of source proportioning valves. The distillation device may have a concentrate output and distillate output respectively coupled to a concentrate flow path and a distillate flow path. The concentrate output may be disposed in a concentrate reservoir of the distillation device. The system may further comprise a first heat exchanger including a portion of the distillate flow path and a second heat exchanger including a portion of the concentrate flow path, a flow path from the fluid source in heat exchange relationship with each of the first and second heat exchanger. The system may further comprise a distillate sensor assembly in communication with the distillate flow path downstream of the portion of the distillate flow path included in the first heat exchanger and configured to generate a distillate temperature measurement. The system may further comprise a concentrate level sensor disposed within the concentrate reservoir and configured to output a concentrate data signal. The system may further comprise a controller configured to determine a total open state time of the source proportioning valves based at least in part on the concentrate data signal, a target concentrate rate, and a minimum open state time for at least one of the source proportioning valves. The controller may be configured to allocate percentages of the total open state command to each of the source proportioning valves based in part on the distillate temperature measurement and the minimum open state time. 
     In some embodiments, the system may further comprise at least one source sensor in communication with the source fluid flow path. In some embodiments, the controller may be configured to allocate percentages of the total open state command to each of the source proportioning valves based in part on a source sensor data signal. In some embodiments, the source sensor data signal may be a temperature data signal indicative of a current source fluid temperature. In some embodiments, the controller may be configured to allocate the percentages of the total open state command to each of the source proportioning valves based on a control loop which uses a target distillate temperature determined by the controller based on the current source fluid temperature. In some embodiments, the system may further comprise at least one concentrate temperature sensor in communication with the concentrate fluid flow path. In some embodiments, the controller may be configured to determine a total open state time of the source proportioning valves based at least in part on a concentrate temperature data signal generated by the at least one concentrate temperature sensor. In some embodiments, the controller may be configured to allocate the percentages of the total open state command to each of the source proportioning valves based on a control loop which uses a target concentrate temperature and the concentrate temperature data signal as inputs. In some embodiments, the controller may allocate a non-zero percentage of the total open state command to at least one of the set of source proportioning valves. In some embodiments, the controller may be configured to determine a total open state time of the source proportioning valves based at least in part on a feed forward term. 
     In accordance with another embodiment of the present disclosure a method of calibrating an operating speed set point of a impeller compressor disposed in a flow communication pathway between an evaporator and condenser of a vapor compression distillation device, the impeller compressor for compressing low pressure stream generated in the evaporator to a high pressure steam output to the condenser, may comprise driving the impeller rotation to a first speed based on a target low pressure steam temperature and a measured low pressure steam temperature from a low pressure steam temperature sensor. The method may further comprise executing a binary type search to determine the operating speed set point. 
     In some embodiments, executing the binary type search may comprise computing a speed command based on the target low pressure steam temperature and the measured low pressure steam temperature. In some embodiments, executing the binary type search may comprise calculating a delta between the speed command and a starting speed and comparing the delta to a range. In some embodiments, executing the binary type search may comprise shrinking the range when the delta is outside of the range and resetting the starting speed. In some embodiments, executing the binary type search may comprise entering a stabilization state for a period of time before resetting the starting speed. In some embodiments, executing the binary type search may comprise comparing the measured low pressure steam temperature to the target low pressure steam temperature. In some embodiments, executing the binary type search may comprise incrementing a timer when the measured low pressure steam temperature to the target low pressure steam temperature are within a predefined range of one another. In some embodiments, executing the binary type search may comprise saving a current speed command as the operating speed set point when the timer has incremented to a predetermine value. 
     In accordance with an embodiment of the present disclosure, a fluid distillation apparatus may comprise at least one controller and a source inlet in selective fluid communication with a fluid source via at least one valve. The fluid vapor distillation apparatus may further comprise an evaporator in fluid communication with the source inlet. The fluid vapor distillation apparatus may further comprise a steam chest coupled to the evaporator and in fluid communication with a compressor. The fluid vapor distillation apparatus may further comprise a concentrate reservoir attached to the steam chest via an inflow path. The concentrate reservoir may be disposed laterally to the steam chest such that at least a portion of the concentrate reservoir is at even height with the steam chest. The fluid vapor distillation apparatus may further comprise a condenser in fluid communication with an outlet of the compressor via a straight line flow path. The straight line flow path may include a condenser inlet having a fenestrated segment with a plurality of fenestrations. The fenestrations may establish a flow path from the condenser inlet to the condenser. The fluid vapor distillation apparatus may further comprise a product process stream reservoir coupled to the condenser by a product reservoir inlet. The product process stream reservoir may be disposed laterally to the condenser such that at least a portion of the product process stream reservoir is at even height with the condenser. 
     In some embodiments, the inflow path may include an obstruction. In some embodiments, the obstruction may include a plate. The plate may have a segment which extends into the concentrate reservoir at an angle substantially perpendicular to the inflow path. In some embodiments, the obstruction may extend into the concentrate reservoir and divide the concentrate reservoir into a first portion and a second, sheltered portion. In some embodiments, the fluid vapor distillation apparatus may further comprise a venting pathway extending from the concentrate reservoir to the steam chest. In some embodiments, the venting pathway may extend substantially parallel to and above the inflow path with respect to gravity. In some embodiments, the product reservoir inlet may be adjacent a product accumulation surface of the condenser. In some embodiments, the compressor may be driven by a motor mounted in a receiving well recessed into the side of the steam chest. In some embodiments, the compressor may include an impeller which rotates about an axis which passes through at least a portion of the steam chest and is off-center, but parallel with respect to a longitudinal axis of the steam chest. 
     In accordance with another embodiment of the present disclosure a water vapor distillation apparatus may comprise a sump and an evaporator having a first side in communication with the sump. The evaporator may have a second side in fluid communication with a steam chest. The water vapor distillation apparatus may further comprise a concentrate reservoir attached to the steam chest via an inflow path having a first portion and second portion. The second portion may be at least in part by an obstruction. The obstruction may extend into the concentrate reservoir in a direction transverse to the first portion and may divide the concentrate reservoir into an unsheltered section and a sheltered section. The water vapor distillation apparatus may further comprise a float assembly disposed in the sheltered section. The float assembly may be displaceable over a displacement range inclusive of points at even height with all steam chest liquid levels in an expected range of steam chest liquid levels. The water vapor distillation apparatus may further comprise a sensor configured monitor a position of the float assembly and output a data signal indicative of a liquid level in the steam chest based on the position of the float assembly. The water vapor distillation apparatus may further comprise a compressor having an inlet establishing fluid communication with the steam chest and an outlet establishing fluid communication with a condenser. 
     In some embodiments, the sensor may be an encoder. In some embodiments, the float assembly may include at least one magnet. In some embodiments, the sensor may be a hall effect sensor. In some embodiments, the float assembly may be attached to a pivot. In some embodiments, the float assembly may be displaceable about the pivot. In some embodiments, the obstruction may extend into the concentrate reservoir at an angle substantially perpendicular to the first portion of the inflow path. In some embodiments, the water vapor distillation apparatus may further comprise a venting pathway extending from the concentrate reservoir to the steam chest. In some embodiments, the venting pathway may extend parallel to and above the first portion of the inflow path. In some embodiments, the venting pathway may have a smaller cross-sectional area than that of the first portion of the inflow path. 
     In accordance with another embodiment of the present disclosure, a water vapor distillation apparatus may comprise a sump having a source fluid input. The water vapor distillation apparatus may further comprise an evaporator having a first side in fluid communication with the source fluid input via the sump and a second side in fluid communication with a steam chest. The evaporator may be configured to transform source fluid from the source fluid input to low pressure vapor and concentrate as source fluid travels toward the steam chest. The water vapor distillation apparatus may further comprise a concentrate reservoir attached and disposed laterally to the steam chest. The concentrate reservoir may include a concentrate level sensor configured to monitor the level of concentrate in the steam chest and generate a data signal indicative of the level of concentrate. The water vapor distillation apparatus may further comprise a compressor having a low pressure vapor inlet establishing fluid communication with the steam chest and a high pressure vapor outlet establishing fluid communication with a condenser via a condenser inlet. The water vapor distillation apparatus may further comprise a condenser in heat transfer relationship with a plurality of exterior surfaces of the evaporator. The condenser may be configured to condense a high pressure vapor stream from the compressor by contacting the high pressure vapor stream with the plurality of exterior surfaces of the evaporator. The condenser may include a condensing portion and a condensate accumulation or storage portion. The water vapor distillation apparatus may further comprise an auxiliary condensate reservoir in fluid communication with the condensate accumulation portion. The auxiliary condensate reservoir may be attached to the condenser adjacent an accumulation surface of the accumulation portion, The auxiliary condensate reservoir may include a condensate level sensor configured monitor a level of condensate in the accumulation portion and generate a data signal indicative of a percentage which the accumulation portion is filled with condensate. 
     In some embodiments, the accumulation portion may have a volume less than ten liters. In some embodiments, the plurality of exterior surfaces may be exterior surfaces of a plurality of evaporator tubes included in the evaporator. In some embodiments, the plurality of exterior surfaces may be exterior surfaces of between 90-100 evaporator tubes included in the evaporator. In some embodiments, the plurality of exterior surfaces may be exterior surfaces of between 70-80 evaporator tubes included in the evaporator. In some embodiments, the condensate level sensor may include a float assembly attached to a pivot. In some embodiments, the float assembly may be displaceable about the pivot over a displacement range inclusive of points at even height with a range of levels defined by the accumulation portion. In some embodiments, the concentrate level sensor may include a float assembly disposed in a sheltered section of the concentrate reservoir separated from an unsheltered portion of the concentrate reservoir by a barrier. In some embodiments, the float assembly may be attached to a pivot and may be displaceable about the pivot over a displacement range inclusive of points at even height with all steam chest concentrate levels in an expected range of steam chest liquid levels. In some embodiments, the concentrate level sensor may be disposed within a sleeve which forms the barrier. 
     In accordance with another embodiment of the present disclosure, a concentrate level control system for a fluid vapor distillation apparatus may comprise a source fluid input in selective fluid communication with a source fluid reservoir via at least one input valve. The concentrate level control system may further comprise an evaporator in fluid communication with the source input and in fluid communication with a steam chest. The evaporator may be configured to transform source fluid from the source fluid input into a vapor stream and a concentrate stream as the source fluid travels toward the steam chest. The concentrate level control system may further comprise a concentrate reservoir attached and disposed lateral to the steam chest via an inflow path and including an outlet in selective communication with a concentrate destination via an outlet valve. The concentrate level control system may further comprise a concentrate level sensor configured to generate a data signal indicative of a concentrate level in the steam chest. The concentrate level control system may further comprise a controller configured to deliberately alter the concentrate level in a predetermined pattern by governing actuation of the at least one inlet valve via a fluid input control loop as well as analyzing the data signal. The controller may be further configured to actuate the outlet valve to a closed state when the data signal indicates the concentrate level is below a first threshold and actuate outlet valve to an open state when the concentrate level is above a second threshold. 
     In some embodiments, the predetermined pattern may create a sawtooth waveform when concentrate level is plotted over time. In some embodiments, wherein the period of the sawtooth waveform may be dependent at least in part upon a fluid input command from the fluid input control loop. In some embodiments, the fluid input command may be determined based on a predetermined target concentrate production rate. In some embodiments, the controller may be configured to operate in a plurality of operational states and the predetermined target concentrate production rate may be state specific. In some embodiments, the controller may analyze the data signal on a predetermined basis. In some embodiments, wherein the concentrate level may be assigned a predefined expected range and the first threshold may be less than or equal to 50% of a maximum level of the expected range. In some embodiments, the first threshold may be between 40% and 50% of the maximum level of the expected range. In some embodiments, the concentrate level may be assigned a predefined expected range and the second threshold may be greater than or equal to 50% of a maximum level of the expected range. In some embodiments, the second threshold may be between 50% and 60% of the maximum level of the expected range. In some embodiments, wherein the concentrate level may be assigned a predefined expected range and the first threshold may be less than or equal to 40% of a maximum level of the expected range. In some embodiments, the first threshold may be between 40% and 30% of the maximum level of the expected range. In some embodiments, the concentrate level may be assigned a predefined expected range and the second threshold may be greater than or equal to 45% of a maximum level of the expected range. In some embodiments, the second threshold may be between 45% and 55% of the maximum level of the expected range. In some embodiments, the concentrate level may be assigned a predefined expected range and the first and second thresholds may be defined as a percentage of a maximum level of the expected range. The second threshold may be between 4 and 20 percentage points greater than the first threshold. In some embodiments, the concentrate destination is a mixing can. 
     In accordance with another embodiment of the present disclosure a method for controlling a level of concentrate in a distillation device and verifying fluid flow within the distillation device may comprise inputting a source fluid to the distillation device though at least one inlet valve. The method may further comprise evaporating at least a portion of the source fluid to generate a vapor and a concentrate as the source fluid travels toward a steam chest. The method may further comprise collecting concentrate in a concentrate reservoir attached and disposed lateral to the steam chest via an inflow path. The method may further comprise providing a data signal indicative of a concentrate level in the steam chest from a concentrate level sensor disposed in the concentrate reservoir. The method may further comprise altering, with a controller, the concentrate level in a predetermined pattern by governing actuation of the at least one inlet valve via a fluid input control loop as well as analyzing the data signal and actuating an outlet valve of the concentrate reservoir to a closed state when the data signal indicates the concentrate level is below a first threshold and to an open state when the concentrate level is above a second threshold. 
     In some embodiments, altering the concentrate level may comprise altering the concentrate level to create a sawtooth waveform when concentrate level is plotted over time. In some embodiments, analyzing the data signal may comprise analyzing the data signal on a predetermined basis. In some embodiments, the method may further comprise assigning a predefined expected range to the concentrate level and setting the first threshold at less than or equal to 50% of a maximum level of the expected range. In some embodiments, setting the first threshold may comprise setting the threshold to between 40% and 50% of the maximum level of the expected range. In some embodiments, the method may further comprise assigning a predefined expected range of the concentrate level and setting the second threshold at greater than or equal to 50% of a maximum level of the expected range. In some embodiments, setting the second threshold comprising setting the second threshold between 50% and 60% of the maximum level of the expected range. In some embodiments, the method may further comprise assigning a predefined expected range to the concentrate level and setting the first threshold at less than or equal to 40% of a maximum level of the expected range. In some embodiments, setting the first threshold may comprise setting the threshold to between 40% and 30% of the maximum level of the expected range. In some embodiments, the method may further comprise assigning a predefined expected range of the concentrate level and setting the second threshold at greater than or equal to 45% of a maximum level of the expected range. In some embodiments, setting the second threshold comprising setting the second threshold between 45% and 55% of the maximum level of the expected range. In some embodiments, the method may further comprise assigning the concentrate level a predefined expected range and setting the first and second thresholds as a percentage of a maximum level of the expected range, the second threshold being between 4 and 20 percentage points greater than the first threshold. 
     In accordance with another embodiment of the present disclosure a temperature control system for controlling temperature of a product process stream of a distillation device to a request temperature may comprise a source fluid input in selective fluid communication with a source fluid reservoir via a set of fluid input valves. The system may further comprise an evaporator in fluid communication with the source input and in fluid communication with a compressor. The evaporator may be configured to transform source fluid from the source fluid input into a vapor stream and a concentrate stream as the source fluid travels toward the compressor. The system may further comprise a condenser in fluid communication with the compressor configured to transform pressurized vapor from the compressor into condensate. The system may further comprise a condensate flow path and a concentrate flow path including respective first and second heat exchangers. The first and second heat exchangers may each include a heat exchanging portion of a source fluid flow path from the source fluid reservoir. The heat exchanging portion may be downstream the source fluid input valves. The system may further comprise a condensate temperature sensor configured to generate a data signal indicative of a condensate temperature. The condensate temperature sensor may be disposed on the condensate flow path downstream the first heat exchanger. The system may further comprise a controller configured to actuate the set of input source valves based on a first control loop which governs a total open state time for all input source valves of the set of input source valves and a second control loop which receives the data signal and the requested temperature and divides the total open state time between all of the input source valves to adjust the condensate temperature to the requested temperature. 
     In some embodiments, the heat exchanging portions of the source fluid flow paths within the first and second heat exchanger may be disposed countercurrent to their respective condensate and concentrate flow paths. In some embodiments, the system may further comprise a destination device in fluid communication with the condensate flow path via a point of use valve. In some embodiments, the requested temperature may be generated by the destination device. In some embodiments, the destination device may be a medical system. In some embodiments, the medical system may be configured to mix at least one dialysate solution. In some embodiments, the destination device may be a dialysis machine. In some embodiments, the destination device may be a hemodialysis machine. In some embodiments, at least one of the first and second control loop may be a PID control loop. In some embodiments, the gain of at least one of the terms of the PID control loop may be zero. In some embodiments, a feed forward term may be combined with the output of the second control loop. In some embodiments, the feed forward term may be based off an estimated division of total open state time. In some embodiments, the system may further comprise a concentrate level sensor configured to output a concentrate level data signal indicative of a concentrate level within the distillation device. The first control loop may be configured to receive a target concentrate level and the current concentrate level data signal and as inputs to the first control loop. In some embodiments, the controller may be further configured to adjust a heater duty cycle based at least in part on the total open state time for all input source valves of the set of input source valves. In some embodiments, the controller may be configured to increase the heater duty cycle when the open state time for all of the input source valves of the set of input source valves is increased. 
     In accordance with another embodiment of the present disclosure a method for controlling the temperature of a product process stream of a distillation device to a requested temperature may comprise governing a flow of source fluid input to the distillation device by actuation, with a controller, a set of source fluid valves. The method may further comprise converting, in an evaporator, at least a portion of the source fluid input into a vapor and a concentrate. The method may further comprise condensing, in a condenser, the vapor into a condensate. The method may further comprise removing at least a portion of the condensate and the concentrate from the distillation device through respective condensate and concentrate flow paths. The method may further comprise exchanging heat, in a first heat exchanger, between the flow of source fluid and the condensate flow path and exchanging heat, in a second heat exchanger, between the flow of source fluid and the concentrate flow path. The method may further comprise providing a condensate temperature data signal to the controller from a temperature sensor on the condensate flow path located downstream the first heat exchanger. The method may further comprise determining, with a controller, a total open state time for the set of fluid input valves between set of fluid input valves based on a first control loop and dividing the total open state time between the set of fluid input valves based on a second control loop which receives the temperature data signal and a requested temperature. 
     In some embodiments, the method may further comprise flowing the condensate and concentrate through the condensate and concentrate flow paths in a direction countercurrent to the flow of the source fluid. In some embodiments, the method may further comprise providing the condensate to a destination device by actuating a point of use valve downstream the temperature sensor. In some embodiments, the requested temperature may be generated by the destination device. In some embodiments, the destination device may be a medical system. In some embodiments, the method may further comprise mixing a dialysate using the condensate. In some embodiments, the destination device may be a dialysis machine. In some embodiments, the destination device may be a hemodialysis machine. In some embodiments, at least one of the first and second control loop may be a PID control loop. In some embodiments, the method may further comprise setting at least one of the gains of the PID control loop to zero. In some embodiments, wherein the method may further comprise combining a feed forward term with the output of the second control loop. In some embodiments, the method may further comprise determining the feed forward term based off an estimated division of total open state time. In some embodiments, wherein the method further comprises inputting a current concentrate level provided by a concentrate level sensor and a target concentrate level to the first control loop. In some embodiments, the method may further comprise adjusting a heater duty cycle based at least in part on the total open state time for all input source valves of the set of input source valves. In some embodiments, adjusting the heater duty cycle may comprise increasing the heater duty cycle when the open state time for all of the input source valves of the set of input source valves is increased. 
     In accordance with another embodiment of the present disclosure a temperature control system for controlling the temperature of a product process stream of a distillation device to a requested temperature may comprise a first source fluid input and a second fluid source input in selective fluid communication with source fluid reservoirs respectively via a first set of fluid input valves and a second set of fluid input valves. The system may further comprise an evaporator in fluid communication with the first and second source fluid input and in fluid communication with a compressor. The evaporator may have a heating element to transform source fluid from the first and second source fluid inputs into a vapor stream and a concentrate stream as the source fluid travels toward the compressor. The system may further comprise a condenser in fluid communication with the compressor. The condenser may be configured to transform pressurized vapor from the compressor into condensate. The system may further comprise a condensate flow path and a concentrate flow path including respective first and second heat exchangers. The first and second heat exchangers may each include a heat exchanging portion of a source fluid flow path from the source fluid reservoirs, the heat exchanging portion being downstream the sets of source fluid input valves. The system may further comprise a condensate temperature sensor configured to generate a data signal indicative of a condensate temperature. The condensate temperature sensor may be disposed on the condensate flow path downstream the first heat exchanger. The system may further comprise a controller configured to actuate the first set of input source valves based on a first control loop which governs a total open state time for all input source valves of the first set of input source valves and a second control loop which receives the data signal and the requested temperature and divides the total open state time between all of the input source valves of the first set of input source valves to adjust the condensate temperature to the requested temperature. The controller may be configured to monitor at least one process variable and to actuate the second set of input source valves when one of the at least one process variable is outside of a predefined threshold. 
     In some embodiments the first set of fluid input valves may include at least one valve not included in the second set of fluid input valves. In some embodiments, one of the first and second source fluid inputs may be temperature controlled. In some embodiments, the second source fluid input may be temperature controlled. In some embodiments, the second source fluid input may be a hot fluid input. In some embodiments, the at least one process variable monitored by the controller may be a heating element duty cycle. In some embodiments, the at least one process variable monitored by the controller may be an output of the first control loop. In some embodiments, the at least one process variable may be a compressor speed. In some embodiments, the heat exchanging portion of the source fluid flow path may be a common flow path for fluid from the first and second source fluid input. 
     In accordance with another embodiment of the present disclosure a temperature controls system for controlling the temperature of a product process stream of a distillation device to a request temperature may comprise a source fluid input in selective fluid communication with a source fluid reservoir via a set of fluid input valves. The system may further comprise an evaporator in selective fluid communication with the source fluid input via a bypass valve and in fluid communication with a compressor. The evaporator may be configured to transform source fluid from the source fluid input into a vapor stream and a concentrate stream as the source fluid travels toward the compressor. The system may further comprise a condenser in fluid communication with the compressor configured to transform pressurized vapor from the compressor into condensate. The system may further comprise a condensate flow path and a concentrate flow path including respective first and second heat exchangers. The first and second heat exchangers may each include a heat exchanging portion of a source fluid flow path from the source fluid reservoir, the heat exchanging portion being downstream the source fluid input valves. The system may further comprise a condensate temperature sensor configured to generate a data signal indicative of a condensate temperature. The condensate temperature sensor may be disposed on the condensate flow path downstream the first heat exchanger. The system may further comprise a controller configured to actuate the set of input source valves based on a first control loop which governs a total open state time for all input source valves of the set of input source valves and a second control loop which receives the data signal and the requested temperature and divides the total open state time between all of the input source valves to adjust the condensate temperature to the requested temperature. The bypass valve may be disposed in the source fluid flow path upstream of the heat exchanging portion of the source fluid flow path. The bypass valve may have a divert valve state which directs fluid from the source reservoir to a drain destination. The controller may be configured to actuate the bypass valve to the divert valve state when the controller determines at least one process variable is outside of a predetermined threshold. 
     In some embodiments the at least one process variable may be a relationship between the condensate temperature and a source fluid temperature provided by a source fluid temperature sensor. In some embodiments, the at least one process variable may be a source fluid temperature sensed by a source fluid temperature sensor. In some embodiments, the at least one process variable may be defined at least in part by the condensate temperature and a source fluid temperature sensed by a source fluid temperature sensor. In some embodiments, the controller may alter the duty cycle of at least one of the input source valves when the bypass valve is in the divert valve state. In some embodiments, the controller may increase the duty cycle of at least one of the input source valves when the bypass valve is in the divert valve state. In some embodiments, the controller may alter the duty cycle of at least one of the input source valves to 90-100% when the bypass valve is in the divert valve state. In some embodiments, one of the at least one of the input source valves may be a valve controlling flow of source fluid through the heat exchanging portion of the first heat exchanger. 
     In accordance with another embodiment of the present disclosure a temperature controls system for controlling the temperature of a product process stream of a distillation system to a requested temperature may comprise a source fluid input in selective fluid communication with a source fluid reservoir via a set of fluid input valves. The system may further comprise a distillation device configured to generate a concentrate stream and a condensate stream. The system may further comprise a condensate flow path and a concentrate flow path including respective first and second heat exchangers. The first and second heat exchangers may each include a heat exchanging portion of a source fluid flow path from the source fluid reservoir, the heat exchanging portion being downstream the source fluid input valves. The system may further comprise a condensate temperature sensor configured to generate a data signal indicative of a condensate temperature. The condensate temperature sensor may be disposed on the condensate flow path downstream the first heat exchanger. The system may further comprise a point of use device in selective communication with the condensate flow path. The point of use device may have an outlet fluid path for output fluid generated by the point of use device. The output fluid path may have a third heat exchanger including a heat exchanging portion of a branch of the source fluid flow path. The system may further comprise a controller configured to actuate the set of input source valves based on a first control loop and a second control loop which govern the fluid of source fluid through the heat exchanging portions of the first and second heat exchangers and based on at least one process variable. The controller may actuate a branch valve to the branch of the source fluid flow path when the at least one process variable is outside a predetermined threshold. 
     In some embodiments, the at least one process variable may a relationship between the condensate temperature and a source fluid temperature provided by a source fluid temperature sensor. In some embodiments, the at least one process variable may a source fluid temperature sensed by a source fluid temperature sensor. In some embodiments, the at least one process variable may be defined at least in part by the condensate temperature and a source fluid temperature sensed by a source fluid temperature sensor. In some embodiments, the point of use device may be a medical device. In some embodiments, the point of use device is a dialysis machine. In some embodiments, the point of use device is a hemodialysis machine or a peritoneal dialysis machine. In some embodiments, the point of use device may be a dialysate admixing device. In some embodiments, the branch of the source fluid flow path may be disposed upstream of the heat exchanging portion of the source fluid flow path in the first and second heat exchangers. In some embodiments, the output fluid may be a dialysate effluent. 
     In accordance with another embodiment of the present disclosure a condensate accumulation rate control system for controlling a rate of condensate accumulation within a distillation device may comprise a source fluid input in selective fluid communication with a source fluid reservoir via a set of fluid input valves. The system may further comprise an evaporator in fluid communication with the source input and in fluid communication with a compressor having an impeller operatively coupled to an impeller motor. The evaporator may be configured to transform source fluid from the source fluid input into a vapor stream and a concentrate stream as the source fluid travels toward the compressor. The system may further comprise a condenser in heat transfer relationship with a plurality of exterior surfaces of the evaporator. The condenser may be configured to condense a high pressure vapor stream from the compressor by contacting the high pressure vapor stream with the plurality of exterior surfaces of the evaporator. The system may further comprise a condensate levels sensor configured to sense a current level of condensate in the condenser. The system may further comprise at least one controller configured to govern a rotation speed of the impeller by periodically generating an impeller motor command based on a last motor speed command, a motor speed goal, and a speed command increment limit. The motor speed goal may be calculated by a control loop which receives the current condensate level and a desired condensate level as control loop inputs. 
     In some embodiments, the speed command increment limit may be ≤10 rpm/sec. In some embodiments, wherein the speed command increment limit may be ≤5 rpm/sec. In some embodiments, the controller may be configured to compare the impeller motor command to a minimum command speed threshold and maximum command speed threshold and adjust the impeller motor command to a modified impeller motor command equal to the minimum command speed threshold when the impeller motor command is below the minimum command speed threshold and equal to the maximum command speed threshold when the impeller motor command is above the maximum command speed threshold. In some embodiments, the minimum command speed threshold is between 1500-2500 rpm. In some embodiments, the maximum command speed threshold is calculated each time the motor speed command is generated. In some embodiments, the maximum command speed threshold may be calculated based on at least one motor parameter. In some embodiments, the system may further comprise a motor temperature sensor configured to output a temperature data signal indicative of a temperature of the impeller motor and a power factor correction current monitoring circuit configured to output a PFC data signal indicative of a current power factor correction current, the maximum command speed threshold being calculated based on a the temperature data signal and the PFC data signal. In some embodiments, the maximum command speed may be capped a predetermined value. In some embodiments, wherein the predetermined value may be between 4500-6500 rpm. In some embodiments, the predetermined value may be 5000 rpm. In some embodiments, the predetermined value may be about 2.5 times larger than the minimum command speed threshold. 
     In accordance with another embodiment of the present disclosure a method for controlling a rate of condensate accumulation within a distillation device may comprise providing a source fluid input to the distillation device. The method may further comprise evaporating, in an evaporator, at least a portion of the source fluid input into a low pressure vapor. The method may further comprise compressing, via an impeller, the low pressure vapor into a high pressure vapor. The method may further comprise condensing, in a condenser, the high pressure vapor into a condensate and transferring heat from the high pressure vapor to the evaporator. The method may further comprise providing a level of condensate within the condenser sensed by a condensate level sensor to a controller. The method may further comprise calculating, with the controller, a motor speed goal based on the level of condensate and a desired condensate level. The method may further comprise governing, with a controller, a rotation speed of the impeller by periodically generating an impeller motor command based on a last motor speed command, a motor speed goal, an a speed command increment limit. 
     In some embodiments, the speed command increment limit is ≤10 rpm/sec. In some embodiments, the speed command increment limit is ≤5 rpm/sec. In some embodiments, the method may further comprise comparing, with the controller, the impeller motor command to a minimum command speed threshold and maximum command speed threshold and adjusting the impeller motor command to a modified impeller motor command equal to the minimum command speed threshold when the impeller motor command is below the minimum command speed threshold and equal to the maximum command speed threshold when the impeller motor command is above the maximum command speed threshold. In some embodiments, the minimum command speed threshold may be between 1500-2500 rpm. In some embodiments, the minimum command speed threshold may be 2000 rpm. In some embodiments, the method may further comprise calculating the maximum command speed threshold each time the motor speed command is generated. In some embodiments, calculating the maximum command speed threshold may comprise calculating the maximum command speed threshold based on at least one motor parameter. In some embodiments, the method may further comprise providing a temperature data signal indicative of a temperature of the motor from a motor temperature sensor to the controller and providing a power factor correction data signal indicative of a current power factor correction current from a monitoring circuit to the controller. In some embodiments, the method may further comprise calculating the maximum command speed threshold based on the temperature data signal and the power factor correction data signal. In some embodiments, the method may further comprise capping the maximum command speed threshold at a predetermined value. In some embodiments, the predetermined value may be between 4500-6500 rpm. In some embodiments, the predetermined value may be 5000 rpm. In some embodiments, the predetermined value may be or may be about 2.5 times larger than the minimum command speed threshold. 
     In accordance with an embodiment of the present disclosure a fluid vapor distillation apparatus having first and second separable sections may comprising; a source inlet in selective fluid communication with a fluid source via at least one valve. The apparatus may further comprise a sump downstream the source inlet. The apparatus may further comprise an evaporator having a plurality of tubes in fluid communication with the sump. The apparatus may further comprise a steam chest coupled to the evaporator and in fluid communication with a compressor. The apparatus may further comprise a condenser in fluid communication with an outlet of the compressor. The condenser may surround the plurality of tubes. The apparatus may further comprise a support plate rotatably coupled to a pivot and attached to the first section. The apparatus may further comprise a housing coupled to the second section via at least one mount. The first and second section may be held together in a first state via one or more fastener and disconnected from one another in the second state in which the first section rotatable about the pivot. 
     In some embodiments, the at least one mount may be an isolation mount. In some embodiments, the first section may include the sump, evaporator, and condenser. In some embodiments, the second section may include the steam chest and condenser. In some embodiments, the pivot may include a bias member. In some embodiments, the bias member may be in a relaxed state when the first and second section are in the first state and may be in a compressed state when the first and second section are in the second state. In some embodiments, the bias member may have a relaxed state and an energy storing state. The support plate may have a displacement path between a first position when the bias member is in the relax state and a second position when the bias member is in the energy storing state. In some embodiments, the displacement path may be a linear displacement path. In some embodiments, the displacement path may be parallel to an axis of the pivot. In some embodiments, the bias member may be a gas spring. 
     In accordance with another embodiment of the present disclosure a distillation device may comprise a source fluid input in selective fluid communication with a source fluid reservoir via a set of fluid input valves. The device may further comprise an evaporator in fluid communication with the source input and in fluid communication with a compressor. The evaporator may be configured to transform source fluid from the source fluid input into a vapor stream and a concentrate stream as the source fluid travels toward the compressor. The device may further comprise a condenser in fluid communication with the compressor configured to transform pressurized vapor from the compressor into condensate. The device may further comprise a condensate flow path and a concentrate flow path including respective first and second heat exchangers. The first and second heat exchangers may each include a heat exchanging portion of a source fluid flow path from the source fluid reservoir. The heat exchanging portion may be downstream the source fluid input valves. The device may further comprise a condensate temperature sensor configured to generate a data signal indicative of a condensate temperature. The condensate temperature sensor may be disposed on the condensate flow path downstream the first heat exchanger. The device may further comprise an output to a destination device. The device may further comprise a controller configured to actuate the set of input source valves based on a first multimodal control loop which generates a number of provisional total open state commands for all input source valves of the set of input source valves. The controller may be configured to actuate the set of input source valves based on a slider which generates a single total open state command from the number of provisional commands. The controller may be configured to actuate the set of input source valves based on a a second control loop which receives the data signal and the requested temperature and allocates the total open state command between all of the input source valves to adjust the condensate temperature to a temperature set point. 
     In some embodiments, the heat exchanging portions of the source fluid flow paths within the first and second heat exchanger may be disposed countercurrent to their respective condensate and concentrate flow paths. In some embodiments, the controller may be configured to operate in a plurality of operational states and the temperature set point may be dependent upon the state. In some embodiments, the device further comprises a destination device in fluid communication with the condensate flow path via a point of use valve. In some embodiments, the destination device may be a medical system. In some embodiments, the medical system may be configured to mix at least one dialysate solution. In some embodiments, the destination device may be a dialysis machine. In some embodiments, the destination device may be a hemodialysis machine. In some embodiments, at least one of the first multimodal controls loop and second control loop may include a PID control loop. In some embodiments, the gain of at least one of the terms of the PID control loop may be zero. In some embodiments, the number of provisional total open state commands may be adjusted by the output of at least one adjuster control loop. In some embodiments, the distillation device may further comprise a sump. The sump may be intermediate the source input and evaporator. One of the at least one adjuster control loop may be configured to produce an output based on a target sump temperature and current sump temperature measured by a sump temperature sensor configured to generate a data signal representative of a temperature of fluid in the sump. In some embodiments, one of the at least one adjuster control loop may be configured to produce an output based on a target vapor temperature and current vapor temperature measured by a vapor temperature sensor configured to generate a data signal representative of a temperature of the vapor stream. In some embodiments, the device may further comprise a concentrate level sensor configured to output a concentrate level data signal indicative of a concentrate level within the distillation device. The controller may be configured to determine a current blowdown rate from the concentrate level data signal. The first multimodal control loop may be configured to receive a target blowdown rate and the current blowdown rate data signal and as inputs. In some embodiments, at least one of the provisional total open state commands may be a first production temperature state command and at least one of the provisional total open state commands may be a second production temperature state command. In some embodiments, the device may further comprise an evaporator level sensor configured to output an evaporator data signal. The controller may be configured to generate at least one of the provisional total open state commands based at least in part on inputs of a target evaporator sensor level and the evaporator data signal. In some embodiments, the target evaporator sensor level and the evaporator data signal may be input into a derivative controller. In some embodiments, the derivative controller may be a PID controller having a D term gain at least one order of magnitude greater than the P and I term. 
     In accordance with another embodiment of the present disclosure, a water vapor distillation apparatus may comprise a sump having a source fluid input. The apparatus may further comprise an evaporator having a first side in fluid communication with the source fluid input via the sump and a second side in fluid communication with a steam chest. The evaporator may be configured to transform source fluid from the source fluid input to low pressure vapor and concentrate as source fluid travels toward the steam chest. There may be a non-uniform liquid level in the evaporator during operation. The apparatus may further comprise an evaporator reservoir disposed laterally to the evaporator and in fluid communication therewith via the sump. The evaporator reservoir may include a level sensor configured to monitor a level of a water column in the evaporator reservoir and generate a data signal indicative of the level of the water column. The apparatus may further comprise a compressor having a low pressure vapor inlet establishing fluid communication with the steam chest and a high pressure vapor outlet establishing fluid communication with a condenser via a condenser inlet. The apparatus may further comprise a condenser in heat transfer relationship with a plurality of exterior surfaces of the evaporator. The condenser may be configured to condense a high pressure vapor stream from the compressor by contacting the high pressure vapor stream with the plurality of exterior surfaces of the evaporator. The condenser may include a condensing portion and a condensate accumulation portion. The apparatus may further comprise a processor configured to actuate a set of input source valves to the source fluid input based in part on the data signal. 
     In some embodiments, the level sensor may include a displaceable member which is displaceable over a displacement range which is smaller than the height of the evaporator reservoir. In some embodiments, the level sensor may include a displaceable member which is displaceable over a displacement range extending from a first end portion of the evaporator reservoir to at least a midpoint of the evaporator reservoir. The displacement range may be a distance less than 70% of the height of the evaporator reservoir. In some embodiments, the first end may be an end of the evaporator reservoir most distal to the sump. In some embodiments, the evaporator reservoir may be in communication with the steam chest via a venting pathway extending from a first end potion of the evaporator reservoir. In some embodiments, the venting pathway may extend from the evaporator reservoir to a concentrate reservoir attached and disposed laterally to the steam chest. In some embodiments, the height of the evaporator reservoir may be greater than the height of the evaporator. In some embodiments, the processor may be configured to determine a total open state time for the set of input source valves based in part on a target water column level and a current water column level determined via analysis of the data signal. In some embodiments, the processor may be configured to determine the total open state time for the set of input source valves based in part on the output of a PID controller which receives the target water column level and the current water column level as inputs. In some embodiments, a gain for at least one of a P term, I term, and D term of the PID controller may be zero. In some embodiments, a gain for a D term of the PID controller may be at least one order of magnitude greater than a gain for a P term and an I term of the PID controller. In some embodiments, a gain for a D term of the PID controller may be more than two orders of magnitude greater than a gain for a P term and an I term of the PID controller. In some embodiments, the processor may be configured to determine the total open state time based in part on a target blowdown rate and a current blowdown rate as indicated from a blowdown level data signal produced by a blowdown level sensor in a blowdown reservoir attached to the steam chest. In some embodiments, the processor may be configured to determine a total open state command in part based on the output of at least one adjuster control loop. In some embodiments, one of the at least one adjuster control loop may be configured to produce an output based on a target sump temperature and current sump temperature measured by a sump temperature sensor configured to generate a data signal representative of a temperature of fluid in the sump. In some embodiments, one of the at least one adjuster control loop may be configured to produce an output based on a target vapor temperature and current vapor temperature measured by a vapor temperature sensor configured to generate a data signal representative of a temperature of the vapor stream. In some embodiments, the controller may be configured to alter a total open state command for the set of input source valves in response to a change in the water column level indicated by the data signal. In some embodiments, the controller may be configured to alter a total open state command for the set of input source valves in proportion to a rate of change in the water column as indicated by the data signal. 
     In accordance with another embodiment of the present disclosure a method of controlling flow of a source fluid into a distillation device may comprise establishing a non-uniform liquid level in an evaporator of the distillation device by boiling liquid in the distillation device. The method may further comprise sensing, with a first level sensor, a liquid column level in an evaporator reservoir in fluid communication with the evaporator and disposed at even height with the evaporator. The method may further comprise sensing, with a second level sensor, a concentrate level in a concentrate reservoir in fluid communication with the evaporator. The method may further comprise generating, with a processor, a source inlet valve open time command based at least in part on the concentrate level and a target concentrate accumulation rate as well as a delta between the liquid column level and a target liquid column level. The method may further comprise commanding a number of source inlet valves to open based on the source inlet valve open time command. 
     In some embodiments, sensing the liquid column level may comprise displacing a displaceable member over a displacement range which is smaller than a height of the evaporator reservoir. In some embodiments, sensing the liquid column level may comprise displacing a displaceable member over a displacement range extending from a first end portion of the evaporator reservoir to at least a midpoint of the evaporator reservoir. The displacement range may be a distance less than 70% of a height of the evaporator reservoir. In some embodiments, the first end may be an end of the evaporator reservoir most distal to a sump of the distillation device. In some embodiments, the method may further comprise venting the evaporator reservoir, via a venting pathway, into a steam chest of the distillation device disposed superiorly to the evaporator. In some embodiments, the venting pathway may extend from the evaporator reservoir to a concentrate reservoir attached and disposed laterally to the steam chest. In some embodiments, generating the source inlet valve open time command may comprise inputting the delta to a PID controller. In some embodiments, a gain for at least one of a P term, I term, and D term of the PID controller may be zero. In some embodiments, a gain for a D term of the PID controller may be at least one order of magnitude greater than a gain for a P term and an I term of the PID controller. In some embodiments, a gain for a D term of the PID controller may be more than two orders of magnitude greater than a gain for a P term and an I term of the PID controller. In some embodiments, generating the source inlet valve open time command may comprise determining a current concentrate accumulation rate from the concentrate level and calculating a delta between a target concentrate rate and a current concentrate accumulation rate. In some embodiments, generating the source inlet valve open time command may comprise generating an output of at least one adjuster control loop. In some embodiments, the method may further comprise sensing a current sump temperature with a sump temperature sensor and generating the output of at least one adjuster control loop comprises producing the output based on a target sump temperature and current sump temperature. In some embodiments, the method may further comprise sensing a temperature of a vapor stream in the distillation device with a vapor temperature sensor. In some embodiments, generating the output of at least one adjuster controller may comprise producing the output based on a target vapor temperature and current vapor temperature. In some embodiments, the method may further comprise altering the source inlet valve open time command in response to a change in the liquid column level. In some embodiments, the method may further comprise altering the source inlet valve open time command in proportion to a rate of change in the liquid column level. 
     In accordance with another embodiment of the present disclosure a fluid vapor distillation apparatus may comprise at least one controller. The apparatus may further comprise a source inlet in selective fluid communication with a fluid source via at least one valve. The apparatus may further comprise an evaporator in fluid communication with the source inlet. The apparatus may further comprise a steam chest coupled to the evaporator and in fluid communication with a compressor. An exterior surface of the steam chest may form a portion of an inlet flow path to the compressor and a portion of an outlet flow path to an outlet of the compressor. The apparatus may further comprise a concentrate reservoir. The concentrate reservoir may be attached to the steam chest via an inflow path and disposed laterally to the steam chest such that at least a portion of the concentrate reservoir is at even height with the steam chest. The apparatus may further comprise a condenser in fluid communication with the outlet of the compressor via a straight line flow path. The straight line flow path may include a condenser inlet fixedly attached to a sheet having a first face defining a portion of the steam chest and an opposing face defining a portion of the condenser. The apparatus may further comprise a product process stream reservoir coupled to the condenser by a product reservoir inlet, and disposed laterally to the condenser such that at least a portion of the product process stream reservoir is at even height with the condenser. 
     In some embodiments, the inflow path may include an obstruction. In some embodiments, the obstruction may include a wall which extends into the concentrate reservoir at an angle substantially perpendicular to the inflow path. In some embodiments, the obstruction may extend into the concentrate reservoir and divide the concentrate reservoir into a first portion and a second, sheltered portion. In some embodiments, the obstruction may include at least one vent port. In some embodiments, the product reservoir inlet may be adjacent a product accumulation surface of the condenser. In some embodiments, the compressor may be driven by a motor partially disposed within a receiving well recessed into the side of the steam chest. In some embodiments, the compressor may include an impeller which rotates about an axis which extends lateral to the steam chest and is parallel with respect to a longitudinal axis of the steam chest. 
     In accordance with another embodiment of the present disclosure, a distillation device may comprise a source fluid input in selective fluid communication with a source via a set of fluid input valves. The device may further comprise an evaporator in fluid communication with the source input and in fluid communication with a compressor having an impeller operatively coupled to an impeller motor. The evaporator may be configured to transform source fluid from the source fluid input into a vapor stream and a concentrate stream as the source fluid travels toward the compressor. The device may further comprise a condenser in heat transfer relationship with a plurality of exterior surfaces of the evaporator. The condenser may be configured to condense a high pressure vapor stream from the compressor by contacting the high pressure vapor stream with the plurality of exterior surfaces of the evaporator. The device may further comprise a concentrate level sensor configured to sense a current level of concentrate in a concentrate reservoir having an inflow path disposed above the evaporator and having a long axis which extends alongside the evaporator. The device may further comprise at least one controller configured to govern a rotation speed of the impeller in a low temperature distillate production state and a high temperature distillate production state by periodically generating an impeller motor command based on a low temperature distillate production nominal speed command in the low temperature distillate production state and a high temperature distillate production nominal speed command in the high temperature distillate production state. The low temperature distillate production nominal speed command may be a faster motor speed command than the high temperature distillate production nominal speed command. 
     In some embodiments, an adjustment may be made to the impeller motor command based on a data signal from the concentrate level sensor indicative of a level of concentrate in the concentrate reservoir. In some embodiments, the adjustment may be limited by an impeller motor command increment limit. In some embodiments, the impeller motor command increment limit may ≤10 rpm/sec. In some embodiments, the impeller motor command increment limit may be ≤5 rpm/sec. In some embodiments, the impeller motor command may be decremented when the data signal indicates that the level of concentrate in the concentrate reservoir is greater than a first threshold. In some embodiments, the first threshold may be defined as the concentrate level at which the concentrate reservoir is between 65-80% full. In some embodiments, the impeller motor command may be held to no greater than a previously commanded impeller motor command value when the data signal indicates that the level of concentrate in the concentrate reservoir is greater than a first threshold. In some embodiments, the first threshold may be defined as the concentrate level at which the concentrate reservoir is between 65-80% full. In some embodiments, the impeller motor command may be incremented when the data signal indicates that the level of concentrate in the concentrate reservoir is greater than a second threshold. In some embodiments, the high temperature distillate production nominal speed command may a calibrated value defined during manufacture. In some embodiments, the high temperature distillate production nominal speed command may be less than 80% of the low temperature distillate production nominal speed command and more than 70% of the low temperature distillate production nominal speed command. In some embodiments, the low temperature distillate production nominal speed command may be 4500 rpm. 
     In accordance with another embodiment of the present disclosure a method of controlling a compressor of a distillation device may comprise opening at least one fluid input valve to deliver source fluid into a sump of the distillation device from a fluid source. The method may further comprise transforming source fluid into a concentrate stream and vapor stream in an evaporator. The method may further comprise determining, with a processor, a state specific compressor speed command. The compressor speed command may be based on a low temperature distillate production nominal speed command in a low temperature distillate production state and based on a high temperature distillate production nominal speed command in a high temperature distillate production state. The low temperature distillate production nominal speed command may be a faster motor speed command than the high temperature distillate production nominal speed command. The method may further comprise generating, with the processor, a final command speed based on the compressor speed command. The method may further comprise commanding, with the processor, rotation of an impeller of the compressor at the final command speed. The method may further comprise compressing the vapor stream via the compressor. The method may further comprise condensing the vapor stream into a condensate and transferring heat to the evaporator as the vapor stream condenses. 
     In some embodiments, the method may further comprise sensing, with a level sensor, a level of concentrate in a concentrate reservoir in fluid communication with the evaporator. In some embodiments, generating the final command speed may comprise determining an adjustment to the compressor speed command based on the level of concentrate. In some embodiments, determining the adjustment may comprise decrementing the compressor speed command when the level of concentrate is greater than a first threshold. In some embodiments, the first threshold may be defined as the concentrate level at which the concentrate reservoir is between 65-80% full. In some embodiments, determining the adjustment may comprise holding the final command speed to no greater than a previously commanded final command speed when the level of concentrate is greater than the first threshold. In some embodiments, determining the adjustment may comprise decrementing the compressor speed command when the level of concentrate is greater than a second threshold. In some embodiments, generating the final command speed may comprise determining an adjustment to the compressor speed command. In some embodiments, the adjustment may be limited by an increment limit. In some embodiments, the increment limit may be ≤10 rpm/sec. In some embodiments, the increment limit may be ≤5 rpm/sec. In some embodiments, the high temperature distillate production nominal speed command may be a calibrated value defined during manufacture. In some embodiments, the high temperature distillate production nominal speed command may be less than 80% of the low temperature distillate production nominal speed command and more than 70% of the low temperature distillate production nominal speed command. In some embodiments, the low temperature distillate production nominal speed command may be 4500 rpm. 
     In accordance with another embodiment of the present disclosure a distillation device may comprise a sump in selective fluid communication with a source via a set of fluid input valves. The device may further comprise at least one heating element and a least one sump temperature sensor in the sump. The sump temperature sensor may be configured to generate a sump temperature data signal. The device may further comprise an evaporator having a first side in fluid communication with the sump and a second side in fluid communication with a compressor having an impeller operatively coupled to an impeller motor. The evaporator may be configured to transform source fluid from the source fluid input to vapor stream and concentrate as source fluid travels toward the steam chest. The device may further comprise a condenser in heat transfer relationship with a plurality of exterior surfaces of the evaporator. The condenser may be configured to condense a high pressure vapor stream from the compressor by contacting the high pressure vapor stream with the plurality of exterior surfaces of the evaporator. The device may further comprise a concentrate level sensor configured to sense a current level of concentrate in a concentrate reservoir having an inflow path disposed above the evaporator and having a long axis which extends alongside the evaporator. The device may further comprise a vapor temperature sensor disposed in a flow path of the vapor stream and configured to generate a vapor temperature data signal. The device may further comprise at least one controller configured to determine a duty cycle command for the at least one heating element. The duty cycle command may be based at least in part upon a target temperature of the vapor stream, the vapor temperature data signal, the sump temperature data signal and a total source open command for the set of fluid input valves. 
     In some embodiments, the target temperature of the vapor stream may be 108° C. In some embodiments, the controller may be configured to adjust the duty cycle command to conform with at least one limit. In some embodiments, the limit may be a maximum power consumption limit. In some embodiments, the controller may be configured to adjust the duty cycle command based at least in part on a power consumption of the compressor. In some embodiments, the controller may be configured to calculate a limit for the duty cycle command by determining a power consumption of the compressor and subtracting the power consumption of the compressor from a predefined power value. In some embodiments, the predefined power value may be defined as a maximum total power for the system. In some embodiments, the duty cycle command may be limited to a predefined maximum duty cycle. In some embodiments, the predefined maximum duty cycle may not greater than a 90% duty cycle. In some embodiments, the target temperature of the vapor stream may be state specific. In some embodiments, the target temperature in a low temperature distillate production state may be higher than the target temperature in a high temperature distillate production state. In some embodiments, the target temperature of the vapor stream in a first state may be 108° C. and the target temperature of the vapor stream in a second state may be 104° C. In some embodiments, the target temperature in a first state may be 4° C. hotter than the target temperature in a second state. In some embodiments, the target temperature in a first state may be at least 95% of the target temperature in a second state, but less than the target temperature in the second state. In some embodiments, the controller may be configured to determine a feed forward term used to determine the duty cycle command based on the total source open command for the set of fluid input valves and at least one thermodynamic characteristic of the source fluid. In some embodiments, the thermodynamic characteristic may be a specific heat of the source fluid. In some embodiments, the target temperature of the vapor stream may be 111-112° C. 
     In accordance with an embodiment of the present disclosure a method of heating fluid in a distillation device may comprise opening at least one fluid input valve to deliver source fluid into a sump of the distillation device from a fluid source. The method may further comprise sensing a sump temperature of the source fluid in the sump via a temperature sensor. The method may further comprise sensing a vapor temperature of a vapor stream generated from the source fluid. The method may further comprise comparing, with a processor, the vapor temperature to a target vapor temperature. The method may further comprise inputting a delta between the vapor temperature and the target vapor temperature to a first controller and generating a first controller output. The method may further comprise providing an input based at least in part upon the first controller output and sump temperature to a second controller and generating a second controller output. The method may further comprise altering the second controller output into an altered second controller output based on a total open state time of the at least one fluid input valve. The method may further comprise commanding a duty cycle for a heating element in the sump based on the altered second controller output and at least one limit. 
     In some embodiments, the target vapor temperature may be in a range of 108° C.-112° C. In some embodiments, the at least one limit may include a maximum power consumption limit. In some embodiments, the at least one limit may include a limit based at least in part on a power consumption of a compressor in the distillation device. In some embodiments, the method may further comprise calculating a limit of the at least one limit by determining a power consumption of the compressor and subtracting the power consumption of the compressor from a predefined power value. In some embodiments, the predefined power value may be defined as a maximum total power for the system. In some embodiments, the at least one limit may include a predefined maximum duty cycle limit. In some embodiments, the predefined maximum duty cycle may not be greater than a 90% duty cycle. In some embodiments, the target vapor temperature of the vapor stream may be state specific. In some embodiments, target temperature in a low temperature distillate production state may be higher than the target temperature in a high temperature distillate production state. In some embodiments, the target temperature in a first state may be 4° C. hotter than the target temperature in a second state. In some embodiments, the target temperature in a first state may be at least 95% of the target temperature in a second state, but less than the target temperature in the second state. In some embodiments, the second controller output into an altered second controller output may comprise determining a feed forward term based on the total source open command of the at least one fluid input valve and at least one thermodynamic characteristic of the source fluid. In some embodiments, the thermodynamic characteristic may be a specific heat of the source fluid. 
     In accordance with an embodiment of the present disclosure, a water distillation device may comprise a sump in selective fluid communication with a fluid source via a set of source proportioning valves. The device may further comprise an evaporator in fluid communication with the sump. The device may further comprise a steam chest coupled to the evaporator and in fluid communication with a compressor. The device may further comprise a concentrate reservoir attached to the steam chest via an inflow path and having a concentrate level sensor configured to generate a concentrate level data signal indicative of fill percentage of the concentrate reservoir. The concentrate reservoir may be coupled to a concentrate flow path. The device may further comprise a condenser coupled to an outlet of the compressor and in fluid communication with a condensate flow path. The device may further comprise a first and second heat exchanger including a heat exchanging portion of a source fluid flow path from the fluid source. The heat exchanging portion of the first heat exchanger may be in heat exchange relationship with the condensate flow path and the heat exchanging portion of the second heat exchanger in heat exchange relationship the concentrate flow path. The heat exchanging portions of the source fluid flow path may be downstream the source proportioning valves. The device may further comprise at least one distillate sensor in communication with the condensate flow path at a point downstream the first heat exchanger. The device may further comprise a controller configured to determine a total open state time of the source proportioning valves based at least in part on the concentrate data signal and a target concentrate rate. The controller may be configured to allocate percentages of the total open state command to each of the source proportioning valves based on at least one distillate sensor data signal from the at least one distillate sensor. 
     In some embodiments, the condenser may include a condensing portion and a condensate accumulation portion. In some embodiments, the condenser may be in fluid communication with a condensate reservoir including a condensate level sensor configured to monitor a level of condensate in the condensate reservoir and generate a condensate data signal indicative of a fill percentage of the condensate accumulation portion. The condensate reservoir may be intermediate the condenser and concentrate flow path. In some embodiments, the controller may be configured to maintain a target fill percentage of the condensate accumulation portion based on the output of a PID control loop which uses as inputs the target fill percentage and a delta between the target fill percentage and the current fill percentage as indicated by the condensate data signal. In some embodiments, the target fill percentage may be equivalent to at least one liter and less than 2 liters. In some embodiments, the condenser may be in fluid communication with a condensate reservoir including a condensate level sensor configured to monitor a level of condensate in the condensate reservoir and generate a condensate data signal indicative of a fill percentage of the condensate reservoir. The condensate reservoir intermediate the condenser and concentrate flow path. In some embodiments, the at least one distillate sensor may include a temperature sensor. In some embodiments, the at least one distillate sensor data signal may be a temperature data signal indicative of a current condensate temperature after passing through the heat exchanger. In some embodiments, the controller may be configured to allocate the percentages of the total open state command to each of the source proportioning valves based on a control loop which uses a target condensate temperature and the current condensate temperature as inputs. In some embodiments, the target temperature may be at least 35° C., but no greater than 40° C. In some embodiments, the target temperature may be at least 20° C., but no greater than 30° C. 
     In accordance with another embodiment of the present disclosure, a distillation system may comprise a distillation device in selective fluid communication with a fluid source via a set of source proportioning valves. The distillation device may have a concentrate output coupled to a concentrate flow path and may have a condensate output coupled to a condensate flow path. The system may further comprise a first and second heat exchanger including a heat exchanging portion of a source fluid flow path from the fluid source downstream of the source proportioning valves. The heat exchanging portion of the first heat exchanger may be in heat exchange relationship with the condensate flow path and the heat exchanging portion of the second heat exchanger may be in heat exchange relationship the concentrate flow path. There may be a dedicated source proportioning valve for each heat exchanger. The system may further comprise a condensate sensor assembly in communication with the condensate flow path at a point downstream of the first heat exchanger. The system may further comprise a controller configured to, in a first operating state, split a commanded flow of source fluid from the fluid source between the source proportioning valves based on a first target temperature and a delta between the first target temperature and a current concentrate temperature received by the controller from the condensate sensor assembly. In a second mode, the controller may be configured to allocate the entire commanded flow to the source proportioning valve dedicated to the second heat exchanger and open the source proportioning valve dedicated to the first heat exchanger at a duty cycle which may be no greater than a predefined limit. 
     In some embodiments, the predefined limit may be 5%. In some embodiments, the predefined limit may be 2%. In some embodiments, the condensate sensor assembly may include redundant temperature sensors. In some embodiments, the first and second heat exchanger may be helical and formed by winding the heat exchanger around the exterior of the distillation device. In some embodiments, the first operating state may be a low temperature distillate production state and the second operating state may be a hot temperature distillate production state. In some embodiments, the first target temperature may be at least 35° C., but no greater than 40° C. In some embodiments, the controller may be configured to open the source proportioning valve dedicated to the first heat exchanger based upon a second target temperature and a delta between the second target temperature and the current concentrate temperature in the second operating state. In some embodiments, the second target temperature may be at least 65° C. hotter than the first target temperature. In some embodiments, the second target temperature may be at least 50° C. hotter than the first target temperature. In some embodiments, the second target temperature may be greater than 95° C. and less than 100° C. in some embodiments, the second target temperature may be 96° C. In some embodiments, the second target temperature may be at least double the first target temperature. In some embodiments, the second target temperature may be at least 2.5 times the first target temperature. In some embodiments, the second target temperature may be at least 3.5 times the first target temperature. In some embodiments, the system may further comprise an evaporator level sensor disposed in an evaporator reservoir in fluid communication with an evaporator of the distillation device. The controller may be configured to, in the second operational state, determine the total flow command at least in part based on an evaporator level data signal indicative of a level of a water column in the evaporator reservoir. In some embodiments, the first target temperature may be at least 20° C., but no greater than 30° C. In some embodiments, the first target temperature is 25° C. 
     In accordance with another embodiment of the present disclosure a method of controlling and allocating a flow of source fluid into a distillation device may comprise sensing, with a concentrate level sensor, a concentrate level in a concentrate reservoir in fluid communication with an evaporator of the distillation device. The method may further comprise sensing a temperature of product fluid produced by the distillation device at a point downstream of a product heat exchanger which places product fluid in heat exchange relationship with incoming source fluid. The method may further comprise determining, with a processor, a concentrate accumulation rate based on the concentrate level. The method may further comprise calculating, with a processor, a first delta between the concentrate accumulation rate and a first target concentrate accumulation rate and a second delta between the concentrate accumulation rate and a second target concentrate accumulation rate. The method may further comprise determining, with a processor, a first provisional open state command and second provisional open state command for a first and second source inflow proportioning valve. The first provisional open state command may be based on the first delta and the second provisional open state command based on the second delta. The method may further comprise computing, with a processor, a final open state command from the provisional open state time commands. The method may further comprise dividing, with the processor in a first operational state, the final open state command between the first source inflow proportioning valve and second inflow proportioning valve. The first source inflow proportioning valve may lead to a product heat exchanger. The dividing may be based on a delta between a target product temperature and the temperature of the product fluid. The method may further comprise allocating, with the processor in a second operational state, an entirety of the final open state command to the second source inflow proportioning valve. The method may further comprise opening, via a command from the processor, the first source inflow proportioning valve at a duty cycle which is no greater than a predefined limit with the processor in the second operational state. 
     In some embodiments, the first target accumulation rate may be greater than the second target accumulation rate. In some embodiments, computing the final open state command may comprise inputting the first provisional open state command and second provisional open state command into a slider. In some embodiments, computing the final open state command may comprise generating a hybrid command from the first and second provisional source open state commands. In some embodiments, computing the final open state command may comprise determining a first state fraction and a second state fraction and multiplying the first provisional open state command by the first state fraction and multiplying the second provisional open state command by the second state fraction. In some embodiments, computing the final open state command comprises adjusting the command from predominately the first provisional open state command to predominately the second provisional open state command during a transition between the first operational state and the second operational state. In some embodiments, computing the final open state command may comprise adjusting the command from purely the first provisional open state command to purely the second provisional open state command during a transition between the first operational state and the second operational state. In some embodiments, the second operational state may be a hot distillate production state. In some embodiments, the dividing may comprise determining an open state command for the first source inflow proportioning valve based on a delta between a target product temperature and the temperature of the product fluid and determining an open state command for the second source inflow proportioning valve by subtracting the open state command from the first source inflow proportioning valve from the final open state command. In some embodiments, the predefined limit may be a limit of less than 5%. In some embodiments, the predefined limit may be a limit of less than 2%. In some embodiments, the determining the second provisional open state command further may comprise sensing a level of a liquid column, with an evaporator level sensor, in an evaporator reservoir in fluid communication with the evaporator. The second provisional open state command may be based in part on a delta between the level of the liquid column and a target level of the liquid column. In some embodiments, the second provisional open state command may be based on a rate of change in the delta between the level of the liquid column and the target level of the liquid column. 
     In accordance with an embodiment of the present disclosure a medical system may comprise at least one concentrate fluid. The system may further comprise a distillation device having an evaporator, a condenser, and a purified product water heat exchanger having a source fluid flow path and a purified product water flow path in heat exchange relation with one another. The system may further comprise a medical treatment device the medical treatment device may include a treatment fluid preparation circuit in selective fluid communication, via a point of use valve, with the purified product water flow path. The medical treatment device may include a treatment device processor configured to command mixing of the at least one concentrate and purified water to generate a prescribed treatment fluid with the treatment fluid preparation circuit. The system may further comprise a communications link between the treatment device processor of the medical treatment device and a distillation device processor of the distillation device. The medical treatment device processor may be configured to transmit mode commands to the distillation device processor. The system may further comprise a sensor assembly in communication with the purified product water flow path. The system may further comprise a source valve intermediate a fluid source and the source fluid flow path. The distillation device processor may be configured to actuate the source valve based at least in part on the mode commands and data from the sensor assembly. 
     In some embodiments, the sensor assembly may include at least one temperature sensor and at least one conductivity sensor. In some embodiments, the distillation device processor may be configured to actuate the source valve based at least in part on the mode commands and temperature data from the sensor assembly. In some embodiments, the distillation device processor may be configured to actuate the source valve based at least in part on the mode commands and data from the sensor assembly and a target set point for purified water. In some embodiments, the target set point may be a temperature set point. In some embodiments, the target set point may be determined by the distillation device processor based on the mode commands. In some embodiments, the target set point may be based off a first mode command of the mode commands which may be in the range of 20-30° and a target set point based off a second mode command of the mode commands which may be greater than 90° C. 
     In some embodiments, the medical treatment device may be a dialysis machine. In some embodiments, the medical treatment device may be a hemodialysis device. In some embodiments, the treatment fluid may be a dialysis fluid. In some embodiments, the condenser may include a condensing section and a product storage section. The product storage portion may have a volume of at least one liter. In some embodiments, the distillation device processor may be further configured to govern operation of a compressor motor of the distillation device based at least in part on the mode commands. In some embodiments, the distillation device processor may be further configured to govern operation of a concentrate outlet valve of the distillation device based at least in part on the mode commands. 
     In accordance with an embodiment of the present disclosure a medical system may comprise a distillation device having and evaporator, a source inlet flow path to a source input in fluid communication with the evaporator, a condenser, a purified product water output flow path in fluid communication with the condenser. The system may further comprise a first and second filter in the source inlet flow path. The system may further comprise a plurality of pressure sensors including a first pressure sensor upstream the first filter and a second pressure sensor downstream the second filter. The system may further comprise a medical treatment device the medical treatment device including a treatment fluid preparation circuit in selective fluid communication, via a point of use valve, with the purified product water output flow path. The system may further comprise a communications link between a treatment device processor of the medical treatment device and a distillation device processor of the distillation device. The distillation device processor may be configured to conduct a first filter replacement check based on data from the plurality of pressure sensors and the treatment device processor may be configured to conduct a second filter replacement check and command the distillation device processor into a filter replacement mode, via the communications link, when either of the first or second filter replacement check fails. 
     In some embodiments, the second filter replacement check may include a check of a number of days elapsed since installation of the first and second filter against a limit. In some embodiments, the medical treatment device may include a graphical user interface. In some embodiments, the second filter replacement check may include a check of a user input on the graphical user interface against at least one predefined criteria. In some embodiments, the system may further comprise a sampling port disposed intermediate the first and second filter and the predefined criteria may be a water chemistry test strip criteria. In some embodiments, the water chemistry test strip criteria may be a chlorination level criterion. In some embodiments, the distillation device processor may be configured to command a flush of the first and second filter prior to at least one of the first filter replacement check or second filter replacement check. In some embodiments, the distillation device processor may be configured to conduct the first filter replacement check based on a filter output pressure data signal from the second pressure sensor. In some embodiments, the distillation device processor may be configured to indicate a failure of the first filter replacement check when the filter output pressure is below a threshold. In some embodiments, the distillation device processor may be configured to conduct the first filter replacement check based on a delta between a pressure upstream of the first and second filter as indicated by the first pressure sensor and a pressure downstream of the first and second filter as indicated by the second pressure sensor. In some embodiments, the distillation device processor may be configured to indicate a failure of the first filter replacement check when the delta is less than a threshold. 
     In accordance with another embodiment of the present disclosure A medical system may comprise a distillation device having a source water input and a fluid output flow path. The system may further comprise a medical treatment device including a plurality of fluid flow paths, a plurality of valves, at least one fluid pump, and a fluid inlet in selective fluid communication, via a point of use valve, with the fluid output flow path. The system may further comprise a communications link between the medical treatment device and distillation device. The system may further comprise a sensor assembly in communication with the fluid output flow path. The system may further comprise a treatment device processor configured to actuate the plurality of valves and the at least one fluid pump to pump a high temperature fluid through the plurality of fluid flow paths. The system may further comprise a distillation device processor configured to govern operation of the distillation device based on at least one data signal from the sensor assembly and a mode command sent over the communications link from a treatment device processor of the medical treatment device to produce and output the high temperature fluid to the fluid output flow path during a first period in which the point of use valve is commanded open by the distillation device processor and a second period in which the point of use valve is commanded closed by the distillation device processor and a valve to a flow path in fluid communication the fluid output flow path is commanded open. 
     In some embodiments, the source water input may be in fluid communication with a non-temperature controlled fluid source. In some embodiments, the medical treatment device may be a dialysis machine. In some embodiments, the medical treatment device may be a hemodialysis machine. In some embodiments, the plurality of fluid flow paths may include a first flow path and second flow path separated from one another by a semi-permeable membrane. In some embodiments, the plurality of fluid flow paths may be included in at least a blood pumping cassette and a dialysate pumping cassette. In some embodiments, the medical treatment device may include a fluid reservoir and the treatment device processor may be configured to send a signal to the distillation device processor to end the first period based on an amount high temperature fluid contained in the fluid reservoir. In some embodiments, the medical treatment device may include a heater. In some embodiments, the at least one data signal may include at least one temperature data signal. In some embodiments, the distillation device may include a compressor and the distillation device processor may be configured to govern operation of the compressor via a compressor speed command determined based in part on of the mode command. In some embodiments, the distillation device processor may be configured to govern operation of the distillation device based on the least one data signal and another mode command sent over the communications link from a treatment device processor to produce and output a medical treatment fluid component to the fluid output flow path. In some embodiments, the plurality of flow paths may comprise a medical treatment fluid mixing circuit and the treatment device processor may be configured to command operation of the at least one pump and plurality of valves to mix the medical treatment fluid component with at least one concentrate in fluid communication with the plurality of flow paths in accordance with a predetermined prescription. 
     The details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features and advantages will become apparent from the description, the drawings, and the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other aspects will become more apparent from the following detailed description of the various embodiments of the present disclosure with reference to the drawings wherein: 
         FIG. 1  depicts an example schematic diagram of a water purification system; 
         FIG. 2  depicts another example schematic diagram of a water purification system; 
         FIG. 3  depicts another example schematic diagram of a water purification system 
         FIG. 4  depicts another example schematic diagram of a water purification system; 
         FIG. 5  depicts exemplary embodiment of the system shown in  FIG. 1 ; 
         FIGS. 6-7  depict views of portions of a system with a hot section housing of the system removed; 
         FIG. 8  depicts views of exemplary heat exchangers; 
         FIG. 9  depicts a cross-sectional view of a portion of the exemplary heat exchangers  6008  in  FIG. 8 ; 
         FIG. 10  depicts a cross sectional view of an example purifier filled with source fluid; 
         FIG. 11  depicts an exploded view of a portion of a purifier; 
         FIG. 12  depicts a top down view of a portion of a purifier with a portion of a concentrate reservoir cut away; 
         FIG. 13  depicts a cross sectional view of an example concentrate reservoir; 
         FIG. 14-15  depict a perspective view of an interior volume of an example steam chest; 
         FIG. 16  depicts another cross sectional view of an example concentrate reservoir; 
         FIG. 17  depicts a perspective view of an example purifier and concentrate reservoir; 
         FIG. 18  depicts an exploded view of an example steam chest and mist eliminator; 
         FIGS. 19-20  depict views of an example flow path convoluter; 
         FIG. 21  depicts a view of an example drip tray; 
         FIG. 22  depicts an exploded view of a drip tray and mist eliminator; 
         FIG. 23  depicts an example compressor exploded away from an example steam chest; 
         FIG. 24  depicts an exploded view of an example compressor; 
         FIG. 25  depicts another exploded view of an example compressor; 
         FIG. 26  depicts a top down view of an example compressor; 
         FIGS. 27 and 28  depict cross sections taken at the indicated planes of  FIG. 26 ; 
         FIG. 29  depicts another top down view of an example compressor; 
         FIGS. 30 and 31  depict cross sections taken at the indicated planes of  FIG. 29 ; 
         FIG. 32  depicts a view of an example purifier with a steam chest, mist eliminator, and condenser inlet coupler exploded away; 
         FIG. 33  depicts a perspective view of an example condenser inlet including fenestrations; 
         FIG. 34  depicts a cross sectional view of an example purifier showing high pressure vapor within the purifier; 
         FIG. 35  depicts a perspective view of another example condenser inlet; 
         FIG. 36  depicts a side view of an evaporator condenser of an example purifier with a portion of a product reservoir cut away; 
         FIG. 37  depicts a perspective view of an example purifier including a number of venting flow paths; 
         FIG. 38  depicts a perspective view of an example purifier including a number of product flow paths; 
         FIG. 39  depicts a side view of an example purifier including a number of product flow paths; 
         FIGS. 40 and 41  depicts an example sensing manifold; 
         FIGS. 42 and 43  depict perspective views of an example mixing can; 
         FIG. 44  depicts a side view of an example purifier with a pivot of an example support plate for the purifier exploded apart; 
         FIG. 45  depicts a side view of an example purifier with a fastener coupling first and second sections of the purifier removed; 
         FIG. 46  depicts a side view of an example purifier with a fastener coupling first and second section of the purifier removed and the first section displaced away from the second along a displacement path; 
         FIG. 47  depicts a side view of an example purifier with a fastener coupling first and second section of the purifier removed and the first section displaced away from the second about an arcuate path defined by the pivot; 
         FIG. 48  depicts a front perspective view of an example system similar to that shown in  FIG. 3 ; 
         FIG. 49  depicts a rear perspective view of the example system shown in  FIG. 48 ; 
         FIG. 50  depicts a front perspective view of an example system with a portion of an enclosure of the example system removed; 
         FIG. 51  depicts a rear perspective view of an example system with a portion of an enclosure of the example system removed; 
         FIG. 52  depicts a perspective view of portions of an example purifier including a number of source fluid flow paths; 
         FIG. 53  depicts a perspective view of portions of an example purifier including a number of source fluid flow paths; 
         FIG. 54  depicts a side view of an example source inlet manifold; 
         FIG. 55  depicts a side view of an example product heat exchanger manifold; 
         FIG. 56  depicts views of exemplary heat exchangers; 
         FIG. 57  depicts a cross-sectional view of a portion of the exemplary heat exchangers  6008  in  FIG. 56 ; 
         FIG. 58  depicts a top down view of an example purifier; 
         FIG. 59  depicts a cross sectional view extending through a product reservoir and product reservoir level sensor of a purifier taken at the indicated plane of  FIG. 58 ; 
         FIG. 60  depicts an exploded view of an example evaporator condenser of a purifier; 
         FIG. 61  depicts another exploded view of an example evaporator condenser of a purifier; 
         FIG. 62  depicts an enlarged detailed view of the indicated region of  FIG. 61 ; 
         FIG. 63  depicts a cross sectional view extending through a blowdown reservoir and blowdown reservoir level sensor of a purifier taken at the indicated plane of  FIG. 58 ; 
         FIG. 64  depicts a view of portions of an example purifier with a portion of a steam chest of the example purifier cut away; 
         FIG. 65  depicts an enlarged detailed view of the indicated region of  FIG. 64 ; 
         FIG. 66  depicts a cross sectional view of an example blowdown reservoir and blowdown level sensor; 
         FIG. 67  depicts a perspective view of portions of an example purifier including a number of blowdown flow paths; 
         FIG. 68  depicts an exploded view of an example steam chest; 
         FIG. 69  depicts an example steam chest and compressor, the compressor being exploded away from steam chest; 
         FIG. 70  depicts an example compressor and steam chest, the compressor being exploded apart; 
         FIG. 71  depicts an exploded view of an example compressor; 
         FIG. 72  depicts a top down view of an example compressor and steam chest; 
         FIG. 73  depicts a cross-sectional view taken at the indicated plane of  FIG. 72 ; 
         FIG. 74  depicts a cross-sectional view taken at the indicated plane of  FIG. 72 ; 
         FIG. 75  depicts a top down view of an example compressor and steam chest; 
         FIG. 76  depicts a cross-sectional view taken at the indicated plane of  FIG. 75 ; 
         FIG. 77  depicts a cross-sectional view taken at the indicated plane of  FIG. 75 ; 
         FIG. 78  depicts an exploded view of an example evaporator condenser and steam chest, the steam chest being exploded away from the evaporator condenser; 
         FIG. 79  depicts a cross sectional view of an example purifier, the cross sectional view extending through a midplane of a product reservoir and product reservoir level sensor of the example purifier; 
         FIG. 80  depicts a perspective view of portions of an example purifier including a number of venting flow paths; 
         FIG. 81  depicts an exploded view of an example mixing reservoir and blowdown heat exchanger manifold; 
         FIG. 82  depicts a perspective view of portions of an example purifier including a number of product flow paths; 
         FIG. 83  depicts an exploded view of an example product heat exchanger manifold; 
         FIGS. 84A-B  depict a flow diagram detailing a number of state changes which may occur during operation of an example system; 
         FIG. 85  depicts a flowchart depicting a number of example actions which may be used in an integrity testing state; 
         FIG. 86  depicts a flowchart detailing a number of example actions which may be used in a fill state of a system; 
         FIG. 87  depicts a flowchart detailing a number of example actions which may be used during a fill of a purifier; 
         FIG. 88  depicts a flowchart detailing a number of example actions which may be used in a heat state of a system; 
         FIG. 89  depicts a flowchart detailing a number of example actions which may be used to flush filters of a system; 
         FIG. 90  depicts a flowchart detailing a number of example actions which may be used to dispense a water sample; 
         FIG. 91  depicts a flowchart detailing a number of example actions which may be used to prepare a system for filter replacement; 
         FIG. 92  depicts a flowchart detailing a number of example actions which may be used in a production preparation state of a system; 
         FIG. 93  depicts a flowchart detailing a number of example actions which may be used in a production start up state of a system; 
         FIG. 94  depicts a flowchart detailing a number of example actions which may be used in a water production state of a system; 
         FIG. 95  depicts a flowchart detailing a number of example actions which may be used in a hot water production preparation state of a system; 
         FIG. 96  depicts a flowchart detailing a number of example actions which may be used in a hot water production state of a system; 
         FIG. 97  depicts a flowchart detailing a number of example actions which may be used in a hot water production state of a system when the system is in a self disinfection mode; 
         FIG. 98  depicts a flowchart detailing a number of example actions which may be used in stand-by state of a system; 
         FIG. 99  depicts a flowchart detailing a number of example actions which may be used to control a liquid level in a purifier; 
         FIG. 100  depicts an example product temperature control diagram; 
         FIGS. 101A-B  depict another example product temperature control diagram; 
         FIG. 101C  depicts an alternative temperature control diagram to the portion of a control diagram presented in  FIG. 101B  where both product and blowdown temperature are controlled; 
         FIG. 102  depicts a flowchart detailing a number of example actions which may be used to determine a fill rate of a reservoir; 
         FIG. 103  depicts a flowchart detailing a number of example actions which may be used to update a fill rate determination with a fill rate estimate; 
         FIG. 104  depicts a flowchart detailing a number of example actions which may be used to adjust a target blowdown rate value; 
         FIG. 105A  depicts a flowchart detailing a number of example actions which may be used adjust source proportioning valve commands; 
         FIG. 105B  depicts a flowchart detailing a number of example actions which may be used adjust source proportioning valve commands; 
         FIGS. 106A-B  depict a flowchart detailing a number of example actions which may be used to determine source proportioning valve commands; 
         FIG. 107  depicts a flowchart detailing a number of example actions which may be used to divert product water; 
         FIG. 108  depicts a flowchart detailing a number of example actions which may be used to monitor for errors during operation of a system; 
         FIG. 109  depicts a flowchart detailing number of example actions which may be used to control a liquid level in a purifier; 
         FIG. 110  depicts a flowchart detailing a number of example actions which may be used to control a motor of a compressor; 
         FIG. 111  depicts a flowchart detailing a number example actions which may be used to automatically calibrate a nominal motor speed value; 
         FIG. 112  depicts a flowchart depicting a number of example actions which may be used in automatic calibration for a motor speed set point 
         FIG. 113  depicts a flowchart depicting a number of example actions which may be used in automatic calibration for a motor speed set point  FIG. 114  a flowchart  7960  depicting a number of example actions which may be used in automatic calibration for a motor speed set point 
         FIG. 115  depicts a flowchart detailing a number of example actions which may be used to control a liquid level within a purifier; 
         FIG. 116  depicts a flowchart detailing a number of example actions which may be used to monitor for errors during operation of a system; 
         FIG. 117  depicts an example heater control diagram; 
         FIG. 118  depicts a flowchart detailing a number of example actions which may be used determine a feed forward command for a compressor motor controller; 
         FIG. 119  depicts a flowchart detailing a number of example actions which may be used to monitor for errors during operation of a system; 
         FIG. 120  depicts a block diagram of a system including a bearing feed flow sensor; 
         FIG. 121  depicts a flowchart detailing an number of example actions which may be used to monitor for flow from a bearing feed pump; 
         FIG. 122  depicts a flowchart detailing a number of example actions which may be used to determine a product reservoir outlet valve command; 
         FIG. 123  depicts a flowchart detailing a number of example actions which may be used to adjust a product reservoir outlet valve duty cycle based on data from a product level sensor and product temperature sensor; 
         FIG. 124  depicts a flowchart detailing a number of example actions which may be used to adjust a product reservoir outlet valve duty cycle based on data from a product level sensor; 
         FIG. 125  depicts a flowchart detailing a number of example actions which may be used to adjust a product reservoir outlet valve duty cycle based on data from one or more product temperature sensor; 
         FIG. 126  depicts a flowchart depicting a number of example actions which may be used to determine the presence of an abnormal source water temperature within a system; 
         FIG. 127  depicts a flowchart depicting a number of example actions which may be used to adjust a temperature set point of a process stream; 
         FIG. 128  depicts a flowchart detailing a number of example actions which may be used to control and electronics cooling valve of a system; 
         FIG. 129  depict a flowchart depicting a number of example actions which may be used to control cooling of an electronics housing of a system; and 
         FIG. 130  depicts a flowchart depicting a number of example actions which may be executed to control the temperature of a blowdown process stream output from a heat exchanger. 
     
    
    
     Like reference symbols in the various drawings indicate like elements. 
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       FIG. 1  depicts a schematic diagram of an exemplary water purification system  6000 . The system  6000  may draw water from a source  6002  and purify the water to remove various contaminants making the water fit for consumption at a point of use. The point of use in the exemplary diagram is a medical system  6004 . The purified output of the system  6000  may, in certain examples, be used as a component of a medical treatment fluid used by the medical system  6004 . The system  6000  may, however, be used to provide water for drinking purposes or for other devices which require water meeting specific quality standards. Medical systems  6004  which may be used with the purification system  6000  may include various dialysis systems. The medical system  6004  may be a system for mixing therapeutic agents such as dialysate. The medical system  6004  may also orchestrate a dialysis (peritoneal or hemo) treatment for a patient. In specific examples, the medical system  6004  may be a peritoneal dialysate mixing system or may be a hemodialysis system such as those described in U.S. patent application Ser. No. 12/072,908 filed Feb. 27, 2008 and entitled Hemodialysis Systems and Methods, now U.S. Pat. No. 8,246,826, issued Aug. 21, 2012 (Attorney reference F65); U.S. patent application Ser. No. 12/199,055 filed Aug. 27, 2008 and entitled Enclosure for a Portable Hemodialysis System, now U.S. Pat. No. 8,393,690, issued Mar. 12, 2013 (Attorney reference G20); and U.S. Non Provisional patent application Ser. No. 16/370,039 filed Mar. 29, 2019 and entitled Liquid Pumping Cassettes and Associated Pressure Distribution Manifold and Related Methods (Attorney reference Z35), each of which is hereby incorporated herein by reference in its entirety. 
     Various systems, methods and apparatus described in U.S. patent application Ser. No. 13/952,263 filed Jul. 26, 2013 and entitled Water Vapor Distillation Apparatus, Method and System, now U.S. Pat. No. 9,604,858, issued Mar. 28, 2017 (Attorney reference K95) which is incorporated herein by reference in its entirety; and U.S. patent application Ser. No. 10/713,617 filed Nov. 13, 2003 and entitled Pressurized Vapor Cycle Liquid Distillation, now U.S. Pat. No. 7,597,784, issued Oct. 6, 2009 (Attorney reference D91) which is hereby incorporated herein by reference in its entirety, may be used together with any one or more embodiments of water distillation apparatus, methods and methods described herein. Therefore, additional embodiments are contemplated, some of which include one or more apparatus, systems and methods described in-the above referenced documents. 
     As shown, water may travel from a source  6002  to at least one filter  6006 . The source  6002 , may be a source  6002  which would meet US EPA requirements for drinking water. The source  6002  may for example meet the requirements of the National Primary Drinking Water Regulations (40 CFR 141) which is hereby incorporated herein by reference in its entirety. It should be noted that this disclosure is not bound by any definitions provided in § 141.2 or in any other portion of the above incorporated by reference document. In specific embodiments, the source or source fluid reservoir  6002  may be a residential water line which dispenses water from a municipal water supply or private water supply. The at least one filter  6006  may be an activated charcoal filter. Other filter types which remove expected undesirable component(s) of the source  6002  water like oxidizers such as chlorine, chloramines, etc. may also be used. In certain embodiments, two redundant filters  6006  may be included in the system  6000 . From the at least one filter  6006 , the water may pass onto one or more heat exchangers  6008 A, B. 
     In the example embodiment, a first heat exchanger  6008 A and second heat exchanger  6008 B are depicted. These heat exchangers  6008 A, B may be countercurrent heat exchangers. Fluid entering each heat exchanger  6008 A, B may be placed in a heat exchange relationship with at least one process stream from the water purifier  6010  of the system  6000 . The at least one process stream in each heat exchanger  6008 A, B may be different process streams, though the heat exchangers  6008 A, B may each mutually carry at least one common process stream as well. Where multiple streams are carried by a single heat exchanger, the streams may be separated as described in relation to any heat exchangers described herein. In specific embodiments, one heat exchanger  6008 A may carry a purified or product process stream, while the other may carry all other process streams from the water purifier  6010  (blowdown, retentate, vented gases, volatiles, or other discarded process streams). Such heat exchangers  6008 A, B may respectively be referred to as a product heat exchanger and blowdown heat exchanger. 
     A valve or valves may be included to provide control over the proportions of filtered source water flowing to one heat exchanger  6008 A, B versus the other. This may allow for water flowing from the at least one filter  6006  through each of the heat exchangers  6008 A, B to be altered in temperature to a greater or lesser degree. Likewise, it may allow for the process streams traveling through the heat exchangers  6008 A, B to be altered in temperature to a greater or lesser degree. In some embodiments, the total mass flow or total incoming fluid from the at least one filter  6006  through both of the heat exchangers  6008 A, B may be generally constant or controlled by an otherwise unrelated control algorithm as the proportion of incoming fluid directed to each heat exchanger  6008 A, B is manipulated. The total mass flow of fluid from the at least one filter  6006  through the heat exchangers  6008 A, B may also fluctuate in tandem with this proportion. 
     From the heat exchangers  6008 A, B the filtered source flow may recombine and enter the purifier  6010  for purification. The purifier  6010  may remove or reduce a concentration of at least one contaminant and likely multiple contaminants in the source water. The water purifier  6010  may be any of the water vapor distillation devices described herein though other distillation devices or water purification devices may also be used. In the example system  6000 , the water purifier  6010  is capable of purifying water to quality standards sufficient to support usage of the purified water in the medical system  6004 . The water may for example conform to quality standards issued by a government organization, standards organization, NGO, or other appropriate organization. Where the medical system  6004  is a dialysis system, the standards may, for example, be those in the USP Water for Hemodialysis Monograph which is hereby incorporated by reference herein in its entirety. 
     The water purifier  6010  may produce a number of process streams. The process streams may be fluid streams and may include, but are not limited to, a product water stream, a blowdown water stream, and a gaseous vented stream. Some of these streams may be contained in process stream reservoirs after being generated in the water purifier  6010 . In the example illustration, a product water reservoir  6012  and blowdown reservoir  6014  are included. These reservoirs  6012 ,  6014  may include an interior volume sized to contain a volume of fluid from their respective process streams. Each reservoir  6012 ,  6014  may also include a level sensor to determine the volume of the respective process stream in each reservoir. 
     The process streams may exit the water purifier  6010  or reservoirs  6012 ,  6014  and proceed to the heat exchangers  6008 A, B of the system  6000 . As these streams pass through the heat exchangers  6008 A, B heat transfer may occur between the process streams and the source water en route to the purifier  6010  from the at least one filter  6006 . In general, the process streams may transfer heat to the source water thus cooling the process streams and elevating the temperature of the source water. Where a gaseous process stream passes through a heat exchanger  6008 A, B the heat exchange may cause at least a portion of the gaseous process stream to condense. 
     As mentioned above, the mass proportion of source water transiting through each heat exchanger may be varied. The mass proportion may, for example, be controlled to bring the product stream temperature into conformance with a predetermined temperature range or threshold. This temperature requirement may be an acceptable usage temperature range or threshold for the medical system  6004 . The medical system  6004  may accept water at temperatures below a certain threshold and/or within a certain range and the mass proportion of source water flow may be controlled to ensure the product stream is in conformance with any such criteria. Where the medical system  6004  is a hemodialysis system, the threshold may be around the average human body temperature (e.g. 37° C.+/−5° C.). 
     The system  6000  may additionally include at least one sensor assembly  6016 . The at least one sensor assembly  6016  may monitor a characteristic of interest or multiple characteristics of interest of one or more of the process streams. Potential characteristics of interest may include, but are not limited to, temperature, concentrations of dissolved ions, conductivity, optical characteristics, turbidity, presence of particular compounds or elements and any other water quality characteristics described elsewhere herein. In some specific embodiments, a sensor assembly  6016  may monitor the quality of water exiting a first or product heat exchanger  6008 A. Conductivity and temperature may, for example, be measured. Data from the at least one sensor assembly  6016  may provide feedback for a controller (e.g. P, PI, PID) which governs the mass proportion of source water flowing through each heat exchanger  6008 A, B. Additionally, data from the at least one sensor assembly  6016  may inform operation of a divert valve allowing the product water stream to either proceed to the medical system  6004  or to a drain  6018  or discard location. If, for example, conductivity of the product water is greater than a predefined threshold, the divert valve may be actuated to divert the product water to the drain  6018  until the conductivity falls back to acceptable levels. 
     The drain  6018  may also be used to receive any product water which is generated in excess by the water purifier  6010 . If the medical system  6004  does not require water and the product reservoir  6012  is full, product water may be diverted to the drain  6018 . The drain  6018  may also receive other process streams from the water purifier  6010  such as the blowdown stream and any other waste streams. The drain  6018  may be any suitable destination such as a municipal drain or the like. 
     Referring now to  FIG. 2 , another representational block diagram of an example of system  6000  from  FIG. 1  is shown. The example system  6000  includes a source check valve  6030  which allows one way flow from the source  6002  into the rest of the system  6000 . Additionally, a shut off valve  6032  is included. This shut off valve  6032  may be mechanical (e.g. a ball valve) or may be operated by a controller  6034 . The shut off valve  6032  may be actuated to prevent source fluid from entering the system in the event of a failure condition or in other undesirable situations. The example system  6000  also includes a pressure transducer  6036  which may be in data communication with the controller  6034  and sense the pressure of incoming source water. 
     The exemplary system  6000  includes a first filter  6006 A and a second filter  6006 B. An additional coarse filter (not shown) for preventing ingress of large sediment may be included upstream the first filter  6006 A and second filter  6006 B in some embodiments. The first filter and second filter  6006 A, B may be activated charcoal filters (e.g. 5-6 L activated charcoal filters). These filters  6006 A, B may serve as organic contaminant and/or oxidizer removal elements and may remove chemicals like chlorine, chloramines, and others from the source water. 
     In specific implementations, the first and second filter  6006 A, B may be substantially identical redundant filters. The filters  6006 A, B may be separated by a fluid flow pathway which includes a test or sampling port  6038 . The sampling port  6038  may allow for a user to periodically (e.g. before each use or on another predetermined schedule) draw fluid filtered via the first filter  6006 A for manual testing. 
     The sampling port  6038  may include a valve (e.g. manually operated valve) which, when actuated, allows a sample to be dispensed into a testing receptacle or the like. In some embodiments, the sampling port  6038  may be accompanied by a push button which mechanically opens a flow path for water to travel for dispensing through the sampling port  6038 . A controller  6034  may also receive a signal upon depression of the push button. In certain embodiments, the sampling valve may be controller actuated and be commanded open by the controller  6034  upon receipt of a button depression signal by the controller  6034 . The sampling port  6038  may be associated with a user interface, e.g. a graphical user interface and the button may be a soft button displayed on a touch screen. In other embodiments, the user interface may be simple and include one or more lights (e.g. LEDS) to convey status information (power, system state, sample ready, faults, etc.). 
     Manual testing may depend on the type of chemicals likely to be present in the source  6002  and may include free chlorine and/or total chlorine tests. In alternative embodiments, a meter for sensing concentrations of expected chemicals (e.g. chlorine meter) may be included instead of or in addition to the test port  6038 . Such a meter may be in data communication with the controller  6034  which may analyze data generated via the meter. The test port  6038  and/or meter may allow for a user to determine when the filters  6006 A, B need to be swapped out. In some embodiments, the system  6000  may prevent operation of the water purifier  6010  until the controller  6034  receives a signal indicative of an acceptable filtration of water exiting the first filter  6006 A. Alternatively or additionally, the medical system  6004  may not accept water from the system  6000  unless a data signal indicative of an acceptable filtration from the first filter  6006 A is received. Where testing is manually performed, the signal may be generated via a user input to a user interface of the system  6000  or via a user input to a user interface of the medical system  6004 . The signal may also be generated by a test meter as well. 
     After passing through the second filter  6006 B, the filtered source water may enter a valve manifold  6039 . Upon entering the valve manifold  6039 , the pressure of the water may be regulated to a predetermined pressure by a pressure regulator  6040 . The predetermined pressure may be between 15-30 psig (e.g. 20 psig). The pressure and temperature of the water may be sensed by a pressure sensor  6044  and temperature sensor  6042  which are in data communication with the controller  6034 . Filtered source water may then proceed to a blowdown heat exchanger  6008 B and product water heat exchanger  6008 A. 
     The flow path leading to the blowdown heat exchanger may extend to an electronics housing  6046  of the system  6000 . As water travels to the blowdown heat exchange  6008 B, the route of the flow path may establish a heat exchange relationship with the electronic components of the electronics housing  6046 . Thus, the filtered source water may serve to cool the electronics in the electronics housing  6046  while en route to the blowdown heat exchanger  6008 B. Alternatively or additionally, source water en route to the product heat exchanger  6008 A may be routed into heat exchange relationship with the electronics of the electronics housing  6046 . As shown, the electronics housing  6046  may be associated with an electronics temperature sensor  6048  which provides temperature data to the controller  6034 . In certain embodiments, there may be a plurality of temperature sensors  6048  in the electronics housing  6046  for added redundancy and/or to monitor specific components (e.g. a power module). 
     Source proportioning control valves  6050 A, B may be operated by the controller  6034  to govern the mass proportion of source water flowing through each of the blowdown and product heat exchangers  6008 A, B. As mentioned above, the mass proportion may be chosen to achieve a desired temperature of one or more of the process streams from the water purifier  6010 . It should be noted, however, that the mass proportion may also be controlled to ensure adequate cooling of the electronics housing  6046 . In some embodiments, at least a predefined proportion of incoming source water may be provided to the blowdown heat exchanger  6008 B to ensure adequate cooling. The controller  6034  may also alter the mass proportion for the heat exchangers  6008 A, B in the event that temperature data from the electronics temperature sensor  6048  indicates the temperature of the electronics housing  6046  is above a threshold. 
     After passing through the blowdown and product heat exchangers  6008 A, B the filtered source water streams may recombine and enter a sump  6052  of a water purifier  6052  through a source fluid input included in the sump  6052 . The sump  6052  may includes at least one heating element  6054 . The at least one heating element  6054  may be a resistive heater. A thermal fuse  6056  may also be included as a failsafe measure. The at least one heating element  6054  may heat the sump  6052  contents based on controller  6034  analysis of data from a sump temperature sensor  6058 . Each heating element  6054  may be associated with a temperature sensor  6059  to provide data on the temperature at the heating element  6054 . The at least one heating element  6054  may provide heat energy to incoming source water to aid in or cause evaporation of the source water within an evaporator  6060  of the water purifier  6010 . The evaporator  6060  may be at least partially formed from a shell and tube type heat exchanger as described elsewhere in the specification. The top (with respect to the force of gravity) of the evaporator  6060  may include a steam chest  6072 . The evaporator  6060  may transform source fluid from the source fluid input into a low pressure vapor and concentrate stream as source fluid travels toward the steam chest  6072   
     As the source water boils, vapor may rise from the now more concentrated source water and pass through a mist eliminator  6062  located in the steam chest  6072 . The mist eliminator  6062  may inhibit water molecules still in liquid phase from exiting the evaporator  6060 . The mist eliminator  6062  may, for example, be any of the exemplary mist eliminators described herein. After mist removal, the water vapor may travel to a compressor  6064 . The compressor  6064  may be any suitable compressor such as any of those described herein. The compressor  6064  may compress the water vapor and in the process increase the temperature of the water vapor. The system  6000  may include a pre-compression temperature sensor  6066  and post compression temperature sensor  6068 . Data from these temperature sensors  6066 ,  6068  may be provided to the controller  6034  and the controller  6034  may utilize this data to control the compressor  6064 . 
     A compressor temperature sensor  6070  (or redundant compressor temperature sensors) may further be included to provide the controller  6034  temperature data related to the compressor  6064 . 
     In some embodiments, the controller  6034  may included a plurality of processors which may control different system  6000  components. In some embodiments, a main control processor and a peripheral control processor may be included in the controller  6034 . The peripheral control processor may control the at least one heating element  6054  and the compressor  6064  while the main control processor receives sensor data and controls other components of the system  6000 . The processors may exchange data to facilitate division of responsibilities. For example, sensor data and/or high level commands from the main control processor may be provided to the peripheral control processor. The peripheral control processor may provide its command outputs to the main control processor. 
     As pure vapor passes from the evaporator  6060  to the compressor  6064 , impurities in the source water may be concentrated to form a blowdown process stream. In the example embodiment, the blowdown process stream may pass from the evaporator  6060  and into the blowdown reservoir  6014 . The blowdown reservoir  6014  may be disposed lateral to the steam chest  6072  and in communication therewith. A blowdown level sensor  6074  may be included in association with the blowdown reservoir  6014  and be in data communication with the controller  6034 . The blowdown level sensor  6074  may directly measure and generate a data signal indicative of a level of concentrate or blowdown in the steam chest  6072 . Data from the blowdown level sensor  6074  may be used by the controller  6034  to ensure a sufficient amount of concentrate is maintained in the evaporator  6060  as well as to confirm a desired amount of blowdown flux is present. The blowdown reservoir  6014  as well as the sump  6052  may be in direct communication with a drain  6018  via fluid conduits in the event excess fluid needs to be drained out of the water purifier  6010 . 
     A product water process stream may be formed by the condensing vapor passed from a high pressure vapor outlet of the compressor  6064  to the condenser  6076 . At least a portion of this vapor may condense on a section of the evaporator  6060  which is in communication with the condenser  6076 . In various embodiments, the condenser  6076  may be in a heat exchange relationship with a number of exterior surfaces of the evaporator  6060 . The latent heat of condensation provided within the condenser  6076  from the condensing water may aid in the evaporation of the source water in the evaporator  6060 . 
     As shown, a product reservoir  6012  may be attached to and in communication with the condenser  6076  volume. The product reservoir  6012  may include a product level sensor  6078  in data communication with the controller  6034 . The product level sensor  6012  may be used to determine a volume of product water which is available for use and may also be used to confirm fluid is flowing from the product reservoir  6012 . The product reservoir  6012  may be positioned such that it is at even height with a portion of the condenser  6076 . Thus the product level sensor  6078  may measure both a level of water within the product reservoir  6012  as well as a level of water within the condenser  6076 . From this, a total volume of available product water may be surmised. The product reservoir  6012  may be disposed such that the product level sensor  6078  may measure available product levels of up to 1-10 L (e.g. 1, 2, 5 or 6 L) though any volume range is possible. In this sense the product reservoir  6012  may serve as an auxiliary product reservoir. 
     Where the product level sensor  6078  measures the condensate level within the condenser  6076 , the condenser may be divided into to two sections. The first section may be a condensing section. The second section may be a condensate accumulation section. The volume of the second section may be equal to the maximum available product level to be measured. When the second section is not full, the unfilled portion of the second section may act similarly to the first section and provide condensing surfaces for high pressure vapor to condense upon. The product reservoir  6012  may be fluidically connected to the condensate accumulation section adjacent a condensate accumulation surface where the condensate first begins to collect (e.g. the bottom of the condenser  6076 ). This may allow the product level sensor  6078  to begin measuring an accurate amount of available product water soon after the process stream starts accumulating. 
     The product reservoir  6012  may also be in communication with a feed pump  6080 . The feed pump  6080  may pump fluid from the product reservoir to the compressor  6064 . This fluid may act as a coolant for the compressor  6064  as well as a lubricating fluid for one or more bearing of the compressor  6064 . As the bearing feed may be a source of purified water, a return path may not be included. Instead, the fluid may enter the compressor  6064  after usage and be returned to the condenser  6076  without compromising its purity. The pressure and temperature of the bearing feed fluid may be monitored by bearing feed pressure sensor  6081  and a bearing feed temperature sensor  6083  each in data communication with the controller  6034 . 
     After exiting the reservoirs  6012 ,  6014  the blowdown and product process streams may flow to their respective heat exchangers  6008 A, B. With respect to the product process stream, after passing through the product heat exchanger  6008 A, the stream may pass a number of sensors  6082 A-D downstream of the product heat exchanger  6008 A. These sensors  6082 A-D may sense various characteristics of interest of the product stream. The characteristics of interest may be any of those mentioned herein, however, in specific embodiments; the sensors  6082 A-D may include first and second conductivity sensors and first and second temperature sensors. In some embodiments, one or more of the sensors  6082 A-D may be included together as part of a sensor assembly. The controller  6034  may monitor data produced by the sensors  6082 A-D to determine how to route the product stream. In the event that the product water meets quality requirements (e.g. in a predetermined temperature range and below a predetermined conductivity threshold) of the medical system  6004 , a point of use valve  6086  may be actuated to allow the product stream to pass to the medical system  6004 . A medical system check valve  6088  may be included to ensure that this flow is unidirectional. 
     If the product stream quality conflicts with at least one requirement of the medical system  6004 , the controller  6034  may actuate a diverter valve  6084 . When actuated, the diverter valve  6084  may establish a flow path to a drain  6018  destination where the process stream is discarded. A drain check valve  6090  may be included to ensure flow to the drain  6018  from the system  6000  is unidirectional. 
     The blowdown stream may also be directed to the drain  6018 . Before reaching the drain  6018 , however, the blowdown stream may pass to a mixing reservoir  6092  through a check valve  6097 . As shown, a blowdown reservoir outlet valve  6094  may gate flow of cooled blowdown from the blowdown heat exchanger  6008 B to the mixing reservoir  6092 . A blowdown temperature sensor  6096 , which may be in data communication with the controller  6034 , may monitor the temperature of blowdown entering the mixing reservoir  6092 . The mixing reservoir  6092  may also be in selective communication with the condenser  6076  via a controller  6034  actuated vent valve  6098 . The vent valve  6098  may be periodically actuated to vent steam, volatiles, air, or other non condensable gases from the condenser  6076  to maintain optimal operation of the water purifier  6010 . A vacuum break  6099  may be included on the vent line to avoid build up of a vacuum within the purifier  6010  as the purifier  6010  cools (e.g. after use) and its interior pressure decreases. Within the mixing reservoir  6092 , the vented gases may combine with the relatively low temperature blowdown process stream to cool and condense the vented gases. Thus, hot gases may be safely vented from the condenser  6076  as needed. 
     If needed, a controller  6034  operated source divert valve  6100  may be opened to allow source water to enter the mixing reservoir  6092  to provide further cooling. Actuation of the source divert valve  6100  may be based at least in part on the temperature of the blowdown stream as determined from data provided by the blowdown temperature sensor  6096 . Additionally or alternatively, actuation of the source divert valve  6100  may be based at least in part on the amount of venting or the duty cycle of the vent valve  6098  and/or the temperature of the electronics housing  6046 . The source divert valve  6100  may also be actuated to an open state by the controller  6034  in the event the water purifier  6010  already has an adequate supply of source water. The source divert valve  6100  may also be used to flush the filter elements  6006 A, B prior to a sample being taken. The source divert valve  6100  may also allow for rapid flow of source fluid to cool the electronics housing  6046  in the event that temperature sensor  6048  indicates the temperature of the electronics housing  6046  is in breach of predefined threshold criteria. 
     Components of the system  6000  which operate at high temperatures may be partitioned into a hot section housing  6102  of the system  6000 . As mentioned elsewhere herein, this section may be insulated to increase the efficiency of the system  6000 . A leak sensor  6104  may be included in the hot section  6102  to monitor the integrity of the system  6000  and provide data to the controller  6034 . The leak sensor  6104  may include a conductivity sensor which monitors for the presence of liquid in the hot section  6102 . Alternatively, the leak sensor may be an optical sensor monitoring a drip tray or similar reservoir. 
     Referring now to  FIG. 3 , an exemplary block diagram of a system  6000  is depicted. The system  6000  in  FIG. 3  includes a number of differences in comparison to  FIG. 2 . As shown, the system  6000  in  FIG. 3  includes an evaporator reservoir  6015  which is in fluid communication with the evaporator  6060  and disposed external to the evaporator  6060 . The evaporate reservoir  6015  may include a evaporator level sensor  6073  in data communication with the controller  6034 . The evaporator level sensor  6012  may be used to determine a volume of water contained within the evaporator and may be used to confirm fluid is flowing from the into the evaporator  6060 . The evaporator reservoir  6015  may be positioned such that it is at even height with a portion of the evaporator  6060 . Thus the evaporator level sensor  6073  may measure both a level of water within the evaporator reservoir  6015  as well as a level of water within the evaporator  6060 . These values may be used to help inform filling of the evaporator  6060  during start-up or at other times which the water level has yet to reach the blowdown reservoir  6012 . These values may also be used as input variables to various control loops for the purifier  6010  running on the controller  6034  during production of a product stream. 
     The system  6000  may also include an air filter  6093 . The air filter may be a HEPA air filter or air filter with a pore size of 0.2 microns or less. The air filter may be in series with a check valve  6095  leading to the vacuum break  6099  for the purifier  6010 . This filter may serve as a precaution against the ingress of detritus or micro-organisms during operation of the vacuum break  6099 . The system  6000  may also include an over-pressure relief valve  6091  which may open to vent pressure from the purifier  6010  in the event that pressure in the purifier  6010  rises above a predefined value. The relief valve  6091  may be purely mechanical or under control of a controller  6034  depending on the embodiment. 
     The example system depicted in  FIG. 3  also includes a single drain  6018 . The diverter valve  6084  may gate a flow path leading to the mixing can  6092 . When product water needs to be sent to drain  6018  (e.g. does not meet sensing criteria or too much product water has accumulated in the condenser  6076 ) the diverter valve  6084  may be actuated to open the flow path. In certain embodiments, the controller  6034  may control to a target product level in the product reservoir  6014  or condenser  6076 . The discarded product may then flow through a check valve  6085  to the mixing can  6092 . Once combined with all other waste or discard process streams the fluid in the mixing can  6092  may proceed onward to the drain  6018 . 
     The line to the medical system  6004  may be insulated as shown by the heavier line weight. This may help to prevent and loss of heat as fluid travels from the sensors  6082 A-D to the medical system  6004 . In certain embodiments where the water may be provided to the medical system  6004  at high temperatures, the insulation may prevent a user from contacting a hot line. Any suitable insulation may be used. 
     Referring now to  FIG. 4 , another exemplary block diagram of a system  6000  is depicted. In the example diagram, a third heat exchanger  6008 C is depicted. This heat exchanger  6008 C may be a countercurrent heat exchanger similar to other heat exchangers described herein. The exemplary third heat exchanger may exchange heat between a source fluid for the purifier and a hot output stream from the medical system  6004 . The hot output stream from the medical system  6004  may be a discard stream from the medical system  6004  in some embodiments. For example, the third heat exchanger  6008 C may receive spent dialysate or effluent from a hemodialysis or peritoneal dialysis device. Such a third heat exchanger  6008 C may help to increase efficiency and facilitate temperature control of various process streams of the system  6000  where a hot output stream from the medical system  6004  is available. 
     The third heat exchanger  6008 C is positioned intermediate the at least one filter  6006  and the first and second heat exchangers  6008 A, B. Filtered source fluid exiting the at least one filter may pass through the third heat exchanger  6008 C before passing onto the first and second heat exchangers  6008 A, B. Alternatively, the third heat exchanger  6008 C may be placed intermediate the at least one filter  6006  and only one of the first and second heat exchangers  6008 A, B (e.g. the product water heat exchanger  6008 A). The third heat exchanger  6008 C may also be included as an optional fluid path for source fluid flowing through the system  6000 . In such implementations, the system  6000  may include a branch fluid pathway which is gated by one or more branch valve. When desired, the one or more valve may be actuated so as to establish source fluid flow to the third heat exchanger  6008 C or direct it through a separate fluid pathway to the first and second heat exchangers. A branch valve may, for example, be actuated based on a control loop to establish and break a flow path for the source fluid through the third heat exchanger  6008 C. The third heat exchanger  6008 C may also be disposed (with or without a valved branch fluid pathway) intermediate the product heat exchanger  6008 A and the medical system  6004  or the sensor assembly  6016 . 
     The third heat exchanger  6008 C may be arranged to transfer heat from the hot output of the medical system  6004  to the source fluid en route to the purifier  6010 . This may help to lower the added energy needed to cause phase change of the source fluid in examples where the purifier  6010  is a distillation device. Alternatively, where the third heat exchanger  6008 C is intermediate the product heat exchanger  6008 A and the sensor assembly  6016 , the output of the medical system  6004  may aid in heating or cooling of the product process stream depending on the temperature differential between the two fluids. In the example shown, the hot output of the medical system  6004  is directed to a discard or drain destination  6018  in the example embodiment. In other embodiments, the third heat exchanger  6008 C may also act as a cooler for the medical system  6004 . The medical system  6004  may, in some embodiments, recirculate fluid through the third heat exchanger  6008 C to exchange heat with a relatively cool source fluid flow. This may, for example, be desirable if the product process stream provided to the medical system  6004  is too warm for a particular operation. Whether the output from the medical system  6004  is recirculated to the medical system  6004  or dumped to the drain destination  6018  after heat transfer in the third heat exchanger  6008 C may be controlled by one or more valves. 
     Still referring to  FIG. 4 , a bypass valve  6009  is included on one of the first and second heat exchangers  6008 A, B. This bypass valve  6009  may be leveraged to provide additional cooling to one or more process stream from the purifier  6010  as it passes through the heat exchanger  6008 A, B. In the example embodiment, the bypass valve  6009  is included on the source water output of the product heat exchanger  6008 A. The bypass valve  6009  may allow for source fluid exiting the product heat exchanger  6008 A to be diverted directly to a drain destination  6018  as shown. Such a bypass valve  6009  may be used when excess cooling of the product process stream may be needed. The bypass valve  6009  may be actuated to a divert state and the duty cycle of at least one of the valves controlling the flow of source water through the first and second heat exchangers  6008 A, B may be altered (e.g. increased to 90-100%). Thus, relatively cool source water may be transferred through the product heat exchanger  6008 A at a rapid rate to quickly draw in heat from the product process stream to aid in lowering the product process stream to a target temperature. This large volume of rapidly flowing source water may be dumped to the drain destination via the bypass valve  6009  if the source fluid volume is in excess of the demand from the purifier  6010 . The bypass valve  6009  may be actuated to the divert state when a controller  6034  (see, e.g.,  FIG. 2 ) determines at least one process variable is outside of a predetermined threshold. The at least one process variable may be a relationship between or defined in part by a condensate temperature take downstream the condensate heat exchanger  6008 A and the source fluid temperature. 
     On the other hand, if the temperature of a process stream exiting the first or second heat exchanger  6008 A, B is too low, a controller  6034  (see, e.g.,  FIG. 2 ) of the system  6000  may command source fluid be drawn in, at least partially, from an alternative fluid source  6003 . The alternative fluid source  6003  may be temperature controlled and may be a hot water source. The hot water source may be a domestic hot water heater or reservoir, a heated reservoir component of the system  6000 , or any other suitable hot water source. In the example shown, only a first fluid source and the second, alternative fluid source are shown, however, in other embodiments, there may be more than one alternate fluid source  6003 . The first fluid source may be associated with a first set of fluid input valves and the second fluid source may be associated with a second set of fluid input valves including at least one valve not in the first set of input valves. 
     By drawing the source fluid at least partially from the alternative fluid source  6003 , the temperature drop of process streams from the purifier  6010  as they transit through the first and second heat exchanger  6008 A, B may be decreased. Additionally, fluid may be drawn from the alternative fluid source  6003  in the event that a process variable is in breach of a predefined threshold. For example, fluid may be drawn from the alternative fluid source  6003  if the heating element  6054  duty cycle, source valve command duty cycle  6432  (see, e.g.,  FIGS. 100-101C ), and/or compressor  6072  speed is above a predetermined threshold. This may help to allow the purifier  6010  to purify more fluid in the same amount of time or may help to minimize demand on various components of the purifier  6010  such as the heating element  6054  or the compressor  6072 . 
     Referring now to  FIG. 5 , an exemplary embodiment of the system  6000  shown in  FIG. 1  is depicted. For sake of clarity, only source water carrying fluid lines  6126  are shown in  FIG. 5 . Source water may enter the system  6000  at a connector  6120 . A manual shutoff valve  6032  may be included to prevent flow of source water to the system  6000 . The source water may flow through a number of filters  6006 A, B. In the example shown, these filters may be 5 L activated carbon filters. A user operated sample port  6038  is included between the filters  6006 A, B. The sample port  6038  in the example includes a manually actuated ball type valve. Pre and post filtration pressure transducers  6036 ,  6044  may also be included. The system  6000  includes a pressure regulator  6040  which may control the source water pressure to a predefined value (e.g. 20 psig). 
     The source water flow may be split so as to facilitate individually allocating the source water to the product and blowdown heat exchangers  6008 A, B. En route to the blowdown heat exchanger  6008 B, a source water fluid line  6126  may extend to an electronics heat exchanger inlet  6122 . Source water may flow through a fluid conduit in the electronics housing  6046  and exit the electronics housing  6046  through an electronics heat exchanger outlet  6124 . Thought not shown, the flow conduit in the electronics housing  6046  may be routed in a non straight line or meandering (e.g. switchbacked) pattern to help maximize heat transfer. A source water fluid line  6126  extending from the electronics heat exchanger outlet  6124  may provide a fluid path for the source water to the blowdown heat exchanger  6008 B. A branch may be included on this section of source water fluid line  6126  allowing source water flow to be diverted to a mixing reservoir  6092  if desired. The source water fluid lines  6126  may enter the hot section housing  6102  via a product heat exchanger pass through  6128  and a blowdown heat exchanger pass through  6130  in the hot section housing  6102 . 
     Referring now also to  FIGS. 6-7 , views of portions of the system  6000  are shown with the hot section housing  6102  removed. Again, for sake of clarity, only source water fluid lines  6126  and not those carrying various process streams are shown. The source water fluid lines  6126  may couple onto source water inlets  6132 A, B of the respective heat exchangers  6008 A, B. The source water may flow through the heat exchangers  6008 A, B to respective source water outlets  6134 A, B. After exiting the heat exchangers  6008 A, B the source water streams may recombine and proceed through a source water line  6126  leading to the sump  6052  of the water purifier  6010 . 
     Referring now also to  FIG. 8 , a view of exemplary heat exchangers  6008 A, B is shown. The heat exchangers  6008 A, B may each be arranged as helices of tubing through which the source water and various process streams of the system  6000  may flow. The helices formed by each of the heat exchangers  6008 A, B may have substantially constant radii and pitch. The heat exchangers  6008 A, B may be arranged in concentric fashion with one of the heat exchangers  6008 A, B having a smaller radius and being positioned inside of the other. In the exemplary embodiment depicted in  FIG. 8 , the blowdown heat exchanger  6008 B is positioned inside the product heat exchanger  6008 A. The length of the fluid pathways in the product and blowdown heat exchangers  6008 A, B may be substantially equal. The pitch of each heat exchanger  6008 A, B may be substantially equal. Consequentially, the interior or smaller radiused heat exchanger  6008 B may be greater in height that the outer heat exchanger  6008 A. 
     A cross-sectional view of a portion of the exemplary heat exchangers  6008 A, B is shown in  FIG. 9 . As shown, each heat exchanger  6008 A, B includes a large diameter source flow conduit  6136 A, B which forms the exterior surface of the heat exchangers  6008 A, B. These source flow conduits  6136 A, B are shown having substantially equal diameters, however, their diameters may differ with one being larger than the other in some examples. 
     Within the source flow conduits  6136 A, B are conduits in which process streams from the water purifier  6010  are carried. The product water heat exchanger  6008 A may include at least one product flow conduit  6138  positioned within its source flow conduit  6136 A. Each of the at least one product flow conduit  6138  may be of equal diameter or may be of differing diameters. The blowdown heat exchanger  6008 B includes a plurality of interior flow conduits. In the specific example in  FIG. 9 , the blowdown heat exchanger includes a blowdown flow conduit  6140  and a venting flow conduit  6142  within its source flow conduit  6136 B. In some embodiments, additional flow conduits may be included therein. For example, multiple blowdown or venting conduits  6140 ,  6142  may be included within the source flow conduit  6136 B. The blowdown flow conduit  6140  and venting flow conduit  6142  may be positioned side-by-side as shown or may be braided or interwoven together in some embodiments. The product flow conduits  6138  may be similarly braided or interwoven depending on the embodiment. 
     As best shown in  FIG. 9 , to maximize the compactness of the heat exchangers  6008 A, B, the pitch of the heat exchanger  6008 A, B helices may be relatively shallow. For example, the pitch may be between 5-40% greater than the outer diameter of the source flow conduits  6136 A, B. In other embodiments, the pitch may be about equal to the outer diameter of the source flow conduit  6136 A, B and each revolution of the helices may touch those adjacent to it. A pitch greater than the outer diameter of the source flow conduits  6136 A, B may be desirable where the source flow conduits  6136 A, B are constructed of a material which efficiently conducts heat such as stainless steel or another metal. Where the source flow conduits  6136 A, B are made from high temperature silicon or a similar material, the gap between revolutions may be decreased or omitted. The gap may also be omitted if a material with high thermal conductivity is used. 
     Referring now to  FIGS. 10-11 , additional views of an exemplary system  6000  are shown. After source water (shown as stippling in  FIG. 10 ) passes into the sump  6052  the water may begin to fill a number of evaporator tubes  6140 . The evaporator tubes  6140  may extend through the condenser  6076  from the sump  6052  volume to the steam chest  6072  volume. A first and second tube sheet  6142 A, B may include receiving orifices  6144  for accepting the ends of each of the evaporator tubes  6140 . The tube sheets  6142 A, B may hold the evaporator tubes  6140  in a generally evenly spaced pattern within the condenser  6076  volume. The tube sheets  6142 A, B may also form a seal or include gasket members which form a seal around the ends of the evaporator tubes  6140 . This seal may prevent fluid communication between the evaporator tubes  6140  and the interior volume of the condenser  6076 . At least one plate  6143  may also be included in the condenser  6076  to act as a baffle which directs incoming vapor to an exterior surface of the evaporator tubes  6140 . The second tube sheet  6142 B may form the bottom wall of the steam chest  6072 . As source water enters the steam chest  6072  the water may pool within the bottom of the steam chest  6072  on top of the second tube sheet  6142 B. 
     In the example embodiment, less than 100 (specifically 96) evaporator tubes  6140  are included. In other embodiments, a greater or lesser number of evaporator tubes  6140  may be included. Each evaporator tube  6140  may have a substantially equal diameter. The evaporator tube  6140  diameters may be between 5-10% (e.g. ˜6%) of the diameter of the condenser  6072 . In some embodiments, the evaporator tubes  6140  may not all be of equal diameter. At least one or more of the evaporator tubes  6140  may be of a different diameter. 
     In some embodiments, evaporator tubes  6140  may differ in diameter depending on their location. For example, evaporator tubes  6140  in a first section of the evaporator may be a first diameter, while those in a second section may be a second diameter, those in a third section may be a third diameter, and so on. In some embodiments, those extending through a central region of the condenser  6076  volume may be a first diameter and those in a region more distal to the central region may be a second diameter. The first diameter may be larger or smaller than the second diameter depending on the embodiment. In some embodiments, an evaporator tube  6140  diameter gradient may be established from evaporator tubes  6140  which extend through a central portion of the condenser  6076  volume and those located most distally to the evaporator tubes  6140  in the central portion. For example, progressively larger or smaller tubes may be included as distance from the central portion increases. 
     The evaporator tubes  6140  may take up between 25 and 50% (e.g. ˜37%) of the interior volume of the condenser  6076 . The material from which the evaporator tubes  6140  are constructed may vary depending on the embodiment; however, a material with a high thermal conductivity may be used. The material used may be any of those described elsewhere herein. 
     In some embodiments, the evaporator tubes  6140  may be made from a material which is the same as or similar to the material used to construct the tube sheets  6142 A, B. Both the evaporator tubes  6140  and tube sheets  6142 A, B may be a metal material with a high thermal conductivity. Stainless steel may be used in some examples. The evaporator tubes  6140  may be welded, brazed, or otherwise joined to the tube sheets  6142 A, B. This may allow for the total size of the purifier  6010  to be decreased when compared to an embodiment in which the tube sheets are constructed from an elastomeric material like ethylene propylene diene monomer (EPDM) rubber. Where welded, braised, or similarly attached, the joints between the tube sheets  6142 A, B and the individual evaporator tubes  6140  may also form fluid tight seals. Thus the tube sheets  6142 A, B may be thinned while still maintaining a robust seal between the condenser  6076  volume and the sump  6052 /steam chest  6072 . 
     Though not shown in this embodiment, the evaporator tubes  6140  may include a filler element (see, e.g.,  FIG. 62 ) such as a rod which fills a proportion of the cross sectional area of each of (or potentially only some) the evaporator tubes  6140 . This may encourage a thin layer or film of source fluid to be present between exterior of the filler element and the interior surface of the evaporator tube  6140  within which the filler element is disposed. 
     Referring now to  FIGS. 12-16 , as heat from heating element  6054  (see, e.g.,  FIG. 2 ) and condensing vapor in the condenser  6076  evaporates the source water, a blowdown process stream or concentrate may be generated. The blowdown process stream may fill a portion of the steam chest  6072  volume. As shown, a blowdown or concentrate reservoir  6014  may be attached to the side of the steam chest  6072 . An obstruction  6146  (best shown in  FIG. 13 ) may be included in or define part of the inflow path  6148  from the steam chest  6072  to the blowdown reservoir  6014 . For example, the inflow path  6148  may include a first portion  6333 , and a second portion  6335 . This second portion may be at least partially defined by the obstruction  6146 . The obstruction  6146  may be a weir or similar barrier which shelters a portion of the blowdown reservoir  6014 . The obstruction  6146  may substantially prevent splashing and other violent liquid motion due to boiling in the steam chest  6072  from upsetting liquid in the sheltered portion  6334 . A portion of the inflow path  6148  may be disposed within the interior volume of the blowdown reservoir  6014 . 
     The obstruction  6146  shown includes a plate which is integral with a wall of the inflow path  6148  and opposite an inflow port  6336  from the steam chest  6072 . The plate also extends downward into the blowdown reservoir  6012  at an angle transverse to the first portion  6333  of the inflow path  6148 . This segment may block splashing and other disturbances from passing into the sheltered portion  6334  from the unsheltered portion  6337 . As shown, a venting pathway  6338  may also be included to allow gases displaced by incoming blowdown or generated due to evaporation to exit the blowdown reservoir  6012 . The venting pathway  6338  may run substantially parallel to and above (with respect to the gravity) the first portion  6333  of the inflow path  6148 . The venting pathway  6338  in the example embodiment may lead to the steam chest  6072 . The venting pathway  6338  may have a smaller cross sectional area than the first portion  6333  of the inflow path  6148 . A venting orifice  6152  may be included in the wall of the steam chest  6072  and establish fluid communication between the venting pathway  6338  and steam chest  6072 . The venting orifice  6152  may be of smaller cross sectional area than the venting pathway  6338 . 
     As mentioned above, liquid level within the blowdown reservoir  6014  may be sensed by a blowdown level sensor  6074 . Any suitable sensor for measuring the liquid level within the blowdown reservoir  6014  may be used, however, a float-type sensor similar to those described elsewhere herein is depicted. The blowdown level sensor  6074  may include a float assembly including a float  6154  attached to an arm  6156 . In the example, the float  6154  is depicted as a hollow structure attached to the end of the arm  6156 . In other embodiments, the float  6154  may be solid and made of a buoyant material which is resistant to heat and corrosion. The arm  6156  may be coupled to a pivot  6158 . Preferably, the blowdown level sensor  6074  may be disposed in the sheltered portion  6334 . 
     As the liquid level within the blowdown reservoir  6014  changes, the float  6154  position may rise and fall in kind across a float sweep range. As the float  6154  is attached to the arm  6156 , the arm  6156  may pivot about the pivot  6158 . The blowdown level sensor  6074  may include a hall effect sensor  6160  which, referring now primarily to  FIG. 16 , monitors the position of at least one magnet  6155  which displaces as the liquid level changes. The at least one magnet  6155  may be located on the float  6154  or the arm  6156  for example. In the example shown, two magnets  6155  may be mounted adjacent the pivot  6158 . The blowdown reservoir  6014  may be disposed so as to allow the blowdown level sensor  6074  to directly measure the liquid level in the steam chest  6072  at least when the purifier  6010  is in certain states (e.g. start-up). The sweep range or displacement range of the float  6154  may be selected such that the float  6154  may rise along with the liquid level in the steam chest  6072 . Though the example, embodiment is described having a hall effect sensor  6160  other types of sensors may also be used. For example, some embodiments may include a rotary encoder or potentiometer instead of or in addition to a hall effect sensor. 
     The sweep range of the float assembly may be selected such that the range is inclusive of points at even height with all steam chest liquid levels to be expected during at least certain purifier  6010  operational states (e.g. start up). Thus, the blowdown level sensor  6074  may be a direct level sensor which directly measures the level of concentrate (if in the expected range) within the steam chest  6072  to which the blowdown reservoir  6014  is attached. 
     In some embodiments, while purified liquid is being produced by the purifier  6010 , the liquid level may be sensed less directly. For example, blowdown level sensor  6074  may have a sweep range inclusive of points above the expected range of liquid levels in the steam chest  6072 . The turbulent boiling action occurring in the steam chest  6072  may occasionally splash liquid into the blowdown level sensor  6074  to fill the blowdown level sensor  6074 . The controller  6034  (see, e.g.,  FIG. 2 ) may analyze the rate of blowdown accumulation to determine if the liquid level in the steam chest  6072  is in an expected range. In the event that the rate is outside of a defined range, it may be determined the liquid level in the steam chest  6072  is requires adjustment or is abnormal. 
     Referring now to  FIG. 17 , a perspective view of the purifier  6010  and blowdown reservoir  6014  is shown. Only blowdown flow conduits are shown in  FIG. 17  for sake of clarity. As shown, the blowdown reservoir  6014  may be attached to a blowdown flow conduit  6162  which serves as an outlet to the blowdown reservoir. The outlet may establish a flow path from the blowdown reservoir  6014  to the blowdown heat exchanger  6008 B. A blowdown reservoir valve  6356  (see, e.g.  FIG. 42-43 ) may also be included to control the purging of the blowdown process stream from the purifier  6010 . The blowdown reservoir valve  6356  may be operated by a controller  6034  (see, e.g.,  FIG. 2 ) to maintain the liquid level within the steam chest  6072  within a desired range. Data from the blowdown level sensor  6074  may be used to inform actuation of the blowdown reservoir valve  6356 . As the level in the steam chest  6072  may be directly monitored via the blowdown level sensor  6074 , the level of concentrate within the steam chest  6072  may be controlled to a known level via the blowdown reservoir valve  6356 . 
     A number of manual drain valves  6166 ,  6168  may also be included. These manual drain valves  6166 ,  6168  may be used to empty the purifier  6010  during maintenance or other non use periods. In the example shown in  FIG. 17 , a manual drain valve  6166  is associated with the blowdown reservoir  6014 . A manual drain valve  6168  is also associated with the sump  6052 . These manual drain valves  6166 ,  6168  may be hand operated ball valves in specific implementations. Though these valves  6166 ,  6168  are described as manually operated, they may also be actuated by a controller  6034  in other embodiments. 
     Referring now to  FIG. 18 , an exploded view of an exemplary steam chest  6072  is shown. The steam chest  6072  may include a mist eliminator assembly  6062 . The mist eliminator assembly  6062  may help to prevent liquid phase water from passing beyond the steam chest  6072  of the water purifier. The mist eliminator assembly  6062  may establish a tortuous path from boiling liquid in the bottom of the steam chest  6072  to a compressor  6064  of the system  6000 . The tortuous path may make it difficult for any liquid phase water droplets entrained in the vapor to pass all the way through the mist eliminator assembly  6062 . 
     In the example shown, the mist eliminator assembly  6062  includes a number of mist eliminating strata  6170 A-C. The strata  6170 A-C include a number of openings  6172  which are spaced to create a long, meandering travel pathway for the vapor. The first stratum  6170 A includes openings  6172  around its periphery. These openings  6172  are spaced generally at regular angular intervals about the stratum  6170 . The next stratum  6170 B includes a single, central opening  6172 . Thus the second stratum  6170 B forces vapor to change direction and travel from the sides of the steam chest  6072  to the center of the steam chest  6072  in order to proceed to the next stratum  6170 C. The third stratum  6170 C includes openings disposed along its periphery similarly to the first stratum  6170 A. Again, the vapor is forced to change direction and flow from the center of the steam chest  6072  to the sidewalls  6174  of the steam chest  6072 . In other embodiments, the number of strata may differ. 
     Any liquid phase water droplets may tend to fall out of the vapor due to the directional changes and long travel path necessary to navigate the strata  6070 A-C of the mist eliminator assembly  6062 . Each stratum  6170 A-C of the mist eliminator assembly  6062  may have a sloped surface which allows any liquid phase water to easily drain out of the mist eliminator assembly  6062 . In the example embodiment, the strata  6070 A-C are all shaped as conic frustums which slope downwards towards the sidewalls  6174  of the steam chest  6072 . A small gap between the strata  6170 A-C of the mist eliminator assembly  6062  and the sidewalls  6174  may exist to allow liquid phase water to fall back into the pool of liquid at the bottom of the steam chest  6062 . 
     Referring now also to  FIGS. 19-21  in addition to  FIG. 18 , the mist eliminator assembly  6062  may also include a compressor feed channel  6176  through which vapor transits before reaching a compressor  6064 . The compressor feed channel  6176  may accommodate a flow path convoluter  6178  or vane pack. The flow path convoluter  6178  or vane pack may split the incoming vapor into a number of discreet flow channels  6180 . Each of the flow channels  6180  may include at least one flow redirection feature(s)  6182 . Again, these redirection features  6182  may serve to help eliminate any liquid phase water droplets which are advancing through the mist eliminator assembly  6062 . 
     As best shown in  FIG. 19 , the flow path convoluter  6178  may include a number of individual plate members  6184  which are held together by connector shafts  6186 . The plate members  6184  are arranged in a nested or layered arrangement with progressively smaller plate members  6184  being placed more proximally toward the center of the steam chest  6072 . The flow channels  6180  are defined by the gap between each adjacent plate member  6186  of the flow path convoluter  6178 . In some embodiments, each flow path  6180  may be defined by equal sized gaps. The gaps, may be less than 1 cm, for example, approximately 4.5 mm in some specific embodiments. Each of the individual plates  6184  includes a number of angled segments  6188  which make up the redirection features  6182 . As best shown in  FIG. 18  the flow path convoluter  6178  may also have a stepped region  6190  which compliments and may abut against the wall of the compressor feed channel  6176 . 
     Referring now to  FIG. 21 , a drip tray  6192  may form one of the walls of the compressor feed channel  6176 . A drip tray  6192  may catch and direct any liquid phase water droplets removed by the flow path convoluter  6178 . The drip tray  6192  may include a number of recessed features  6194  which liquid will tend to flow into. The recessed features  6194  may include a drain  6196  at their most recessed portion to allow liquid to exit the compressor feed channel  6176 . In the example shown, two types of recesses  6194  may be included. Some of the recesses are depicted as troughs which include a grade that deepens the trough as proximity to the drain  6196  increases. The troughs may generally be aligned with flow redirection features  6182  of a flow path convoluter  6178  when the flow path convoluter  6178  is installed within the compressor feed channel  6176 . A funnel type recess may also be included in the drip tray  6192 . The funnel type recess may be shaped as a conic frustum whose drain  6196  forms an opening in the frustum. The funnel type recess may be disposed at a location downstream of the flow path convoluter  6178  when the flow path convoluter  6178  is installed within the compressor feed channel  6176 . 
     Referring now primarily to  FIG. 22 , the third stratum  6170 C of the mist elimination assembly  6062  may include a berm member  6198 . The berm member  6198  may project from the third stratum  6170 C to the drip tray  6192 . As shown, the berm member  6198  is shaped as a segment of a spiral. The berm member  6198  also includes a hooked portion  6200  which is roughly perpendicular to the portion of the berm member  6198  from which it extends. The berm member  6198  is disposed such that all drains  6196  of the drip tray  6192  are on a first side of the berm member  6198 . Liquid passing through the drains  6196  to the surface of the third stratum  6170 C may flow along the surface of the third stratum  6170 C and be redirected by the berm member  6198 . As the berm member  6198  is shaped as a segment of a spiral and the surface of the third stratum  6170 C is sloped, the berm member  6198  may redirect liquid along a down sloping path toward an end  6202  of the berm member  6198 . This end  6202  may be positioned adjacent an opening  6172  along the periphery of the third stratum  6170 C. 
     Referring now primarily to  FIGS. 23 and 24 , after passing through the mist eliminator assembly  6062 , vapor may be compressed by a compressor  6064 . The compressor  6064  may be an impeller type compressor  6064 , though other compressor varieties may be used in alternative embodiments. The compressor  6064  in the example embodiment is mounted in an off-center location with respect to the longitudinal axis of the steam chest  6072 . The steam chest  6072  includes a receiving well  6210  which is recessed into the side wall  6174  of the steam chest  6072 . This receiving well  6210  protrudes into the interior volume of the steam chest  6072 . The various strata  6170 A-C of the mist eliminator assembly  6062  may include well accommodating voids  6212  (see, e.g.,  FIG. 22 ) which accept the receiving well  6210 . A motor  6214  may seat within the receiving well  6210 . The motor  6214  may, for example, be or be similar to any of those described elsewhere herein. The motor  6214  may receive power via a motor power cable  6226 . 
     The motor  6214  may drive an impeller  6216  which is mounted within a compressor housing  6218 A, B. The impeller  6216  is attached to an impeller rotor assembly  6232  which may be caused to rotate via operation of the motor  6214 . The impeller  6216  shown may be a single stage design, but multistage designs such as any of those described herein may alternatively be used. As the compressor  6064  is mounted in an off-center location, the rotation axis of the impeller  6216  may also be off-center to the longitudinal axis of the steam chest  6074 . The rotation axis of the impeller  6216  may pass through the steam chest  6074  and run parallel to the longitudinal axis of the steam chest  6074 . 
     Vapor may enter the compressor housing  6218 A, B through an inlet  6220 , be compressed by the rotating impeller  6216 , and exit the compressor  6064  through an outlet  6222  at an increased pressure and temperature. The temperature of vapor entering the compressor  6064  at the inlet  6220  may be sensed by an inlet temperature sensor  6066 . Likewise, the temperature of compressed vapor exiting the compressor  6062  through the outlet  6222  may be sensed by an outlet temperature sensor  6068 . These temperature sensors  6066 ,  6068  may be thermistors, thermocouples, or any other suitable temperature sensor. 
     The compressor  6064  may also include a number of mounts  6224 . These mounts  6224  may include a fastener  6228  which extends though a mounting projection  6230  included on a portion of the compressor housing  6218 A, B. The fasteners  6228  may couple into a portion of the housing  6102  (see, e.g.,  FIG. 5 ). This may allow for the compressor  6064  and any attached components to remain in place within the housing  6102  when other components of the purifier  6010  are removed. As further described later herein, the evaporator  6060 , condenser  6076 , sump  6052 , and potentially other components may be removed during maintenance. The mounts  6224  may allow for the compressor  6064  and any attached components (e.g. the steam chest  6072 ) to remain robustly suspended from the housing  6102  without other support. The mounts  6224  may include elastomeric elements allowing the mounts  6224  to be isolation mounts. In some embodiments, the elastomeric elements may be the series  60011  mounts available from Era Industrial Sales of 80 Modular Ave, Commack, N.Y. 
     Referring now to  FIGS. 25-28 , the impeller  6216  may be captured between a first and second compressor housing portion  6218 A, B. The first and second compressor housing portions  6218 A, B may each include a compression duct recess  6234 A, B (best shown in  FIG. 25 ). When the compressor  6064  is assembled, these recesses may cooperate to form a compression duct  6236 . The vanes  6238  of the impeller  6238  may be disposed and travel within the compression duct  6236  during operation. Additionally, the compression duct  6236  may form a portion of the flow path of the vapor entering the compressor  6064  thus allowing compression of the vapor by rotation of the impeller  6216 . As shown, the compression duct  6236  is generally torriodal in shape. 
     Interrupting the torriodal shape of the compression duct  6236  may be a reduced clearance segment  6240  of the compression duct recesses  6234 A, B positioned between the inlet  6220  and outlet  6222  of the compressor  6064 . The reduced clearance segment  6240  may help isolate the high pressure section of the compressor  6064  (near the outlet  6222 ) from the low pressure section of the compressor  6064  (near the inlet  6220 ). The reduced clearance segment  6240  acts as a stripper plate and blocks an amount of the high pressure vapor from passing back toward the inlet  6220  from the area near the outlet  6222 . In some embodiments, substantially only the vapor between the impeller blades  6238  may be able to pass between the inlet  6220  and outlet  6222  regions. Decompression channels  6242  formed by recesses in the reduced clearance segment  6240  may be included adjacent the inlet  6220 . These decompression channels  6242  may allow for high pressure vapor to expand to a lower pressure to minimize its impact on incoming low pressure vapor from the mist eliminator assembly  6062 . In the example, the decompression channels  6242  are substantially wedge shaped. The distance between the two housing sections  6218 A, B at the location of the decompression channel  6242  may be about 5-35% greater (e.g. at or about 9 or 10% greater) than the distance between the two housing sections  6218 A, B at the reduced clearance segment  6240 . 
     Referring now also to  FIGS. 29-31 , cross-sectional views of the inlet  6220  and outlet  6222  to the compressor  6064  taken at the indicated lines in  FIG. 29  are depicted. The inlet  6220  ( FIG. 30 ) may be formed from flow channels provided in the first and second compressor housing portion  6218 A, B as well as a first and second cover member  6244  A, B. The first cover member  6244 A may be attached to the first compressor housing portion  6218 A. The first cover member  6244 A seals the inlet  6220  from the external environment and may be coupled to the first compressor housing portion  6218 A via fasteners or any other suitable coupling. A gasket member  6246  may be included to help aid in establishing a suitable seal. The first cover member  6244 A may be shaped as a shallow dish or cup. 
     The second cover member  6244 B may be attached to the second compressor housing portion  6218 B via fasteners or any other suitable coupling. The second cover member  6244 B may form a seal between the interior of the inlet  6220  and the external environment. A gasket member  6248  may be included to aid in establishing a suitable seal. The gasket members  6246 ,  6248  and other gasket members described herein may be o-rings (shown), planar gaskets, form in place gaskets or any other compressible or elastomeric member. The second cover member  6244 B may be shaped as an elongated dome or stadium shape. The second cover member  6244 B may also include a port  6250 . The port  6250  may allow for installation of an inlet vapor temperature sensor  6066 . 
     The inlet  6220  may also include a dividing body  6252  which splits the incoming low pressure vapor flow into a plurality of flow paths. In the example shown, the dividing body  6252  is a bifurcating body which divides the incoming vapor into first and second streams. A first stream created by the dividing body  6252  may lead to a first side  6254 A of the impeller  6216 . The second stream may lead to a second side  6254 B of the impeller  6216 . The dividing body  6252  may also form part of the wall of the compression duct  6236 . In the example embodiment, the dividing body  6252  includes a portion of the reduced clearance segment  6240  of the compression duct  6236 . 
     The outlet  6222  may be formed via flow channels in the first and second compressor housing portions  6218 A, B as well as a cover member  6256  and a condenser inlet coupler  6258 . The cover member  6256  may be attached via fasteners or another suitable coupling to the second compressor housing portion  6218 B. The cover member  6256  may form a seal between the interior of the outlet  6222  and the external environment. A gasket member  6260  may be included to aid in establishing a suitable seal. The cover member  6256  may include a port  6264 . The port  6264  may allow for installation of an outlet vapor temperature sensor  6068 . As shown, the cover member  6256  may be generally dome shaped. 
     Similarly to the inlet  6220 , the outlet  6222  may include a dividing body  6266 . The dividing body  6266  may combine the exiting high pressure vapor flow from a plurality of flow paths into a single flow path. In the example shown, the dividing body  6266  is a bifurcating body which combines the outgoing vapor into a single stream. A first stream created by the dividing body  6252  may lead from the first side  6254 A of the impeller  6216  toward the condenser inlet coupler  6258 . The second stream may lead from a second side  6254 B of the impeller  6216  to the condenser inlet coupler  6258 . Both streams may be combined at the condenser inlet coupler  6258 . The dividing body  6266  may be shaped such that the first and second streams are combined before reaching the condenser inlet coupler  6258 . The dividing body  6266  may also form part of the wall of the compression duct  6236 . In the example embodiment, the dividing body  6266  includes a portion of the reduced clearance segment  6240  of the compression duct  6236 . 
     While the compressor  6064  may be mounted in an off-center position with respect to the purifier  6010 , the compressed high temperature vapor may exit the compressor  6064  substantially in line with the axis of the purifier  6010 . After exiting the compressor  6064 , the compressed vapor may follow a substantially straight line path into the condenser  6076 . To facilitate this, the condenser inlet coupler  6258  may have a center point which is substantially in line with the axis of the purifier  6010 . Such a straight line flow path into the condenser  6076  may help to minimize flow losses in the fluid exiting the compressor  6064 . 
     Referring now to  FIG. 32 , an exploded view of various components of a purifier  6010  is shown. As shown, the condenser inlet coupler  6258  may attach through the wall of the steam chest  6072  to an intermediate conduit  6270 . The condenser inlet coupler  6258  may include a rounded or chamfered edge  6272  to facilitate mating of the condenser inlet coupler  6258  to the intermediate conduit  6270 . To aid in creating a seal at the interface of the condenser inlet coupler  6258  and the intermediate conduit  6270 , a gasket member may be included. The gasket member may be an o-ring or torriodal ring shaped elastomeric or compliant member. 
     One or more stratum  6070 A-C of the mist elimination assembly  6062  may include a sleeve projection  6276  which is sized to accept a portion of the intermediate conduit  6270 . The intermediate conduit  6270  may include an indented region  6286  in its exterior surface. The indented region  6286  may be shaped complimentarily to a gasket member  6280  which may seat into the indented region  6286 . When assembled, the gasket member  6280  may be compressed between an interior face of the sleeve projection  6276  and the exterior face of the intermediate conduit  6270 . This compression may prevent liquid in the lower portion of the steam chest  6072  from passing between the interior of the sleeve projection  6276  and exterior of the intermediate conduit  6270  and into the mist eliminator assembly  6062 . The gasket member  6280  may also aid in positionally locating the mist elimination assembly  6062 . 
     The intermediate conduit  6270  may seat and seal against an end of the condenser inlet  6274 . This seal may inhibit any flow from the steam chest, which may contain concentrated blowdown, into the condenser inlet  6274 . As shown, at least one gasket member  6282 ,  6284  may be included to help create a robust seal between intermediate conduit  6270  and the condenser inlet  6274 . In the example embodiment a number of gasket members  6282 ,  6284  are included to create redundant seals. When assembled, high pressure compressed vapor from the compressor  6064  may pass through the condenser inlet coupler  6258 , the intermediate conduit  6270 , and condenser inlet  6274  along a straight line path formed by these components before entering the evaporator-condenser housing  6268 . 
     Referring now to  FIG. 33-34 , the condenser inlet  6274  may extend through the second tube sheet  6142 B to the first tube sheet  6142 A. The tube sheets  6142 A, B, which may be made of a compressible material, may form a seal around the exterior of sealing segment  6290  portions of the condenser inlet  6274 . The portions of the condenser inlet  6274  which seal against the tube sheets  6142 A, B may be smooth, solid lengths of tubing. As the condenser inlet  6274  is hollow, an interior plug  6294  may be placed within the condenser inlet  6274  near the first tube sheet  6142 A. This plug  6294  may create a seal preventing fluid communication between the condenser  6076  and sump  6052 . The plug  6294  may be a disc which is welded or otherwise coupled into the condenser inlet  6274 . Additionally, at least one drain port  6296  may be included adjacent the plug  6294  to encourage draining of product process stream  6298  from the condenser inlet  6274 . Alternatively, the condenser inlet  6274  may only extend through the second tube sheet  6142 B and extend a small distance if at all into the interior volume of the condenser  6076 . In such embodiments, the first tube sheet  6142 A may include a solid section in place of the void which seals around the sealing segment  6290  of the condenser inlet  6274 . 
     The condenser inlet  6274  may include a fenestrated segment  6288  as well. The fenestrated segment  6288  may be included between the sealing segments  6290  of the condenser inlet  6274 . This fenestrated segment  6288  may include a number of fenestrations  6292 . The fenestrations  6292  may act as vapor flow diffusers and help to create a uniform distribution of high pressure vapor (shown as stippling) entering the condenser  6076 . The fenestrations  6292  may be any shape including, but not limited to, circular, round, ovoid, elliptical, polygonal, and star shaped. In the example, the fenestrations  6292  are elongate rectangles with rounded corners. The fenestrations  6292  may be included in a number of sets disposed at different locations about the fenestrated segment  6288 . In the example shown, there are four sets which are spaced evenly from one another. Within each set, the fenestrations  6292  may also be placed at substantially even angular intervals from one another. Fenestrations  6292  may, for example be placed every 30-60° (e.g. every 45°). 
     An alternative condenser inlet  6274  is depicted in  FIG. 35 . As shown, the condenser inlet  6274  includes a fenestrated region  6288  and sealing regions  6290 . The fenestrations  6292  are round and roughly circular in this example. Additionally, the condenser inlet  6274  includes a solid span  6300  which is devoid of fenestrations  6292 . The solid span  6300  may be positioned within the condenser  6076  when the purifier  6010  is assembled. The fenestrated section  6288  is located on a portion of the compressor inlet  6274  proximal the compressor  6064 . Thus the fenestrated section  6288  may be located such that it is the first portion of the condenser inlet  6274  within the condenser  6076  to receive high pressure steam from the compressor  6064 . At the transition from the fenestrated region  6288  and solid span  6300  a plug  6294  (see, e.g.  FIG. 33 ) may be included. 
     Referring primarily to  FIGS. 34 and 36  as the high pressure and temperature vapor entering the condenser  6076  begins to condense, a product process stream  6298  may begin to collect at the bottom of the condenser  6076 . Additionally, the latent heat of condensation may be transferred to the evaporator tubes  6140  aiding in the evaporation of new incoming source water. A product reservoir  6012  may be included and may be attached to the evaporator-condenser housing  6268 . The product reservoir  6012  may be attached to the evaporator condenser housing  6268  via a product reservoir inlet  6302 . The product reservoir inlet  6302  may be disposed adjacent a product accumulation surface such that the product process stream  6298  may begin to fill the product reservoir  6012  shortly after or as the product water begins to collect. In the example, the product accumulation surface is the first tube sheet  6142 A. 
     As shown, a product level sensor  6078  may be included within the product reservoir  6012 . The product level sensor  6078  may be a float type sensor and include a float  6304  coupled to an arm  6306  which displaces about a pivot point  6308 . Similarly to the blowdown level sensor  6074  (see, e.g.,  FIG. 16 ), the product level sensor  6078  may include a number of magnets  6310 . As the level of liquid within the product reservoir  6012  rises and falls, the arm  6306  may rotate about the pivot point  6308  as the float  6304  is displaced. The position of the magnets  6310  may be tracked by a Hall Effect sensor  6322  (see, e.g.,  FIG. 38 ) to determine the level of liquid within the product reservoir  6012 . 
     The product reservoir  6012  is disposed such that the product level sensor  6078  may directly sense a liquid level not only within the product reservoir  6012  but also within the condenser  6076 . To facilitate this, the product level sensor  6078  may be disposed such that the sweep range of the float  6304  may pass above the product reservoir inlet  6302 . Thus, the condenser  6076  may also double as a product stream reservoir whose volume may be monitored via the product level sensor  6078 . As such, the product reservoir  6012  may be described as an auxiliary product reservoir. In certain embodiments, the sweep range of the float  6304  may be selected such that the product level sensor  6078  may measure a volume of product in the condenser  6076  up to 4-10 L (e.g. 6 or 6.5 L). 
     The product reservoir  6012  may include a product outlet  6312  from which the product process stream may exit the product reservoir  6012 . This outlet  6312  may be connected to a product flow conduit leading to the product heat exchanger  6008 A as described elsewhere herein. The example outlet  6312  is located in line with the bottom interior surface  6316  of the product reservoir  6012 . The product reservoir  6012  may also include a venting port  6314 . The venting port  6314  may allow for gases to be displaced out of the product reservoir  6012  as high pressure vapor from the compressor  6064  condenses within the condenser  6076  and begins to fill the product reservoir  6012 . A condenser vent  6318  may also be included to relieve excess pressure, volatiles, and non-condensable gasses from the condenser  6076  as needed. Both the vent port  6314  and condenser vent  6318  may be attached to a vent flow path  6320 . 
     Referring now to  FIG. 37 , a perspective view of a system  6000  is shown. Fluid lines other than the vent flow paths  6320  have been hidden in  FIG. 37  for sake of clarity. Venting gases from the evaporator-condenser housing  6268  and the product reservoir  6012  may travel along the vent flow paths  6320  to a pressure relief assembly  6324 . The pressure relief assembly  6324  may include a pressure relief valve  6326 . The pressure relief valve  6326  may be a failsafe valve which opens in the event of an over pressure condition forming in the purifier  6010 . In the event the pressure relief valve  6326  is forced open, venting gas may vent via a vent flow path  6320  attached to the pressure relief valve  6326  outlet. The pressure relief valve  6326  may be set to open at a predetermined pressure which may in some specific examples be at or about 15 psig. The pressure relief assembly  6324  may also include a vacuum break  6330 . The vacuum break  6330  may allow for the purifier  6010  to equalize with ambient pressure during cool down. The vacuum break  6330  may, for example, include a check valve which allows the purifier  6010  to hold pressure during operation, but draw in ambient air if the interior of the purifier  6010  is below ambient. 
     From the pressure relief assembly  6324 , gases may travel to a vent flow path  6320  which runs through the blowdown heat exchanger  6008 B. In some embodiments, a vent valve  6328  may be included to control the flow of gases to the blowdown heat exchanger  6008 B. The gases may run through the blowdown heat exchanger  6008 B in countercurrent fashion to source water entering the system  6000 . These gases may transfer thermal energy to the incoming source water, warming the source water. The cooling of these gases may allow for some of these gases to condense as they pass through the heat exchanger  6008 B making them easier to dispose of. 
     Referring now to  FIGS. 38 and 39  two perspective views detailing product flow paths  6322  an example system  6000  are shown. Only the product flow paths  6322  and not those of source water or other process streams are shown in  FIGS. 38 and 39  for sake of clarity. As shown, product water leaving the product reservoir  6012  may flow to both the product heat exchanger  6008 A and a bearing feed pump  6080 . In the example embodiment a branch fitting  6332  is included to split the product flow for this purpose. Product water flowing through the heat exchanger  6008 A, may exit the heat exchanger  6008 A at reduced temperature after transferring heat to the incoming source water. The cooled product water may flow out of the product heat exchanger through a product flow path  6322 . The bearing feed pump  6080  may pump a portion of the product water leaving the product reservoir  6012  to the compressor  6064 . The bearing feed pump  6080  may be a solenoid pump. As described elsewhere herein, the product water may be used to lubricate an impeller bearing. 
     Referring now primarily to  FIGS. 40-41 , the cooled product process stream exiting the product heat exchanger  6008 A may proceed to a sensing manifold  6340 . Product may flow into the sensing manifold at an inlet port  6342  and flow along an interior flow path in communication with one or more sensors  6082 A,  6082 B. In the example embodiment, two sensors  6082 A,  6082 B are shown, however, other embodiments may include additional sensors. In some embodiments, redundant sets of identical sensors  6082 A,  6082 B may be included. The at least one sensor  6082 A,  6082 B may be a conductivity sensor or conductivity and temperature sensor. Other sensor types which may provide a data signal related to water quality such as turbidity, pH, Redox Potential, TDS, analyte sensors, TOC, etc. may also be included. 
     The sensing manifold  6340  may also include a valve or valves  6344  which may be operated by a controller  6034  (see, e.g.,  FIG. 2 ) to direct the product process stream based on data provided from the at least one sensor  6082 A,  6082 B. If the water quality (e.g. conductivity value) is outside of a threshold value, a valve leading to a drain flow path  6346  may be opened. If the water quality (e.g. conductivity) is in compliance with a predetermined threshold value, the controller  6034  (see, e.g.,  FIG. 2 ) may actuate the valve or valves  6084 ,  6086  to direct the product process steam to a medical system flow path  6348 . The valves  6084 ,  6086  may also be actuated by the controller  6034  based on signals the controller  6034  receives from a medical system  6004  (see, e.g.  FIG. 2 ). 
     Referring now primarily to  FIGS. 42-43 , the cooled vent and blowdown stream exiting the blowdown heat exchanger  6008 B may travel to a mixing can  6350 . In some embodiments, the vent stream may not be routed through the blowdown heat exchanger  6008 B and instead be routed directly to the mixing can  6350 . As shown, the mixing can  6350  includes a port  6352  to which a blowdown flow conduit  6162  is attached. The Mixing can  6350  also includes a port  6354  to which a vent flow path  6320  is attached. Inflow to the mixing can  6350  may be controlled by valves  6356 ,  6358  which respectively control communication from the blowdown port  6352  and steam port  6354  to an interior volume of the mixing can  6350 . An additional port  6360  coupled to a source fluid line  6126  may also be included. After mixing, fluid may exit the mixing can  6350  via an outlet port  6362  which may be coupled to a drain conduit  6364 . 
     A mixing can  6350  may be used to combine a number of process streams from the purifier. The vent stream, for example, may be mixed with the cooled blowdown stream to ensure that any hot gas which may have made it through the blow down heat exchanger  6008 B is quenched to a relatively low temperature. As shown, the mixing can  6350  also includes at least one sensor  6096  which in the example embodiment may be a temperature sensor. A controller  6034  (see, e.g.,  FIG. 2 ) may monitor data from the sensor  6096  and determine if the temperature within the interior volume of the mixing can  6350  is below a predefined threshold. If the interior of the mixing can  6350  is too hot, cool source water may enter the mixing can through the source shunt port  6360 . A shunt valve  6100  (see, e.g.,  FIG. 2 ) may be included upstream of the mixing can  6350  (or attached to the mixing can in some embodiments) to control the flow of source water into the mixing can  6350 . In the example embodiment, the mixing can  6350  also includes a vacuum break  6330 . The vacuum break  6330  may be included on the mixing can  6350  instead of on the pressure relief assembly  6324  as previously described. 
     In some embodiments, and referring now primarily to  FIG. 44 , a portion of the purifier  6010  may be attached to a pivot  6365 . The pivot  6365  may allow the attached portion of the purifier  6010  to be easily removed from the purifier  6010  for cleaning, replacement, to provide easy access to other portions of the purifier  6010  or for other maintenance purposes. A pivot  6365  may, for example, allow for the evaporator-condenser housing  6268  to be removed for inspection or a clean out of place operation such as a descaling procedure. In the example, both the evaporator-condenser housing  6268  and sump  6052  are arranged for removal via rotation about the pivot  6365 . 
     As shown in  FIG. 44 , the pivot  6365  is attached to a support plate  6370 . The support plate  6370  may extend under the sump  6052  to support the removable components. In some embodiments, the support plate  6370  may also be fastened to the sump  6052  to aid in retaining and positioning of the removable components on the support plate  6370 . Support members  6372  may be included to reinforce the support plate  6370  depending on the material of the support plate  6370  and weight of the removable components. 
     The purifier  6010  may be provided in a number of sections (e.g. a first and second) which are coupled to one another via fasteners in a first state. The fasteners may include at least one clamp. In the example embodiment, the fasteners are shown as band clamps  6374 . Referring now also to  FIGS. 45-46 , once, in a second state, the band clamp  6374  which couples the evaporator-condenser housing  6268  to the steam chest  6072  is removed the full weight of the evaporator-condenser housing  6268 , sump  6052 , and any attached components may be supported by the pivot  6365 . As shown best in the exploded view of  FIG. 44 , a bias member  6376  may be included in the pivot  6365 . As a result of the band clamp  6374  being removed, the bias member  6376  may be caused to transition to an energy storing state such as a compressed state (best shown in  FIG. 46 ). When the bias member  6376  is in the compressed state, the pivot  6365  and removable components may be displaced away from the steam chest  6072 . The amount of displacement may be chosen to provide clearance for the top of the condenser inlet  6274  as the removable components are swung away from the rest of the purifier  6010 . The displacement path of the support plate  6370  and the attached components may linear, though need not be in all embodiments. Specifically, the displacement path may be along or parallel to the axis of the pivot  6365 . In the exemplary embodiment the bias member  6376  may be a corrosion resistant gas spring. Other types of bias members  6376  may also be used such as coil springs, spring washers, disc springs, compressible elastomer, air bladders, or any other suitable bias member. 
     Once the bias member  6376  has transitioned to a compressed state or energy storing state, and referring now also to  FIG. 47 , the removable components (the sump  6052  and evaporator-condenser housing  6268  in the example) may be rotated about the axis  6378  of the pivot  6365 . Thus, the removable components may be swung away from the rest of the purifier  6010  and detached from the pivot plate  6370 . If these components are to be removed for out of place cleaning, a spare, replacement set of components may be placed onto the pivot plate  6370  and swung back into place minimizing downtime. After being swung back into place, the bias member  6376  may aid in reassembly as the bias member  6376  will help lift the replacement set of components into position. 
     Referring now to  FIGS. 48-49 , an example system  6000  similar to that shown representationally in  FIG. 3  is depicted. As shown, the system  6000  includes an enclosure  6550 . The enclosure  6550  is roughly rectangular in shape. As shown, the front for the enclosure  6550  includes two doors  6552 A,  6552 B. Additionally, a sampling recess  6554  is included in the front of the enclosure  6550 . The sampling recess  6554  may include a perforated tray  6556  upon which a cup, glass, or similar vessel may rest while water is dispensed from the sampling port  6038  (see, e.g.,  FIG. 3 ) of the system  6000 . Any spilt sample fluid may collect in a catch basin provided under the perforated tray  6556 . LEDs or similar lighting may be included to illuminate the sampling recess  6554 . In the example embodiment, a sample may be dispensed via the depression of a button  6558  which may, in some embodiments, be backlit. 
     The rear of the enclosure  6550  may include an opening through which a source connector  6560  for a source fluid line extends. A drain connector  6562  may extend through the back of the enclosure  6550  as well. Each of the source connector  6560  and drain connector  6562  may be quick-connect fitting depending on the embodiment. Power and data connections  6561  may also be provided through the rear of the enclosure  6550 . 
     The top of enclosure  6550  may be generally flat and include an outlet line  6564  for purified water. As shown, this outlet line  6564  may be insulated to help maintain temperature within the line and protect against contact with a user when very hot. A medical system  6004  or other point of use system or device may be disposed on top of the enclosure  6550  and placed into fluid communication with the outlet line  6564 . In some embodiments, the medical system  6004  or other system or device may be affixed (e.g. bolted, clamped, or otherwise mechanically retained). Alternatively, such a system or device may passively rest on top of the enclosure  6550 . Shelving  6566 , platforms, receptacles, or similar structures may be coupled to the enclosure  6550  for storage. In some embodiments, the shelving  6566  or receptacles may hold components utilized by a medical system  6004  or other device during use (e.g. acid reservoir and bicarbonate reservoir for a hemodialysis machine). 
     The enclosure  6550  may include a number of interior compartments which may be insulated from one another. For example, the enclosure  6550  may include a hot section housing  6102  where high temperature components of the system  6000  are housed insulated from the rest of the system  6000 . The other compartments of the enclosure  6550  may be cool section housings  6103 A, B which remain relatively cool in comparison to the hot section housing  6103 . The purifier  6010  (see, e.g.  FIG. 52 ) and heat exchangers  6008 A, B (see, e.g.,  FIG. 52 ) may be included in the hot section housing  6102 . In some embodiments, the purifier  6010  and heat exchangers  6008 A, B may have a foot print of less than 200 in 2  (e.g. less than 180 in 2 ). The height of the purifier  6010  may be less than 30 inches (e.g. 26.5 inches or less). 
     Referring now also to  FIG. 50  a front view of the enclosure  6550  is depicted with the doors  6552 A, B removed. As shown, a first filter  6006 A and second filter  6006 B may be included behind the doors  6552 A, B. The sampling port  6038  may be disposed intermediate the two filters  6006 A, B such that the sample is representative of the filtering ability of only the first filter  6006 A. In other embodiments, additional sampling ports  6038  may be included and there may be an ability to collect a sample downstream of both the first and second filter  6006 A, B. The filters  6006 A, B may be identical and may be 5-6 L activated carbon filters in certain embodiments. The filters  6006 A, B may be placed behind doors  6552 A, B to simplify replacement of the filters  6006 A, B after they have fulfilled a predetermined usage life or the controller  6034  determines that the filters  6006 A, B need to be replaced. The filtration source lines  6568  may be routed through cool section channels  6570  from cool section housing  6103 B to cool section housing  6103 A. The channels  6570  may be routed under or over portion of the hot section housing  6102  compartment. 
     Referring now also to  FIG. 51 , a rear perspective view of the system  6000  is shown with the rear panel of the enclosure  6550  removed. As shown, various manifolds  6572 ,  6574 ,  6576 ,  6578  as well as the mixing reservoir  6092  may be included in cool section housing  6103 B. In other embodiments, all of the manifolds  6572 ,  6574 ,  6576 ,  6578  may be combined into a single unitary manifold. The manifolds  6572 ,  6574 ,  6576 ,  6578  are described in greater detail later in the specification. A catch basin  6587  may be included beneath the manifolds  6572 ,  6574 ,  6576 ,  6578  and may include a leak sensor (not shown). The electronics for the system  6000  may also be included in the cool section housing  6103 B. In the example embodiment, the electronics are divided into a first and second electronics housing  6046 A, B. In other embodiments, a single housing may be used. Various data and power cabling may be fed through pass-through  6580  in portions of insulating material  6584  disposed in the walls of the hot section housing  6102 . The portion of insulating material  6584  may be insulating foam or elastomer material which is compressible in certain embodiments. The portions of insulating material  6584  in the example embodiment are depicted as plug like structures which are disposed in openings to the hot section housing  6102  from the interior of the cool section housing  6103 . These portions of insulating material  6584  may be in a compressed state against the walls of the openings in the hot section housing  6102 . Additionally, the pass-throughs  6580  may be compressed around any cabling (not shown) extending therethrough. This may help to establish a tight seal between the hot section housing  6102  and the cool section housing  6103 B. A line leading to air filter  6093  may also pass through a wall of the hot section housing  6102  to reach the air filter  6093 . 
     Referring now to  FIGS. 52 and 53 , perspective views of the system  6000  are shown with the enclosure  6550  removed. For sake of clarity, only source water carrying fluid lines are shown in  FIGS. 52-53 . Source water may enter the system  6000  at a source connector  6560  through a source connection line  6582 . In the example embodiment, and referring now also to  FIG. 54 , the source connector  6560  is included on an inlet manifold  6572 . The inlet manifold  6572  may also include a flow control valve  6032 , a check valve  6030  (see, e.g.,  FIG. 3 ), and one or more sensors. In the exemplary embodiment, a temperature sensor  6042  and pressure sensor  6036  are included on the inlet manifold  6572 . In other embodiments additional sensors which sense different characteristics of the incoming source water or sensors providing redundancy for those shown may be included. 
     From the source manifold  6572 , the source fluid may flow through the filters  6006 A, B and may be sampled through sampling port  6038  depending on the system  6000  mode or state  6000 . After filtration, source water may flow to a filtered source fluid connector  6568  included on a product heat exchanger manifold  6578 . Referring now also to  FIG. 55 , the product heat exchanger manifold  6578  may include a pressure regulator  6040  which may control the source water pressure to a predefined value (e.g. 10-30 psig). A post filtration pressure sensor  6044  may also be included in the product heat exchanger manifold  6578 . Readings from pressure sensor  6036  (see  FIG. 54 ) and pressure sensor  6044  may be compared by the controller  6034  to determine a pressure drop through the filters  6006 A, B. This pressure drop may be compared against a predetermined range of expected values. This may allow the controller  6034  to detect a clogged filter or detect a scenario in which the pressure drop is unexpectedly low or high. From the product heat exchanger manifold  6578 , the source fluid may flow to the product heat exchanger  6008 A, through a source line  6590 . A source proportioning control valve  6050 A for source water flow to the product heat exchanger  6006 A may also be disposed in the product heat exchanger manifold  6578 . 
     The flow path leading to the blowdown heat exchanger  6008 B may extend to an electronics housing  6046 A (see, e.g.  FIG. 51 ) of the system  6000  such that the source flow may serve to cool the electronics housing  6046 A. Alternatively or additionally, source water en route to the product heat exchanger  6008 A may be routed into heat exchange relationship with the electronics of the electronics housing  6046 A. In the example depicted in  FIGS. 52 and 53 , the electronics cooling line  6592  is routed in a path which doubles back upon itself at two locations before connecting to the blowdown heat exchanger manifold  6574 . The source fluid may flow from the blowdown heat exchanger manifold  6574  to the blowdown heat exchanger through a source line  6590  based on the operation of a source proportioning control valve  6050 B disposed in the blowdown heat exchanger manifold  6574 . A source divert valve  6100  may also be included in the blowdown heat exchanger manifold  6574  to allow source water to flow into a mixing reservoir  6092  which, in the example embodiment, is directly attached to the blowdown heat exchanger manifold  6574 . 
     As the source water passes through the heat exchangers  6008 A, B, it may be heated by various process streams of the purifier  6010  which are at a high temperature relative to the incoming source water. In turn, the various process streams may be cooled. After source fluid is passed through the heat exchangers  6008 A, B, it may be joined into a single stream at a flow joiner  6594  (e.g. Y-fitting, T-Fitting, U-Fitting, or the like) and be plumbed into the sump  6054  of the purifier  6010 . The sump  6054  may be a metal cast component in some embodiments. 
     Referring now also to  FIG. 56 , a view of the exemplary heat exchangers  6008 A, B is shown. The heat exchangers  6008 A, B may each be arranged as helices of tubing through which the source water and various process streams of the system  6000  may flow. The helices formed by each of the heat exchangers  6008 A, B may have substantially constant radii and pitch. At the ends of the heat exchangers  6008 A, B the pitch may become greater as shown. The heat exchangers  6008 A, B may be arranged in concentric fashion with one of the heat exchangers  6008 A, B having a smaller radius and being positioned inside of the other. In the exemplary embodiment depicted in  FIG. 56 , the blowdown heat exchanger  6008 B is positioned inside the product heat exchanger  6008 A. Each of the heat exchangers  6008 A, B may be disposed around the purifier  6010  to increase compactness of the system  6000 . The length of the fluid pathways in the product and blowdown heat exchangers  6008 A, B may be substantially equal. In some embodiments, the helices of the heat exchangers may be formed using the exterior surface of the purifier  6010  as a form. In such embodiments, the heat exchangers  6008 A, B may touch the sidewalls of the purifier  6010 . 
     A cross-sectional view of a portion of the exemplary heat exchangers  6008 A, B is shown in  FIG. 57 . As shown, each heat exchanger  6008 A, B includes a large diameter source flow conduit  6596 A, B which forms the exterior surface of the heat exchangers  6008 A, B. Within the source flow conduits  6596 A, B are conduits in which process streams from the water purifier  6010  are carried. The product water heat exchanger  6008 A in the exemplary embodiment includes three product flow conduit  6598  positioned within its source flow conduit  6596 A. The example blowdown heat exchanger  6008 B includes a single interior flow conduit  6599  within its source flow conduit  6596 B. This interior flow conduit  6599  may carry a concentrate or blowdown process stream from the purifier  6010 . In some embodiments, additional flow conduits may be included therein. Where the heat exchangers  6008 A, B are concentric and nested on inside the other, the innermost heat exchanger may include a layer of insulation  6597 . This may help to prevent transfer of heat to/from the purifier  6010 . In other embodiments, both heat exchangers  6008 A, B may include a layer of insulation  6597 . 
     Referring primarily to  FIG. 59 , a cross section of an example purifier  6010  taken at line  59 - 59  of  FIG. 58 , after source water passes into the sump  6052  the water may begin to fill a number of evaporator tubes  6140  as well as an evaporator reservoir  6015 . The evaporator reservoir  6015  may be disposed laterally to the evaporator  6060  and may have a cylindrical shape. In the example embodiment, the evaporator reservoir  6015  is greater in height than the evaporator  6060 . The evaporator reservoir  6015  may be in fluid communication with the sump  6052  through evaporator reservoir inlet  6604  extending to the sump  6052 . In the example, the evaporator reservoir inlet  6604  is positioned at a first end portion of the evaporator reservoir  6015 . The evaporator reservoir inlet  6604  may connect to the sump  6052  at a point where source water may begin to pass into the evaporator reservoir  6015  shortly after it begins being introduced into the sump  6052 . This may allow the fluid level in the evaporator reservoir  6015  to be substantially even with the level of fluid in the evaporator  6060 . An opposing second end of the evaporator reservoir  6015  may include a vent port which is attached to a venting pathway in fluid communication with the steam chest  6072  via a port  6612  (see, e.g.,  FIG. 65 ) of a blowdown reservoir  6014 . 
     The evaporator reservoir  6015  may include a level sensor  6073  which measures a liquid level in the evaporator  6060  based on displacement of a float  6606  within the evaporator reservoir  6015 . Displacement of the float  6606  may displace a potentiometer wiper in certain embodiments. In other embodiments, the float  6606  may include one or more magnet whose displacement is tracked by a Hall Effect sensor array. Alternatively, the sensor may be an XM-XT (e.g. XM-700) series sensor available from Gems Sensors Inc. of One Cowles Road, Plainville, Conn. Any other suitable sensor may be used as well. 
     The evaporator reservoir  6015  may be disposed such that a portion of the interior volume of the evaporator reservoir  6015  is even with any points in a controllable range or an expected range of evaporator  6060  liquid level values at least during a certain state(s) or mode(s) of operation of the purifier  6010  (e.g. a filling state or draining state). The displacement range of the float  6606  may be chosen to accommodate sensing over this range. In some embodiments, the displacement range of the float  6606  may only be a portion of the extent of the evaporator reservoir  6015 . For example, the displacement range of the float  6606  may only be about half (40%-60%) of the extent or height of the evaporator reservoir  6015 . In the example embodiment, the displacement range is roughly limited to the top half of the evaporator reservoir  6015 . In certain embodiments, the displacement range may extend from a top end portion of the evaporator reservoir  6015  at least to a midpoint of the evaporator reservoir  6015 , but not be greater than 70% of the extent of the evaporator reservoir  6015 . In some embodiments, the controller  6034  may receive a data signal from the level sensor  6073  in the form of a percent of float  6606  displacement along the float&#39;s  6606  entire displacement range. 
     During purified water producing modes or states, steam bubbles may be present in the evaporator tubes  6140  and a significant amount of splashing due to vigorous boiling may typically occur. As a result, there may not be a clear or discernible liquid level in the evaporator  6060  of the purifier  6010 . Instead, the liquid level may be non-uniform and highly dynamic. In such states, the evaporator level sensor  6073  may not measure the liquid level in the evaporator  6060 . Instead, the evaporator level sensor  6073  may be used to monitor other characteristics which may be useful in controlling operation of the system  6000 . For example, data related to the height of a relatively calm water column which may be present in the evaporator reservoir  6015  may be output by the evaporator level sensor  6073 . During operation, the evaporator level sensor  6073  may operate similar to a manometer. The height of the water column read by the evaporator level sensor  6073  may vary depending at least in part based on the pressure of vapor present in the evaporator  6060  and steam chest  6072 . The height of the water column read by the evaporator level sensor  6073  may also vary depending at least in part based on an average phase change location of fluid in the evaporator tubes  6140 . In some embodiments, the water column height output from the evaporator level sensor  6073  may be monitored during production of purified water. In the event that the water column begins to displace from a target location, the controller  6034  of the system  6000  may increase power to at least one of the heater  6054  and compressor  6064  perhaps in proportion to the rate at which the water column is displacing. Alternatively or additionally, the controller  6034  may decrease the amount of source water brought into the purifier  6010  by lowering the duty cycle of any source flow proportioning valves  6050 A, B. Again, this duty cycle alteration may be done in proportion to the rate of displacement of the water column level. During production of purified water, the water column may be at 50-60% of the height of the evaporator  6060 . In embodiments, where the displacement range of the evaporator level sensor  6073  is limited to the top half of the evaporator reservoir  6015 , the controller may target a float  6606  displacement of about 10% from the bottom of its displacement range. 
     The evaporator tubes  6140  and referring now primarily to  FIG. 60  may extend through the condenser  6076  from the sump  6052  volume to the steam chest  6072  volume. A first and second tube sheet  6142 A, B may include receiving orifices  6144  for accepting the ends of each of the evaporator tubes  6140 . The tube sheets  6142 A, B may hold the evaporator tubes  6140  in a generally evenly spaced pattern within the condenser  6076  volume. In the example embodiment, the tube sheets  6142 A, B may be constructed from a metal material which is brazed into connection with the evaporator tubes  6140  preventing fluid communication between the evaporator tubes  6140  and the interior volume of the condenser  6076 . The second tube sheet  6142 B may form the bottom wall of the steam chest  6072 . Use of metal tube sheets  6142 A, B may help to increase the compactness of the purifier  6010 . 
     In the example embodiment, less than 80 (specifically 76) evaporator tubes  6140  are included. In other embodiments, a greater or lesser number of evaporator tubes  6140  may be included. Each evaporator tube  6140  may have a substantially equal diameter which is between 6-12% (e.g. ˜8%) of the diameter of the condenser  6072 . In some embodiments, the evaporator tubes  6140  may not all be of equal diameter. The evaporator tubes  6140  may take up between 35 and 65% (e.g. ˜49.5%) of the interior volume of the condenser  6076 . The material from which the evaporator tubes  6140  are constructed may vary depending on the embodiment; however, a material with a high thermal conductivity may be used. The material used may be any of those described elsewhere herein. In embodiments where the evaporator tubes  6140  are brazed onto the tube sheets  6142 A, B, the materials chosen for the evaporator tubes  6140  and tubes sheets  6142 A, B may be any suitable material amenable to such a brazing operation. Stainless steel may be used in certain embodiments. In some embodiments, and as shown in  FIG. 60 , a sleeve  6688  providing part of the pathway from a compressor  6064  (see, e.g.,  FIG. 3 ) to the condenser  6076  also be brazed into place on one of the tube sheets  6142 A, B. 
     The evaporator tubes  6140  may include a filler element which fills a proportion of the cross sectional area of each of (or potentially only some) the evaporator tubes  6140 . In the example embodiment, the filler element is depicted as a substantially cylindrical rod  6600  which includes a number of nubs or other protuberances  6602  on the exterior of the rod  6600 . These nubs  6602  may aid in centering the rods  6600  within the evaporator tubes  6140 . This may encourage a thin layer or film of source fluid (a thin annulus in the example) to be present between exterior of the filler element and the interior surface of the evaporator tube  6140  within which the filler element is disposed. 
     Referring now primarily to  FIGS. 61 and 62 , a nub  6602  disposed at an end of the rod  6600  may rest on the tube sheet  6142 B defining the bottom of the steam chest  6072 . This nub  6602  may keep the bottom of the rod  6602  suspend above the bottom surface of the sump  6052 . Also shown in  FIG. 61 , a layer of insulation  6605  may be included in some embodiments. The layer of insulation  6605  may be placed around the condenser  6076 . The layer of insulation  6605  may insulate the purifier  6010  from heat exchange with the heat exchangers  6008 A, B in embodiments where the heat exchangers  6008 A, B are wrapped directly around the exterior of the purifier  6010  when wound into their respective helices. Other embodiments may be similarly insulated. 
     Referring now primarily to  FIGS. 63-66 , as heat from heating element  6054  (see, e.g.,  FIG. 3 ) and condensing vapor in the condenser  6076  evaporates the source water, a blowdown process stream or concentrate may be generated. The blowdown process stream may fill or be splashed about via vigorous boiling into a portion of the steam chest  6072  volume. As shown, a blowdown or concentrate reservoir  6014  may be attached to the side of the steam chest  6072 . In the example embodiment, the long axis of the blowdown reservoir extends alongside, but not through the evaporator  6060 . An enclosed sluiceway  6610  may extend from the steam chest  6072  and form a first portion  6624  of an inflow path  6614  to the blowdown reservoir  6014 . This sluiceway  6610  may be a cast part. Sluiceway  6610  may be coupled to an enclosure  6616  which defines a portion of the interior volume of the blowdown reservoir  6014 . In the example embodiment, the enclosure  6616  is a substantially cylindrical body or can type structure which extends downward from the sluiceway  6610 . An outlet port  6618  may be included in the bottom of the blowdown reservoir  6014  such that blowdown fluid may be emptied from the purifier  6010  as governed by a controller  6034  (see, e.g.,  100 A-B). 
     As best shown in  FIG. 66 , the blowdown reservoir  6014  includes an insert  6620  in the example embodiment. The insert  6620  in the example embodiment is a sleeve which is generally cylindrical. The insert  6620  may be inserted through the top of the enclosed sluiceway  6610  and coupled thereto. The insert  6620  may have a similar cross sectional shape to that of the enclosure  6616 , but be smaller in size so as to allow the insert  6620  to be nested inside the enclosure  6616 . When assembled, there may be a gap between the interior wall of the enclosure  6616  and the exterior of the insert  6620 . The insert  620  may also be disposed substantially concentrically with an axis of the enclosure  6616 . In the example shown, the insert  6620  is a tube. The gap may form a second portion  6626  of the inflow path  6614  to the blowdown reservoir  6014 . Thus the wall of the insert  6620  may act as an obstruction which shelters a portion  6628  of the blowdown reservoir  6014  and provides a barrier against effects of splashing and other violent liquid motion in the steam chest  6072 . The insert  6620  may include an opening  6630  to allow for flow of liquid from the inflow path  6614  to the sheltered portion  6628 . In the example, the bottom of the tube shaped insert  6620  is open, however, in other embodiments, the insert  6620  may include fenestrations, a mesh section, or grated section instead. A level sensor  6074 , such as any of those described elsewhere herein may be placed in the sheltered portion  6628  of the blowdown reservoir  6014 . This may allow the level sensor  6074  to sense a level of blowdown present in the steam chest  6072  which is substantially unadulterated by momentary disturbances introduced from violent or energetic boiling. In some embodiments, the controller  6034  may receive a data signal from the level sensor  6074  in the form of a percent of float displacement along its entire displacement range. In some examples, a one percent displacement may be equivalent to a change in volume of 1-2 ml (e.g. 1.86 ml) within the blowdown reservoir  6014 . 
     The insert  6620  includes various vent ports  6632  which may allow for gas to be displaced as the liquid level in the blowdown reservoir  6014  changes or as evaporation occurs. The vent ports  6632  may be located near or above the expected liquid level range during certain states of operation of the purifier  6010 . For example, the vent ports  6632  may be above the expected range of liquid levels during production of purified water. These vent ports  6632  may allow for gas to be displaced in or out of the sheltered portion  6628  as the float  6627  of the sensor  6074  displaces. A port  6612  may also be included in the wall of the enclosed sluiceway  6610  and allow for connection to the evaporator reservoir  6015  via a venting conduit. This may allow for gas to be displaced in and out of the evaporator reservoir  6015  as needed. 
     Referring now to  FIG. 67 , a perspective view of the purifier  6010  is shown. Only blowdown flow conduits  6634  are shown in  FIG. 67  for sake of clarity. As shown, the blowdown reservoir  6014  may be attached to a blowdown flow conduit  6634  which serves as an outlet to the blowdown reservoir  6014 . The outlet may establish a flow path from the blowdown reservoir  6014  to the blowdown heat exchanger  6008 B. A blowdown reservoir valve  6636  may also be included to control the purging of the blowdown process stream from the purifier  6010 . In the example embodiment, the blowdown reservoir valve  6636  is included in the blowdown heat exchanger manifold  6574 . The blowdown reservoir valve  6636  may be operated by a controller  6034  (see, e.g.,  FIG. 3 ) to maintain a flow of concentrate out of the purifier  6010 . Data from the blowdown level sensor  6074  may be used to inform actuation of the blowdown reservoir valve  6636 . As the rate of blowdown accumulation may be monitored via the blowdown level sensor  6074 , the level of concentrate within the system  6000  may be controlled via alteration of the duty cycle of the blowdown reservoir valve  6636 . As blowdown exits the blowdown heat exchanger  6008 B, the blowdown may flow into a mixing reservoir  6092  coupled to the blowdown heat exchanger manifold  6574 . A drain line  6638  may be attached to the mixing reservoir  6092  to allow waste streams to be purged out of the system  6000 . 
     Referring now also to  FIG. 68 , an exploded view of an exemplary steam chest  6072  is shown. A gasket  6641  may be included to help establish a fluid tight seal between the steam chest and the tube sheet  6142  B forming a bottom of the steam chest  6072  volume. The steam chest  6072  may include a mist eliminator assembly  6062 . In the example shown in  FIG. 68 , the mist eliminator assembly  6062  includes four strata  6640 A-D which redirect the flow of vapor as it proceeds toward the compressor  6064  similarly to as described in relation to  FIG. 18 . An over-pressure relief valve  6091  is included in the top of the steam chest  6072  in the example embodiment and may open in the event pressure in the purifier  6010  rises above a predefined threshold. 
     Referring now primarily to  FIG. 69-74 , after passing through the mist eliminator assembly  6062 , vapor may be compressed by a compressor  6064 . The compressor  6064  may be an impeller type compressor  6064 , though other compressor varieties may be used in alternative embodiments. The compressor  6064  in the example embodiment is mounted in an off-center location with respect to the longitudinal axis of the steam chest  6072 . The steam chest  6072  includes a receiving well  6646  for the compressor  6064  motor  6644 . The receiving well  6646  may be recessed into the side wall  6648  of the steam chest  6072 . The example receiving well  6646  protrudes into the interior volume of the steam chest  6072 . One or more of the various strata  6640 A-D of the mist eliminator assembly  6062  may include well accommodating voids  6642  (see, e.g.,  FIG. 68 ) which accept the receiving well  6646 . The motor  6214  may, for example, be or be similar to any of those described elsewhere herein. 
     The motor  6214  may drive an impeller  6652  which is mounted within a compressor housing  6650 A, B. The compressor housing  6650 A, B may be a cast part in certain embodiments. The impeller  6652  may be any design described herein including a single stage design (shown) or a multistage design. Vapor may enter the compressor housing  6650 A, B through an inlet  6654 , be compressed by the rotating impeller  6652 , and exit the compressor  6064  through an outlet  6656  at an increased pressure and temperature. The temperature of vapor entering the compressor  6064  at the inlet  6654  may be sensed by an inlet temperature sensor  6066 . Likewise, the temperature of compressed vapor exiting the compressor  6064  through the outlet  6656  may be sensed by an outlet temperature sensor  6068 . 
     In some embodiments, the bearing for the motor  6644  may be applied via a coating process (e.g. plasma coating). The coating may be applied over an undercut region. This coating may also be applied to the end races. The coating may for example be a chromium oxide coating. 
     The compressor  6064  may also include a number of mounting points  6658 . These mount points  6658  may accommodate fasteners  6660  which extends though the mounting points  6658 . The fasteners  6660  may couple the compressor  6064  to at least one bracket  6662  which extends from another portion of the purifier  6010  and aids in supporting the weight of the compressor  6064 . Two brackets  6662  are included in the example embodiment. The fasteners  6660  may also couple the compressor  6064  to a surface  6663  of the steam chest  6072 . 
     Referring now primarily to  FIG. 74 , one or more gasket  6664  may be compressed between this surface  6663  of the steam chest  6072  and the compressor housing  6650 A to establish a fluid tight seal between the components. The one or more gasket  6664  may also allow for an exterior surface of the steam chest  6074  to provide part of the inlet  6654  and/or outlet  6656  flow paths to and from the compressor  6064 . In the example embodiment shown in  FIG. 74 , the bottom of the inlet  6654  and outlet  6656  flow paths to the compressor  6064  are formed by the top exterior surface  6663  of the steam chest  6072 . 
     Referring now also to  FIGS. 75-77 , cross-sectional views of the inlet  6654  and outlet  6656  to the compressor  6064  taken at the indicated lines in  FIG. 75  are depicted. The inlet  6654  ( FIG. 76 ) may be formed from flow channels provided in the first and second compressor housing portion  6650 A, B, a cover member  6666 , and the top exterior surface  6663  of the steam chest  6072  as mentioned above. Similarly to as described in relation to  FIG. 30 , the incoming low pressure vapor flow may be split (e.g. bifurcated as shown) into a plurality of flow paths by a dividing body  6674 . The cover member  6666  may be attached to the second compressor housing portion  6650 B. The cover member  6666  may seal the inlet  6654  from the external environment and may be coupled to the second compressor housing portion  6650 B via fasteners or any other suitable coupling. A gasket member  6670  may be included to help aid in establishing a suitable seal. The cover member  6660  may be shaped as a curved ramp as shown in the cross section in  FIG. 76 . This shape may help to gently redirect vapor exiting the steam chest  6072  into the compression duct  6672  of the compressor  6064  and may help limit the amount of turbulence in the flow entering the compressor  6064  from the steam chest  6072 . A port  6680  may be included in the cover member  6660  to allow for introduction of a temperature sensor  6066  into the low pressure vapor inlet  6654  flow path. 
     The outlet  6656  ( FIG. 77 ) may be formed via flow channels in the first and second compressor housing portions  6650 A, B, a second cover member  6676  and the top exterior surface  6663  of the steam chest  6072  as mentioned above. Similarly to as described in relation to  FIG. 31 , the ejected high pressure vapor flow may be combined as it passes a dividing body  6684  from a plurality of flow paths into a single flow path. 
     The second cover member  6676  may be attached via fasteners or another suitable coupling to the second compressor housing portion  6650 B. The second cover member  6676  may form a seal between the interior of the outlet  6656  and the external environment. A gasket member  6678  may be included to aid in establishing a suitable seal. The second cover member  6676  may be shaped as a curved ramp similarly to cover member  6660 . This shape may help to gently redirect vapor exiting the compression duct  6672  into a condenser inlet  6686  (see, e.g.,  FIG. 78 ) and may help limit turbulence. The cover member  6676  may include a port  6682 . The port  6682  may allow for installation of an outlet vapor temperature sensor  6068 . 
     While the compressor  6064  may be mounted in an off-center position with respect to the purifier  6010 , the compressed high temperature vapor may exit the compressor  6064  substantially in line with the axis of the purifier  6010 . After exiting the compressor  6064 , the compressed vapor may follow a substantially straight line path into the condenser  6076 . To facilitate this, the condenser inlet  6686  extending from the compressor outlet  6656  may have a center point which is substantially in line with the axis of the purifier  6010 . Such a straight line flow path into the condenser  6076  may help to minimize flow losses in the fluid exiting the compressor  6064 . 
     Referring now to  FIG. 78 , an exploded view of various components of a purifier  6010  is shown. As shown, the condenser inlet  6686  may extend through the wall of the steam chest  6072 . The condenser inlet  6686  may include a sleeve  6688  which projection from the tube sheet  6142 B. The sleeve  6688  may be brazed, welded, integrally formed with, or otherwise coupled to the tube sheet  6142 B. To aid in creating a seal at the interface of the the sleeve  6688  and other portion of the condenser inlet  6686 , a gasket member or members may be included. This seal may inhibit any flow of concentrated blowdown from the steam chest  6072 , into the condenser inlet  6686  or condenser  6076 . When assembled, high pressure compressed vapor from the compressor  6064  may pass through the condenser inlet  6686  to the condenser  6076  along a straight line path. 
     Referring now primarily to  FIG. 79 , as the high pressure and temperature vapor entering the condenser  6076  begins to condense, a product process stream may begin to collect at the bottom of the condenser  6076 . Additionally, the latent heat of condensation may be transferred to the evaporator tubes  6140  aiding in the evaporation of new incoming source water. A product reservoir  6012  may be included and may be attached to the evaporator-condenser housing  6268 . The product reservoir  6012  may be attached to the evaporator-condenser housing  6268  via a product reservoir inlet  6692 . The product reservoir inlet  6692  may be disposed adjacent a product accumulation surface such that the product process stream  6690  may begin to fill the product reservoir  6012  shortly after or as the product water begins to collect in the condenser  6076 . In the example, the product accumulation surface is the first tube sheet  6142 A. 
     As shown, a product level sensor  6078  may be included within the product reservoir  6012 . The product level sensor  6078  may be any suitable sensor described herein. The product reservoir  6012  is disposed such that the product level sensor  6078  may directly sense a liquid level not only within the product reservoir  6012  but also within the condenser  6076 . Thus, the condenser  6076  may double as a product stream reservoir whose volume may be monitored via the product level sensor  6078 . As such, the product reservoir  6012  may be described as an auxiliary product reservoir. In certain embodiments, the product level sensor  6078  may measure a volume of product in the condenser  6076  up to 4 L. In some embodiments, the controller  6034  may receive a data signal from the level sensor  6078  in the form of a percent of float displacement along its entire displacement range. In some examples, a one percent displacement may be equivalent to a change of volume in the evaporator and evaporator reservoir of 40-50 ml (e.g. 43 ml). 
     The product reservoir  6012  may include a product outlet  6694  (best shown in  FIG. 82 ) from which the product process stream may exit the product reservoir  6012 . This outlet  6694  may be connected to a product flow conduit leading to the product heat exchanger  6008 A as described elsewhere herein. The example outlet  6694  is adjacent the bottom interior surface  6316  of the product reservoir  6012 . The product reservoir  6012  may also include a venting port  6696 . The venting port  6696  may allow for gases to be displaced out of the product reservoir  6012  as condensed liquid within the condenser  6076  begins to fill the product reservoir  6012 . In the example embodiment, the vent port  6696  is plumbed back into the condenser  6076 . 
     Referring now to  FIG. 80 , a perspective view of a system  6000  is shown. Fluid lines other than the vent flow paths  6700  have been hidden in  FIG. 80  for sake of clarity. As shown, a condenser vent  6698  may be included in the condenser  6076  to relieve excess pressure, volatiles, and non-condensable gasses from the condenser  6076  as needed. Venting gases from the condenser  6076  may travel along vent flow paths  6700  to a venting valve  6098 . The venting valve  6098  may be included on the blowdown heat exchanger manifold  6574 . In some embodiments, the duty cycle of the venting valve  6098  may be determined based on the low pressure steam temperature as indicated by data from a compressor inlet temperature sensor  6066  (see, e.g.,  FIG. 76 ). A current low pressure steam temperature may be compared to a target low pressure steam temperature. The target may be at or around 112° C. A P, PI, or PID controller may be fed the difference between these two values and provide a duty cycle command as an output. This output may be limited to a mode or state specific minimum duty cycle and a mode or state specific maximum duty cycle (e.g. 100%). Alternatively, the venting valve  6098  may be operated on a fixed duty cycle (e.g. a duty cycle less than 15 or 20%). The venting valve  6098  duty cycle may be a preset parameter for various states or modes of the system  6000 . During a water production state, the duty cycle may be set or have a mode or state specific minimum of 8-12% (e.g. 10%). When in a high temperature production state, the duty cycle may be lower. For example, the duty cycle of the venting valve  6098  may be set at or have a mode or state specific minimum of 3-7% (e.g. 5%). In the event that the venting valve  6098  duty cycle remains at or above predetermined threshold (e.g. 100%) for more than a certain period of time (e.g. a number of minutes, such as five minutes), an error may be generated by the controller  6034 . 
     To cool hot gases vented from the condenser  6076 , the blowdown heat exchanger manifold  6574  may direct gas to a mixing reservoir  6092  after passing through the venting valve  6098 . The mixing reservoir  6092  may be any of those described herein, but in the example embodiment is directly attached to the blowdown heat exchanger manifold  6574 . The mixing reservoir  6092  may have a tray like shape as shown. Alternatively, any other suitable shape could be used. 
     Referring now also to  FIG. 81 , which shows an exploded view of the blowdown heat exchanger manifold  6574  and mixing reservoir  6092  assembly, a venting heat exchanger  6702  may be included. The venting heat exchanger  6702  may be disposed in the interior volume of the mixing reservoir  6092  when fully assembled. In the example embodiment, the venting heat exchanger  6702  is a helical coil which defines a flow path for gases vented from the condenser  6076 . In some embodiments the venting heat exchanger  6702  may include a plate type heat exchanger. In such embodiments, a wall (e.g. bottom wall) of the mixing reservoir  6092  may be formed at least partially from the venting heat exchanger  6702 . During operation, the mixing reservoir  6092  may contain a volume of liquid sufficient to at least partially submerge the venting heat exchanger  6702 . As venting gases pass through the venting heat exchanger  6702  they may enter a heat exchange relation with the submerging liquid. This may help to cool down or condense in flowing gases before the vented process stream proceeds out of the venting heat exchanger  6702  into the main interior volume of the mixing reservoir  6092 . The venting heat exchanger  6702  may be constructed from a material having a high thermal conductivity to facilitate this heat transfer. 
     The blowdown manifold  6574  may be attached to the mixing can  6092  in any suitable manner. In the example embodiment, the blowdown manifold  6574  is attached to the mixing can  6092  via fasteners (not shown). A gasket  6703  may be sandwiched between the mixing can  6092  and blowdown manifold  6574  when assembled to help establish a fluid tight seal. 
     Referring now to  FIG. 82  a perspective view detailing product flow paths  6706  of an example system  6000  are shown. Only the product flow paths  6322  and not those of source water or other process streams are shown in  FIG. 82  for sake of clarity. As shown, product water leaving the product reservoir  6012  may flow to both the product heat exchanger  6008 A and a bearing feed pump  6080 . Individual dedicated outlets may be included on the product reservoir  6012  for directing water to the product heat exchanger  6008 A and bearing feed pump  6080  may be included. The bearing feed pump  6080  may pump a portion of the product water leaving the product reservoir  6012  to the compressor  6064 . The bearing feed pump  6080  may be a solenoid pump, diaphragm pump, or any other suitable pump. As described elsewhere herein, the product water may be used to lubricate an impeller bearing. In the example embodiment the bearing feed pump  6080  is included in bearing feed manifold  6576  which may include a pressure sensor  6081  and temperature  6083 . Data from these sensors may be monitored by a controller  6034  to verify proper function of the bearing feed pump  6080  (see, e.g.  FIG. 115 ). 
     After passing through the heat exchanger  6008 A, product water may exit at reduced temperature after transferring heat to the incoming source water. The cooled product water may flow out of the product heat exchanger  6608 A through a product flow path  6706  to a product heat exchanger manifold  6578 . 
     Referring now also to  FIG. 83 , once in the product heat exchanger manifold  6578 , the product water may pass one or more sensors  6082 A-D. In the example embodiment, the sensors  6082 A-D are included in a sensor assembly  6708  which is coupled into the product heat exchanger manifold  6578 . The sensors  6082 A-D may be redundant pairs of conductivity sensor and temperature sensors. Other sensor types which may provide a data signal related to water quality such as turbidity, pH, redox potential, TDS, analyte sensors, TOC, etc. may also be included. 
     The product heat exchanger manifold  6340  may also include a valve or valves  6344  which may be operated by a controller  6034  (see, e.g.,  FIG. 3 ) to direct the product process stream based on data provided from the at least one sensor  6082 A-D. If the water quality (e.g. conductivity value or temperature) is outside of a threshold value, a diverter valve  6084  leading to the mixing reservoir  6092  may be opened. In the example embodiment, a divert line  6708  is included to connect the product heat exchanger manifold  6578  to the mixing reservoir  6092  via the blowdown heat exchanger manifold  6574 . The diverter valve  6084  may also be operated by the controller  6034  to maintain a target level of fluid in the condenser  6076 . This level may be preset (potentially for each of a number of different operational modes) or may be altered in conjunction with an anticipated demand determined by a device (e.g. medical system  6004 ) at a point of use. A PID or PI control loop may be used based on readings from the product level sensor  6078  to set a duty cycle for the diverter valve  6084 . In the event the product level as indicated by data from the product level sensor  6078  is above a certain first percent (e.g. 40-60% and 50% in some examples) a notification may be generated by the controller  6034 . In the event the product level as indicated by data from the product level sensor  6078  is above a certain second percent (e.g. 80-95% and 90% in some examples) an error or alarm may be generated by the controller  6034 . 
     If the water quality (e.g. conductivity or temperature) is in compliance with a predetermined threshold value, the controller  6034  (see, e.g.,  FIG. 3 ) may actuate a point of use valve  6086  to direct the product process steam to an outlet flow path  6564  which may be a flow path to a medical system  6004  (see, e.g.  FIG. 3 ). The valves  6084 ,  6086  may also be actuated by the controller  6034  based on signals the controller  6034  receives from a medical system  6004 . Any of the systems  6000  described herein may operate in a number of different modes. 
     These modes may govern operation of the device at a high level. In each of these modes, the controller  6034  may control the system  6000  differently depending on what the mode is designed to accomplish. For example, some modes may be used by the controller  6034  to establish or maintain prerequisite conditions for a next mode before the controller  6034  transitions to that mode. Other modes may keep the system  6000  in a ready state (e.g. filled and up to temperature) where purified water may be produced with relatively little delay. At a lower level, the controller  6034  may, for example, operate the system  6000  in at least one state for each mode and may transition the system  6000  through a number of states in each mode. During a typical use of the system  6000 , the controller  6034  may pass between a number of modes. Certain transitions between specific modes may, however, be prohibited. A number of example modes and exemplary allowed transitions are shown in table 1 as follows: 
     
       
         
           
               
               
             
               
                   
                 TABLE 1 
               
             
            
               
                   
                   
               
               
                   
                 To: 
               
            
           
           
               
               
               
               
               
               
               
               
               
               
            
               
                   
                 Idle 
                 Normal 
                 Hot 
                 Fail Safe 
                 Override 
                 Standby 
                 Sample 
                 Disinfect 
                 Replace prep 
               
               
                   
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
               
            
               
                 From Idle 
                 False 
                 True 
                 False 
                 True 
                 True 
                 True 
                 True 
                 False 
                 True 
               
               
                 From Normal 
                 True 
                 False 
                 True 
                 True 
                 False 
                 True 
                 False 
                 False 
                 False 
               
               
                 From Hot 
                 True 
                 False 
                 False 
                 True 
                 False 
                 True 
                 False 
                 True 
                 False 
               
               
                 From Fail Safe 
                 False 
                 False 
                 False 
                 False 
                 False 
                 False 
                 False 
                 False 
                 False 
               
               
                 From Override 
                 True 
                 False 
                 False 
                 True 
                 False 
                 False 
                 False 
                 False 
                 False 
               
               
                 From Standby 
                 True 
                 True 
                 False 
                 True 
                 False 
                 False 
                 True 
                 False 
                 True 
               
               
                 From Sample 
                 True 
                 True 
                 False 
                 True 
                 False 
                 True 
                 False 
                 False 
                 False 
               
               
                 From Flush 
                 True 
                 False 
                 False 
                 True 
                 False 
                 True 
                 False 
                 False 
                 False 
               
               
                 From Disinfect 
                 True 
                 False 
                 False 
                 True 
                 False 
                 True 
                 False 
                 False 
                 False 
               
               
                 From Replace Prep 
                 True 
                 False 
                 False 
                 True 
                 False 
                 False 
                 False 
                 False 
                 False 
               
               
                   
               
            
           
         
       
     
     Depending on the embodiment, a medical system  6004  which serves as a point of use for the system  6000  may generally control mode switching. Any other point of use device such as systems which are not medical systems or perhaps those for producing water for drinking or other domestic consumption purposes may have similar control. The medical system  6004  may make determinations as to which mode of system  6000  operation may be needed and instruct the controller  6034  to orchestrate the switch when needed by the medical system  6004 . The medical system  6004  may query the controller  6034  for information from the system  6000  in order to make mode switching determinations. The controller  6034  may also or instead provide information to the medical system  6004  on a predefined basis. The controller  6034  of the system  6000  may transition the system  6000  to a failsafe mode without instruction from the medical system  6004  (though the medical system  6004  may also command the system  6000  into failsafe mode as well). The controller  6034  of the system  6000  may switch between states within a mode depending on certain operating characteristics or parameters. State switching determinations may be made be the controller  6034  without direct instruction from the medical system  6004 . 
     Some modes, such as an override mode (where included in the embodiment) may only be accessible via a technician or similar maintenance personnel. This mode may allow for manual control of various valves, control set points or targets, and other parameters via a technician interface. The technician interface may, for example, be a laptop, PC, tablet, smart phone, or the user interface of a point of use device. A technician may require one or more of a particular piece of hardware, password, encoded key, or the like to access the override mode. 
     Referring now to  FIGS. 84A-84B , a flow diagram  7430  depicting various operating states during a typical use of an embodiment of the system  6000  is shown. As shown, an idle state may be entered in block  7432 . In the idle state, the controller  6034  may close all valves and disable any control loops, level controllers, stop the motor, etc. A command may be sent to each valve to close individually. The idle state may be used in an idle mode which may be a starting mode for the system  6000  upon power-on. The system  6000  may also be able to transition to idle mode from any other mode save fail safe mode. In some embodiments, the idle state may be utilized when the system  6000  is in either the idle mode or failsafe mode. The idle state may, however, not be exitable in failsafe mode. A service call may need to be rendered before use of the device is again allowed. 
     In some embodiments, a point of use device may command a transition to stand-by mode upon receipt of a communication for the system  6000  that the system has been powered on and is in idle mode. The stand-by mode may bring the system  6000  to a point where the system  6000  is ready to quickly produce purified water. This may include filling the purifier  6010  of the system  6000  and heating the fluid contained in the purifier  6010 . If the purifier  6010  is properly filled and heated, the stand-by mode may maintain the system  6000  at this fill level and temperature. 
     Upon receipt of the command to enter stand-by mode, the controller  6034  may transition the system  6000  to a stand-by state. The stand-by state of the stand-by mode may be used to maintain the purifier  6010  fill level and temperature. The stand-by state is described in greater detail with relation to  FIG. 98 . The stand-by state may be exited if one of the fill level or temperature is outside of respective limits. 
     In alternate embodiments, and as shown, in some embodiments, the controller  6034  may transition from idle state to an integrity test state in block  7434 . In various embodiments, the integrity test state may test various components of the system  6000  to ensure that the components are operating as expected. The integrity test state is described in greater detail and with relation to  FIG. 85 . 
     In the example flow diagram  7340 , the controller  6034  transitions the system  6000  to a fill state in block  7436 . The purifier  6010  may be filled in the fill state. The fill state is described in greater detail with relation to  FIGS. 86 and 87 . The controller  6034  may then transition the system  6000  into a heat state in block  7438 . The heat state may heat fluid in the purifier  6010  to a temperature set point. The heat state is described in greater detail in relation to  FIG. 88 . A transition back to the stand-by state may be made in block  7440  once the temperature has reached the set point. 
     After the medical system  6004  (or other point of use device) receives a communication indicating the system  6000  is being maintained at a fill level and temperature in stand-by state, the medical system  6004  may command the system  6000  to transition into a flush mode. A flush state may be used in this mode. In the example, the flush state is entered in block  7442 . In the flush state source water may flow into the system  6000  and through any filters  6006 A, B of the system  6000 . This may be done before a water sample is taken to ensure that the integrity of the filters is suitable. It may also serve to ensure that the any water which may be taken in a subsequent water sample is more representative of the filtration abilities of the filters  6006 A, B. The flush mode is described in greater detail with respect to  FIG. 89 . Certain characteristics of interest related to the filters  6006 A, B may be monitored in the flush state. If, in block  7444 , the characteristics of interest are deemed acceptable, a sampling state may be entered in block  7446 . If, in block  7444 , they are not acceptable, a filter replacement preparation state may be entered in block  7448 . 
     Depending on the embodiment, data collected during this monitoring may be communicated to the medical system  6004  (or other point of use device) and the medical system  6004  may make the acceptability determination. In other embodiments, the controller  6034  of the system  6000  may make a pass/fail determination based on the data collected during this monitoring. The pass/fail determination may be communicated to the medical system  6004 . If the filters are deemed acceptable, the medical system  6004  may command a mode transition into a sampling mode. This may provoke the entry into the sampling state in block  7446 . If the filters are not acceptable, the medical system  6004  may command a mode transition into a replacement preparation mode. This may prompt entry into the filter replacement preparation state and this state may be entered in block  7448 . 
     In the replacement preparation mode the filters  6006 A, B and lines to and from the filters  6006 A, B may be depressurized so that the filters  6006 A, B may be detached with minimal water spillage. This may occur in a filter replacement preparation state which is described in greater detail in relation to  FIG. 91 . New filters may be installed and a replacement filter flush state may be entered in block  7450 . This state is further described in relation to  FIG. 91 . Characteristics of interest related to the filters  6006 A, B may be monitored in the replacement flush state and may be required to conform with acceptability criteria before the sampling state can be entered. 
     In the sampling state, the controller  6034  may operate a sampling port  6038  to dispense a sample of filtered water for testing. If, in block  7452 , the test is acceptable, stand-by state may be entered in block  7454 . If, in block  7452 , the test is unacceptable, the replacement filter preparation state may be entered in block  7448 . In certain examples, the test may be performed manually (e.g. with one or more test strip) and the results may be input directly to a user interface of the medical system  6004 . The transition into the replacement filter preparation state or stand-by state may be in response to a command from the medical system  6004  to enter one of the replacement preparation mode or stand-by mode. This command may be generated based on whether the testing was acceptable or unacceptable. 
     When the medical system  6004  is ready (e.g. start-up testing completed, required user interactions received), the medical system  6004  may command the system  6000  into a normal water production mode. In the normal water production mode, the controller  6034  may bring the system  6000  through a number of states. Initially, the controller  6034  may enter a production preparation state in block  7456 . In this state, the controller  6034  may prepare to start the compressor  6064 . This may include running a bearing feed pump  6080  for a period of time. The production preparation state is further described in relation to  FIG. 92 . The controller  6034  may then enter a production start-up state in block  7458  during which the compressor  6064  is brought up to operating speed. The production start up state is further described in relation to  FIG. 93 . The controller  6034  may then enter a production running state in block  7460 . This state is further described in relation to  FIG. 94 . 
     Certain characteristics of interest related to the purified water produced by the system  6000  may be monitored in the production running state. If, in block  7462 , it is determined a diversion of product water from the point of use is needed, the controller  6034  may transition the system  6000  into a stand-by state in block  7464  or production divert state in block  7466 . The transition to a stand-by state in block  7464  may occur if the conductivity of the product water rises above a predetermined threshold (e.g. 10 μS). The transition to the production divert state in block  7466  may occur if the temperature of the product water rises above a predefined threshold. In the divert state, product water may be routed to a drain  6018  of the system  6000  and prevented from passing to the point of use device. The divert state is further described in relation to  FIG. 94 . If, in block  7468 , diversion is no longer needed (e.g. temperature is back within limits), the controller  6034  may return the system  6000  to the production running state in block  7460 . 
     The controller  6034  may stay in the normal water production state until receipt of a command from the medical system  6004  (or other point of use device) to change mode. The medical system  6004  may, for example, command a mode change after completing a therapy. Where components of the medical system  6004  are reusable, the medical system  6004  may command a mode change to a hot water production mode. This mode may provide hot water to the medical system  6004  which the medical system  6004  may use to disinfect itself. Upon receiving a command to enter the hot water production mode, the controller  6034  of the system  6000  may enter a hot transition state in block  7470 . In this state, the controller  6034  may slew the motor speed toward its hot operating speed and may transition between a normal production control loop and a hot water production control loop. This state is further described in relation to  FIG. 95 . The controller  6034  may transition the system  6000  into a hot production state in block  7472 . In this state, hot purified water may be produced and provided to the medical system (or other point of use device). The hot production state is further described in relation to  FIG. 96 . If, in block  7474 , the conductivity of the product water rises above a threshold, the controller  6034  may transition the system  6000  into a stand-by state in block  7464 . In some embodiments, a divert state may be entered if the temperature is below a threshold. Where the medical system  6004  includes a heater, however, such an entry into a divert state may not be necessary. 
     The hot water production states may also be used in a self disinfect mode for the system  6000 . This mode may be entered by the system  6000  automatically after the medical system  6004  indicates the hot water mode is not needed. Alternatively, the medical system  6004  may command the system  6000  into the self disinfect mode. In this mode, the hot water production states may be used to run hot water through various lines of the system  6000 . This mode is further described in relation to  FIG. 97 . 
     Once hot water production is no longer needed, the system  6000  may be commanded into the stand-by mode. The controller  6034  may maintain the system  6000  such that it is ready to produce purified water quickly when it is next needed. This may also help to increase the efficiency of the system  6000  as a significant amount of energy may be required to bring the system  6000  up to operation temperatures from a cold start up. 
     Referring now to  FIG. 85 , a flowchart  7500  depicting a number of example actions which may be executed in an integrity testing state is shown. The integrity test state may be entered in block  7502 . In the integrity testing state, the controller  6034  may issue commands to each valve included in the system  6000  to transition to a closed state in block  7504 . In block  7506 , the controller  6034  may command the motor speed to zero, the bearing feed pump to an off state, and the heater duty cycle to zero. If, in block  7508 , one or more valve did not close as commanded and/or if the motor, bearing feed pump, and heater were not off as commanded, an error may be generated in block  7510 . If, in block  7508 , the all of the valves closed as commanded and the motor, bearing feed pump, and heater were all off as commanded, the controller  6034  may command a test of various electrical relays of the system  6000  in block  7512 . Relays tested may be those on an AC high voltage bus of the system  6000 . These relays may be commanded to a particular state and a voltage reading from the bus may be taken to verify the relays changed state as commanded. If, in block  7514 , the relay test does not pass, an error may be generated in block  7510 . If the relay test passes in block  7514 , the controller  6034  may transition the system  6000  to a next state in block  7516 . This state may, for example, be a fill state in certain embodiments. 
     It should be noted that the integrity test state may be entered each time the system  6000  is powered on, but may also be entered before beginning to provide water to a point of use device (e.g. a medical system  6004 ) each time the point of use device commands the system  6000  out of a stand-by state, for example. Where the point of use device is a medical system  6004  such as a dialysis system, the system  6000  may progress through the integrity test state before providing water for each individual therapy performed by the medical system  6004 . 
     In the context of a dialysis system, therapies may typically be performed on a relatively consistent basis. The system  6000  may operate in stand-by mode for some amount of time when the patient is, for example, at work or going about their day during their waking hours. By remaining in stand-by state, the system  6000  may quickly be ready to produce water for use in a therapy when needed. As therapies may generally be started when a patient readies for bed, the controller  6034  may command the system  6000  to enter the integrity testing state based on a preprogrammed schedule which ensures system  6000  integrity has been verified shortly before a therapy is likely to begin or scheduled to begin. Alternatively or additionally, the integrity test state may be entered after a self disinfect state is completed in some embodiments. 
     Referring now to  FIG. 86 , a flowchart  7230  depicting a number of example actions which may be executed in a fill state is shown. The fill state may be entered in block  7232 . In the fill state, a source valve controller such as those described in relation to  FIG. 100 or 101A-101C  may be enabled. Other controllers, for example, a heater controller, compressor motor controller, and bearing feed pump controller may be disabled. The product reservoir outlet valve may be closed and a vent valve  6098  (see, e.g.,  FIG. 3 ) may be opened in block  7236 . The source valve controller may fill the purifier  6010  in block  7236  as well (e.g. as described in relation to  FIG. 87 ). 
     In block  7238 , the controller  6034  may receive a data signal from the product reservoir level sensor  6078  (see, e.g.,  FIG. 3 ) indicative of the liquid level in the product reservoir  6012  (see, e.g.,  FIG. 3 ). If, in block  7240 , the product level is less than a minimum value, the controller  6034  may transition the system  6000  to a first state (e.g. stand-by state) in block  7242 . The minimum level may be a level of 5-15% (e.g. 10%) and may ensure the bearing feed pump  6080  (see, e.g.,  FIG. 3 ) has an ample supply of fluid to lubricate the compressor  6064  (see, e.g.,  FIG. 3 ) bearing. If, in block  7240 , the product level is greater than the minimum value, the controller  6034  may transition the system  6000  to a second state (block  7245 ) if, in block  7244 , the evaporator  6060  (see, e.g.,  FIG. 3 ) level is at or above a threshold (e.g. 50% or 55%) in block  7244 . The second state may be a heating state. If, in block  7244 , the evaporator  6060  is not above the threshold and the purifier  6010  is filling too slowly in block  7246 , an error may be generated at block  7248 . For example, if a timer of 5-10 minutes (e.g. 5 minutes) elapses the error may be generated. 
     Referring now to  FIG. 87 , an example flowchart  7130  detailing a number of actions which may be executed to fill an evaporator  6060  (see, e.g.,  FIG. 3 ) of a purifier  6010  (see, e.g.  FIG. 3 ) is shown. This may occur, for example, during a fill state of a production mode or stand-by mode of system  6000  operation. The controller  6034  (see, e.g.,  FIG. 3 ) of the system  6000  may control the source proportioning valves  6050 A, B (see, e.g.,  FIG. 3 ) during a fill state such that the evaporator  6060  is filled quickly while mitigating potential for overshoot. 
     As shown, the controller  6034  may determine a delta between a current fill level of the evaporator  6060  and a target level in block  7132 . The current level may be sensed via an evaporator level sensor  6073  (see, e.g.,  FIG. 3 ) which is in data communication with the controller  6034 . The target level may be a predefined value. If, in block  7134 , the compressor motor of the purifier  6010  is running, the controller  6034  may command the source proportioning valves  6050 A, B closed in block  7136 . The controller  6034  may wait for the motor to stop or slow down to a relatively low speed before filling the evaporator  6060 . The source proportioning valves  6050 A, B may be closed in block  7140  if the current level is above the target level in block  7138 . The evaporator may also be drained in block  7138  and a new delta between the target and current value may be determined in block  7132 . 
     If the motor is off in block  7134 , and the evaporator level is below the target in block  7138 , the controller  6034  may fill the evaporator  6060 . If, in block  7142 , the delta determined in block  7132  is not within a predetermined range of the target, the duty cycle for the source proportioning valves  6050 A, B may be set to 100% in block  7144 . This may allow the evaporator  6060  to be filled as rapidly as possible. If, in block  7146 , the delta from block  7132  is within a predefined range of the target, the duty cycle for the source valves may be set to a slow fill duty cycle value in block  7146 . In some embodiments, the range of block  7142  may be inclusive of values within 25% of the target level or 20% of the target level. The slow fill duty cycle may be around 20-35% (e.g. 25%). This may help to prevent any overshoot of the target level. Once, in block  7148 , the target level has been reached, the fill may complete in block  7150 . 
     Referring now primarily to the example flowchart  7260  in  FIG. 88 , the controller  6034  (see, e.g.,  FIG. 3 ) may also prepare the purifier  6010  (see, e.g.,  FIG. 3 ) for water purification by getting fluid in the purifier  6010  up to a temperature or temperature range. In some embodiments, multiple temperature targets may be used. For example, a target low pressure vapor temperature and target sump temperature may be used. The controller  6034  may, for example, heat the fluid in the evaporator  6060  (see, e.g.,  FIG. 3 ) to a point at which the purifier  6010  can be transitioned into a purified water production state. 
     As shown, the heat state may be entered in block  7262 . In the heat state, the controller  6034  may, in block  7264 , close outlets to the purifier  6010  and close inlets to the purifier  6010 . The compressor  6064  (see, e.g.,  FIG. 3 ) and bearing feed pump  6080  (see, e.g.,  FIG. 3 ) may be disabled in block  7264  as well. The fluid in the purifier  6010  may then be heated by the heating element  6054  (see, e.g.,  FIG. 3 ) to a temperature target in block  7266 . The controller  6034  may also vent the purifier  6010  by actuating a vent valve  6098  (see, e.g.,  FIG. 3 ) in block  7266 . The venting valve  6098  may be actuated to achieve or maintain a vapor temperature set point. The controller  6034  may govern actuation of the vent valve  6098  as described elsewhere herein (see, e.g., description of  FIG. 80 ). 
     The controller  6034  may receive a product level measurement from a product level sensor  6078  in block  7268 . If, in block  7270  the product level is below a minimum, the controller  6034  may transition the system  6000  into a standby state in block  7272 . The minimum may be 7-15% (e.g. 10%) in certain embodiments. Otherwise the controller  6034  may receive a sump temperature value and a low pressure vapor temperature value in block  7274 . These may be respectively received via a data signal from a sump temperature sensor  6059  (see, e.g.,  FIG. 3 ) and low pressure vapor temperature sensor  6066  (see, e.g.,  FIG. 3 ). If one or both of these values is not above a respective target in blocks  7276  and  7278 , the controller  6034  may return to block  7264  and continue heating and venting. If the sump temperature and low pressure vapor temperatures are above respective minimum values, the controller  6034  may transition the system  6000  to a next state. This state may, for example, be a stand-by state. 
     Referring now primarily to the exemplary flowchart  7160  in  FIG. 89 , a flush state may be used in the flush mode. Upon entry to the flush state in block  7162 , a cooling valve  6100  (see, e.g.  FIG. 3 ) may be opened and source proportioning valves  6050 A, B (see, e.g.  FIG. 3 ) to the heat exchangers  6008 A, B (see, e.g.  FIG. 3 ) may be closed in block  7164 . The cooling valve  6100  may be operated at 100% duty cycle during flushing. In block  7166 , the controller  6034  (see, e.g.,  FIG. 3 ) may receive filtration data from various sensors monitoring the filters  6006 A, B. For example, data from pre and post filtration pressure transducers  6036 ,  6044  may be received. If, in block  7168  the post filtration pressure is below a minimum pressure (e.g. 10 psi or more) the controller  6034  may continue monitoring the filtration data in block  7166  unless, in block  7170 , a timeout period has elapsed. If the timeout period has elapsed, the controller  6034  may generate a timeout error in block  7172 . The timeout period may be 7-15 minutes (e.g. 10 minutes). In some embodiments, if a timeout error is generated in block  7172 , the filters  6006 A, B may need to be replaced. 
     If, in block  7168 , the post filtration pressure is above a minimum pressure the controller  6034  may determine a pressure drop between the pre-filtration pressure sensor  6036  measurement and the post-filtration pressure sensor  6044  measurement in block  7174 . If, in block  7176 , the pressure drop is below a predefined limit, the controller  6034  may continue monitoring the filtration data in block  7166  unless, in block  7170 , a timeout period has elapsed. A timeout error may be generated in block  7172  if the timeout period has elapsed. If, in block  7176 , the pressure drop is larger than the predefined limit, a flushing timer may be incremented in block  7178 . The predefined limit for the pressure drop may be at least 1 psi. 
     If, in block  7180 , the flushing timer has not been incremented above its minimum limit (e.g. 5 minutes), the controller  6034  may continue monitoring the filtration data in block  7166  unless, in block  7170 , a timeout period has elapsed. A timeout error may be generated in block  7172  if the timeout period has elapsed. Though not shown, in the event that the post-filtration pressure value or pressure drop between pre and post filtration sensors  6036 ,  6044  falls below their respective minimums, the flushing timer may be reset to zero. If, in block  7180 , the flushing timer has been incremented above a minimum value, the controller  6034  may transition the system  6000  to a next mode or state in block  7182 . Alternatively, the controller  6034  may notify a point of use device (e.g. medical system  6004  of  FIG. 3 ) and the point of use device may direct the controller  6034  to transition the system  6000  to another mode or state. The next mode may be a sampling mode. 
     A sampling state may be used in the sampling mode. In the sampling state, and referring now to the example flowchart  7190  shown in  FIG. 90 , the controller  6034  may dispense a sample for manual testing. This may again be used to determine the suitability of the filters  6006 A, B. In other embodiments, a digital testing meter may be used and the testing may not be manual. As shown, the sampling state may be entered in block  7192 . The cooling valve  6100  (see, e.g.,  FIG. 3 ) duty cycle may be set to a sampling duty cycle (e.g. 50%) in block  7194 . If provided, a sampling port  6038  (see, e.g.  FIG. 3 ) illuminator may be powered in block  7194  as well. If, in block  7196 , a depression of the sampling button is not detected, the sampling valve may remain closed in block  7198 . If, in block  7196 , a sampling button is depressed the sampling valve may be opened in block  7200 . In some embodiments, the sampling valve may be commanded closed by the controller  6034  if the sampling button remains depressed for more than a predefined period of time. For example, the controller  6034  may close the sampling valve after 5 seconds. 
     Referring now primarily to exemplary flowchart  7210  in  FIG. 91 , in the event that the filters  6006 A, B (see, e.g.,  FIG. 3 ) should be replaced, the controller  6034  (see, e.g.,  FIG. 3 ) may transition the system  6000  into a filter replacement preparation state. The filters  6006 A, B may be required to be replaced in the event that a water sample from the filtration arrangement fails a quality test (e.g. chlorine or chloramines testing). The filters  6006 A, B may also be required to be replaced in the event that the pressure drop through the filters  6006 A, B is out of a predefined range or the post filtration pressure measured downstream of the filters  6006 A, B is too low. In some embodiments, the filters  6006 A, B may require replacement based on a usage characteristic. For example, volume filtered, time filtering source water, time since install, etc. In certain embodiments, the controller  6034  may be commanded into a replacement mode by an attached point of use device (e.g. medical system  6004  of  FIG. 3 ) in the event a quality test fails or other characteristics of interest related to the filters  6006 A, B indicate replacement may be necessary. 
     When in a replacement mode, the controller  6034  may progress through a replacement preparation state and a replacement flush state. As shown in  FIG. 91 , a filter replacement preparation state may be entered in block  7212 . All valves except for a cooling valve  6100  (see, e.g.,  FIG. 3 ) may be closed in block  7214 . This may allow any water pressure in system  6000  to be released to the drain  6018  (see, e.g.,  FIG. 3 ) of the system  6000 . The controller  6034  may monitor post filtration pressure data in block  7216 . Once, in block  7218 , the post filtration pressure is below a threshold value, the controller  6034  may wait a predefined amount of time (e.g. 10 seconds) in block  7220 . If the pressure rises above the threshold during the wait period, the wait period may reset from zero once the pressure again falls below the threshold. The cooling valve may be closed in block  7222 . The controller  6034  may also transition the system  6000  to idle in block  7222 . A user may then decouple the used filters from the system  6000  and install a new set of filters before the next use. 
     Once the new filters  6006 A, B have been installed, the controller  6034  may transition the system  6000  to a new filter flush state. In some examples, completion of installation of the new filters  6006 A, B may be indicated via a user interface of the point of user device. The controller  6034  may transition the system  6000  to the new filter flush state upon receipt of a communication from a point of use device that the user has indicated new filters have been installed. The new filter flush state may be similar to the flush state described in relation to  FIG. 89 . The timeout period may be greater for the new filter flush state. In some embodiments, the timeout period may be 20 minutes or double that of the normal flush timeout period. Additionally, the filters  6006 A, B may be flushed for a greater period of time during a new filter flush. In some embodiments, the minimum limit used in block  7178  for a new filter flush may be 15 minutes or 3 times that used in a normal flush. After flushing, the controller  6034  or point of use device may require the system  6000  collect another water sample to ensure that the new filters  6006 A, B are suitable. 
     Once the filters  6006 A, B have been deemed suitable, the controller  6034  (see, e.g.,  FIG. 3 ) may begin preparing the purifier  6010  (see, e.g.,  FIG. 3 ) for water purification. In some embodiments, a point of use device (e.g. medical system  6004  of  FIG. 3 ) may direct the controller  6034  to transition the system  6000  to a normal purified water production mode once the filters  6006 A, B have passed any checks. The normal purified water production mode may produce product water at a temperature around 30-40° C. (e.g. 37° C.). In other embodiments the normal purified water production temperature may be lower. For example, where the point of use device (e.g. medical system  6004  of  FIG. 3 ) includes a heater, the target temperature may be lower than a temperature at which the point of use device will be using the water. In some examples, the target temperature may be 20-30° C. (e.g. 25° C.). The controller  6034  may alternatively prepare the system  6000  for production of purified water by transitioning the system  6000  into a stand-by mode. This may help to minimize the amount of time needed to begin production of purified water  6010  once a point of use device or system commands a mode change into a normal purified water production mode. This preparation may, for example, include maintaining a temperature and fill level of the purifier  6010  to a point at which the purifier  6010  can be transitioned into a purified water production state. 
     Referring now primarily to the example flowchart  7290  in  FIG. 92 , the controller  6034  (see, e.g.,  FIG. 3 ) may also prepare the purifier  6010  (see, e.g.,  FIG. 3 ) for water purification by starting the bearing feed pump and controlling the blowdown level to a starting fill percent. As shown, in block  7292 , the controller  6034  may transition the system  6000  to a production preparation state. The bearing feed pump may be commanded to run by the controller  6034  in block  7294 . The blowdown level may also be controlled to a starting level in block  7294 . The motor may remain off and the product outlet valve may remain closed in the production preparation state. Venting of the purifier  6010  may continue as needed to maintain a target vapor temperature in the purifier  6010 . A timer may be incremented in block  7296 . This timer may be required to accumulate past a predefined amount of time which is sufficient to lubricate a bearing for the compressor  6064  (see, e.g.,  FIG. 3 ) motor. This may be, for example, 15 seconds to 1 minute (e.g. 30 seconds). If, in block  7298 , the blowdown level is at or below a predefined level (e.g. 35%) and the timer has accumulated past the predefined threshold in block  7300 , the controller  6034  may transition the system  6000  to the next state. In some embodiments, the controller  6034  may generate an error (not shown) if the timer accumulates past a certain value (e.g. 5 minutes). The next state may be a production start-up state. 
     In the production start-up state, and referring now primarily to the flowchart  7480  of  FIG. 93 , the compressor  6064  (see, e.g.,  FIG. 3 ) may be brought up to speed and set points for various control loops of the system  6000  may be set. Any product water produced may be diverted to drain  6018  (see, e.g.,  FIG. 3 ) and prevented from being in fluid communication with the point of use device or system in this state. Additionally, the production start-up state may monitor various operating characteristics of interest for conformance with predefined criteria. The controller  6034  may not allow transition to production running state until the operating characteristics of interest are in conformance with their predefined criteria. 
     As shown, the production start-up state may be entered in block  7482 . In block  7484 , control set points for various control loops of the system  6000  may be set. The control loops may be run in block  7486 . The compressor motor may be slewed toward its operating speed in block  7488 . If, in block  7490 , the production transition conditions have not been met, the controller  6034  may return to block  7486 . Otherwise, the controller  6034  may check if a minimum time for which the transition conditions have been satisfied has elapsed in block  7492 . If this time has elapsed, the controller  6034  may transition the system to a production running state in block  7494 . Otherwise, the controller  6034  may return to block  7486 . 
     The production transition conditions may include criteria related to the temperature and/or conductivity of product water exiting product heat exchanger  6008 A (e.g. as read by sensors  6082 A-D of  FIG. 3 ). For example, the temperature may be required to be less than a few degrees (e.g. 2° C.) above the temperature set point for the production running state. The conditions may also include a criterion related to the temperature delta between the source water entering the system and the purified product water entering and/or exiting the product heat exchanger  6008 A. These conditions may also include a criterion related to the compressor  6064  speed. For example, the compressor speed may be required to be greater than a minimum production running speed. The conditions may also include criteria related to the blowdown level or rate and the product level. Additionally, there may be a timer during which all criteria must be satisfied in order for the controller  6034  to deem the production conditions met. Individual timers for each criterion or sub sets of criteria may also be used. 
     In some examples, the production start-up state may also be entered prior to entering a hot water production state. Similar criteria may be imposed before a transition into hot water production state is allowed though the values for each particular criterion may differ if the system  6000  is to transition into a hot water production state. 
     Referring now primarily to the example flowchart  7310  in  FIG. 94 , after preparations (e.g. in production preparation state and production start-up state) have been completed, the controller  6034  (see, e.g.,  FIG. 3 ) may transition the system  6000  into a purified water production state or production running state. As shown, the production running state may be entered in block  7312 . In block  7314 , the controller  6034  may run various control loops of the system  6000 . For example, a divert controller may be run in block  7314 . The divert controller may divert water produced by the system  6000  as described elsewhere herein (see, e.g.,  FIGS. 83 and 122 ). The controller  6034  may also run a venting controller in block  7314 . The venting controller may vent vapors from the purifier  6010  as described elsewhere herein (see, e.g.,  FIG. 80 ). The controller  6034  may also run a heater controller in block  7314 . The heater may be controlled as described elsewhere herein (see, e.g.,  FIGS. 117-119 ). The controller  6034  may further run a motor controller in block  7314 . The motor may be controlled as described elsewhere herein (see, e.g.,  FIGS. 109-116 ). The controller  6034  may also run a blowdown controller and incoming source water splitting controller in block  7314 . This may be accomplished as described elsewhere herein (see, e.g.,  FIG. 100-101C ). A timer may also be incremented in block  7316 . 
     If, in block  7318 , the product temperature leaving the product heat exchanger  6008 A (see, e.g.,  FIG. 3 ) rises above a threshold, the controller  6034  may transition the system  6000  to a product water divert state in block  7320 . This threshold may be around body temperature (e.g. 37° C.) in certain examples. Similarly, if a conductivity threshold for the product water is breached (not shown), the product divert state may be entered in block  7320 . In some embodiments, a breach of a conductivity threshold may provoke a transition to stand-by state. The temperature and conductivity may be sensed by sensors  6082 A-D (see, e.g.,  FIG. 3 ). The product water divert state may also be entered in block  7320 , if, in block  7322 , the product level falls below a threshold value. This value may, for example, be 20% and may be measured by a product level sensor  6078  (see, e.g.,  FIG. 3 ). Once, in block  7324 , any sensor readings and the product level conform with their respective thresholds a divert timer may be incremented in block  7326 . This divert timer may be required to increment passed a predefined value before the divert state is exited and product water may be produced for dispensation to a point of use in communication with the system  6000 . If, in block  7328 , the divert timer has not yet incremented passed the predefined amount, the controller may return to block  7324 . Once the divert timer has incremented beyond the predefined amount, the controller  6034  may transition the system  6000  back to the water production state in block  7312 . 
     When in the water production state, the controller  6034  may transition the system  6000  into a hot water production preparation state in block  7332 , if, in block  7330 , a hot water mode request is received (e.g. from a point of use device) by the controller  6034 . If the product temperature and product level are in conformance with their respective thresholds in blocks  7318 ,  7322 , and no hot water request has been received in block  7330 , purified water may continue to be produced. In other embodiments, the transition to a hot water production preparation state may be automatic. These transitions may be based on a time accumulation of the timer incremented in block  7316 . The hot water production preparation state may be entered in block  7332  if, in block  7334 , the timer has accumulated greater than an expected usage time. Where the system  6000  is providing purified water for a medical system  6004  (see, e.g.,  FIG. 3 ), the expected usage time may be a therapy time. The therapy time may be communicated from the medical system  6004  to the controller  6034  of the system  6000  and updated if a change is made. Once the timer has incremented above the therapy time, for example, the controller  6034  may transition the system  6000  into a hot water production preparation state  7332 . If, in block  7334 , the timer has not incremented above the threshold, the controller  6034  may return to block  7316  and continue producing purified water. 
     Referring now primarily to the example flowchart  7340  in  FIG. 95 , in a hot water production preparation state, set points for a number of different parameters of the system  6000  may be altered to hot production set points over some period of time. The period of time may be a predefined period of time such as 10-20 minutes (e.g. 15 minutes). In some embodiments, each set point may be altered to its respective hot production set point over a (perhaps predefined) period of time specific to that set point. Among other parameter values, the speed of the compressor  6064  (see, e.g.  FIG. 3 ) motor may, for example, be altered to a hot water production speed over some period of time. In certain embodiments, the hot water production speed may be slower than the speed used in normal purified water production state. 
     As shown, in block  7342 , the controller  6034  may transition the system  6000  into the hot water production preparation state. The controller may, in block  7344 , slew the set points toward respective hot water production set points. As mentioned above, the motor speed may be slew toward a hot water production motor speed. Additionally, a blowdown reservoir fill rate may be slewed toward a hot water production blowdown reservoir fill rate. A product temperature set point may be slewed toward a hot water production temperature set point. To determine the slew rate, the period of time mentioned above may be converted into a number of frames which will occur over the period. A delta between the normal production set points and the hot water production set points may be determined. This delta may then be divided by the number of frames to yield a slew increment for each frame. In block  7346 , a difference between the current parameter values and the hot water production set points may be determined. If, in block  7348 , the deltas for each set point are less than thresholds predetermined for each of the respective parameters, the controller  6034  may transition to the next state in block  7350 . This may be a hot water production state. 
     If, in block  7348 , the difference for each is greater than a threshold set for each respective parameter, the controller  6034  calculates a derivative based on data received from at least one temperature sensor in the system  6000  in block  7351 . For example, the controller  6034  may calculate a derivative based on data received from a low pressure steam temperature sensor  6066  in block  7351 . This derivative value may allow for a determination of whether the system  6000  is cooling off or increasing in temperature at an undesirable rate. If, in block  7352 , the derivative is outside of a range, the controller  6034  may adjust (e.g. lower) the slew rate of at least one parameter in block  7354 . For example, the slew rate of the product temperature set point may be lowered. The slew rates may be limited to be within a range which is predefined for each set point. If the derivative value is in an allowable range in block  7352  or if a slew rate has been adjusted in block  7354 , the controller  6034  may check if a timer for the hot water production preparation state has elapsed. If, in block  7356 , the timer has not elapsed, the controller  6034  may continue to slew the parameter set points toward their respective hot water production state targets in block  7344 . If the timer has elapsed in block  7356 , an error may be generated in block  7358 . 
     In certain embodiments, the hot water production state may be used by a number of modes. For example, the hot water production state may be used to provide hot water to a point of use device or system (e.g. medical system  6004  of  FIG. 3 ) in communication with the system  6000 . The hot water production state may also be used in a self disinfect mode. In this mode, high temperature water may be passed from the purifier  6010  through various flow paths of the system  6000  for predefined period of time. In certain examples, the self disinfect mode may only flow hot water through lines which are in direct communication with purified product water carrying lines via a valve. In particular, the self disinfect mode may flow hot water though the divert line and to the drain  6018 . 
     Referring now primarily to the example flowchart  7360  in  FIG. 96 , in a point of use hot water mode, a hot water production state may be entered in block  7362 . The controller  6034  (see, e.g.,  FIG. 3 ), may run a number of controllers in block  7364 . These controllers may be the same as those described above with respect to block  7314  of  FIG. 94 , however, different target set points, gains, feed forwards, etc. may be used. 
     In block  7366  a timer may be incremented. If, in block  7368 , the product level falls below a minimum value, the controller  6034  may transition the system  6000  to a stand-by state. Otherwise, the controller  6034  may continue producing hot water for the point of use device or system until, in block  7372 , the timer increments above a threshold (e.g. 25-40 minutes). Once the timer has incremented above the threshold, the controller  6034  may transition the device to a stand-by state. In other embodiments, the controller  6034  may transition the system  6000  to a stand-by state when the controller  6034  receives a communication from the point of use device or system that it has completed its disinfect operation. 
     In the self disinfect mode, and referring now primarily to the example flowchart  7380  in  FIG. 97 , the hot production state may be entered in block  7382 . The outlet to the point of use device or system may be closed in block  7384 . Hot water produced by the system  6000  may be directed to the drain  6018  by the controller  6034 . This may be done as self disinfects, if performed, may typically occur after a point of use device or system has conducted its own disinfect operation. Consequentially, any lines to the point of use device should already have been disinfected by the hot water output to the point of use device or system. 
     The controller  6034  (see, e.g.,  FIG. 3 ), may run a number of controllers in block  7386 . These controllers may be the same as those described above with respect to block  7314  of  FIG. 94 , however, different target set points, gains, feed forwards, etc. may be used. If, in block  7388 , the product level falls below a threshold, the controller  6034  may transition the system  6000  to a stand-by mode in block  7390 . Otherwise, the controller  6034  may, in block  7392 , receive temperature data signals from one or more product temperature sensor (e.g.  6082 A-D of  FIG. 3 ) and check a diverter valve (e.g.  6084  of  FIG. 3 ) duty cycle. If, in block  7394 , the temperature data signal(s) indicate that the product temperature is above a threshold and a minimum amount of flow is present, a timer may be incremented in block  7396 . If not, the controller  6034  may return to block  7386 . The minimum temperature may be 80° C. in certain embodiments. The minimum temperature may also be defined as 10-20° C. less than the purified product water target temperature for the hot water production state. The duty cycle of the diverter valve  6084  (see, e.g.,  FIG. 3 ) may be required to be at least a certain value (e.g. 10-20%) for the controller  6034  to conclude that the minimum amount of flow is present. Once the timer has incremented above a threshold (e.g. 25-40 minutes), the controller  6034  may transition the system  6000  into a stand-by state in block  7390 . 
     The hot water production state may also have a timeout of, for instance, an hour or more after which the controller  6034  may transition the system  6000  to stand-by. This timeout may be used regardless of whether the system  6000  is in the self disinfect mode or the point of use hot water production mode. 
     Referring now primarily to the example flowchart  7410  in  FIG. 98 , in a stand-by state, the system  6000  may be kept up to temperature and ready to transition to production of purified water. Thus, the amount of time needed to begin purified water production may be minimized. The stand-by state may also be an intermediary state which the controller  6034  transitions the system  6000  into while waiting for a mode or state command from a point of use device or system (e.g. medical system  6004  of  FIG. 3 ). 
     As shown in  FIG. 98 , the stand-by state may be entered in block  7412 . In the stand-by state, the compressor  6064  (see, e.g.,  FIG. 3 ) motor may be turned off, and the bearing feed pump may not be run. These may be turned off or disabled in block  7414 . Additionally, the source proportioning valves  6050 A, B (see, e.g.,  FIG. 3 ) to the purifier  6010  may typically be closed to maintain the water level in the purifier  6010 . This may also be done in block  7414 . In block  7416 , the controller  6034  may control the heater to keep the water in the purifier  6010  at or within range of a target temperature (e.g. 111° C.). The controller  6034  may also control the vent valve to maintain a low pressure vapor temperature target. A timer may be incremented in block  7417 . 
     If, in block  7418 , the evaporator level is below a threshold, a cooling valve gating source flow to the electronics box  6046  may be closed. In block  7422 , the source proportioning valves  6050 A, B to the purifier  6010  may be opened to bring the evaporator level up to the target level. This may be done, for example, as described in relation to  FIG. 86 . If, the evaporator is not below the threshold in block  7418 , the controller  6034  may transition the system  6000  to a next state in block  7426  if, in block  7424 , the timer has been incremented above a threshold. Otherwise, the controller may return to block  7416 . 
     The threshold for the timer may be a predefined amount of downtime between two therapies in embodiments where the point of use device is a medical system  6004  (see, e.g.,  FIG. 3 ). In other embodiments, the controller  6034  may not automatically transition the system  6000  based on a timer and instead the controller  6034  may do so upon receipt of a mode change request from the point of use device or system. The next state may be a normal purified water production state. 
     Referring now to  FIG. 99 , an example flowchart  6390  detailing a number of actions which may be executed to control a liquid level within a system  6000  is depicted. According to the flowchart  6390 , the liquid level may be controlled such that it is deliberately changed over time in a pre-prescribed manner. By monitoring for this deliberate manipulation of the level in the output from a level sensing assembly monitoring the liquid level, a flow assessment may be performed. If the deliberate alteration is not reflected in data collected from the level sensing assembly, it may be deduced that a blockage, pumping issue, valve actuation issue, or similar condition may be present and an error may be generated. The liquid level may additionally be controlled to a specific level setting if desired by departing from the deliberate manipulation of the liquid level. In some embodiments, a controller  6034  (see, e.g.,  FIG. 2 ) may switch between a deliberate level alteration mode and a liquid level maintaining mode based on a predefined basis. 
     The volume containing the liquid level to be maintained may be in fluid communication with a reservoir including a level sensing assembly. The reservoir including the level sensing assembly may be fluidly connected to and laterally disposed with regards to a liquid volume to be controlled. The reservoir including the level sensing assembly may be disposed such that a portion of the reservoir is even with any points in a controllable range or an expected range of liquid level values at least during certain first states of operation of the purifier  6010 . In some embodiments, the reservoir with the level sensing assembly may be laterally disposed but possess an inlet above the expected range of liquid level values during certain second states of operation of the purifier  6010 . During the second states, liquid in the volume to which the reservoir in which the level sensing assembly is disposed may be boiling or splashing out of its expected range and into the inlet. 
     In some embodiments, the liquid level sensor may control the level in two volumes which are fluidically connected. For example, the liquid level sensor may directly control a liquid volume in a first volume where the sensor is located and may indirectly control a liquid level (e.g. to an acceptable or expected operational level range and not necessarily a precise volumetric level) in a second volume which is fluidically in communication with the first volume. The first volume may include at least some points (e.g. the inlet from the second volume to the first volume) which are above the acceptable operational level range of liquid in the second volume. In certain operational states, e.g. the first states described above, the expected range may differ such that the liquid level in the second volume rises to at least to the inlet of the first volume. In such scenarios, the liquid level sensor may directly control both the first and second volume&#39;s liquid levels. This may occur when a purifier  6010  is initially filled after start-up for example. 
     In specific examples, the liquid level to be measured may be the liquid level in an evaporator  6060  of a purifier  6010 . The liquid level sensing assembly may be located in the blowdown reservoir (see, e.g.,  FIGS. 12-16, 63, 66 ). Alternatively, the liquid level to be controlled may be the liquid level in a condenser  6076  of a purifier  6010 . The level sensing assembly may be located in a product reservoir  6012  (see, e.g.,  FIG. 37 ). In other embodiments, the level sensing assembly may be located in an evaporator reservoir (see, e.g.,  FIG. 59 ). In embodiments where the liquid level sensor measures two liquid levels, one directly and a second indirectly, the liquid level sensed directly may be the level in the blowdown reservoir  6014  (see, e.g.  FIG. 2 ). The level in the steam chest  6072  (see, e.g.,  FIG. 2 ) may be sensed indirectly via the liquid level sensed in the blowdown reservoir  6014 . 
     For purposes of example, the flowchart  6390  will be described as if the sensed level starts above a minimum threshold and an outlet to the reservoir is open to lower the liquid level. As shown, a controller  6034  (see, e.g.  FIG. 2 ) of the system  6000  may check, in block  6392 , the level indicated by the level sensing assembly on a predetermined basis. This may be a periodic preset basis (e.g. a fixed time based interval) or perhaps additionally or alternatively in response to the occurrence of a predefined event or events (e.g. valve actuations such as source valve actuations). In block  6394 , the controller  6034  may determine whether the level is less than (or less than or equal to in some examples) a minimum level threshold. The thresholds described in relation to  FIG. 99  are described as percentages of a maximum liquid level of the expected range or controllable range of liquid levels though need not be in all embodiments. The minimum level or threshold may be a value between 40-50% (e.g. 47.5%) in some specific embodiments. In certain other embodiments the minimum level value may be between 30-40% (e.g. 35%). 
     When the level is at or below the minimum threshold, an outlet valve from the reservoir containing the level sensing assembly may be actuated to a closed state by the controller  6034  in block  6396 . The controller  6034  may also set a target level in block  6396 . The target level may be set to the minimum level, for example. The controller  6034  may check the level on a predetermined basis in block  6398 . 
     If the target is equal to or greater than the minimum target, but less than a maximum target in block  6400 , the target may be adjusted by the controller  6034  in block  6402 . The maximum target may be between 90% and 100% (e.g. 95%) of the reservoir volume in certain examples. In the example, the target is adjusted upward according to a formula. The specific formula shown sets the new target equal to: 
       Target current *t*rate 
     Where Target current  is the current target value, “t” is an amount of time until the next level sensing assembly level check, and rate is a desired amount of liquid to transfer to the reservoir containing the level sensing assembly per unit time. This rate may be preset, or may vary depending on the current state the system  6000  is in (e.g. standby, water production, disinfect, etc.). In the context of a blowdown reservoir, the rate may be a concentrate production rate which may be varied by altering the duty cycle of one or more source input valves. The rate may thus determine an amount of source fluid entering the source input of the purifier  6010 . A fluid input control loop (see, e.g.,  FIG. 100-101C ) executed by the controller  6034  may govern actuation of these valves. 
     The controller  6034  may check the level from the level sensor assembly on a predetermined basis in block  6404 . If, in block  6406 , the level is greater than or equal to a maximum level, an outlet valve to the reservoir may be opened and the target may be adjusted down in block  6408 . In the example, the target level is set by the controller  6034  to the minimum level in block  6408 . The maximum level used may be equal to or below the maximum target level. The maximum level may be between 50-60% (e.g. 52.5%) or between 45-55% (e.g. 50%). Alternatively, the maximum level may be between 4 and 20 percentage points greater than the minimum threshold. 
     If, in block  6410 , the blocks  6392 - 6408  of the flowchart  6390  have not been repeated a predefined number of times, the flowchart  6390  may then return to block  6392  and repeat. This repetition may establish a periodic rise and fall in the level of the liquid being controlled. This periodic rise and fall may create a waveform which is generally sawtooth in nature when plotted over time. The period and shape of this waveform, in the context of a blowdown reservoir  6014 , may be dependent on the concentrate production rate created by the fluid input command. In some embodiments, the predefined number of iterations may be a single iteration. If in block  6410 , the blocks  6392 - 6408  have been repeated at least the predefined number of times, the controller  6034  may check for an expected pattern (e.g. a sawtooth-like rise and fall) in block  6412 . Assuming the waveform is present, the shape and period of the waveform may also be checked against an expected nominal waveform for the current operating parameters (e.g. concentrate production). The nominal waveforms may be empirically determined. If in block  6414 , the pattern is detected as expected, the flowchart  6390  may return to block  6392  and repeat. If in block  6414 , it is determined that the pattern is absent, the controller  6034  may generate an error in block  6416 . 
     In some embodiments, additional logic may be employed to prevent, for example, the blowdown reservoir  6014  from draining in certain scenarios. The controller  6034  may, for example, prohibit opening of the drain valve if the blowdown reservoir  6014  fill level is less than a certain amount. If the blowdown reservoir  6014  is empty or nearly empty, the drain valve for the blowdown reservoir  6014  may be prohibited from opening. Additionally, the controller  6034  may prevent the drain valve for the blowdown reservoir  6014  from opening if the pressure within the steam chest  6072  (e.g. as determined from the signal from sensor  6066  of  FIG. 2 ) is below a predetermined value. Likewise, if the pressure is above the predetermined value and the level in the blowdown reservoir  6014  is above a predefined limit (e.g. the reservoir is flooded), the controller  6034  may override the control loop and actuate the drain valve for the blowdown reservoir  6014  to the open position. 
     The controller  6034  may also track an amount of time which the drain valve, for example, to the blowdown reservoir  6014  has been in the open position. In the event that the drain valve to the blowdown reservoir  6014  has remained open for greater than a predefined period of time, an error may be generated in block  6416 . The predefined amount of time may, for example, be between 2 and 7 minutes (e.g. 5 minutes). The controller  6034  may also generate a notification if the reservoir has been draining for more than a second predefined amount of time. The second predetermined amount of time may be less than the first. In some embodiments, the second predetermined amount of time may be between 1-3 minutes (e.g. 2 minutes). 
     The controller  6034  may also track the amount of time taken for a reservoir such as the blowdown reservoir  6014  to fill. For example, if the drain valve for the blowdown reservoir  6014  is closed and the level in the blowdown reservoir  6014  is below the target level for more than a predetermined time limit, an error may be generated in block  6416 . The predefined amount of filling time may, for example be between 5 and 15 minutes (e.g. 10 minutes). Alternatively, the predefined amount of filling time may be at least twice the first predefined amount of draining time. The controller  6034  may only monitor for this excess filling time when the system  6000  is in certain operational states. For example, during a start-up state for hot water production (e.g. for disinfection of a medical system  6004 ), the controller  6034  may not generate an error if the predefined amount of fill time is exceeded. Alternatively, a second predefined amount of fill time greater than the first predefined amount of fill time may be employed in such operational states. In the event the blowdown reservoir level sensor  6074  returns a value greater than a predetermined value designated as a maximum fill level, the controller  6034  may actuate source valves providing fluid the purifier  6010  to the closed state. 
     Referring now to  FIGS. 100-101C  a number of control diagrams  6420 ,  7020  detailing example control systems are shown. These control systems may be used to control the temperature of one or more process stream within a system  6000  to a respective target temperature or temperature range by altering a flow of input source fluid through a plurality of process stream heat exchangers  6008 A, B (see, e.g.  FIG. 3 ). A controller  6034  (see, e.g.,  FIG. 2 ) may collect temperature data on at least one process stream exiting the plurality of heat exchangers  6008 A, B and use the data to divide a mass flow or total amount of incoming source liquid between the heat exchangers  6008 A, B. As the input source fluid is cooler than the output streams of the purifier  6010 , increasing the amount of input source fluid flowing through a heat exchanger  6008 A, B will lower the temperature of the process stream exiting the heat exchanger  6008 A, B. 
     These control diagrams  6420 ,  7020  may for example be implemented in a system  6000  (see, e.g.  FIG. 3 ) producing purified product water for a destination system such as a medical system  6004 . The destination system may generate a temperature request which is provided as the target temperature or temperature range for the product process stream output from the system  6000  or this target temperature may be determined by the controller  6034  depending on, for example a temperature measurement of the incoming source fluid (see, e.g.  FIG. 127 ). The product water may be controlled to a target temperature or temperature range by altering the flow of source water through a product and blowdown heat exchanger  6008 A, B (see, e.g.  FIGS. 6-9  or  FIGS. 56 and 57 ). In some examples, the temperature of the blowdown exiting the purifier  6010  may also be controlled to a target temperature in the same manner allowing for heat to be efficiently recovered by the system  6000  and lowering overall power consumption. 
     The control diagrams  6420 ,  7020  shown each include a fluid input control system or loop  6422  and a flow splitting control system or loop  6424 . The fluid input control loop  6422  may control an overall amount of source water passing through the heat exchangers  6008 A, B and entering the purifier  6010 . To do this, the fluid input control loop  6422  may govern the total or cumulative amount of time the source input valves are in an open state for a given interval. The flow splitting control system or loop  6424  may control the proportion of the source water directed through each of the heat exchangers  6008 A, B. In other words, the flow splitting control loop  6424  may control the proportion of the total amount of open state time (output by the fluid input control loop  6422 ) that each of the individual source input valves is to be allocated. 
     Referring specifically to the fluid input control loop  6422  in  FIG. 100 , the set point may be established based at least in part on a target blowdown level within a steam chest  6072  of the purifier  6010 . A target level calculator  6426  may determine the target blowdown level similarly to as described above in relation to  FIG. 99  or below as described in relation to  FIG. 104 . This target level may be passed to a summer  6428 . A current blowdown level, as determined from data provided from a blowdown level sensor  6074  may also be provided to the summer  6428 . Summers described herein, including summer  6428 , combine their various inputs into an output; use of the word “summer” anywhere herein shall not be construed to mean addition only must be performed. 
     At the summer  6428 , a difference between the current blowdown level and target blowdown level may be found. This output or error value may be passed to a PID controller  6430  which outputs a source duty cycle command  6432 . The source duty cycle command  6432  may govern the overall or total flow of source fluid into the system  6000 . It should be noted that the gains used for the proportional, integral, and derivative terms of the PID controller  6430  may vary depending on the embodiment, and at least one may potentially be set to zero (e.g. the derivative term). 
     In some embodiments, the fluid input control loop  6422  may also receive data from a heater control loop (not shown in  FIG. 100 ). For example, the fluid control loop  6422  may receive the duty cycle command issued for the heating element  6054 . Depending on the heating element duty cycle command, the fluid control loop  6422  may adjust its output. If the heating element duty cycle is above a predetermined threshold, the source duty command  6432  may be attenuated. For example, when the heating element duty cycle is above a predetermined threshold (e.g. 100% duty cycle), the source duty cycle command  6432  may be set to zero or a fraction of the source duty command  6432  generated from the fluid input control loop  6422 . This may help to avoid quenching the evaporator  6060  of the purifier  6010 . Alternatively or additionally, the compressor speed may be incremented upward as the heater duty cycle command gets larger. 
     Referring to the flow splitting control system  6424 , a set point may be established based at least in part on a temperature request provided from a medical system  6004 . This temperature request may vary depending on an operating mode or state of the medical system  6004 . The medical system  6004  may have a first, low temperature operating mode and a second, high temperature operating mode. The low temperature mode may be a therapy mode which generates a temperature request at around or somewhat below (e.g. 20-30° C.) normal human body temperature. The high temperature mode may be a disinfection mode which generates a temperature request at a temperature sufficient to cause disinfection of targeted components of the medical system  6004 . The high temperature mode may also be used for self-disinfection of the system  6000 . The disinfection mode temperature request may depend on the intended contact time of the delivered product water and may be at least, for example, 60° C. but below boiling point (e.g. 96° C.). Alternatively, the destination system may set a production mode for the system  6000  instead of sending a specific temperature set point. The system  6000  may control the temperature to a set point or range defined for that mode. The system  6000  may also control the temperature to a set point or range defined for a state which is used by the controller  6034  in that particular mode. Various modes and states are described in greater depth elsewhere herein. The same source  6002  (see, e.g.  FIG. 3 ) may be used in the low temperature and the high temperature mode. This source may be a non-temperature controlled fluid source. In certain embodiments, the system  6000  may optionally also draw from a hot water source (e.g. residential hot water tank) particularly in the high temperature mode. 
     The temperature request along with a product or condensate output temperature determined from data provided by a product output sensor  6082 E may be passed to a summer  6436  where the difference between the two is determined. The summer  6436  output may then be passed to a temperature PID controller  6438  to generate an output. It should be noted that the gains associated with proportional, integral, and derivative terms of the PID controller  6438  may vary depending on the embodiment. As with the source PID controller  6430  (and all other PID controllers describe herein), at least one of the gains for this PID controller may be set to zero (e.g. the derivative term). 
     At least one disturbance monitor  6440  may also be included in some embodiments. The disturbance monitor may provide data related to the monitored disturbance to a feed forward controller  6442 . The feed forward controller  6442  may generate a disturbance compensation output which is passed to a summer  6444 . Where multiple disturbances are monitored, each disturbance may be associated with its own feed forward controller. The multiple compensation outputs from the plurality of feed forward controllers may be combined in a feed forward summer (not shown) before a combined compensation output is provided to summer  6444 . Alternatively, the feed forward controller  6442  may be based off of rough estimate of what the heat exchanger command should be. This rough estimate may be empirically determined. In such cases, the feed forward controller  6442  may allow the flow splitting control system  6424  to more rapidly make adjustments to reach the target temperature under certain conditions. For example, such a feed forward term may help get the flow splitting control system  6424  to achieve the desired temperature set point quickly upon start-up. 
     At the summer  6444 , the output of the temperature PID controller  6438  and the disturbance compensation output may be added together to generate a heat exchanger command  6446 . The heat exchanger (HX) command  6446  may then be used to compute the amount of incoming source water which will flow through each of the heat exchangers  6008 A, B. In the example embodiment, the heat exchanger command  6446  may be multiplied by the source duty cycle command  6432  in a product generator  6448 . The resulting product may be used as the blowdown heat exchanger command  6450  (referred to as return HX in  FIG. 100 ). The blowdown heat exchanger command  6450  may also be subtracted from the original source duty command in summer  6452  to yield the product heat exchanger command  6454 . The blowdown and product heat exchanger commands  6450 ,  6454  may be used to respectively control a blowdown portioning valve  6050 B and product portioning valve  6050 A. Through this proportioning, the temperature of the product water generated for the medical system  6004  and exiting the product heat exchanger  6008 A may be controlled to the temperature request. When no product water is flowing through the product heat exchanger, all source water may be routed through the blowdown heat exchanger. Alternatively, in some embodiments, a small fraction of the source water may continue to flow through the product heat exchanger  6008 A. 
     Referring now to the example control diagrams  7020  shown in  FIGS. 101A-C , a fluid input control loop  6422  may be a multimodal control loop. In such embodiments, the fluid input control loop  6422  may output multiple provisional values for a source duty cycle command. These values may then be used to determine a single source duty cycle command  7050 . This single source duty cycle command  7050  may be a hybrid command composed based off two or more of the provisional values. Where such a hybrid command is used, the contributions of the provisional commands to the single source duty cycle command may be weighted. For example, 30% of a first provisional command may be added to 70% of a second provisional command to arrive at the single source duty cycle command  7050 . The percentages may be altered during operation, based on operational state or mode changes, sensor data, communications from a point of use system, etc. A controller  6034  of the system  6000  may also use one of the provisional commands as the single source duty cycle command  7050  with any other provisional commands having no effect on the single source duty cycle command  7050 . In other words, 100% of one provisional command and zero percent of any other commands may be added together to generate the single source duty cycle command  7050 . 
     In certain embodiments, the number of provisional source command duty cycles may be equal to the number of modes or states in which a purifier  6010  may generate purified water. For example, the controller  6034  may generate purified water in a hot mode (e.g. for disinfection of a medical system  6004  or the system  6000  itself) and a normal mode. In such embodiments and as shown in  FIG. 101A , the fluid input control loop  6422  may output a provisional value for each of these production modes. Though two are described in relation to  FIG. 101A , a greater number of provisional commands may be generated for other embodiments. 
     As shown, the set point or source duty cycle command  7050  for the fluid input control loop  6422  may be established based in part on a target blowdown rate from the purifier  6010 . A target rate calculator  7022  may determine the target blowdown rate (further described in relation to  FIG. 104 ). In other embodiments, the target rate may be a predefined value. This target rate may be passed to a summer  7023 . A current blowdown rate  7024 , as determined from data provided from a blowdown level sensor  6074  may also be provided to the summer  7023  (further described in relation to  FIGS. 102-103 ). At the summer  7023 , a difference between the current blowdown rate  7024  and target blowdown rate may be found. This output or error value may be passed to a PID controller  7025  which outputs a first provisional source duty command to a summer  7026 . It should be noted that the gains used for the proportional, integral, and derivative terms of the PID controller  7025  may vary depending on the embodiment, and at least one may potentially be set to zero (e.g. the derivative term). 
     In some embodiments, the PID controller  7025  may alter its output value based on a feed forward term before passing the first provisional duty cycle command to the summer  7026 . This feed forward term may be based off an amount of source duty cycle command pre-allocated to recover heat from the blowdown passing through the blowdown heat exchanger  6008 B. For example, the pre-allocated source duty cycle command for the source blowdown proportioning valve  6050 B may be subtracted from the output value of the PID controller  7025  and the result may be passed to summer  7026 . In some embodiments, a minimum amount of incoming source water may be required to flow through the blowdown heat exchanger  6008 B and the blowdown temperature may be controlled to a predefined range (see, e.g.  FIG. 130 ) by altering an amount of source water flowing through the blowdown heat exchanger  6008 B. The feed forward term may pre-allocate a portion of the source duty cycle command generated by the PID controller  7025  to ensure the minimum amount of source flow through the blowdown heat exchanger  6008 B and allot an amount of duty cycle to achieve control to the desired temperature. Where an electronics box  6064  (see, e.g.  FIG. 3 ) may be cooled by incoming source water directed to the blowdown heat exchanger  6008 B (see, e.g.  FIG. 129 ) the feed forward term may similarly pre-allocate a portion of the incoming source water for this purpose. 
     In certain embodiments, and as shown in  FIG. 101A , the fluid input control loop  6422  may also generate a second provisional source duty cycle command. This second provisional source duty cycle command may be based in part on a target blowdown rate for hot water production. A target hot water production blowdown rate calculator  7052  may determine the target rate. Alternatively, the target blowdown rate for this mode may be a predefined value. This target rate may be passed to a summer  7054 . The current blowdown rate  7024 , may also be provided to the summer  7054 . At the summer  7054 , a difference between the current blowdown rate and the target may be found. This output or error value may be passed to a hot production PID controller  7056  which provides an output to summer  7058 . It should be noted that the gains used for the proportional, integral, and derivative terms of the hot production PID controller  7056  may vary depending on the embodiment, and at least one may potentially be set to zero (e.g. the derivative term). 
     The second provisional source duty cycle command may also be based in part on a target level for the evaporator in hot water production. The evaporator target level  7060  may be a predefined value in certain embodiments. This target level may be passed to a summer  7064 . A current evaporator level  7062 , as determined from data provided from an evaporator level sensor  6073  (see, e.g.,  FIG. 3 ) may also be provided to the summer  7064 . At the summer  7064 , a difference between the current evaporator level  7062  and the target level  7060  may be found. This output or error value may be passed to an evaporator controller  7066  which provides an output to summer  7058 . The summer  7058  may combine the output of the evaporator controller  7066  and the hot production PID controller  7056  into the second provisional source duty cycle command. This command may be passed to summer  7036 . 
     In some embodiments, the evaporator controller  7066  may be a PID controller. It should be noted that the gains used for the proportional, integral, and derivative terms of the evaporator control  7066  may vary depending on the embodiment, and at least one may potentially be set to zero. The evaporator controller  7066  may be predominantly a derivative controller. In some embodiments, the evaporator controller  7066  may be a PD controller with the gain on the P term being significantly smaller (e.g. 1-2 or more orders of magnitude) than the D term gain. A target level for the evaporator level may also be used as just described for the generation of the first provisional source duty cycle command as well (not shown). 
     In some embodiments, the fluid input control loop  6422  may also receive data from a heater control loop. For example, the fluid control loop  6422  may receive the target sump temperature  7028  and current sump temperature  7030  and feed them to a summer  7032  which determines a delta between these values. Depending on the values of the target sump temperature  7028 , current sump temperature  7030 , and/or the delta, the fluid control loop  6422  may adjust its output. The determination of whether to apply an adjustment may be made by the controller  6034  as described in relation to  FIG. 105A , B for example. If an adjustment is to be made, a sump adjuster controller  7034  may generate an adjustment output based on an input from the summer  7032 . The sump adjuster controller  7034  may be a PID loop. Depending on the embodiment, the gains on one or more of the terms for the PID loop may be set to zero. For example, the sump adjuster controller  7034  may have the integral and derivative term gains set to zero. In such embodiments, the sump adjuster controller  7034  may behave as a P controller. The output from the sump adjuster controller  7034  may be provided to two summers  7036 ,  7026 . 
     Additionally, in some embodiments, the fluid input control loop  6422  may also receive data from a compressor motor control loop. For example, the fluid control loop  6422  may receive the target low pressure vapor temperature  7038  and current low pressure vapor temperature  7040 . These values may be fed to a summer  7042  which determines a delta between the values. Depending on the values of the target low pressure vapor temperature  7038 , current low pressure vapor temperature  7040 , and/or the delta, the fluid control loop  6422  may adjust its output. The determination of whether to apply an adjustment may be made by the controller  6034  as described in relation to  FIG. 105A , B for example. If an adjustment is to be made, a low pressure vapor adjuster controller  7044  may generate an adjustment output based on an input from the summer  7042 . The low pressure vapor adjuster controller  7044  may be a PID loop. Depending on the embodiment, the gains on one or more of the terms for the PID loop may be set to zero. For example, the low pressure vapor adjuster controller  7044  may have the integral and derivative term gains set to zero. In such embodiments, the low pressure vapor adjuster controller  7044  may behave as a P controller. The output from the low pressure vapor adjuster controller  7044  may be provided to two summers  7036 ,  7026 . Any adjustments from the sump adjuster controller  7034  and low pressure vapor adjuster controller  7044  may be used to alter the first and second provisional duty cycle commands at summers  7026  and  7036  respectively. After any adjustment, the provisional duty cycle commands may be provided to a slider  7048 . 
     The slider  7048  may allow the source duty cycle command  7050  output from the source input control loop  6422  to be a hybrid between different provisional source commands generated by the source input control loop  6422 . The slider  7048  may also allow for one of the provisional source duty cycle commands to be ignored. For example, when the system  6000  is in a hot purified water production mode or state, the first provisional source duty cycle command may have little if any impact on the source duty cycle command  7050 . Likewise, when the system  6000  is in a normal purified water production mode or state, the second provisional source duty cycle command may have little if any impact on the source duty cycle command  7050 . During a transition between two modes or state, the slider  7048  may slowly adjust the command from purely or predominately one of the provisional duty cycle commands to purely or predominately the other of the provisional duty cycle commands. The adjustment may be based off a predefined increment amount per frame for example. A similar slider  7018  (see  FIG. 101C ) may be used for provisional source proportioning commands to the product heat exchanger  6008 A. 
     Using the example of a provisional source command for the hot mode or state and a provisional source command for a normal mode or state, the controller  6034  may determine a hot fraction and normal fraction for the slider  7048  to use. The provisional source commands may then be multiplied by their respective fractions and subsequently added together to determine the source duty cycle command  7050 . When in the normal mode, the hot mode fraction may be zero. When in the hot mode, the normal mode fraction may be zero. During transition from one mode to the other, the new mode fraction may be incremented according to a slew rate limit and the old mode fraction may decremented according to that limit. This may continue until the new mode fraction has been incremented to 100% and the old mode fraction has been decremented to 0% in some examples. 
     Referring to the flow splitting control system  6424 , a set point may be established based at least in part on a temperature request or production mode setting provided from a point of use system such as a medical system  6004 . This temperature request or production mode setting may vary depending on an operating mode or state of the medical system  6004 . The controller  6034  of the system  6000  may determine a target temperature  7068  from the temperature request or production mode setting  7065 . The target temperature may also be determined as described in relation to  FIG. 127  in certain examples. 
     If, at block  7069 , the system  6000  is currently in a normal water production mode, the target temperature  7068  along with a product or condensate output temperature  7070  determined from data provided by a product output sensor (e.g. one or more of sensors  6082 A-D of  FIG. 3 ) may be passed to a summer  7072  where the difference between the two is determined. The summer  7072  output may then be passed to a temperature PID controller  7074  to generate an output. It should be noted that the gains associated with proportional, integral, and derivative terms of the temperature PID controller  7074  may vary depending on the embodiment. At least one of the gains for the temperature PID controller  7074  may be set to zero (e.g. the derivative term). 
     The output of the temperature PID controller  7074  may be limited to a minimum and maximum value at a limiter  7076  to generate a product heat exchanger command  7078 . If, in block  7080 , the system  6000  is in normal production mode or state, the product heat exchanger command may be subtracted from the total source duty cycle command  7050  at summer  7082 . 
     The remaining portion of the source duty cycle command  7050  or commanded source flow may be allocated to the blowdown heat exchanger command  7084 . The output of summer  7082  may be limited by a limiter  7086  to a minimum and maximum value before being set as the blowdown heat exchanger command  7084 . 
     In some embodiments, as shown in  FIG. 101C , some amount of source duty cycle command may be pre-allocated for the blowdown heat exchanger  6008 B. This may allow for greater heat recovery and more efficient cooling of an electronics box  6046  in the system  6000  among other things. Further description is provided above and in relation to  FIG. 130 . This pre-allocated command may be added to the output of summer  7082  in block  7083 . The output of block  7083  may be limited by a limiter  7086  to a minimum and maximum value before being set as the blowdown heat exchanger command  7084 . 
     If the system  6000  is in a hot water production mode or state, the entire source command duty cycle  7050  or commanded source flow may be allocated (after limiting by a limiter  7086 ) to the blowdown heat exchanger command  7084 . The product heat exchanger command  7078  may be independent of the source input control loop  6422 . The limiter  7077  for the product heat exchanger command  7078  in the hot production mode or state may limit the product heat exchanger command to a low value (e.g. less than 5% and in some embodiments a 2% duty cycle) so that added incoming source fluid (in addition to that called for by the source input control loop  6422 ) does not have a problematic effect on blowdown rate control. 
     In some embodiments and as shown in  FIG. 101C , a target temperature  7071  along with a product or condensate output temperature  7070  may be passed to a summer  7073  where the difference between the two is determined. The summer  7073  output may then be passed to a hot temperature PID controller  7075  to generate an output. It should be noted that the gains associated with proportional, integral, and derivative terms of the hot temperature PID controller  7075  may vary depending on the embodiment. At least one of the gains for the hot temperature PID controller  7075  may be set to zero (e.g. the derivative term). The limiter  7077  for the product heat exchanger command  7078  in the hot production mode or state may limit the product heat exchanger command similarly to as described above. A slider  7081  like that described in relation to  FIG. 101A  may be used to facilitate a smooth transition of the product heat exchanger command  7082  as the system  6000  shifts from a normal temperature water production state to a hot water temperature production state. 
     The blowdown and product heat exchanger commands  7078 ,  7084  may be used to respectively control a blowdown portioning valve  6050 B and product portioning valve  6050 A (see, e.g.  FIG. 3 ). Through this proportioning, the temperature of the product water generated for the medical system  6004  and exiting the product heat exchanger  6008 A may be controlled to the temperature target. 
     Referring now to  FIG. 102 , a flowchart  6820  detailing a number of example actions which may be executed to determine a fill rate of a reservoir and control an outlet valve to the reservoir is depicted. In certain embodiments, the reservoir may be the blowdown reservoir  6014  (see, e.g.,  FIG. 3 ) of the system  6000 . The flowchart  6820  will be described as if the sensed reservoir level starts at a minimum level after the reservoir has just finished draining. 
     As shown, in block  6822 , the controller  6034  (see, e.g.  FIG. 3 ) may set a minimum level value as the current level value. The level value may be read from a reservoir level sensor, such as a blowdown level sensor  6074  if the reservoir is the blowdown reservoir  6014 . In block  6824 , the controller  6034  may check the liquid level in the reservoir. This may be done on a predetermined basis, for example, every second or every number of seconds. If, in block  6826 , the liquid level is below the minimum set in block  6822 , the flowchart  6820  may return to block  6822  and set the minimum as the current level. If, in block  6826 , the level is above the minimum level, a timer may be incremented in block  6828 . If, in block  6830 , the timer has not been incremented above a threshold the controller  6034  may continue checking the liquid level and return to block  6824 . If, in block  6830 , the timer has been incremented above a threshold, the controller  6034  may determine a fill rate of the reservoir in block  6832 . Depending on the embodiment, the threshold may be predefined and be at or around 0.025-2 seconds (e.g. 0.5 seconds). The rate determination may be made by determining a delta between a value related to the preceding liquid level and the current liquid level in the reservoir. This delta may then be converted into a rate using the time elapsed since the preceding liquid level value was collected. The fill rate value may be prohibited from falling below zero. In the event the fill rate value would be less than zero, the fill rate value may be reset to zero. The fill rate may be passed to a filter in block  6834 . The filter may be a low pass filter. 
     If in block  6836 , the reservoir is filling, and if, in block  6838 , the fill level of the reservoir is greater than or equal to a maximum fill value, the outlet valve of the reservoir may be opened in block  6840 . The reservoir may then be drained. The incoming source valves may be closed if the outlet to the reservoir is open. If the system is generating hot water, the valve controlling flow of incoming source water to the purifier  6010  through the product heat exchanger may not be commanded closed. Instead, the valve may be opened at a low duty cycle which may be less than 10% (e.g. 2% or 5% or less). The maximum fill value may be the same as the maximum threshold described above in relation to  FIG. 99 . As the reservoir drains, the level of the reservoir may be checked on a predetermined basis in block  6842 . 
     If, in block  6836 , the reservoir is draining and if, in block  6844 , the reservoir level is above a minimum level, the level of the reservoir may be checked on a predetermined basis in block  6845 . If, in block  6836 , the reservoir is draining and if, in block  6844 , the reservoir level is below or at the minimum level, the outlet valve may be closed in block  6846 . The reservoir may then begin filling. The minimum level may be set at any of the values for the minimum threshold described in relation to  FIG. 99 . A fill cycle counter may also be incremented in block  6846 . This fill cycle counter may track the number of fill and drain iterations which have occurred. The controller  6034  may require that this counter has reached at least a certain number of counts before any water produced by the system  6000  is allowed to proceed to a point of use. Additionally, control logic such as that described in relation to  FIG. 101A-C  may not be used until the counter has accumulated a certain number of counts. 
     In some embodiments, during the filling and draining of the reservoir, the outlet valve may be commanded closed by the controller  6034  if the reservoir level is depleted below a near empty threshold (e.g. 5-10%). This may prevent steam and hot vapors from exiting the purifier  6010  through the outlet of the reservoir. Additionally, in some embodiments, the outlet may be commanded closed by the controller  6034  if the pressure in the purifier  6010  drops below a predefined value. This may be determined by the controller  6034  by analyzing a data signal from a pressure sensor. Alternatively, this may be determined by analyzing a temperature data signal received from, for example, the low pressure steam temperature sensor  6066 . In such embodiments, the temperature below which the outlet may be closed may be 104° C. In some examples, the controller  6034  may monitor the total time that the reservoir is filling or draining. If the time elapsed while the reservoir is either filling or draining exceeds a threshold, an error may be generated. In some embodiments, a notification may be generated after a first threshold is exceed and an error may be generated after a second threshold which is greater than the first is exceeded. The notification may be displayed on a user interface of a point of use device in some embodiments. Operation may be allowed to continue after the notification is generated. 
     In certain embodiments, and referring now primarily to the example flowchart  6850  in  FIG. 103 , the fill rate value may be adjusted under certain circumstances. For example, if the controller  6034  (see, e.g.,  FIG. 3 ) determines that draining is taking longer than expected and sensor data indicates that there should be sufficient pressure within the purifier  6010  (see, e.g.,  FIG. 3 ) to drive fluid from the reservoir, the fill rate may be adjusted. For example, the controller  6034  may adjust the fill rate to a high value at which the reservoir would not be capable of draining. 
     As shown, the controller  6034  of the system  6000  may monitor the time that the reservoir is draining in block  6852 . If, in block  6854 , the timer is below a threshold, the operation of the system  6000  may continue as normal in block  6856 . If, in block  6854 , the timer has incremented above the threshold, the operation of the system  6000  may continue as normal in block  6856  if a steam temperature reading is below a minimum threshold (e.g. 104° C.) in block  6858 . If, in block  6858 , the steam temperature is above the minimum threshold, the fill rate may be adjusted in block  6860 . The fill rate may be adjusted to a fill rate estimate at which the reservoir may not be capable of draining. This fill rate may be predefined and may be mode or state specific in certain embodiments. For example, in a normal mode, the fill rate estimate may be set at 250 ml a minute. In a hot product water production mode, the fill rate estimate may be set at 25-35% of the fill rate estimate for normal operation (e.g. 80 ml a minute). The fill rate estimate may vary depending on the embodiment and may be empirically determined. In some embodiments, the predefined fill rate estimate in block  6860  may be the output of an equation. For example, the predefined fill rate estimated may be computed as a product of the target fill rate and an estimating factor which is greater than one. The estimating factor may have a value between 1.25-1.75 (e.g. 1.5) in certain examples. 
     Referring now to  FIG. 104 , a flowchart  8040  detailing a number of example actions which may be executed to adjust a target blowdown rate value is depicted. In certain examples, each mode or state of the system  6000  may have a nominal blowdown rate target setting. The blowdown rate target may be adjusted during operation based on other measured parameters from various sensors included in the system  6000 . For example, in some embodiments, the target blowdown rate may be adjusted based on the temperature of source water entering the system  6000  as read by a source water product temperature sensor  6042  (see, e.g.  FIG. 3 ). 
     As shown, in block  8042 , the controller  6034  (see, e.g.,  FIG. 3 ) may receive a source or supply water temperature from at least one source water product temperature sensor  6042 . If, in block  8044 , the source water temperature is not above a predefined threshold, an adjustment value for the blowdown rate target may be set to zero in block  8046 . The predefined threshold may be between 22-26° C. in certain examples (e.g. 24° C.). If, in block  8044 , the source water temperature is above the predefined threshold an adjustment to the blowdown rate target may be determined in block  8048 . To determine the adjustment, the threshold value may be subtracted from the current temperature value read in block  8042  and the result may be multiplied by an offset factor. In some embodiments, the offset factor may be between in a range of 15-35 mL/min (e.g. 25 mL/min). Thus, the blowdown rate target may be increased by a certain amount for every degree above the threshold temperature value. The adjustment to the blowdown rate target may be limited in block  8050 . For example, the adjustment may be limited to being positive value no greater than 50 mL/min. The adjustment value determined in block  8050  or block  8046  may be filter (e.g. in a low pass filter) in block  8052 . In block  8054 , the target blowdown rate may be set to the current blowdown rate plus the filtered adjustment value determined in block  8052 . 
     Referring now to  FIG. 105A , a flowchart  6874  depicting a number of example actions which may be executed to adjust the output of a source PID loop (e.g.  6430  of  FIG. 100 or 7025, 7058  of  FIGS. 101A-C ) is shown. The adjustment may be made based on the status (e.g. temperature, pressure, etc.) in various portions of the system  6000 . For example, an adjustment may be made based on the sump temperature. An adjustment may additionally or alternatively be based on a temperature of low pressure steam in the purifier  6010 . In the flowchart  6874  depicted in  FIG. 105A , an adjuster based on the sump temperature and an adjuster based on the low pressure steam temperature are shown. 
     As shown, the controller  6034  may receive a sump  6050  temperature data signal from sump temperature sensor  6058  (see, e.g.  FIG. 3 ) in block  6876 . If, in block  6878 , the sump temperature value is less than the target temperature and below a minimum sump temperature threshold, a sump adjuster PID loop (see, e.g.,  7034  of  FIGS. 101A-C ) may be run in block  6880 . As inputs, the sump adjuster PID may be fed the current sump temperature and the target sump temperature. If, in block  6878 , the sump temperature value is either greater than the target or greater than the minimum sump temperature threshold, the sump adjuster PID output may be set to zero in block  6882 . The minimum sump temperature may vary between embodiments and may be mode or state specific within embodiments. For example, the minimum sump temperature may be between 85-95° C. (e.g. 90° C.) when producing purified water and between 75-85° C. (e.g. 80° C.) when producing hot purified water. In some examples, the target sump temperature may be a static value. This value may be mode or state specific. For example, the target sump temperature may be between 100-110° C. (e.g. 105° C.) when producing purified water and between 100-105° C. (e.g. 100° C.) when producing hot purified water. 
     A current low pressure steam temperature may be received by the controller  6034  in block  6884  from, for example, a low pressure steam temperature sensor  6066  (see, e.g.,  FIG. 3 ). If, in block  6886 , this temperature value is above a low value, the temperature value may be fed through a filter in block  6890 . This may generate a filtered low pressure vapor temperature value. In certain embodiments, a low pass filter may be used. If, in block  6886 , the current temperature value is below the low value, the controller  6034  may reset the low value to the current value in block  6888 . The low value may be historical low value, for example, the lowest low pressure steam temperature value previously measured during production or a preceding period of production. If the low value is reset, the filtered value may also be set to the current value. Such an arrangement may allow the filter to filter out noise, but not obscure drops in temperature which may need to be reacted to quickly for optimal results. 
     In some embodiments and as shown in the flowchart  6874 ′ of  FIG. 105B , the low pressure steam temperature received in block  6884 ′ may be filtered in, for example a low pass filter. Block  6886 ′ may check that filtered low pressure steam value to see if it is below the last output from the filter. If, in block  6886 ′, this temperature value is below the last filter output value, the low pass filter may be reinitialized to the current low pressure steam temperature value in block  6888 ′. Otherwise the low pass filter may be updated with the new low pressure steam temperature value in block  6890 ′. 
     Referring again primarily to  FIG. 105A , if, in block  6892 , the filtered low pressure steam value is less than a target value and greater than a minimum threshold, a low pressure steam adjuster PID loop (see, e.g.,  7042  of  FIGS. 101A-C ) may be run in block  6894 . As inputs, the low pressure steam adjuster PID may be fed the filtered low value and the target low pressure steam temperature value. If, in block  6892 , the filtered low value is above the target value or below the minimum value, the low pressure steam adjuster output may be set to zero in block  6896 . The minimum threshold may be a static value which may or may not be mode or state specific. For example, the minimum threshold may be a temperature of 104° C. In some examples, the target may vary between embodiments and may be mode or state specific within embodiments. For example, the target low pressure steam temperature may be between 104-112° C. (e.g. 108° C.) when producing purified water and between 101-107° C. (e.g. 104° C.) when producing hot purified water. After determining the output of the adjusters, the output of the source PID loop (e.g.  6430  of  FIG. 100 or 7025, 7058  of  FIGS. 101A-C ) may be altered, in block  6898 , based on the output of the adjuster PID loops. 
     Referring now to  FIGS. 106A and 106B , a flowchart  6910  depicting a number of example actions which may be executed to determine how to split flow of incoming source water between a plurality of heat exchangers. Flow of incoming source water may, for example, be split between a product heat exchanger and a blowdown heat exchanger. The flow may be split so as to ensure that the product water has been cooled to a desired set point. The splitting of incoming flow may be determined differently depending on the desired set point. For example, during normal production the split may be calculated in a first manner, and during production of hot product water (e.g. for disinfection of a medical system  6004 ), flow may be split in a second manner. 
     As shown, a source command may be determined by a controller  6034  (see, e.g.,  FIG. 3 ) in block  6912 . The source command may be a duty cycle value which may be allocated between the valves controlling the flow of source water into the blowdown and product heat exchangers. The source command may be determined as described in relation to  FIGS. 100-101C  for example. Any adjustments may be applied to the source command in block  6914 . The adjustments may be determined as described elsewhere herein, for example, as described in relation to  FIGS. 105A-B  and  FIGS. 101A-C . 
     If, in block  6916 , the source command is not within limits after any optional adjustment, the source command may be constrained to be in conformance with the limits in block  6918 . For example, the source command may be set to the closest limit value. In certain embodiments, the source command may be limited to be between zero and a number greater than 100%. The maximum limit may be 200% or may be equal to 100% multiplied by the number of source flow proportioning valves  6050 A, B (see, e.g.,  FIG. 3 ) or the number of heat exchangers (see, e.g.  6008 A-C of  FIG. 4 ). The minimum value may also be a number greater than zero in some embodiments. For example, the minimum value may be between 5-15% (e.g. 10%). 
     After the source command has been conformed to any limits in block  6918 , or if, in block  6916 , the source command is within limits, the manner in which incoming source flow is split between heat exchangers may be mode or state specific. If, in block  6920 , the system is producing hot water, the controller  6034  may set the blowdown heat exchanger valve command to the entirety of the source duty cycle command in block  6922 . The value may be limited to 100% if above. The controller  6034  may then apply a slew limit to the product water target temperature in block  6924 . This may cause the current target temperature to be slowly altered to a target temperature set point of the hot water production mode. The controller  6034  may receive a temperature data signal from a temperature sensor (e.g. one of sensors  6082 A-D of  FIG. 3 ) indicating the current product water temperature in block  6926 . This may be fed to a control loop (e.g.  7074  of  FIGS. 101A-C ) and the product valve duty cycle may be set to the output of this control loop in block  6928 . In some embodiments, the duty cycle may have a limit, e.g. may be prevented from being more than 10% (e.g. constrained to 5% or less). 
     If, in block  6920 , the system  6000  is not in a hot water production mode, a maximum product command may be determined by the processor  6034  in block  6930 . The product valve duty cycle may be determined via a control loop (e.g.  7074  of  FIGS. 101A-C ). The product valve duty cycle may be set to the output of this control loop in block  6932 . The product valve duty cycle command may be subtracted from the source command in block  6934  to determine the blowdown valve duty cycle command. If, in block  6936 , the blowdown command is greater than 100%, the product valve command may be increased in block  6938  and the blowdown command may be set to 100% in block  6940 . In the example embodiment, the product command may be increased by an amount equal to the blowdown command minus 100%. If, in block  6942 , the blowdown command is below a minimum threshold, the blowdown command may be set to the minimum threshold in block  6944 . This threshold may be a predefined duty cycle which may be set to less than 10% (e.g. 5%). Alternatively, the threshold may be a calculated value which is determined based on the source command. For example, the blowdown command may be set at a value of at least some percentage (e.g. 10%) of the total source command. In some embodiments, the threshold may be set as the greatest of a number of values. In such examples, the values may be the predefined duty cycle or the percentage of the total source command. In the event that there is a switch between any of the number of values (e.g. from predefined minimum duty cycle to minimum percentage of total command) the command to the blowdown heat exchange valve may be slewed over time to prevent a stepwise transition. This may ensure that excess heat is not dumped out of the system  6000  when blowdown is removed from the purifier  6010 . By implementing limiting to ensure a minimum flow of source is present in the blowdown heat exchanger  6008 B (see, e.g.  FIG. 3 ), more heat may be recovered causing the system  6000  to operate with greater efficiency. Additionally, limiting flow through the blowdown heat exchanger  6008 B may allow for use of this flow to be used from cooling an electronics box  6046  (see, e.g.  FIG. 3 ) of the system  6000  (described in greater detail in relation to  FIG. 129 ) The product and blowdown valve duty cycle commands may be used by the controller  6034  to spilt flow between the heat exchangers of the system  6000  in block  6946 . 
     Referring now to the flowchart  6950  in  FIG. 107 , in some embodiments, the controller  6034  (see, e.g.,  FIG. 3 ) may prevent product water generated by the purifier  6010  from passing to a point of use (e.g. a medical system  6004 ) under certain circumstances. For example, if the level of the blowdown reservoir increases above a threshold for too long, the processor  6034  may divert product water generated by the purifier  6010  to drain  6018  for a period of time or until a predefined volume of product water has been diverted. This may serve to flush the condenser  6076  of the purifier  6010  in the event that any liquid in the steam chest  6072  may have passed into the condenser  6076 . In the flowchart  6950 , a timer is used during such a flush. The processor  6034  may also generate an error if the level in the reservoir becomes too high. 
     As shown, the processor  6034  of the system  6000  may monitor the blowdown level in block  6952 . If, in block  6954 , the blowdown level breaches a first predefined level, an error may be generated in block  6956 . Otherwise, if the blowdown level increases above a predefined second level in block  6958 , a first timer may be incremented in block  6960 . The second predefined level may be lower than the first predefined level. In some embodiments, the first predefined level may be at or above 80% (e.g. 90%) and the second predefined level may be at or above 65% (e.g. 70%). If, in block  6962 , the first timer has been incremented above a predefined threshold, product water from the purifier  6010  may be diverted to a drain  6018  in block  6964 . Otherwise the controller  6034  may return to block  6952 . The predefined threshold for the first timer may be greater than three minutes (e.g. five minutes). If, in block  6966 , the blowdown level falls below the first and second predefined levels, a second timer may be incremented in block  6968 . Otherwise the controller  6034  may return to block  6954 . The first timer may be reset to zero if the blowdown level falls below the first and second predefined levels. If, in block  6970 , the second timer has incremented above a threshold for the second timer, the processor  6034  may allow product water to pass to a point of use such as a medical system  6004  in block  6972 . The threshold for the second timer may be at or about 5 minutes. In some embodiments the threshold for the first timer and the threshold for the second timer may be equal. 
     If, in block  6970 , the second timer is below the threshold, the processor may continue monitoring the blowdown level in block  6974  and incrementing the second timer in block  6968 . If, however, the blowdown level increases above one of the predefined levels in block  6966  an error may be generated in block  6956  or the first timer may be incremented in block  6960  depending on which predefined level has been exceeded. The second timer may also be reset to zero. 
     Referring now to the flowchart  6980  depicted in  FIG. 108 , the controller  6034  may also monitor for scenarios in which the blowdown level is too low for a prolonged period of time. This may allow the controller to identify a fault condition which prevents the purifier  6010  from generating blowdown. As shown, in block  6982 , the controller may monitor the blowdown level. If, in block  6984 , the blowdown level is less than a predefined level, a timer may be incremented in block  6986 . The predefined level may be a level of or less than 5-15% (e.g. 10%). If, in block  6988 , the timer has incremented above a threshold, an error may be generated in block  6990 . The threshold may be set above three minutes (e.g. 5 minutes) in certain embodiments. If, in block  6988 , the timer has not incremented above the threshold, the controller  6034  may continue monitoring the blowdown level in block  6982 . In the event that the blowdown level rises above the predefined level at block  6984 , the timer may be reset to zero. 
     Referring now to  FIG. 109 , an example flowchart  6460  detailing a number of actions which may be executed to control a liquid level within a system  6000  is shown. The liquid may be a first liquid which is within a reservoir in heat transfer and fluid communication with second liquid. The first liquid level may be a condensate formed from condensing vapor evaporated away from the second liquid. The first liquid level may thus be adjusted by controlling an amount of evaporation of the second liquid. According to the flowchart  6460 , the evaporation may be adjusted via operation of a compressor  6064 . The compressor  6064  may serve to increase the pressure and temperature of vapor passing from the evaporating second liquid into the reservoir storing the first liquid. The amount of temperature increase created via the compressor  6064  may serve to alter the amount of heat transfer into the second liquid from the reservoir containing the first liquid. The increase in heat transfer may alter the amount of evaporation of the second liquid and thus lead to more condensate formation and a change in the first liquid level. 
     The first liquid may be a purified water process stream in a condenser  6076  (see, e.g.  FIG. 2 ) of a purifier  6010  (see, e.g.,  FIG. 2 ). The second liquid may be unpurified source water contained in an evaporator  6060  (see, e.g.,  FIG. 2 ) of the purifier  6010 . The purified water level within the condenser  6076  may be depleted by opening an outlet valve to a point of use or a quality sensing system intermediate the condenser  6076  and point of use. Purified water may be consumed at the point of use faster than the purifier  6010  is capable of producing it. A controller  6034  (see, e.g.,  FIG. 2 ) may be used to ensure that a desired reserve level of purified water is available to compensate for such periods of increased demand. 
     In block  6462 , the controller  6034  may receive a current product level or purified water level and determine a desired product level. The current product level may be provided from a product level sensor assembly  6078  (see, e.g.  FIG. 36 ). The desired product level may be a calculated or preset value which may be determined in any suitable fashion. In some embodiments, the desired product level may be determined based off a current rate of product water usage for example. From these values, the controller  6034  may calculate a motor speed goal in block  6464 . The motor speed goal may be the output of a control loop (e.g. a PID, or PI loop) which utilizes the desired product level and current product level as a set point and feedback respectively. 
     In some embodiments, at least one feed forward input may be provided to adjust the motor speed goal. The source duty cycle command (see, e.g.,  FIGS. 100-101A -C) and/or heating element duty cycle command may be used as a feed forward input. The feed forward term may cause the compressor speed goal to be adjusted proportional to the feed forward input provided. For example, if the heating element duty cycle is above a predetermined threshold (e.g. at 90% or 100%) the compressor speed goal may be increased to a predetermined value or by a predetermined amount. This may help to heat fluid in the evaporator  6060  as hotter, high pressure steam will be generated by the compressor  6064 . This steam will then transfer heat to the evaporator  6060  as it condenses. In some embodiments, the compressor speed goal may be increased by a predetermined amount or to a predetermined value if the source valve duty cycle command  6432  is above a predefined threshold. Again, this may help to cause more heat transfer into the fluid in the evaporator  6060 . An increase in the compressor speed goal may also be generated when both the heating element duty cycle and the source valve duty cycle are in a predetermined relationship with one another. For example, the compressor speed goal may be increased as described above if the combined duty cycles of the heating element and source valve are above a predetermined value (e.g. 180-190%). 
     The controller  6034  may then generate a motor speed command in block  6466 . This command may be determined by incrementing the last commanded motor speed toward the motor speed goal by an amount. In some embodiments, the current motor speed, instead of the last commanded motor speed, may be incremented toward the motor speed goal. The amount may be limited to a certain increment limit which serves to limit the acceleration and deceleration of the motor. This slew rate limiting may cause the motor speed to ramp up to the goal. The increment limit may limit the increment to be less than or equal to around 5-10 rpm/sec for any single adjustment. The controller  6034  may also compare the motor speed command, in block  6468  to minimum and maximum speed command values. The minimum value, in some specific embodiments may be around 1500-2500 rpm (e.g. 2000 rpm). The maximum value may differ depending on at least one motor related parameter as, for example, described later in the specification. Though the maximum value may differ depending on various operational factors, this variation may be limited to no more than a predefined hard limit or cap defined as an rpm value. 
     If, in block  6470 , the motor speed command is below the range defined by the minimum and maximum values, the motor speed command may be set to the minimum value in block  6472 . If it is above the range, it may be set to the maximum value in block  6474 . The motor speed command may then be supplied to the motor or to a separate motor controller tasked with low level control of motor operation and interfacing with the motor hardware in block  6476 . Motor speed commands may be periodically generated on a predetermined time interval. Thus, the motor speed command may be updated each time the interval elapses. 
     In certain embodiments, and referring now to the flowchart  7000  in  FIG. 110 , the motor speed command may be based off of a predefined motor speed command which is mode or state specific. For example, the motor speed command may generally be set at a nominal value defined for each mode where the compressor  6064  (see, e.g.  FIG. 3 ) is used. The nominal values may be chosen such that they achieve good level control based upon an expected blowdown rate and product usage rate. The motor speed command may be ramped toward the nominal value defined for the mode or state after the system  6000  has entered that mode state. This may occur in a manner similar to the slew rate limiting described above. Additionally, the motor speed command may be altered from the defined nominal value based on limits for the command which may be calculated periodically during operation of the system  6000 . As shown in the flowchart  7000  in  FIG. 110 , the controller  6034  may receive a blowdown level value in block  7002 . If, in block  7004 , the blowdown level is greater than a predetermined threshold, the last motor speed command may be used in block  7006 . In some embodiments, the motor speed command may be decremented instead. The predetermined threshold may be a blowdown level value of 65-80% (e.g. 75%) in certain embodiments. This may help to avoid causing source water in the purifier  6010  (see, e.g.,  FIG. 3 ) to boil more vigorously in the event that the water level is high. 
     If, in block  7004 , the blowdown level value is below the predetermined threshold, a slew rate limited motor speed command may be determined in block  7008 . The controller  6034  (see, e.g.,  FIG. 3 ) may, for example, adjust the motor speed command by an increment limit toward the nominal motor speed defined for the mode or state the system  6000  is currently in. In certain embodiments, the increment limit may be between 5-10 rpm/sec (e.g. 8 rpm/sec). The nominal motor speed may be set at 4500 rpm for normal product water production. For hot water production, the nominal motor speed may be set below the nominal motor speed for normal product water production. For example, the nominal motor speed may be set at between 2200 rpm-3700 rpm (e.g. 3500 rpm) for hot product water production. The hot product water production nominal motor speed may be 50-80% of the normal product water production nominal motor speed. 
     In block  7010 , the controller  6034  may ensure that the motor speed command is within any motor speed command limits. Such limits are described elsewhere in the specification. In block  7012 , a new motor speed command may be generated 
     The nominal motor speed for hot water production may be a calibrated value in some embodiments. Likewise, in some embodiments, the nominal motor speed for normal temperature water production may also be a calibrated value. Calibrated values may be determined during manufacture and may be based on the specific purifier  6010 . A hot water production nominal motor speed value may, for example, be determined by bringing the system  6000  into a hot water production state and collecting data as the motor speed for the compressor  6064  is altered through a range. Alternatively, the controller  6034  may allocated an amount of time for the motor control loop to settle onto an ideal value. The particular value chosen for the nominal hot water production motor speed may be a speed which is optimal for that particular purifier  6010 . This value may be chosen based on any or any combination of a number of characteristics. For example, the value for the nominal hot water production motor speed may be a value which generates a product water output temperature (e.g. as sensed by sensors  6082 A-D of  FIG. 3 ) above a particular threshold (e.g. 96° C.). The value may be a value at which the low pressure vapor has a temperature of at least some threshold value (e.g. 108° C.). The value may also be a value at which a temperature such as the product water output temperature or a temperature of a vapor stream is relatively stable. The value may also be a value at which the level readings from any level sensors in the purifier  6010  are relatively stable. The value may be chosen based on a relationship between a temperature reading from the low pressure vapor sensor  6064  (see, e.g.  FIG. 3 ) and the high pressure vapor pressure sensor  6068  (see, e.g.  FIG. 3 ). For example, a delta between these values may be required to be greater than a certain amount. These values may also be required to be relatively stable. The vapor pressure values may also be required to be high enough to drive fluid out of the purifier  6010  during operation. The nominal motor speed value for hot water production may also be chosen based on an output amount of product water. The value may, for example, be a value at which at least a certain amount of product water per unit time is produced. 
     Referring now also to  FIG. 111 , a flowchart  7900  detailing example actions which may be used to automatically calibrate a nominal motor speed value. In the example embodiment, the automatic calibration is described in relation to a hot water production motor speed, though automatic calibration of motor speed values for other operational states of the system  6000  may be determined in a similar manner. As shown, in block  7902 , the motor controller operating on the controller  6034  may enter a transition state from normal water production to hot water production. This may for example occur when the system  6000  enters the hot water production preparation state (further described in relation to  FIG. 95 ). As shown in block  7902 , once in transition state, the motor speed may be slewed by toward a value which brings a measured steam temperature toward a target for that steam temperature. The steam temperature may be the low pressure steam temperature as measured by a low pressure steam temperature sensor  6066  (see, e.g.  FIG. 3 ). This slewing of the motor speed may continue until a predetermined amount of time has elapsed. The transition state is further described in relation to  FIG. 112 . In block  7904 , the motor controller may enter a stabilization state for an amount of time. This may ensure that the steam temperature is held at a relatively stable value before proceeding into the next motor controller state. The stabilization state if further described in relation to  FIG. 112 . 
     In block  7906 , the motor controller may enter a hot water production state. This may for example occur when the system  6000  enters a hot water production state (further described in relation to  FIG. 96  for example). As shown, in block  7906 , the motor speed may again be slewed toward a value which brings the measured steam temperature toward a target for that steam temperature. Further description is provided in  FIG. 113  for example. To hone in on the ideal motor speed value for the hot production state, a binary type search may be conducted. In block  7908 , the controller  6034  may determine a delta between the current speed and the hot production state starting motor speed. If, in block  7910 , the delta is outside of a range, the controller  6034  may shrink the range used by the motor controller in block  7912  and re-enter the stabilization state in block  7904 . This may help to ensure that the motor speed has been consistently around the value to be chosen as the ideal calibrated value for hot water production. In some embodiments, the range may defined by bounds of a minimum and maximum allowed value. When the range is shrunk in block  7912 , the value of the bound opposite the bound which was exceeded may be shrunk. For example, the bound exceeded may be multiplied by −0.5 (or some other negative fraction) and the product may be set as the new opposing bound. Further description is provided in relation to  FIG. 114 . 
     If, in block  7910 , the delta is within the range, the controller  6034  may determine a difference between the current steam temperature and the target steam temperature for the hot production state in block  7914 . If, in block  7916 , the delta is not below a threshold, the flowchart  7900  may return to block  7906  and the motor speed controller may slew the motor speed based on the delta. If, in block  7916 , the delta is below the threshold a timer may be incremented in block  7918 . If, in block  7920 , the timer has been incremented above a threshold, the current motor speed may be saved as the ideal calibrated hot water production motor speed value in block  7922 . If, in block  7920 , the timer is not above the threshold, the flowchart  7900  may return to block  7906  and the motor speed controller may slew the motor speed based on the delta. In the event that that the delta rises above the threshold in block  7916 , the timer may be reset to zero. 
     Referring now also to  FIG. 112 , a flowchart  6860  depicting a number of example actions which may be used in automatic calibration for a motor speed set point is depicted. The example flowchart  6860  is described in the context of calibrating a motor speed value for use during a hot water production state. As shown, in block  7862  the motor controller may enter a motor speed transition state with automatic calibration enabled. Typically, this may occur the first time the system  6000  is run (perhaps during manufacturing before release to a consumer). In some embodiments, automatic calibration may be performed after a certain number of running hours are accumulated by the system  6000 . Thus, the motor speed set point may be adjusted to account for differences which may be introduced as the system  6000  ages. 
     In block  7864 , the motor controller may receive a current steam temperature and a target stream temperature for the transition state. The steam temperature may be the low pressure steam temperature as measured by a low pressure steam temperature sensor  6066  (see, e.g.  FIG. 3 ). The target steam temperature may be between 107-110° C.  9  (e.g. 108.5° C.) in certain examples. In block  7866 , the controller  6034  may generate a slew rate command and apply this command to the motor speed. In block  7868 , a transition state timer and an automatic calibration total time may be incremented. If, in block  7870 , the transition state timer is not above a threshold, the controller  6034  may return to block  7864 . The transition state time threshold may be a predefined amount of time which is greater than a typical transition state time when automatic calibration is not enabled. In some embodiments, the transition state timer may be 100-150 minutes (e.g. 130 minutes) or 6-7 times (e.g. 6.5 times) that of the typical transition state time. 
     If, in block  7870 , the transition state timer has elapsed, the controller  6034  may indicate that the transition state has completed and at least one hot water production state controller may be initialized in block  7872 . In block  7874 , the motor controller may enter a calibration stabilization state. In block  7876 , a stabilization state timer may be incremented and the automatic calibration total time may be incremented. Once, in block  7878 , the stabilization state timer has increased above a predetermined threshold, the motor controller may enter a next state in block  7880 . The motor speed at the conclusion of the stabilization state may also be saved as the starting motor speed value for the next state in block  7880 . The next state may be a hot water production state. 
     Referring now to  FIG. 113 , a flowchart  7930  depicting a number of example actions which may be used in automatic calibration for a motor speed set point is depicted. The example flowchart  7930  is described in the context of calibrating a motor speed value for use during a hot water production state. As shown, in block  7932 , the motor controller may enter a hot water production state with automatic calibration enabled. This may occur when the system  6000  enters the hot water production state further described in relation to  FIG. 96 . In block  7934 , at least one hot water state motor controller may be provided a current steam temperature and a target hot water production state temperature. The steam temperature may be the low pressure steam temperature as measured by a low pressure steam temperature sensor  6066  (see, e.g.  FIG. 3 ). 
     If, in block  7936 , the current temperature is below a threshold, the controller  6034  may conclude that the motor speed is too high in block  7938 . If, in block  7940 , the current temperature is above a second threshold or the heater command is saturated, the controller  6034  may conclude that the motor speed is too low in block  7942 . In some embodiments, the heater command may be determined to be saturated in the event that the heater command is above a predefined duty cycle (e.g. 90%). Alternatively or additionally, the heater command may be determined to be saturated if the heater command is at a duty cycle which leaves the system  6000  at a system power draw threshold. 
     If, in block  7944 , the current temperature is not in breach of the first or second threshold in block  7936  and  7940 , the output of a first controller may be used to determine a commanded motor speed in block  7946 . If, in block  7944 , the current temperature is in breach of the first or second threshold in block  7936  and  7940 , the output of a second controller may be used to determine a commanded motor speed in block  7946 . The command may be generated in block  7950 . The first control loop and second control loop may be PID or PI controllers which have different gains. Additionally, the initial output of the first and second controllers may be filtered differently. For example, the first control loop may be low pass filtered have its gains set so as to be less aggressive. Thus, the first control loop may be slower or less reactive than the second control loop. As shown in  FIG. 113 , in the event that a switch between control loops occurs, the control loop may be set so that its initial output is at or near the output of the previous control loop. This may help to avoid a large stepwise change in the command generated in block  7950 . In certain examples, the value of one of the terms, e.g. the integrator term, may be initially set at the value of the integrator term of the other control loop when the switch occurs. 
     Referring now also to  FIG. 114 , a flowchart  7960  depicting a number of example actions which may be used in automatic calibration for a motor speed set point is depicted. The example flowchart  7960  is described in the context of calibrating a motor speed value for use during a hot water production state. As mentioned above in relation to  FIG. 111 , in the hot water production state during automatic calibration (see  FIG. 112 ), the controller  6034  may monitor an amount of change in the motor speed since entry to the hot water state. If this delta increases beyond a certain point, the controller  6034  may exit the hot water production state and re-enter a stabilization state. This may help to ensure that the controller  6034  does not mistake an overshoot or undershoot peak as an ideal speed for the motor in the hot water production state. 
     As shown, in block  7962 , the controller may determine a difference between the current motor speed and the motor speed upon entry to the state. If, in block  7964 , the difference is greater than or equal to a maximum threshold, an opposing minimum threshold value may be reduced in block  7966 . As shown, in block  7966  the minimum difference threshold may be reduced by the product of the current maximum difference threshold and a predefined adjustment factor. This adjustment factor may be a negative fraction such as −0.5. The stabilization state may be re-entered in block  7968 . If, in block  7970 , the difference value from block  7962  is less than or equal to a minimum threshold, the maximum difference threshold may be reduced in block  7972 . As shown, in block  7972  the maximum difference threshold may be reduced by the product of the current minimum difference threshold and a predefined adjustment factor. This adjustment factor may be a negative fraction such as −0.5. The stabilization state may be re-entered in block  7968 . If, in blocks  7964  and  7970 , the delta is within the bounds of the maximum and minimum threshold, the automatic calibration total time may be incremented in block  7974 . 
     As described in relation to  FIG. 111 , the controller  6034  may continue to adjust the motor speed until the steam temperature is close to the target value for a period of time. Once the steam temperature is stable and close to the target value, the current motor speed may be saved as the ideal calibrated motor speed value to be used in the future when the system  6000  enters the hot water production state. 
     Referring now also to the flowchart  6480  shown in  FIG. 115 , a maximum motor speed value may be calculated each time a new motor speed command is generated. The controller  6034 , in block  6482 , may receive a data signal indicative of at least one motor parameter. In the example flowchart  6480 , the parameters listed are the motor temperature and the power factor correction current. In some embodiments, only temperature may be used and the max speed value may not be determined or adjusted based off power factor correction current. The parameters may be respectively generated by a motor temperature sensor (e.g. thermistor or thermocouple) power factor correction current monitoring circuitry associated with the motor. The controller may check, in block  6484 , if the motor temperature is above a threshold. The controller  6034  may also check, in block  6486 , if the power factor correction current is above a threshold. In the event that either is above their predefined thresholds, the controller  6034  may check if, in block  6488 , the current max speed value is above the motor speed command. The max speed may be set to the commanded motor speed in block  6490  if the max speed value is above the motor speed command. After adjusting the max speed value in block  6490  or if the max speed was not above the motor speed command, the max speed value may be lowered in block  6492 . To lower the max speed, the max speed may be decremented down by an amount. In various examples, the amount may be the increment limit described above in relation to  FIG. 109 or 110 . Alternatively, the amount may be less than the increment limit. In certain examples, the amount may be 5 rpm/sec. In the event the max speed value falls below the minimum speed, the max speed may be set equal to the minimum speed value. As shown, the max speed may be adjusted in block  6492 , if, for example, decrementing causes the max speed value to fall below the minimum speed value. 
     The max speed value may also be increased in certain scenarios. For example, if the motor temperature is below a second threshold in block  6494  or if the power factor correction current is below a second threshold in block  6496 , the max speed may be increased in block  6498 . The max speed value may be increased by the increment limit described above in relation to  FIGS. 109 and 110 . Alternatively, the max speed may be increased by an amount less than the increment limit. In certain examples, the amount may be 5 rpm/sec. The second temperature threshold or power factor correction threshold may be the same as or different than the respective first thresholds described above. There may also be a motor speed cap which prevents the max speed value from exceeding a predefined value. In the event the increment would cause the max speed value to be over the cap, the max speed value may be adjusted to the cap. The cap may be around 4500-6500 rpm (e.g. 5000 rpm) in some embodiments. The cap may be about 2-3 times as large (e.g. 2.5×) as the minimum speed value. 
     If the current motor temperature and power factor correction current are between their respective first and second thresholds the max speed may be maintained without change in block  6500 . In block  6502 , the max speed may be provided to a controller such as that described above in relation to  FIG. 100 . Thus, the max speed value may be dynamically adjusted during operation of the system if desired. 
     Referring now to  FIG. 116 , a controller  6034  (see, e.g.,  FIG. 3 ) of the system  6000  may also monitor the compressor motor for atypical operation and may generate a fault condition if warranted. As shown in the flowchart  6740  of  FIG. 116 , the controller  6034  may determine a delta between the current motor speed and the commanded motor speed in block  6742 . If, in block  6744 , this delta is below a predefined threshold the controller  6034  may, in block  6746 , continue commanding normal operation of the motor as described elsewhere herein. The controller  6034  may continue to monitor for atypical motor operation throughout operation. If, in block  6744 , the delta is above the threshold a timer may be incremented in block  6748 . In certain embodiments, the threshold may be set at 400-600 rpm (e.g. 500 rpm). If, in block  6750 , the timer is incremented above a predetermined limit, an error may be generated in block  6752 . The motor may also be disabled and commanded to stop. The timer limit may be less than one minute (e.g. 30 seconds). If, in block  6750 , the timer has not breached the limit, operation may continue normally in block  6746 . If the delta falls below the threshold after exceeding the threshold, any accumulated time for the timer may be reset to zero. In some embodiments, if the delta has risen above the threshold, the delta may be required to fall below the threshold for a period of time before the timer is reset. 
     Referring now to  FIG. 117  an example a control diagram  6510  detailing an example control system is shown. The control system may be a cascade control system and may be used to generate a command  6544  which governs operation of an at least one heating element  6054  of a purifier  6010 . Multiple control loops may be used to generate the command. A first control loop, for example, may indirectly control the heating element  6054  while a second control loop may output a heater duty cycle command directly. In such embodiments, the first control loop may generate a set point for the second control loop. 
     The command may be calculated to get fluid in the purifier  6010  to a target temperature or temperature range (e.g. 102-116° C.) while conforming to various control limits (e.g. power or other electrical limitations) imposed upon the command  6544 . A controller  6034  (see, e.g.,  FIG. 2 ) may collect temperature data on at least one fluid as well as the temperature of a second fluid adjacent the heating element  6054  in the sump  6052 . This data may be used, in conjunction with temperature set points of the first and second fluid to generate the command  6544 . The exemplary control diagram  6510  in  FIG. 117  is also equipped to help quickly react to various disturbances which can rapidly alter temperature within the purifier  6010 . 
     As shown, a temperature reading  6512  of a first process stream may be taken by temperature sensor  6066  in communication with that process stream. In the example, the temperature sensor is a low pressure vapor sensor  6066  which monitors the temperature of vapor entering the compressor  6064 . The temperature reading  6512  may be combined with a target temperature value  6514  in summer  6516 . Again, as previously mentioned, use of the word “summer” anywhere herein shall not be construed to mean addition only must be performed, only that various inputs are combined into an output. The output of summer  6516  may be feed to a control loop for the first fluid temperature  6518 . In the example embodiment, the first fluid temperature control loop  6518  is depicted as a PID control loop which provides an output to summer  6524 . In various embodiments, at least one of the gain values in the first fluid temperature control loop  6518  may be set to zero (e.g. K D ). In some embodiments, at least one gain (e.g. K i ) of the first fluid temperature control loop  6518  may be altered depending on a set of predefined criteria. For example, the altered gain may be decreased (e.g. set to zero) in the event that the output of another control loop becomes saturated. The target temperature  6512  may be a predefined value in certain embodiments and may be mode or state specific. For example, the target temperatures during normal purified water production and hot purified water production respectively may be 108° C. and 104° C. The target temperatures during hot purified water production may be less than, but at least 95% of the target temperature in the normal purified water production state. 
     The target temperature  6512  may also be combined with an offset  6520  in summer  6522 . This offset  6520  may be a predetermined value, for instance −1 to −10° C. (e.g. −4° C.). The offset  6520  may serve to start the control system off in an initial state which reaches any target set points provided more quickly than it would solely under governance of the control loops  6518 ,  6538 . The output of summer  6522  may be combined with the output of the first temperature control loop  6518  in summer  6524 . 
     The current temperature  6528  of the second fluid may be sensed by a temperature sensor  6058  and combined with the output of summer  6524  in summer  6530 . The second fluid may be source fluid which has been received in the sump  6052  of a purifier. The output of summer  6530  may be fed to a second fluid control loop  6532  which may control the temperature of fluid in the sump  6052 . As such, the first fluid temperature control loop  6518  may act as an outer control loop and the second fluid temperature control loop  6532  may act as an inner control loop. Similarly to the first fluid temperature control loop  6518 , the second fluid temperature control loop may be a PID control loop. At least one of the gains in the second fluid control loop  6532  may be set to zero (e.g. K D ). The output of the second fluid temperature control loop  6532  may be a provisional heater command duty cycle. 
     At least one disturbance monitor may also be included in some embodiments. The disturbance monitor may provide data related to the monitored disturbance to a feed forward controller  6536 . The feed forward controller  6536  may generate a disturbance compensation output which is passed to a summer  6538 . Where multiple disturbances are monitored, each disturbance may be associated with its own feed forward controller. The multiple compensation outputs from the plurality of feed forward controllers may be combined in feed forward summer (not shown) before a combined compensation output is provided to summer  6538 . In the example shown in  FIG. 117 , the disturbance is the source command duty cycle  6432  (see, e.g.  FIG. 100 ). As the source command duty cycle  6432  increases a greater volume of relatively cool source fluid may enter the sump  6052  cooling the overall temperature. The feed forward controller  6536  may serve to preemptively adjust the provisional heater command output to compensate for an increased volume of cool source water entering the purifier  6010 . If, for example, the source command duty cycle  6432  is large (e.g. 100%) the feed forward controller  6536  may create an output which increases the provisional duty cycle command for the heating element  6054 . 
     Before providing the feed forward adjusted heater command duty cycle from summer  6538  to the at least one heating element  6054 , the output of summer  6538  may be checked against one or more threshold  6540 . If the output of summer  6538  would cause breach of one of the thresholds, then the heater duty cycle may again be adjusted. The controller  6034  may check the power factor correction current and determine if it is above a predefined limit. In the event it is above the predefined limit, the feed forward adjusted duty cycle command may be altered in current limiter  6542 . For example, the command may be altered to the last commanded heater duty cycle  6544 . Alternatively, the command from summer  6538  may be checked against a maximum heater power limit. This limit may be dynamic and may be set not exceed a maximum system  6000  power. The limit may be determined based at least partially off of an amount of power being allocated to the motor of the compressor  6064  (see, e.g.  FIG. 3 ). The maximum heater  6054  (see, e.g.,  FIG. 3 ) power limit may, for instance, be calculated by subtracting the power allocated for the compressor  6064  motor from a predefined power value (e.g the maximum total power) for the system  6000 . This maximum total power may be at or around 1150 Watts. In some embodiments, the maximum heater  6054  power limit may be expressed in terms of a heater duty cycle. A relationship between heater duty cycle percent and wattage may be used to perform the conversion. This relationship may be empirically determined. Where a duty cycle limit is used, the duty cycle may be limited to a maximum value such as 90%. After alteration, or if the output of summer  6538  is not above the threshold  6540 , a final heater duty cycle command  6544  may be generated. This command may be provided to the heating element  6054 . 
     Referring now to  FIG. 118 , a flowchart  6590  depicting a number of example actions which may be executed to generate a feed forward command is depicted. As shown, in block  6592  a controller may determine a difference between a desired temperature and the source inlet temperature. The desired temperature may, for example, be the target temperature  6514  described in relation to  FIG. 117  or may be otherwise generated by another control loop of the system  6000 . For example, it may be the output from the first fluid temperature control loop  6518  or from summer  6524  of  FIG. 117 . The source inlet temperature may be provided by a temperature sensor monitoring the fluid stream entering the purifier  6010 . In alternative embodiments, a reading of the fluid temperature in the sump  6052  may be used. An estimated mass flow entering the purifier  6010  may also be determined in block  6594 . A sensor may be employed to monitor the mass flow. Alternatively, the mass flow may be estimated by empirically determining a relationship between source inlet valve duty cycle and volume of water entering the purifier. For example, a number of mL per unit time per percent duty cycle may be empirically determined. This value may then be used in block  6594  as an estimate of mass flow into the purifier  6010 . In block  6596 , a controller  6034  may determine an amount of power required to heat the estimated mass flow into the purifier  6010  to the desired temperature. The estimated mass flow, thermodynamic characteristics (e.g. specific heat of water, heat of vaporization, etc.), and the delta between the source or sump temperature and desired temperature may be used to calculate the power required in block  6596 . The power requirement calculated in block  6596  may be used to determine a corresponding heater duty cycle which will act as the feed forward term in block  6598 . A relationship between heater duty cycle percent and wattage may be used to perform the conversion. The feed forward term may be sent to the heating element controller in block  6600 . In some embodiments, the feed forward term may be limited to between a minimum and maximum value defined for the feed forward term before being sent to the heating element controller in block  6600 . In certain embodiments, the feed forward term may be limited to between 0% and 90%. 
     Referring now to  FIG. 119 , a controller  6034  of the system  6000  may also monitor the heater  6054  for atypical operation and may generate a fault condition if warranted. As shown in the flowchart  6760  depicted in  FIG. 119 , the controller  6034  (see, e.g.,  FIG. 3 ) may determine the current heater voltage and the heater current in block  6762 . In block  6764 , the controller  6034  may determine a current heater power. The controller  6034  may get the current heater duty cycle command in block  6766 . The expected heater power may be determined, in block  6768 , from the current heater duty cycle command. A delta between the current heater power and the expected power may be calculated in block  6770 . If, in block  6772 , the delta is below a predefined threshold, the controller  6034  may, in block  6774 , continue commanding normal operation of the heater  6054  as described elsewhere herein. The controller  6034  may continue to monitor for atypical heater operation throughout operation. If, in block  6772 , the delta is above the predefined threshold, a timer may be incremented in block  6776 . If, in block  6778 , the timer has been incremented above a preset timer limit, an error may be generated in block  6780 . Otherwise, operation of the heater  6054  may continue normally in block  6774 . If the delta falls below the threshold after exceeding the threshold, any accumulated time for the timer may be reset to zero. In some embodiments, if the delta has risen above the threshold, the delta may be required to fall below the threshold for a period of time before the timer is reset. 
     Referring now to  FIG. 120 , a representational block diagram of a system  6000  including a bearing feed flow sensor  6562  is depicted. The bearing feed flow sensor  6562  may generate data which indicates that fluid is indeed flowing to an impeller bearing  6560  for an impeller  6216  of the water purifier  6010 . As described elsewhere herein, the fluid source for the bearing feed may be a purified water reservoir  6012  attached to a condenser  6076  of the water purifier  6010 . The bearing feed flow sensor  6562  may also indicate that the flow rate of fluid to the impeller bearing  6560  is within an acceptable predefined range (e.g. around 1 gram/sec). As shown, the bearing feed flow sensor  6562  is positioned downstream of the bearing feed pump  6080 . A bearing feed flow sensor  6562  may additionally or instead be disposed upstream of the bearing feed pump  6080  depending on the embodiment. Any suitable flow sensor may be used as a bearing feed flow sensor  6562 , however, in the exemplary embodiment, the bearing feed flow sensor  6562  is depicted as a thermal sensor. In certain embodiments, the bearing feed flow sensor  6562  may include a thermal sensor and a pressure sensor. Where a thermal sensor is used, the thermal sensor (e.g. a thermocouple or thermistor) may be an inline probe which provides a signal representative of bearing feed flow temperature to a controller  6034  of the system  6000 . The bearing feed flow sensor  6562  and/or pump  6080  may include heat dissipating features  6564  such as fins or similar protrusions which help to rapidly dissipate heat. 
     Referring now to  FIG. 121 , where the bearing feed flow sensor  6562  is a thermal sensor, the temperature data generated by the sensor may indicate presence or absence of fluid flow and/or whether the rate of bearing feed flow is acceptable. As shown in the flowchart  6570  of  FIG. 121 , the bearing feed pump may be activated in block  6572 . Any pre-existing fluid in the bearing feed conduit may be purged and the conduit may be brought up to the temperature of the purified water in block  6574 . The bearing feed flow sensor  6562  may monitor the temperature of the bearing feed stream and provide data representative of the temperature to a controller  6034  (see, e.g.,  FIG. 2 ) in block  6576 . 
     In the event the bearing feed pump  6080  is not properly functioning, an occlusion occurs, or the bearing feed pump  6080  is unable to draw fluid from the product reservoir  6012 , the temperature in the bearing feed conduit may begin to drop. The drop may be relatively significant and in some embodiments may be greater than 1° C. every five seconds. If, in block  6578 , the temperature indicated by the bearing feed flow sensor  6562  drops beyond a predefined value an error may be generated in block  6580 . If, in block  6578 , temperature does not drop below this value, operation may continue in block  6582  as the data indicates flow in the bearing feed conduit is as expected. 
     The predefined temperature value may be a static value in some embodiments. In other embodiments, the temperature value used to generate an error may be calculated based off of another temperature measurement in the system  6000 . For example, the controller  6034  may use a low pressure steam temperature (e.g. from temperature sensor  6066 ) to determine the error temperature value. The error temperature value may be set at 25-35° C. (e.g. 30° C.) less than the low pressure steam temperature. The delta between these two temperatures may be tracked by a controller  6034  to determine if the bearing feed pump  6080  is operating as expected. 
     In some embodiments, the temperature value itself may not be used to determine whether an error exists. Instead, the temperature signal may be further analyzed to potentially offer a faster detection of an abnormal flow condition in the bearing feed conduit. In such embodiments, the temperature signal may be differentiated and rate of change may be used instead of the temperature value. If the rate of change is greater than a predefined rate, the controller  6034  may generate an error in block  6580 . 
     Referring now to  FIG. 122  a flowchart  7100  depicting a number of example actions which may be executed to control a level of product in the condenser  6076  (see, e.g.,  FIG. 3 ) of a purifier  6010  (see, e.g.,  FIG. 3 ). In certain embodiments, the level may be measured via a product reservoir level sensor  6078  in a product reservoir  6012  fluidly connected to the condenser  6076 . The controller  6034  (see, e.g.,  FIG. 3 ) may, as described elsewhere herein, maintain a volume of product water in the condenser  6076  such that the condenser  6076  serves as a reservoir. This may allow for product water to be used at a point of use at a rate faster that it can be produced by the purifier  6010 . The amount maintained in the purifier  6010  may be chosen based off of expected demands and shifts in demand of an attached point of use device or system. Further description is provided in relation to  FIG. 83 . 
     As shown, a controller  6034  of the system  6000  may receive a high pressure vapor temperature in block  7102 . This reading may be supplied via a high pressure vapor temperature sensor  6068  (see, e.g.,  FIG. 3 ). If in block  7104 , the high pressure vapor temperature is below a minimum limit (e.g. 104° C.), a product reservoir outlet may be closed in block  7106 . In some embodiments, the product reservoir outlet may be a diverter valve  6084  (see, e.g.,  FIG. 3 ) which is opened to divert product water to a drain destination  6018  (see, e.g.,  FIG. 3 ) or other reservoir in order to maintain a desired level in the product reservoir  6012 . If, in block  7104 , the high pressure vapor temperature is below the minimum limit, additional product reservoir outlet valves such as a valve leading to a point of use device (e.g. medical system  6004 ) may also be closed. This may aid in a build-up of pressure which may be leveraged to drive flow of product water out of the condenser  6076  and product reservoir  6012 . If, in block  7104 , the high pressure vapor temperature is greater than the minimum limit, the controller  6034  may slew rate limit a current target product level toward a predefined volume storage goal in block  7108 . The predefined volume storage goal may be a level of 30% in the product reservoir  6012 . In some embodiments, this may maintain a buffer volume of 1-2 liters in the condenser  6076  and product reservoir  6012  which a point of use device of system (e.g. medical device  6004  of  FIG. 3 ) may draw from during periods of high purified water usage. 
     The controller  6034  may receive a level from the product reservoir level sensor  6078  in block  7110 . In block  7112 , a level controller may determine a product reservoir outlet (e.g. diverter valve  6084  of  FIG. 3 ) valve duty cycle command. The level controller may be a PID controller which uses a delta between the current level and current target level to generate an output. In such embodiments, one or more of the gains of the PID controller may be set to zero (e.g. that of the derivative term). The controller  6034  may command the outlet valve to operate at the duty cycle determined in block  7122  unless the level in the product reservoir  6012  is determined to be too high in block  7114 , and  7118 . If in block  7114 , the level is above a first threshold an error may be generated  7116 . The first threshold may between 80-95% (e.g. 90%) in some embodiments. If, in block  7118 , the level is greater than a second threshold, a notification may be generated in block  7120 . The second threshold may be less than the first threshold. In some examples, the second threshold may be 45-65% (e.g. 50%). In some embodiments, the controller  6034  may stop operation of the system  6000  in the event that the first threshold is breached. The controller  6034  may allow the system  6000  to continue operating in the event that the second threshold is breached. 
     In some embodiments, the outlet valve duty cycle command generated in block  7112  may be dependent upon at least one sensor value. For example, in some embodiments the outlet valve duty cycle may be dependent upon values from sensors such as the product level sensor  6078  (see, e.g.  FIG. 3 ) or product temperature sensors (e.g.  6082 A-D of  FIG. 3 ). When these sensors indicate that a point of use device (e.g. medical system  6004  of  FIG. 3 ) is currently drawing product water from the product reservoir  6012 , the outlet valve duty cycle command may be altered. This may help to ensure that the product reservoir  6012  and condenser  6076  (see, e.g.,  FIG. 3 ) contain a relatively large reserve volume of distillate for use in the point of use device. Additionally, this may help to ensure that a large increase in mass flow of hot water through the product heat exchanger  6008 A does not spike the product temperature beyond a desired level. Typically, the outlet valve duty cycle command may be decreased (e.g. set to a minimal value or perhaps zero). In some examples, upon a determination that the point of use device is no long consuming water from the system  6000 , the level controller may be restored based on its original output before being decreased. 
     Referring now also to  FIG. 123 , a flowchart  7520  detailing a number of example actions which may be executed to adjust a product reservoir outlet valve duty cycle based on data from a product level sensor  6078  (see, e.g.  FIG. 3 ) and product temperature sensor (e.g.  6082 A-D of  FIG. 3 ) is shown. Though data from both the product level sensor  6078  and product temperature sensor  6082 A-D are used in the example, other embodiments may adjust the product reservoir valve duty cycle using readings from only one of the product level sensor  6078  and product temperature sensor  6082 A-D. 
     As shown, the controller  6034  may receive data from the product level sensor  6078  and find a derivative using the data in block  7522 . If, in block  7524 , the derivative of the product level is below a threshold (e.g. negative or negative beyond a predefined magnitude) the outlet valve duty cycle may be decreased in block  7526 . Such a negative derivative of the product level may indicate product water is being drawn into the point of use device. Alternatively, the point of use device may send a communication to the system  6000  indicating it is drawing product water. In such examples, a derivative may optionally still be computed and checked, for example, to add a double checking redundancy to the system  6000 . When the outlet valve duty cycle is decreased, the output of the level controller may be saved as shown in block  7526 . 
     In block  7528 , the controller  6034  may receive data from each of the product temperature sensors (e.g.  6082 A-D of  FIG. 3 ) and find at least one derivative value using this data. A derivative of the product temperature as sensed by each individual product temperature sensor  6082 A-D may be calculated. In other embodiments, the temperatures from each product temperature sensor  6082 A-D may be averaged and a single derivative may be computed based on these averages. If, in block  7530 , the product temperature derivative is above a threshold (e.g. above some positive value) the outlet valve duty cycle may be decreased in block  7526 . As above, the outlet the output of the level controller may be saved when the duty cycle is decreased in block  7526 . Where derivatives are individually taken for each temperature sensor (e.g.  6082 A-D of  FIG. 3 ) if any of the derivatives breach the threshold the flowchart  7520  may proceed to block  7526 . 
     In some embodiments, an integral of the data from these sensors and/or of the calculated derivative values may also be taken and if in breach of a threshold a decrease in outlet valve duty cycle may be commanded. The output of the level controller may be saved in such instances as well. This may ensure that slow changes due to a point of use device consuming water from the system  6000  are captured. For example, an integral of the data from the product temperature sensors (e.g.  6082 A-D of  FIG. 3 ) may be taken. An integral of the product temperature as sensed by each individual product temperature sensor may be calculated. In other embodiments, the temperatures from each product temperature sensor may be averaged and a integral may be computed based on these averages. 
     The controller  6034  may continue to monitor the sensor data derivatives (and optionally integrals) in blocks  7522 - 7530  after reducing the duty cycle in block  7526 . If, in block  7532 , the product reservoir outlet valve duty cycle command is in a decreased state, and the sensor output derivatives are not in breach of their thresholds in blocks  7524  and  7530 , the level controller output may be restored based on its saved value in block  7534 . The controller  6034  may then continue determining the outlet valve duty cycle command as described above in relation to  FIG. 122 . 
     Referring now also to  FIG. 124 , a flowchart  7800  detailing a number of example actions which may be executed to adjust a product reservoir outlet valve duty cycle based on data from a product level sensor  6078  (see, e.g.  FIG. 3 ) is depicted. In block  7802 , the controller  6034  may find a derivate of the product level based on data received from a product level sensor  6078 . If, in block  7804 , the derivative is less than a threshold and the control loop has not been indicated as reset, the controller  6034  may proceed to block  7806 . In block  7806 , the divert valve control loop command may be saved and the control loop output may be decreased. The controller  6034  may also indicate (e.g. by setting a flag) that the control loop has been reset in block  7806 . In the example, the control loop output is decreased to zero. In certain embodiments, an output of a term such as the I term of the control loop may be decreased (e.g. to zero). The output of the control loop may be subjected to limiting (e.g. the control loop may be prohibited from commanding a negative duty cycle) such that terms of the control loop with negative outputs will have no effect. 
     If, in block  7804 , the derivative is above the threshold and the control loop is indicated as being reset and if, in block  7808 , the derivate is greater than a second threshold, the controller  6034  may proceed to block  7810 . The second threshold may be zero in certain examples. In block  7810 , the controller  6034  may indicate that the control loop has not been reset  7810 . Thus, if the derivative of the product level drops below the first threshold again, the control loop may again be reset. 
     If, in block  7812 , the derivative of the product level increases beyond a third threshold, the control loop hasn&#39;t already been restored, and the saved control loop output is not zero, the controller  6034  may proceed to block  7814 . The third threshold may be set as some positive value. In block  7814 , the controller  6034  may reset the control loop to the saved output value from block  7806 . Additionally, the controller  6034  may indicate the control loop has been restored in block  7814 . In embodiments where output of a term such as the I term of the control loop is decreased in block  7806 , the control loop may be reset to the saved output value from block  7806  less the current contribution from another term or terms of the loop. 
     If, in block  7812 , the derivative of the product level is below the third threshold, the control loop has been restored, or the saved command is zero, and if, in block  7816 , the product level derivative is less than a fourth threshold, the controller  6034  may proceed to block  7818 . The fourth threshold may be zero in some embodiments. In block  7818 , the controller  6034  may save the control loop output value as zero and indicate (e.g. by setting a flag) that the control loop has not been restored. This may allow the control loop to be restored again if when the derivative of the product level increases back to the third threshold. 
     Referring now also to  FIG. 125 , a flowchart  7830  detailing a number of example actions which may be executed to adjust a product reservoir outlet valve duty cycle based on data from one or more product temperature sensor  6082 A-D (see, e.g.  FIG. 3 ) is depicted. In block  7832 , the controller  6034  may find a derivate of the product level based on data received from the product temperature sensor(s)  6082 A-D. As mentioned elsewhere, in embodiments where data from multiple product temperature sensors  6082 A-D is used a derivative of the product temperature as sensed by each individual product temperature sensor  6082 A-D may be calculated. In other embodiments, the temperatures from each product temperature sensor  6082 A-D may be averaged and a single derivative may be computed based on these averages. Also in block  7832 , an integral may be calculated based off any derivative values determined by the controller  6034 . 
     If, in block  7834 , the derivative and/or integral is above respective thresholds for each, the control loop has not been indicated as reset, and the product level temperature is above a predefined value, the controller  6034  may proceed to block  7836 . In block  7836 , the divert valve control loop command may be saved and the control loop output may be decreased. The controller  6034  may also indicate (e.g. by setting a flag) that the control loop has been reset in block  7806 . In the example, the control loop output is decreased to zero. In certain embodiments, an output of a term such as the I term of the control loop may be decreased (e.g. to zero). The output of the control loop may be subjected to limiting (e.g. the control loop may be prohibited from commanding a negative duty cycle) such that terms of the control loop with negative outputs will have no effect. 
     As mentioned above, the controller  6034  may only proceed to block  7836  in the event that the product water temperature is greater than a predefined amount. This may prevent the adjusting the product outlet duty cycle command unless the product temperature gets close to a particular temperature. For example, where the point of use device is a medical system  6004  (see, e.g.,  FIG. 3 ) the system  6000  may be designed to avoid outputting water greater than body temperature (37° C.) for example. In such instances, the predefined temperature threshold may be below this temperature (e.g. 30° C.). 
     Referring again to  FIG. 125 , if, in block  7834 , the derivative and/or integral is below the threshold and the control loop is indicated as being reset and if, in block  7838 , the derivate is less than a second threshold, the controller  6034  may proceed to block  7840 . The second threshold may be zero in certain examples. In some embodiments, the individual derivatives determined from each product temperature sensor  6082 A-D may all be required to be less than the threshold in order for the controller  6034  to proceed to block  7840 . In block  7840 , the controller  6034  may indicate that the control loop has not been reset  7810 . Thus, if the derivative or integral thereof for the product temperature rises above their first thresholds again, the control loop may again be reset. 
     If, in block  7842 , the derivative of the product temperature decreases beyond a third threshold, the control loop hasn&#39;t already been restored, and the saved control loop output is not zero, the controller  6034  may proceed to block  7844 . The third threshold may be set as some negative value. In some embodiments, if any of the individual derivatives determined from each product temperature sensor  6082 A-D are less than the threshold, the controller  6034  may proceed to block  7844 . In block  7844 , the controller  6034  may reset the control loop to the saved output value from block  7836 . Additionally, the controller  6034  may indicate the control loop has been restored in block  7844 . In embodiments where output of a term such as the I term of the control loop is decreased in block  7836 , the control loop may be reset to the saved output value from block  7836  less the current contribution from another term or terms of the loop. 
     If, in block  7842 , the derivative of the product temperature is above the third threshold, the control loop has been restored, or the saved command is zero, and if, in block  7846 , the product temperature derivative is less than a fourth threshold, the controller  6034  may proceed to block  7848 . The fourth threshold may be zero in some embodiments. In block  7848 , the controller  6034  may save the control loop output value as zero and indicate (e.g. by setting a flag) that the control loop has not been restored. This may allow the control loop to be restored again when the derivative of the product level decreases back below the third threshold. 
     Referring now also to  FIG. 126 , a flowchart  7600  depicting a number of example actions which may be executed to determine the presence of an abnormal source water temperature within a system  6000  is shown. Detection of abnormal source temperature may be desired for several reasons. Among other things, such detection may allow the controller  6034  to react in the event that the incoming source water has a temperature which may be make it difficult to achieve a target temperature of one of the process streams exiting the heat exchangers  6008 A, B. For example, as the incoming source water temperature increases, the amount of cooling possible for the process streams in each of the heat exchangers  6008 A, B may decrease. In various embodiments, an abnormal source water temperature may be detected by monitoring the temperature of source water entering the system  6000  with a source water temperature sensor  6036  (see, e.g.  FIG. 3 ). A controller  6034  of the system  6000  may receive the data signals from the temperature sensor  6036  and check the measured temperature against one or more thresholds. In the event that that the temperature exceeds a threshold for more than a predefined period of time, a notification or an error may be generated by the controller  6034 . Though described in relation to the incoming source water, temperature parameters on other process streams (such as any of those described herein) may also be similarly monitored for abnormal temperatures predefined for each stream. 
     As shown in block  7602 , a controller  6034  may monitor for existence of a flow of source water into the system  6000 . Monitoring for flow in block  7602  may include, but is not limited to, reading one or more sensor, reading one or more variable, or checking one or more current command output with the controller  6034 . For example, in certain embodiments, the controller  6034  may check the duty cycle on the source proportioning valves  6050 A, B to the heat exchangers  6008 A, B and perhaps the diverter valve  6100  (see, e.g.  FIG. 3 ). If any of these duty cycles are greater than zero, the controller  6034  may conclude that flow of source water into the system  6000  is occurring. If, in block  7604 , flow of source water into the system  6000  exists, the temperature of the source water may be obtained from a source water temperature sensor  6036  (see, e.g.  FIG. 3 ) by the controller  6034  in block  7606 . Also in block  7606 , the temperature of the water source may be compared with a first temperature threshold and second temperature threshold. The first and second temperature threshold may be determined based on characteristics of a point of use device and characteristics of the heat exchangers  6008 A, B. For example, where the point of use device is a medical system  6004  (see, e.g.,  FIG. 3 ) such as a dialysis machine, the temperature thresholds may be set to be less than body temperature (e.g. 30° C. and 35° C.). If, in block  7606 , the temperature of the source water does not exceed any threshold, a timer, which may be associated each threshold, may be set to zero in block  7608 . If, in block  7606 , the temperature of the water source exceeds the first or second threshold, a timer, associated with each exceeded threshold, may be incremented in block  7610 . If, in block  7612 , the timer exceeds a timeout threshold predefined for each timer an error may be generated in block  7614 . For example, the timeout threshold for one of the first and second temperature thresholds may be set to five seconds. If the associated timer exceeds five seconds, an error may be generated. The error generated may depend on the particular temperature threshold exceeded. For example, an error generated for a breach of the first threshold may be an over temperature notification which may cause a user interface on a point of use device to display an associated screen or screen flow. An error generated for a breach of the second temperature threshold (which may be set higher than the first temperature threshold) may be an over temperature error which may cause the controller  6034  to transition the system  6000  out of a water production state or cause diversion of product water produced by the system  6000  out of a diverter valve  6084 . 
     Referring now also to  FIG. 127 , a flowchart  7650  depicting a number of example actions which may be executed to adjust a temperature set point of a process stream is shown. In various embodiments, adjusting the temperature set point may include measuring the temperature of incoming source water to the system  6000  and setting a desired temperature of a process stream within the system  6000  based on the source water temperature. In some embodiments, an offset may be applied to the source water temperature to arrive at a temperature set point for the process stream. It may be desired to set the target temperature of, for example, the product water exiting the product heat exchanger  6008 A based on the temperature of the source water entering the system  6000 . 
     In block  7652 , the temperature of a water source may be obtained. Obtaining the temperature of the water source in block  7652  may include reading an output from one or more sensor such as a source water temperature sensor  6036  (see, e.g.  FIG. 3 ). In block  7654 , the temperature of the water source may be filtered to generate a filtered temperature. Filtering the temperature of the water source in block  7654  may be achieved by passing the temperature through a filter such as a low-pass filter. In block  7656 , the filtered temperature may be adjusted using an offset value. In certain examples, the offset may be between 7-15° C. (e.g. 10° C.). The offset may be added to the filtered temperature from block  7654  to arrive an offset adjusted temperature. In block  7658 , the offset adjusted temperature may be limited to a desired range. The desired range may for example be approximately 20° C. through approximately 25° C. In block  7660 , a target temperature for the product process stream may be set as the limited temperature output from block  7658 . 
     Referring now also to  FIG. 128 , a flowchart  6710  depicting a number of example actions which may be executed to control cooling of an electronics housing (see, e.g.  6046 A, B of  FIG. 51 ) of a system  6000  is shown. In block  6712 , a target temperature for the electronics housing may be selected. Depending on the embodiment, a system  6000  may operate in a number of different modes and/or states. Mode or state specific cooling schemes for a filter (see, e.g.  6006 A, B of  FIG. 3 ) flushing mode, filter flushing states, water production mode, states used in a water production mode, stand-by mode, a stand-by state, and/or any other modes or states described herein may, for instance, be defined. Cooling of electronics in the system  6000  may be controlled differently depending on the mode or state. For example, a number of predefined target temperatures may be defined, with each being associated with an operating mode or state of the system  6000 . A first mode or state and second mode or state (e.g. flushing state and water production running state) may have a set point of 45° C. though these set points may be different from one another in alternative embodiments. A third mode or state may have a set target range of 40-45° C. The third mode or state may be a mode or state where source water is not being directed into the purifier  6010  on a regular basis (e.g. stand-by mode/state, heating mode/state, etc.) 
     In block  6714 , duty cycle limits on a valve controlling source water flow through a source line in heat exchange relationship with the electronics housing may be set. These limits may be predefined depending on the mode or state in which the system  6000  is in. In certain embodiments, the valve may be the source divert valve  6100  (see, e.g.,  FIG. 3 ). In a first mode or state (e.g. flushing mode or state) a maximum limit of 100% and a minimum limit of 50% may be used. In a second mode or state (e.g. production running state such as a hot water production state), a maximum limit of 25% and a minimum limit of 0% may be used. In a third mode or state (e.g. a stand-by mode or state) a maximum limit of 100% and a minimum limit of 0% may be used. This may allow for sporadic cooling when needed and help prevent excessive usage of source water when the system  6000  is not purifying water. 
     Data from an electronics temperature sensor (see, e.g.,  6048  of  FIG. 3 ) may be received by a controller  6034  (see, e.g.  FIG. 3 ) of the system  6000  in block  6716 . In block  6718 , a delta between the target temperature and the temperature indicated by the electronics temperature sensor may be input to a PID loop run by the controller  6034 . In some embodiments, the gains on one of the terms (e.g. the derivative term) may be set to zero. The output of the loop may be used to set or command a duty cycle for the valve controlling source fluid flow through the electronics housing in block  6720 . The gains of the terms of the PID loop may also be mode or state specific and set depending on which mode or state the system  6000  is in. 
     In modes or embodiments where the target temperature is defined by a range, the controller  6034  may switch the target temperature between values in the range (e.g. the bounds of the range) based upon certain criteria. As shown, in block  6722 , data from an electronics temperature sensor  6048  (see, e.g.,  FIG. 3 ) may be received by the controller  6034 . If, in block  6724 , the sensor data indicates that the current temperature of the electronics housing is greater than a high temperature limit, the target temperature value may be set to a low temperature limit in block  6726 . The high temperature limit may be at or above 45° C. The low temperature limit may be below the high temperature limit, for example, at or below 40° C. If instead, in block  6728 , the sensor data indicates that the current temperature of the electronics housing is less than the low temperature limit, the target temperature value may be set to the high temperature limit in block  6730 . After resetting the target temperature or if the temperature is between the high and low temperature limits, the flowchart  6710  may return to block  6718 . In some embodiments, the PID loop may be reinitialized in the event that the target temperature has been adjusted. Blocks  6722 ,  6724 ,  6728 ,  6730  may not be used in embodiments or modes/states which do not define the target temperature as a range. 
     In some embodiments, control of cooling of an electronics housing (see, e.g.  6046 A, B of  FIG. 51 ) of a system  6000  may be accomplished by controlling the duty cycle of a plurality of valves. As described in greater detail above, source water flowing to both the source divert valve  6100  and a source proportioning control valve  6050 B which gates flow into a blowdown heat exchanger  6008 B. Alteration of the duty cycle of both valves  6100 ,  6050 B may be used to control the temperature of the electronics housing  6046 . Controlling the electronics housing temperature  6046  which both valves may increase efficiency of the system  6000  and limit consumption of water which is used for cooling purposes and then directed to drain  6018 . Thus, a greater proportion of the source water entering the system  6000  may be converted into purified product water. Such multi valve temperature control may be used in modes or states in which the system  6000  is producing water. In some embodiments, this type of control may be utilized when the mode or state entered in block  6712  is a normal temperature water production mode or state. 
     Referring now to  FIG. 129 , a flowchart  7990  depicting a number of example actions which may be executed to control cooling of an electronics housing (see, e.g.  6046 A, B of  FIG. 51 ) of a system  6000  is shown. In block  7992 , the controller may receive temperature data from the electronics box  6046  (see, e.g.  FIG. 3 ). This data may be collected by at least one electronics temperature sensor  6048  (see, e.g.  FIG. 3 ). The temperature data may be feed into a PID loop run by the controller  6034  in block  7994 . This PID loop may be similar to that described in relation to block  6718  of  FIG. 128 . In block  7996 , the output of the PID loop may be subjected to limiting and a total cooling duty cycle command may be generated. For example, the raw output command of the PID loop may be limited to being less than a predetermined duty cycle command. In some embodiments, output may be limited to being less than 15-30% (e.g. 20%). If, in block  7998 , the total command was not greater than a maximum limit, the source proportion valve  6050 B for the blowdown heat exchanger  6008 B may be set to operate at a duty cycle equal to the total command (which will be the same as the raw PID loop output) in block  8000 . In this case, all water used for cooling of the electronics box  6046  may also be used in purification within the purifier  6010 . The maximum limit for the total command may be a predefined duty cycle which may be 10-20% (e.g. 15%) in some examples. If, in block  7998 , the total command value was greater than the maximum limit, a difference between the maximum limit and the total output may be determined in block  8002 . In block  8004 , the duty cycle command for the source proportion valve  6050 B for the blowdown heat exchanger  6008 B may be set to the maximum limit. Also in block  8004 , the source cooling valve  6100  (see, e.g.  FIG. 3 ) duty cycle may be set to the difference determined in block  8002 . In some embodiments, the remaining command value may also be limited. For example, this command may be limited to no more than a 10% duty cycle command in some embodiments. 
     Referring now also to  FIG. 130 , a flowchart  8010  depicting a number of example actions which may be executed to control the temperature of a blowdown process stream output from a heat exchanger  6008 B (see, e.g.  FIG. 3 ) is shown. The temperature of the blowdown process stream may be altered by adjusting an amount of source water which passes through the blowdown heat exchanger  6008 B before entering the purifier  6010 . Control of the temperature of the blowdown process stream may be desirable for a number of reasons. Among others, controlling the temperature of the blowdown process stream may allow for more heat to be recovered within the system  6000 . In certain embodiments and depending on the operating mode or state of the system  6000 , the amount of heat recovery may be sufficient to allow the purifier  6010  to operate with minimal or no power being consumed by the heater  6054  (see, e.g.  FIG. 3 ) included in the purifier  6010 . In certain examples, the amount of heat recovery may be sufficient to allow the heater  6054  to typically operate at a zero percent duty cycle (e.g. a large majority of the time), but may operate for brief periods at duty cycles of 5% or less. Input of energy by a compressor  6064  (see, e.g.  FIG. 3 ) may be adequate to maintain desired operating temperatures within the purifier  6010 . Thus the temperature of the blowdown process stream may be controlled to keep the heater  6054  at a minimal or zero percent duty cycle. This may increase the efficiency of the system  6000 . Depending on the embodiment, the temperature of the blowdown process stream output from the blowdown heat exchanger  6008 B may only be controlled in certain operating modes or states of the system  6000 . For example, the temperature of the blowdown process stream may only be controlled in production states which are non-hot water production states. 
     As shown in  FIG. 130 , the blowdown temperature may be received and passed through a filter by a controller  6034  in block  8014 . The filter may be a filter low pass filter and may determine a historic average blowdown temperature value. This value may be set as a desired blowdown temperature value. If, in block  8016 , the system  6000  is in a production start-up state, the target blowdown temperature may be set to the desired temperature value. A blowdown temperature control loop may be initialized and an extra source valve command cap may be determined in block  8018  as well. This cap may be a predefined additional duty cycle percent which may be added to the blowdown heat exchange source proportioning valve  6050 B when the system  6000  is in a start-up state. In certain embodiments, the cap may be set at 5-15% (e.g. 10%). This may prevent the blowdown temperature control loop from significantly affecting the system  6000  during start-up. 
     If, in block  8016 , the system  6000  is not in a production start-up state, in block  8020  the target temperature for the blowdown process stream exiting the blowdown heat exchanger  6008 B may be set to the desired temperature determined in block  8014 . The target temperature value may also be limited to conform to a predefined range in block  8020 . The predefined range may limit the target blowdown temperature to a range of 45−75° C. in certain embodiments. In block  8022 , the blowdown temperature target may be fed to a blowdown temperature control loop along with a current (perhaps low pass filtered) value of the temperature of blowdown exiting the blowdown heat exchanger  6008 B. The blowdown temperature control loop may include a PID controller which outputs a blowdown valve duty cycle command. It should be noted that the gains used for the proportional, integral, and derivative terms of the blowdown temperature control loop may vary depending on the embodiment, and at least one may potentially be set to zero (e.g. the derivative term). An extra source valve command cap may be determined in block  8022  as well. This cap may be a predefined additional duty cycle percent which may be added to the blowdown heat exchanger source proportioning valve  6050 B when the system  6000  is in a water production state. In certain embodiments, the cap may be set at 20-30% (e.g. 25%). 
     An extra source valve command value may be determined by the controller  6034  in block  8024 . For example, the controller  6034  may use the output from the blowdown temperature control loop as the extra source valve command value in block  8024 . In other embodiments, the extra source valve command may combine the output from the blowdown temperature control loop with a second value determined by the controller  6034 . In embodiments in which the source water flowing to the blowdown heat exchanger  6008 B is used for cooling of an electronics box  6046  of the system  6000  (see, e.g.  FIG. 129 ), a cooling duty cycle contribution may be added to the output of the blowdown temperature control loop. In block  8024 , the extra source valve command may also be limited to the extra source valve command cap set in block  8018  or  8022  depending on the state the system  6000  is in. In block  8026 , the extra source valve command value may be slew limited to yield a slew limited extra source valve command value. In block  8028 , the slewed extra source command value may be added to the blowdown proportioning valve command. In block  8030 , a feed forward term may be generated using the slewed extra command value. This feed forward term may be employed to adjust the total source valve command  7050  (described in greater detail with respect to  FIG. 101A-C ). For example, the feed forward term may cause the slewed extra source valve command value to be removed from the total source valve command  7050  so as to allocate that removed portion of source proportioning valve opening time specifically for control of the blowdown temperature. 
     The system  6000  may communicate with a point of use device or system (e.g. medical device  6004  of  FIG. 3 ) via any suitable communication scheme. The system  6000  and point of use device may, for example, communicate via and electromagnetic or acoustic communications link such as radio frequency, IR, ultrasonic, etc. Example communication protocols may include Bluetooth, Zigbee, Z-Wave, WiFi, ULE, 802.11.15.4, ANT, NFC, EPCGen2, etc. Communication may also be wired. For example, the system  6000  and point of use device may be in hardwired data communication with one another. An Ethernet or similar cable, fiber optic cable, or other light guide type cabling may be used for instance. Communications sent via the communications link may be encrypted. 
     The communications link may be used to, among other things, update software, transfer logging data, coordinate operation of the system  6000  and point of use device. In some embodiments, the medical system  6004  may provide the user interface for the system  6000  and the communications link may facilitate this. Exchange of information between the system  6000  and medical system  6004  may occur based on inputs to the user interface of the medical system  6004 . 
     Software updates may, for example, be downloaded to the point of use device (e.g. via the cloud) and conveyed to the system  6000  via the communications link. During operation, logging data may be provided from the system  6000  to the point of use device on a predetermined schedule. This logging data may be provided as part of a status message. In certain embodiments, a status message may be sent more frequently than the logging data. The logging data may be sent with every five status messages for example and status messages may be sent five times every second. In some embodiments, if an error condition is tripped logging data may be sent with the next status message. This may be done without regard for when a last message with status data was sent. 
     The status message may contain various information which may aid in coordination of the system  6000  with the operation of a point of use device. Status messages may contain a system  6000  identification number which may be unique to the particular system. Status messages may include usage information related to various replaceable components of the system  6000 . For example, the status message may include an install date, hours used data, or the like related to the filters  6006 A, B. The point of use device may require the filters  6006 A, B to be replaced if the filters  6006 A, B were installed 180 or more days prior. If the system  6000  determines the filters  6006 A, B need replacement (see, e.g.,  FIG. 89 ) this may also be conveyed to the point of use device in the status message. In the event that the system  6000  communicates that the filters  6006 A, B need replacement, the point of use device may command the system  6000  into a replacement preparation mode (see, e.g.,  FIG. 91 ). The status message may also be used to communicate to the point of use device whether the filters  6006 A, B need to be flushed. The filters  6006 A, B may be required to be flushed if the system  6000  has been in a stand-by or idle state for greater than a certain period of time. Alternatively, the filters may need to be flushed each time a water sample is to be taken. If the filters  6006 A, B need to be flushed, the point of use device may command the system  6000  to enter a filter flush mode (see, e.g.,  FIG. 89 ). 
     The status message may also include a time since last self disinfect of the system  6000  and/or an indication of whether a disinfection of the system  6000  is needed. Where the point of use device is a medical system  6004  (see, e.g.,  FIG. 3 ) the medical device  6004  may not begin a therapy if the last self disinfect of the system  6000  was greater than a predetermined amount of time in the past (e.g. 72 hours) or if the system  6000  communicates that a self disinfect is needed. The medical system  6004  may command the system  6000  to perform a self disinfection in this event. 
     The status message may also include error information. This information may include an error code for example. The status message may also specify an error tier. For example, the status message may communicate whether the error is a low level error (notification), operating error, or failsafe condition provoking error. The point of use device may use the error level to determine what (if any) reaction should be made. For example, the point of use may continue operation if a low level error is conveyed over the communications link. The error code may be used to determine a screen or screen flow to display via the user interface of the point of use device. 
     The status message may also include an identifier of the mode and/or state the system  6000  is currently in. Lower level information may also be included in some embodiments. For example, the status message may also include an indication of whether the system&#39;s  6000  valve to the point of use device is closed. As discussed elsewhere herein, this valve may be closed under certain circumstances (e.g. product water temperature too cold, conductivity outside of limits, etc.). This type of status information may allow the point of use device to operate in a water conserving mode or pause therapy. It may also allow the point of use device to avoid triggering an error based on a low flow or occlusion detection in the incoming water line. The point of use device may still detect such a condition and communicate this detection to the system  6000  for added redundancy. 
     Where the communications link is used for logging purposes, the log data may include, but is not limited to sensor data, target set points, mode, state, on/off status of various components (e.g. compressor, bearing feed pump), valve commands, and limit values for various controller outputs. These may be collected from any of the sensors, control loops, etc. described herein. 
     With respect to coordination between the system  6000  and the point of use device, the point of use device may send a number of messages to the system  6000  via the communications link. A number of example messages are described in Table 2 as follows: 
     
       
         
           
               
               
             
               
                 TABLE 2 
               
               
                   
               
               
                 Message 
                 Description 
               
               
                   
               
             
            
               
                 Go To Idle 
                 Commands the system 6000 to exit the current  
               
               
                   
                 state and enter idle mode 
               
               
                 Go to Stand-by 
                 Commands the system 6000 to exit the current  
               
               
                   
                 state and enter stand-by mode 
               
               
                 Flush Filter 
                 Commands the system 6000 to enter a flushing  
               
               
                   
                 mode 
               
               
                 Start Filter 
                 Commands the system 6000 to enter a filter  
               
               
                 Replacement 
                 replacement preparation mode 
               
               
                 Filter 
                 Sent, for example, upon receipt of user input on  
               
               
                 Replacement  
                 point of use device user interface indicating the  
               
               
                 Done 
                 user has completed installation of replacement  
               
               
                   
                 filters. Commands the system 6000 to perform  
               
               
                   
                 a replacement filter flush. 
               
               
                 Start Sampling 
                 Commands the system 6000 to enter a sampling  
               
               
                   
                 mode. 
               
               
                 Sampling 
                 Sent, for example, upon receipt of user input on  
               
               
                 Passed 
                 point of use device user interface indicating that  
               
               
                   
                 the water sample is acceptable. Commands system  
               
               
                   
                 6000 to enter normal water production mode. 
               
               
                 Sampling Failed 
                 Sent, for example, upon receipt of user input on  
               
               
                   
                 point of use device user interface indicating that  
               
               
                   
                 the water sample is unacceptable. Commands  
               
               
                   
                 system 6000 to enter stand-by mode. Indicates  
               
               
                   
                 system 6000 may need to replace filters. 
               
               
                 Start Normal 
                 Commands system 6000 to enter normal  
               
               
                 Water Production 
                 production mode 
               
               
                 Start Hot 
                 Commands system 6000 to enter hot production  
               
               
                 Production 
                 mode 
               
               
                 Start Self 
                 Commands system 6000 to enter self disinfect  
               
               
                 Disinfect 
                 mode 
               
               
                 Status 
                 Commands system 6000 to provide a status  
               
               
                   
                 message to point of use device 
               
               
                 Software 
                 Commands system 6000 to enter software  
               
               
                 Update 
                 update mode 
               
               
                 Time Sync 
                 Commands system 6000 to synchronize its real  
               
               
                   
                 time clock 
               
               
                 Error 
                 Indicates acknowledgement that an error  
               
               
                 Acknowledgement 
                 communicated in a status message has been  
               
               
                   
                 received. May clear error from status messages  
               
               
                   
                 generated over a predefined subsequent period  
               
               
                   
                 of time. 
               
               
                   
               
            
           
         
       
     
     The system  6000  may also send the point of use device a number of messages via the communications link. A number of example messages are described in Table 3 as follows: 
     
       
         
           
               
               
             
               
                 TABLE 3 
               
               
                   
               
               
                 Message 
                 Description 
               
               
                   
               
             
            
               
                 Idle  
                 May be sent to indicate that the controller 6034 of the  
               
               
                 Pending 
                 system 6000 is transitioning the system into idle state.  
               
               
                   
                 This message may also indicate that the valve gating  
               
               
                   
                 flow to the point of use device is in a closed state. 
               
               
                 Idle 
                 May be sent to indicate that the system 6000 has  
               
               
                   
                 transitioned to idle state. This message may also indicate  
               
               
                   
                 that the valve gating flow to the point of use device is in  
               
               
                   
                 a closed state. 
               
               
                 Standy-by 
                 May be sent to indicate that the controller 6034 of the  
               
               
                 Pending 
                 system 6000 is transitioning the system into stand-by state.  
               
               
                   
                 This message may also indicate that the valve gating flow  
               
               
                   
                 to the point of use device is in a closed state. 
               
               
                 Stand-by 
                 May be sent to indicate that the system 6000 has  
               
               
                   
                 transitioned to stand-by state. This message may also  
               
               
                   
                 indicate that the valve gating flow to the point of use  
               
               
                   
                 device is in a closed state. 
               
               
                 Filter 
                 May be sent to indicate that the controller 6034 is in filter  
               
               
                 Flushing 
                 flush state. This message may also indicate that the valve  
               
               
                   
                 gating flow to the point of use device is in a closed state. 
               
               
                 Filter 
                 May be sent to indicate that the controller 6034 is in filter 
               
               
                 Replacement 
                 replacement preparation state. This message may also  
               
               
                 Preparation 
                 indicate that the valve gating flow to the point of use  
               
               
                   
                 device is in a closed state. 
               
               
                 Sample 
                 May be sent to indicate that the controller 6034 of the  
               
               
                 Pending 
                 system 6000 is transitioning the system into sampling state.  
               
               
                   
                 This message may also indicate that the valve gating flow  
               
               
                   
                 to the point of use device is in a closed state. 
               
               
                 Sample 
                 May be sent to indicate that the system 6000 is ready to  
               
               
                 Available 
                 dispense a sample upon depression of a sampling button.  
               
               
                   
                 This message may also indicate that the valve gating flow  
               
               
                   
                 to the point of use device is in a closed state. 
               
               
                 Sample 
                 May be sent to indicate that the system 6000 has dispensed  
               
               
                 Complete 
                 a sample. This message may also indicate that the valve  
               
               
                   
                 gating flow to the point of use device is in a closed state. 
               
               
                 Normal 
                 May be sent to indicate that the system is in the normal  
               
               
                 Water  
                 water production mode and is not in the production running  
               
               
                 Production 
                 state. This message may also indicate that the valve gating  
               
               
                 Pending 
                 flow to the point of use device is in a closed state. 
               
               
                 Normal 
                 May be sent to indicate that the system is in the normal  
               
               
                 Water  
                 water production mode and is in the production running  
               
               
                 Production 
                 state. This message may also indicate that the valve gating  
               
               
                   
                 flow to the point of use device is in an open state. 
               
               
                 Hot Water 
                 May be sent to indicate that the system is in the hot water 
               
               
                 Production  
                 production mode and is not in the hot production running  
               
               
                 Pending 
                 state. This message may also indicate that the valve gating  
               
               
                   
                 flow to the point of use device is in a closed state. 
               
               
                 Hot Water 
                 May be sent to indicate that the system is in the hot water 
               
               
                 Production 
                 production mode and is in the hot production running state.  
               
               
                   
                 This message may also indicate that the valve gating flow  
               
               
                   
                 to the point of use device is in an open state. 
               
               
                 Self- 
                 May be sent to indicate that the system is in the  
               
               
                 Disinfect 
                 self-disinfect mode and is in the hot production running  
               
               
                   
                 state. This message may also indicate that the valve  
               
               
                   
                 gating flow to the point of use device is in a closed state. 
               
               
                 Failsafe 
                 May be sent to indicate that the system 6000 has  
               
               
                   
                 transitioned to a failsafe state. This message may also  
               
               
                   
                 indicate that the valve gating flow to the point of use  
               
               
                   
                 device is in a closed state. 
               
               
                   
               
            
           
         
       
     
     The messages sent between the system  6000  and a point of use device or system over the communications link may serve to guide the system  6000  through, for example, the various operational states described in relation to  FIGS. 84A-B . 
     Various alternatives and modifications can be devised by those skilled in the art without departing from the disclosure. Accordingly, the present disclosure is intended to embrace all such alternatives, modifications and variances. Additionally, while several embodiments of the present disclosure have been shown in the drawings and/or discussed herein, it is not intended that the disclosure be limited thereto, as it is intended that the disclosure be as broad in scope as the art will allow and that the specification be read likewise. Therefore, the above description should not be construed as limiting, but merely as exemplifications of particular embodiments. And, those skilled in the art will envision other modifications within the scope and spirit of the claims appended hereto. Other elements, steps, methods and techniques that are insubstantially different from those described above and/or in the appended claims are also intended to be within the scope of the disclosure. 
     The embodiments shown in drawings are presented only to demonstrate certain examples of the disclosure. And, the drawings described are only illustrative and are non-limiting. In the drawings, for illustrative purposes, the size of some of the elements may be exaggerated and not drawn to a particular scale. Additionally, elements shown within the drawings that have the same numbers may be identical elements or may be similar elements, depending on the context. 
     Where the term “comprising” is used in the present description and claims, it does not exclude other elements or steps. Where an indefinite or definite article is used when referring to a singular noun, e.g. “a” “an” or “the”, this includes a plural of that noun unless something otherwise is specifically stated. Hence, the term “comprising” should not be interpreted as being restricted to the items listed thereafter; it does not exclude other elements or steps, and so the scope of the expression “a device comprising items A and B” should not be limited to devices consisting only of components A and B. 
     Furthermore, the terms “first”, “second”, “third” and the like, whether used in the description or in the claims, are provided for distinguishing between similar elements and not necessarily for describing a sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances (unless clearly disclosed otherwise) and that the embodiments of the disclosure described herein are capable of operation in other sequences and/or arrangements than are described or illustrated herein. 
     While the principles of the disclosure have been described herein, it is to be understood by those skilled in the art that this description is made only by way of example and not as a limitation as to the scope of the disclosure. Other embodiments are contemplated within the scope of the present disclosure in addition to the exemplary embodiments shown and described herein. Modifications and substitutions by one of ordinary skill in the art are considered to be within the scope of the present disclosure.