Patent Publication Number: US-2022221194-A1

Title: &#34;off&#34; state monitoring for conservation override apparatus and method

Description:
RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Patent Application Ser. No. 63/137,713 filed on Jan. 14, 2021, which is hereby incorporated herein by reference in its entirety. 
    
    
     BACKGROUND 
     The Field of the Invention 
     This invention relates to optimizing timing of energy use in electrical devices, and, more particularly, to novel systems and methods for detecting and overriding the state of such devices, even when unpowered. 
     The Background Art 
     Everyone is familiar with “rush hour” in traffic. Rush hour is legendary because such vast numbers of individuals in their vehicles, whether private or public transportation, are all on roadways and thoroughfares prior to and following a conventional work day. Surrounding these traffic rush hours is the peak demand time on utilities. For example, as families arise in the morning and prepare for work, school, or other daily activities, they will begin to use hot water, stoves, furnaces, and other utility-supplied appliances and equipment. Hot water in a modern home draws a large fraction, typically about half of the total energy use of a home. Accordingly, utilities, needing to supply energy in its various forms to households and businesses, implement demand schedules coordinated with pricing. 
     Industrial users, home users, and the like may obtain a better utility rate for either off-peak, or time-distributed (uniform; reduced maximum) demands for energy (e.g., gas or electricity). Shifting use to an “off-peak” time or otherwise modifying use can reduce, stabilize, or otherwise ease demands on distribution systems. Meanwhile, utilities may “load-shed” by denying power to certain users or devices in order to balance and limit power distribution. 
     Various systems have been developed to control the timing of draws or usage of electricity in various industrial and household processes. For example, in order to reduce overall use, many water heaters and furnaces are converted to “pulsed” operation. Such units, if fueled, have no pilot lights, but rather use a new ignition of a flame with every call for heat. If electric, they may likewise remain dormant until heat is called for. Likewise, water heater tanks have been shrunk, further insulated, or provided with mechanism to reduce power for hot water at peak times. 
     Current systems for monitoring, control, and delivery of heat energy require frequent switching of comparatively large electrical currents (full operational loads). Monitoring may be impossible when a heater is “off.” Also, precision of monitoring and control may be limited. It would be an advance in the art to provide a better, more accurate, more responsive, more durable, and more reliable system for detecting and controlling the state of a water heater. It would be an advance to monitor a heater even when it is off, in order to override conservation measures and avoid delivery undesirably cool water. 
     SUMMARY OF THE INVENTION 
     In view of the foregoing, in accordance with the invention as embodied and broadly described herein, a method and apparatus are disclosed in one embodiment of the present invention as including a system relying on a controller for a water heater of a type having a lower and an upper heating element. These may be controlled by corresponding thermostats. Thermostats may be thermo-mechanical, meaning they mechanically respond to temperature in order to switch power to a heating element on or off. 
     In one embodiment, a controller includes a power relay connecting an alternating current (A/C) source of current through the relay to the water heater. The thermostats control electric energy to the heating elements. In one contemplated embodiment, a lower thermostat is set at a “set point,” with a “dead band” straddling it. The thermostat will control a switch to deliver current when its temperature drops below the lower bound of the dead band nominal set point. The thermostat will shut the switch off when its temperature exceeds a certain upper value above the nominal set point. The lower and upper values define a dead band wherein the heating element operates. Thus a set point is “nominal” for operation of and reference to a dead band. 
     The upper thermostat has its set point at a value lower than that of the lower thermostat. Thus, it will only engage when its temperature drops to its set point, because the lower heating element is not keeping up with demand and maintaining all water above the lower element at its set point. As a matter of thermal engineering, unobstructed free convection in an insulated tank of water operates comparatively rapidly. This means thermal (buoyant) rising and mixing is vigorous enough that all liquid above a source of heat will effectively have the same temperature for most practical purposes. 
     The switching effected by an upper thermostat may initially direct power to the lower thermostat and to operate within its own (lower) dead band unless and until it must in a cold water event (CWE), wrest control away. Thus, the upper thermostat takes control when it becomes too cool (arrives at its set point; bottom of its dead band) as the water temperature has already descended below the set point (bottom of dead band) of the lower thermostat. The lower thermostat is ceded control when the upper thermostat shuts down at a sufficient temperature and time evidencing that it is not needed to heat water. 
     Meanwhile, between the electrical grid and the water heater is a new controller. Here, consider the grid to include every connecting line from a source, such as a public utility, up through any connecting box and circuit breaker system and line servicing the venue or location of the end device (e.g., appliance; water heater). Herein, an appliance means a user of electrical power for heating. Typically it may include any water heater, hot tub, spa, pool, whirlpool, therapy pool, industrial heater of fluids (especially liquids), or the like. Whenever the term “water heater” is used, it is an example for any and all appliances. 
     The controller may include an electric parameter measurement unit (EPMU). The EPMU may either include or cooperate with a power monitor (PM). The EPMU may include an electrical measurement circuit (EMC). A power relay (PR) may connect in various ways to the incoming power line to measure electric parameters of upstream power and downstream loads. In some embodiments, the EPMU is activated only when power to the appliance has been switched off. In others, the EPMU may be active when power is connected. The EPMU may be connected and operable both when power to the appliance is connected and when it is disconnected. 
     The PR may include a double throw (DT) switch, and may be a single pole, double throw (SPDT) relay. In one embodiment, the EPMU may be powered and operable only when the PR disconnects a first pole powering the appliance to connect a second pole connecting the EPMU to the appliance. The EPMU may provide a comparatively small amount of power compared to operational (heating) power (approximately an order of magnitude less voltage, and multiple orders of magnitude less current). 
     In other embodiments, an EPMU, as a parallel circuit with respect to the PR. It can be testing (measuring) an electrical parameter in the circuit through the appliance while operational power runs from the PR to the appliance. Connected in parallel, it also operates when the operational level of power to the appliance is shut off by the PR. 
     In either type of mechanism, a trickle current enables sensors to detect a parameter (e.g., resistance, voltage, current, etc.) through the heating element tested. That parameter is processed to determine a state of the appliance, such as which heating unit is active, what the condition of the system is, and so forth. Thus, the processor can send a resulting instructional signal to the PR to change the state by switching power. 
     Herein, reference to a single pole double throw relay or SPDT, is one of the simplest ways to implement the invention. In fact in the parallel circuit EPMU embodiments, even a single pole single throw (SPST) relay, which electrically connects at only a single pole to be on an disconnects to be off, may be used as a PR. However, in some embodiments, it needs to be of the SPDT type. It switches from its normally closed pole on the A/C input (grid) side to the normally open pole on the EPMU side. 
     A distinct advantage to this connection scheme of an A/C source and EPMU, each connecting to a PR controlling the power feeding a water heater, permits an almost instantaneous check of a parameter like resistance, reflecting the state of the appliance. Thus, any time the control mechanisms (e.g., thermostats, etc.) of a water heater call for heat, or to shut off heat, the EPMU may provide an instantaneous reading of one or more electrical parameters. The EPM then continues to monitor (measure and report) the value of the parameter even when operational power to the appliance is shut off. This provides great benefits. The parameter may be processed by a processor to determine the state of the appliance. In one embodiment that parameter depends on and reflects a temperature of a heating element and which element is operating, and therefore the state of the appliance. 
     A temperature of inadequately heated water is detected by the upper thermostat. This indicates a need for higher temperature, to be met by switching from the lower heating element (unit) to the upper heating element. That element, thus engaged by itself, affects only the water above it. It applies its rated heat output thus into a smaller volume (about 20 to 50 percent of the tank, typically about a third). Thus the heat per gallon is increased, although only a smaller volume of heated water will be available. This rapid response may override other conservative measures in place, but spare a user receiving water at too low temperature. 
     Through all of this operation of the appliance, the controller need only determine what the state of the appliance is. Based on that state, the controller may respond by providing timely the power connection needed. The system dramatically reduces the number of times the PR needs to switch, similarly reduces the current and voltage across it needed to measure the parameter. These result in a much longer calendar lifetime for the PR as well as a significantly (orders of magnitude) faster response to a state change of the appliance. An apparatus and method in accordance with the invention may more precisely and quickly determine the current state and dictate appropriate action by the PR. Thus, energy efficiency (conservation methods) may be implemented, yet monitoring continues in the off” state. A user need not even be aware that the upper heating element has been engaged, heating a reduced volume of water (only that above it), more rapidly than the entire tank could respond, thereby preventing a cold shower or cold laundry. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing and other objects and features of the present invention will become more fully apparent from the following description and drawing. Understanding that this drawing depict only typical embodiments of the invention and is, therefore, not to be considered limiting of its scope, the invention will be described with additional specificity and detail through use of the accompanying drawing in which: 
         FIG. 1  is a schematic block diagram of one embodiment of a system in accordance with the invention wherein a controller provides operational power delivery to and testing (measurement) of an appliance (here a water heater as an example). A power relay (PR) connects a low-power, low voltage, low-current electrical parameter measurement unit (EPMU) to provide repeated and virtually instantaneous measurement. The electrical parameter reflects the state of the appliance. A process or the analysis parameter, determines the state of the appliance, and programmatically initiates a suitable, programmed response controlling the PR, thereby controlling the state; 
         FIG. 2  is a schematic block diagram of a system and process for balancing operational requirements of an appliance, such as a water heater or the like, to provide power-saving operation like load shedding desired by a utility, while still overriding it to avoid a cold water discharge by that appliance; 
         FIG. 3  is a schematic block diagram of a method for determining a state of appliance by monitoring an electrical parameter in a controller, in an appliance, or both in order to track certain electrical parameters, determine the state of the appliance, and, when appropriate, instruct a power relay to override other conservation requests or conditions, in order to power up an appliance to avoid a cold discharge; 
         FIG. 4  is a schematic block diagram of a method using a resistance measurement circuit (RMC) for monitoring an appliance, and controlling a power relay to balance the competing needs of power conservation and avoiding a cold water discharge event where the RMC detects an electrical parameter, even when the power relay is off, and especially when it is off; 
         FIG. 5  is a schematic block diagram of a process of monitoring the appliance continuously by a parallel capacitive dropper (CD) or triac “Dimmer” (TD) to determine the operational state of the appliance and determine whether to instruct a power relay to override a power-conserving condition to avoid a cold water discharge, and 
         FIG. 6  is a schematic chart representing a graph of a parameter measured by a CD or TD type EPMU. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     It will be readily understood that the components of the present invention, as generally described and illustrated in the drawings herein, could be arranged and designed in a wide variety of different configurations. Thus, the following more detailed description of the embodiments of the system and method of the present invention, as represented in the drawings, is not intended to limit the scope of the invention, but is merely representative of various embodiments of the invention. The illustrated embodiments of the invention will be best understood by reference to the drawings, wherein like parts are designated by like numerals throughout. 
     Referring to  FIG. 1  and  FIGS. 1 through 6  generally, a system  10  may be implemented in accordance with the invention to measure and control heating of liquid in a container  11  or tank  11 . A system  10  may include just the controller  12 , or may include the water heater  14 , or even a source  24  of power. The controller  12  is responsible to control power to the appliance  14 , such as a water heater  14 . In this electronic age, a more complex native controller  13  may be built into a commercial water heater  14 . On the other hand, a conventional “native controller” may reduce to simply a set of upper and lower heating elements  16 ,  18 , activated in response to corresponding, thermomechanical thermostats  17 ,  19 . In the figures, broken lines indicate optional devices and positions. Square brackets also represent non-required options. 
     For example, a water heater  14  may be defined by a wall  15 , which may form a tank  11  inside an insulated region covered by an outer covering or the like. The specific construction is not important at this point, to the invention. Nevertheless, a wall  15  defines a volume  11 . The volume  11  may be characterized as the contents  11 , or the tank  11 , and so forth. By whatever mechanism, the volume  11  contains water  11  that is heated by the water heater  14 . The appliance  14  may have a liquid level  29  that leaves space above itself. In certain embodiments, the liquid level  29  will simply be the top of the tank  11  of the appliance  14 . 
     In the illustrated embodiment, the water heater  14  includes a lower element  16  driven by electrical power to heat up, in turn heating up the contents  11 , or the tank volume  11 . A thermostat  17  is positioned just above the lower element  16 . This is because water in a tank  11  will typically circulate in unobstructed, free convection comparatively rapidly. Any variation in temperature with height above the lower element  16  may range from a few degrees to as little as a fraction of a degree, depending on the insulation of the wall  15 . 
     Similarly, an upper element  18  is also associated with an upper thermostat  19  placed just above the upper element  18 . This serves the same purpose of similarly detecting the temperature above the upper element  18  at any time. The lower thermostat  17  operates based on a higher “set point” temperature than does the upper thermostat  19 . The upper element  18  is not powered unless its temperature is below its own set point, which is below the set point temperature of the lower thermostat  17 . The upper thermostat  19  diverts a power to the lower thermostat unless and until it itself is triggered on. 
     In the controller  12 , a power relay  20  (PR  20 ) operates to turn on or shut off power to the appliance  14 . One or more processors  21  may be responsible to process data incoming and outgoing, between an optional power monitor  25 , an EPMU  26 , the PM  25 , and the PR  20 . It  21  may, but need not, communicate across a digital internetwork  36   c,  such as the Internet  36   c.  The relay  20  controls power delivered to an output line  22  (circuit  22 ), selectively connecting the appliance  14  to, and disconnecting it from, a current source  24 , typically an alternating current (A/C) source  24 . 
     The power monitor  25  may be responsible for power delivery to the appliance  14  when on. It may measure current, voltage, frequency, and any other electrical parameter of interest corresponding to power from the source  24  through the line  22  to the appliance  14 . For example, it may be configured to be part of an EPMU  26  when operated with the CD  26   b  or TD  26   c  in certain embodiments. For example operating a measurement device  25  in conjunction with a capacitive dropper  26   b  (CD  26   b ) or triac dimmer  26   c  (TD  26   c ), constitutes an EPMU  26  using a parallel circuit detection scheme, as explained hereinbelow. Meanwhile, the EPMU  26  connects to the relay  20  in one of multiple optional arrangements, including serial and parallel connections. Various integrated circuits  27   a,    27   b,  and network connections may also be in components within the system  10 . 
     In general, a system  10  may be thought of as including a controller  12 , or the controller  12  may itself be considered a system  10  to be installed between a power source  24  and an appliance  14 . In another sense, one may think of a system  10  and method  60 ,  100 ,  110 ,  120  as including all three  12 ,  14 ,  24 . Nevertheless, the system  12  or controller  12  provides a significant benefit in reliability of the PR  20 , its operational response time, lifetime, and more. Moreover, it responds to a cold water event (CWE), a condition when the upper thermostat  19  is triggered on to ameliorate a risk or of sub-temperature (too cold) water delivered by the appliance. 
     For simplification of control, only a single element  16 ,  18  is operational (powered) at any given time. Recall that the tank  11  is at virtually a single temperature above an active heating element  16 ,  18 . This is a direct result of substantially unobstructed free convection as hot plumes of liquid rise from a heating element  16 ,  18  to the top liquid level  29 . Ultimately, free convection results in fluid repeatedly cycling up to the surface, back down to the heating element, and mixing to equalize temperature throughout. Thus only the lower heating element  16  need operate, so long as it can deliver water (liquid) at a temperature corresponding to the set point of its thermostat  17 . 
     However, what happens if demand (outflow) from an outlet  48   b  is too great? What if load shedding turned the appliance off? What happens when the lower element  16  does not keep temperature in the tank at the nominal set point of the lower thermostat? Eventually the temperature may fall. When it does, and if it continues, eventually the temperature at the upper thermostat  19  will drop below its own set point. This triggers the upper thermostat to take the incoming power and switch it to go through the upper thermostat  19  and heating element  18 . 
     Due to free convection (buoyancy of a heated water plume in a tank  11  at a lower temperature), the upper heating element  18  does not heat any liquid below itself. A temperature profile will reflect a lowest temperature below any active heating element  16 ,  18 , a steep gradient (temperature rise as a function of distance upward) along the vertical extent of that active element  16 ,  18 , followed eventually by a virtually constant temperature above the active element  16 ,  18 . 
     Therefore, once the upper thermostat  19  switches power to the upper heating element  18 , or heating unit  18 , temperature below it cannot rise. Only liquid within the vertical extent of the unit  18  can rise in temperature, sending a vertical plume upward from the unit  18 , and heating the liquid above the heating unit  18  to a temperature. This alleviates the cold water event more quickly than the lower heating unit  16  could have, for two reasons. First, less water (liquid) lies above the upper heating unit  18 . Second, the upper unit  18  should have the same construction as the lower unit  16 , and thus the same heating capacity (energy output per unit time). Therefore the same rate of heat transfer into a smaller volume and mass of liquid results in a faster temperature rise of that liquid. The liquid below is not heated, as hot, buoyant plumes in a fluid only rise. 
     All processes take time. So, one is left with the problem of how to detect the state  89  of the appliance  14  (e.g., water heater  14 ), and how to respond with appropriate power from the power source  24  through the controller  12 . The appliance  14  has several distinct states  89  and corresponding transitions therebetween. The controller  12  needs structural and operational mechanisms to effectively measure a parameter in the appliance  12  that reflects the state  89  thereof. It needs some scheme to process that parameter to identify the state  89 . It then needs a method to use that identification of the state  89  to control delivery of power from the source  24  to the appliance  14 , and hardware in the controller  12  to do so. 
     In one embodiment of a controller  12 , a power relay  20  (PR  20 ) may operate. It may be of a single pole single throw (SPST) type if the EPMU  26  connects like the EMC  26   a  in parallel with the PR  20 . It relies on a double throw (DT), needing only a single pole, double throw (SPDT) if the EPMU  26  is connected in series to the PR  20 . In such a case, the PR  20  includes a pole  28  normally closed (NC) and a pole  30  that is normally open (NO). In the illustrated embodiment, a switch  32  is normally closed with the pole  28 , carrying power from a power source  24  through the controller  12  to the device  14 . 
     A native controller  13  may be an electronic device  13 , but need not be. It may typically be the simple switching mechanisms of two thermomechanical thermostats  17 ,  19  operating to switch power to their corresponding heating units  16 ,  18  as described hereinabove. Native simply means it  13  is provided from a manufacturer with the manufactured appliance  14 . 
     An optional, communication device  34  in the controller  12  may be connected through a series of links  36   a,    36   b,    36   c  to a communication device  38  at a utility  40 . It permits some additional functionality but is not necessary. Collecting and communicating data are helpful for receiving information from a utility or another requesting load shedding. They can help with certain aspects of the invention, but are not necessary. 
     For example, a utility  40  may have policies, protocols, controls, agreements, and the like providing for power shutdowns at times in order to “load-shed” to balance line loads, remove unnecessary peak power delivery, reduce customer costs, and so forth. A utility  40  may want to communicate through a communication device  38   a,  based on inputs and outputs to a processor  38   b  relying on a data collection device  38   c.  Various data that may collected in a database  38   d.  A communications device  34  in the controller  12  may connect by a series of links  36   a,    36   b,    36   c,  but such is not required for satisfactory operation of the controller  12 . 
     Referring to  FIG. 1 , and  FIG. 1  through generally, a water heater  14  or other appliance  14  having multiple heating units  16 ,  18  may benefit from a controller  12  electrically connected to control power to, and detect the state  89  of, the water heater  14 . A significance of this connection scheme is that the controller  12  may be installed on the utility side (e.g., power grid side; breaker box side, etc.) rather than requiring modifications of a water heater  14  itself (the appliance  14  side of the power circuit). Operation of a system  10  in accordance with the invention does not require a modification of any appliance  14 . 
     In the illustrated embodiments, the controller  12  may include a PR  20  feeding A/C power to an output line  22  (circuit) powering the appliance  14 . The PR  20 , being a single pole, double throw (SPDT) type is normally closed when connected to the A/C source  24  through a switch box  23 , circuit breaker  23 , or the like  23 . The PR has a first pole  28  normally closed (NC) by the switch  32 , connecting power to feed the line  22 . Thus a normally closed (NC) position feeds alternating current through the pole  28  to the switch element  32  feeding the line  22  powering the appliance  14 . The line  22  and appliance  14  constitute a circuit as in standard electrical schematics. 
     Whenever the PR  20  opens the switch  32 , it  32  moves to the opposite, normally open (NO), pole  30 . In a first option, the switch  32  on the pole  30  connects the line  22  to the resistance measurement circuit  26   a  (RMC  26   a ) as an EPMU  26 . In a second option, the PR  20  may be the same or a single throw (ST) relay  20 , with a capacitive dropper  26   b  (CD  26   b ) circuit connected in parallel with the PR  20 . Opening the PR  20  shuts off power through the switch  32 , but not through the CD  26   b.  In a third option, when the PR  20 , acting as an ST relay  20 , is opened, it shuts off power through the switch  32  but not through a parallel triac dimmer circuit  26   c  (TD  26   c ). The last two options may rely on the power monitor  25  (PM  25 ) to measure electrical parameters reflecting current, voltage, resistance, etc. through them. These three foregoing options are all shown, but are mutually exclusive. Thus, in  FIG. 1 , only one of the circuits  26   a,    26   b,    26   b  would exist in the controller  12 . 
     Whichever EPMU  26  is used, it provides only a comparative trickle of current (orders of magnitude less than operational current required to heat a heating unit  16 ,  18 ). An EPMU may use modest current (e.g., milliamps vs. 20-40 amp heating) at a modest voltage. Voltage is typically an order of magnitude less than that required to operate the heating units  16 ,  18  (e.g., 3 to 15 volts, rather than 110 to 220 volts). The RMC  26   a  also measures from its own power provided to the appliance  14  through the line  22  any electrical parameters of interest (e.g., current, voltage, resistance, power, etc. through it to the appliance  14 ), typically resistance. In this embodiment, the PM  25  is useful for other monitoring, but not necessary to the operation of the RMC  26   a  as an EPMU  26   a.    
     In the second option, the CD  26   b  is connected in parallel with the switch  32  when closed and powering the appliance. Its electrical parameters (e.g., current, voltage, resistance, power, etc. through it to the appliance  14 ) may be measured by the PM  25 . Similarly, the third option relies on a PM  25  to measure any selected electrical parameter through the TD  26   c  circuit connected in parallel with the PR  20 . Thus, a trickle of current passes through the TD  26  whether the switch  32  is open or closed, and the PM  25  may measure that or other parameters. 
     The controller  12  permits power-shedding. Otherwise, the PR  20  would have to be toggled multiple times in order to continue to monitor. If a PR  20  is good for operation for one hundred thousand cycles, and every power-shedding event is causing five, ten, or a hundred switches, the life of the relay is greatly shortened. With the controller  12  and its RMC  26   a  in place, the relay  20  only needs to switch when power is to be shut off, according to conservation on requests from the utility  40  or the controller  12   
     The measurement taken by an EPMU  26  in any configuration is used to identify the state  89  of the appliance  14 . In the context of saving energy, the tank  11  may be maintained at temperature by the lower heating unit  16  during low-demand or off-peak times. During power shedding it may be off. However, once a large draw of water is taken from the outlet  48   b,  the water may cool. The lower thermostat  17  powers the lower heating unit  16  only when on, and only in response to the temperature drop caused by relatively “cold” incoming liquid through the inlet  48   a.  Conventionally, a bi-metallic, thermomechanical thermostat  17  responds to water temperature directly, but slowly. Temperature detection takes seconds, but temperature change takes minutes. A controller  12  in accordance with the invention responds much more quickly and accurately to the state of the heaters  16 ,  18 , not the water. The EPMU  26  requires minimum number of actuations and current draw through the PR  20  to take the necessary measurements in any configuration of EPMU  26 . 
     The state  89  of the appliance  14  in the example includes conditions of on (powered), and off (unpowered), with the latter including a “top” mode (top heat) in which the top heating unit  18  is powered, and a “bottom” mode (bottom heat) in which only the bottom heating unit  16  is powered. The two conditions, one with two modes, constitute three states  89  of the water heater  14 . The water heater  14  itself, in this example, is one that entirely controls itself. If line  22  delivers power to the appliance  14 , the appliance operates under the control of its two thermostats, as described hereinabove. 
     The transitions between states  89  typically include “off to bottom on,” because temperature of a lower thermostat  17  is above its dead band temperature (defined between T max /off above a nominal set point temperature and T min /on below that set point). When hot water is released through an outlet  48   b  from the tank, the lower thermostat  17  soon experiences cold incoming water from the inlet  48   a.  When temperature in the thermostat drops below the dead band, it directs power to the lower heating unit  16 . 
     The power relay  20  may be embodied in one of several configurations. Two of the currently contemplated embodiments include a single pole double throw type in which the switch  32  moves between a pole  28  that is normally closed to a pole  30  that is normally open. When the switch  32  moves away from the pole  28 , power between the utility source  24  and the appliance  14  is completely shut off. This kind of event may be precipitated by a request for reduction or usage. Such a request may come through a communication device  34  and the controller  12  receiving a communication from a utility  40  through its communication system  38   a  and the links  36   a,    36   b,    36   c.  A utility may declare or request a load shedding event by a user. Accordingly, the controller  12  having received through the communication device  34  such an instructional request. It may instruct the processor  21  to open the power relay  20 . In this event, the power relay is still under the controller  12 , and may be closed back to the pole  28  by the controller  12  because of some overriding reason. 
     One overriding reason is if the appliance  14  is at risk of delivering through its outlet  48   b  too cold water. It may be on or off, but is monitored and determined to be close to such a cold water delivery. The processor  21 , after proper monitoring and decision making, may instruct the power relay  20  to close the switch  32  against the pole  28 . 
     On the other hand, a controller  12  or processor  12  may have programming based on a calendar. For example, every processor  21  has a clock and that clock may be used to feed information to a calendar specifying times of day when the power relay  20  should be closed and other times that it should be opened, against the pole  30 . For example, a utility will typically offer better power rates for off-peak use. Accordingly, a user of an appliance  14  may set a controller  12  to restrict access by the appliance  14  to power during certain hours. Likewise, a processor  21  may receive information from either a utility  40 , an owner of an appliance  14 , or from some algorithm in the processor  21  itself to determine that the power relay  20  should be opened (off). Closed, in the normally closed position, is the switch  32  being closed against the pole  28 . Open means that the switch  32  has opened the power circuit between the appliance  14 , PM  25  and utility source  24 . 
       FIG. 1  includes three alternative embodiments for circuits enabling sensing (monitoring, measuring) of condition or the sensing a parameter that will reflect the condition  89  (state  89 ) of the appliance  14 . These are not used together. There is no need to use two of them. However, any of these alternate circuits might be used in order to detect a parameter, detect a value thereof, and provide that parameter to the processor  21 . In the illustrated embodiment, the RMC  26   a  will connect to the apparatus  14  or appliance  14  whenever the switch  32  is in the normally open position on the pole  30 . The processor may then use the value to determine the state  89  of the appliance  14 . It may then programmatically provide instructions to the power relay  20 . 
     On the other hand, either the capacitive dropper  26   b  or the triac dimmer  26   c  may connect in parallel with the PR  20 . Either may monitor the appliance  14  (electrical parameters associated therewith). Both operate while the PR  20  is closed or open. Either of those circuits  26   b,    26   c  may connect in parallel to the power relay  20  and switch  32 . Meanwhile, when the power relay  20  is in the open position, each of the sensor circuits  26   b,    26   c  is still connected but permitting very little power to flow to the appliance  14 , only enough to continue producing a signal to be monitored by the PM  25 . 
     In the alternative, the resistance measurement circuit  26   a  or RMC  26   a  operates when the PR  20  with a double throw switch  32  is disconnected from power, in the normally open position  30 . 
     Referring to  FIG. 2 , with its associated  FIGS. 3 through 6 , a process  60  or system  60  may include providing  62  by a utility  40  certain power and management functionality. Meanwhile, a facility protects  64  itself by breakers  23  between its power distribution on system and a utility source  24  powering an appliance  14 . Likewise, monitoring and control  66  are a responsibility of the controller  12  connected to an appliance  14 . Operation  68  of the appliance  14  may be thought of as a system and method  68  for transitioning the appliance  14  between different states  89  of operation. If an electronic or software system is embedded or embodied in a native controller  13 , then this may be a sophisticated measurement and control mechanism  13 . On the other hand, in certain contemplated embodiments of an appliance  14  to which the controller  12  may apply, the operation of the appliance  14  is controlled entirely within itself. The relationship between the lower thermostat  17  and upper thermostat  19  controls their respective heating units  16 ,  18 . Thus, a controller  12  operates regardless of the source  24  or the appliance  14 . 
     Thermomechanical thermostats  17 ,  19  each control a mechanical switch that shifts electricity or directs electricity to the lower unit  16  or upper heating unit  18  according to a protocol and connection. For example, in one embodiment, the thermostat  19  may operate a double throw relay, while the lower thermostat  17  only needs a single throw type. In such an embodiment, the upper thermostat  19  may, based on temperature that it senses, direct all the power through a first pole to the thermostat  17  corresponding to the heating element  16 . A second, opposite, pole associated with the upper thermostat  19  may switch the power to itself whenever the upper thermostat  19  detects that a lower bound of the dead band of its control set point exceeded downward. 
     This is but one embodiment of an appliance  14 . By whatever mechanism, the appliance  14  may be taken as it exists from a manufacturer. Installed at a venue, its user or owner may control it with a controller  12  in order to better optimize and trade off the desire of a user conservation. This may be by lower power rates, lower power usage, off peak use, or the like. It may be traded against or overridden the desirability of not permitting the outlet  48   b  of the appliance  14  to ever put out liquid at too low (unacceptable) temperature. Ultimately, hot fluid delivery  70  is the functional purpose of an appliance  14 . Power conservation is a desirable objective, but a failure of delivery  70  of hot fluid from the tank  11  is highly undesirable. 
     Thus, providing  62  power and power management, a system  10 ,  12  in accordance with the invention and a process  60  may operate in a condition of full power  72 , load shedding condition  74  (by request, demand, calendar, or the like), or a condition of no power  76 , which would be off  76 . Meanwhile, the facility, or venue for the appliance  14  and controller  12  will provide protection, typically in a breaker  23  or breaker box  23 , connected back to a utility  40  or other electrical grid. To provide protection  64 , the breaker system  23  may have one of three states  89  or conditions  78 ,  80 ,  82 . It may have an “all on” condition  78 , in which all circuits are on. In a condition  80 , some circuits are on. In a condition  82 , all circuits are off. Again, circuits being turned off may occur because a breaker  23  was overloaded and has switched off. Likewise, certain circuits may be disabled intentionally, or circuits may simply be idle. Regardless, providing protection  64  is the responsibility of the breaker system  23 . 
     The controller  12  receives power through a line  28  (single line represents a circuit). The controller  12  monitors and controls  66  connections between the line  28  and the appliance  14 . Thus, the controller  12  simply accepts the power coming from the utility source  24  in whatever condition it is, and determines how and when to deliver power to the appliance  14 . Typically, in accordance with the diagram of  FIG. 1 , any one of three circuits may monitor. Control  66  includes a condition  84  or state of connect and test  84 . This occurs in either of the circuits  26   b,    26   c  with the power monitor  25  monitoring the electrical parameter to be measured and recorded. 
     A connect or test condition  86  is the situation wherein the RMC  26   a  is used as both a source of power and a monitor of the electrical parameter, reflecting a state  89  of the appliance  14 , to be measured. Other mechanisms or conditions  88  may also exist. For example, the RMC  26   a  does not require the power monitor  25 . The CD unit  25   b  does require the power monitor. Likewise, the TD unit  26   c,  or TD circuit  26   c,  does require the power monitor  25  to detect the electrical parameter. However, the PR  25  is capable of detecting any of several commonly measurable parameters such as voltage, current, resistance, frequency, power, or the like being passed through the lines  28  passing through the PM  25  in the line  28  or circuit  28  to the controller  12  and the appliance  14 . 
     If frequency drifts, the PM  25  may instruct the processor  21  to shut off the PR  20 . Likewise, if voltage wanes or some other anomaly occurs from the utility source  24 , the power monitor  25  may detect that anomaly and instruct the processor  21  to shut down the power to the line  22 . In particular, a fast frequency response (FFR) may militate for the power monitor  25  to instruct the processor  25  to open the switch  32  (instruct the power relay  20  to open the switch  32 ). 
     The operation  68  of the appliance  14  has three distinct states  89 . The three states  89  are upper heating unit  18  on  90 , lower heating unit  16  on  92 , and off  94 . The off condition  94  may exist for any reasons mentioned hereandabove. A utility source  24  may be shut off by a breaker  23 , another switch, or the utility  40  itself. Similarly, the off condition  94  may also exist because the PR  20  has opened the switch  32 . Regardless of how it arrives at that condition  94 , the appliance  14  is in the off condition  94 . 
     On the other hand, the differentiation and control of the upper on condition  90  and the lower on condition  92  depend on the protocol built into the native controller  13  or thermostat  17 ,  19  in the appliance  14 . Electronically, a native controller  13  may be programmed in any suitable manner of no interest to the controller  12 . However, the two on conditions  90 ,  92  affect the controller  12 . If the operation  68  is in an on condition  90 , then the PR  20  needs to provide power to the appliance  14 . If power upstream from the controller  12  is off, nothing can be done by it. Otherwise, PR  20  should still close the switch  32 . 
     One reason for this is that an upper on condition  90  indicates that, for whatever reason, the lower heating unit  16  is incapable of keeping up with the demand for water at temperature leaving the outlet  48   b.  Water through the inlet  48   a  (along with thermal inertia if it has been off) is cooling the tank  11  and its contents faster than the lower heating unit  16  can keep up. The upper heat on condition  90  exists because the upper thermostat  19  has triggered and turned on the upper heating unit  18 . This occurs in response to the upper thermostat  19  sensing a temperature that below its set point, which is already lower than the set point of the lower thermostat  17 . The controller  12  needs to interfere to assure sufficiently hot water at the outlet  48   b.    
     As described hereinabove, each of the heating units  16 ,  18  heats all the water or other liquid above it when activated. Accordingly, only one of the heating units  16 ,  18  ever needs to be on at a given time. The control mechanism directing power to the lower heating element  16  or upper heating element  18  may be done in any suitable manner. However, a double throw switch operated by the upper thermostat  19 . So long as it is not triggered, itself, it directs power to the lower thermostat  17 . Thus, directing power between the upper and lower units  16 ,  18 . The lower thermostat  17  needs only a single throw switch (off/on) to turn the lower heating element  16  on or off according to the set point for temperature sensed by the lower thermostat  17 . 
     Delivery  70  of hot fluid from the outlet  48   b,  may also have one of three states  96 ,  97 ,  98  or conditions  96 ,  97 ,  98 . It may be off  96 , due to no demand, transient  97 , or in a steady state  98 , meaning the lower heating unit  16  is keeping up with demand, switching on  92  only by its own thermostat  17 . The upper thermostat  19  need never trigger unless its temperature descends below the dead band of its set point. A transient condition  97  will exist when the upper heating unit  18  is operating in a somewhat urgent mode  97 , heating a smaller volume of liquid in the tank  11 , above it. This transient condition arrives for either two reasons. The heating element  18  may or may not be able to keep up with demand. Temperatures actuating the thermostat  19  may never get above its dead band. Also, any heating by the upper heating unit  18  is temporary. Once the draw of water or other liquid from the outlet  48   b  has slowed sufficiently or has come to a stop, the upper heating unit  18  will heat all the liquid thereabove, which will then exceed the top limit of the dead band of the set point for upper thermostat  19 , which will then direct power back to the lower thermostat  17  and heating unit  16 . 
     Referring to  FIG. 3 , while continuing to refer generally to  FIGS. 1 through 6 , a process  100  for determining the state  89  of the appliance  14  may include inputting  102  a monitored parameter to the processor  21 . Typical parameters may be anything measurable electrically as known in the art. For example, voltage current, resistance, power, frequency, and the like may measure either directly or calculated from another directly measurable parameter. 
     Logic may be illustrated in several different models, this one using steps and decisions is one. This schematic is not controlling of all the ways that the process may be done. The point is that a test  103  may determine whether a change has been detected in whatever parameter is being measured. If no significant change outside of possible noise is detected, then continued input  102  of the monitor parameter may continue until the test  103  reveals a change. A change detected typically means that an event has occurred within the appliance  14  changing its state  89 . Again, the state  89  transitions from off  94  to lower heating unit on  92 . 
     The transition to upper heating on  90  may typically change from a lower heating unit on condition  92 . The transition to off  94  is most frequently from the lower heating unit on condition  92 . However, the transition from the upper heating unit on  90  may go directly to off  94 . Alternatively, it may go directly to the on condition  92 . The controller  66  need not be aware of the transitions. However, transitions may cause spikes in the value of the parameter measured, long term changes in the value itself and may show increasing and decreasing values as the measured parameter steadies out. Moreover, different heating units  16 ,  18  may even have different resistances, even if only a small fraction of and Ohm. 
     If a change is detected  103 , an algorithm or program in the processor  21  may determine  104  the previous state  89 ,  104  as described below. The test  104  for the previous state  89  results in ongoing inputting  102  if the previous condition was an upper heating unit on  90 . Similarly, if the previous condition was off  94 , inputting  102  may continue. Parameters become available through whichever of the various types of sensing units  26   a,    26   b,    26   c  is the EPMU  26 . Because a limited number of transition paths typically exist between the operational conditions  90 ,  92 ,  94 , a change from a known previous state  89  may help infer the current state  89 . For example, if the previous state  89  was off  94 , then the new state  89  may typically be lower heat on  92 . However, if the previous state  89  was lower heat on  92 , then the current state  89  should be either off  94  or upper heat on  90 . If off  94 , an open circuit in the heater has an effectively infinite resistance, easily detectable. If resistance is similar to that of a previous state, then the heating unit  16 ,  18  has been changed. 
     If the previous state  89  was lower heat, then if the test  105  indicates that the lower heat is now off  94 , then inputting  102  continues. However, if the previous state  89  was lower heat on  92 , and the state  89  has changed but is not off  94 , then the lower heating unit  16  is not keeping up with demand. Thus, the change in state  89  has been a return of control to the upper thermostat  19  and the engagement of the upper heating unit  18 . At this point, the processor instructing  106  the PR  20  to override any existing instruction to conserve energy is appropriate, maybe even necessary, in order to avoid a cold water discharge through the outlet  48   b.    
     Referring to  FIG. 4 , a process  110  for the RMC  26   a  to act as an EPMU  26  and power supply is illustrated. In this embodiment, monitoring  111  by the option power monitor  25  is unnecessary for this purpose. It may still be useful for others. Such monitoring  111  still has other valuable uses, such as monitoring line frequency in the line  28 , and the like. However, as a control for the power relay  20  based on the state  89  of the appliance  14 , the power monitor  25  is unnecessary. In fact, communication  34  with the utility  40  is likewise unnecessary in such an embodiment, but has other valuable uses like communicating requests for load-shedding. 
     In this illustrated example, the RMC  26   a  is reporting to, or being monitored by, the processor  21 . Accordingly, a test  112  may determine whether the PR  20  is closed. If so, then monitoring  111  may simply continue. However, if the PR  112  is not closed  112 , then the RMC  26   a  sends power enough to the appliance to sense the measured parameters it will sense as an EPMU  26 . 
     With the PR  20  open (on pole  30 ), the process  110  moves on to powering  113  by the RMC  26   a  the circuit through the normally off pole  30 , switch  32 , line  22 , and appliance  14 . Any suitable electrical parameters may be monitored  114 . Nevertheless, the power provided  113  by the RMC  26   a  is much lower in voltage (e.g., 3 to 20, typically 5 volts), much lower in current (e.g., milliamps), much lower in total power, and will not damage substantially the contacts on the switch  32  of the power relay  20 . Power operations may use about 5 to 40 amps, usually 10 to 30). Corresponding voltages may be 110 to 220. 
     Power relays  20  suffer most of their damage from two causes. The first is arc damage caused by opening and closing contacts between the switch  32  and the poles  28 ,  30 . Every time a contact is opened or closed, it draws an arc, if carrying operational (heating) power. At the voltages and currents across the PR  20 , drawing an arc is a given. Contact materials and so forth may help delay failure, but it will happen. The other principle failure mode is mechanical failure due to parts moving, stressing, and failing mechanically. 
     In the illustrated example, power for measuring parameters, as provided by the RMC  26   a,  is so much lower in voltage, current, and overall power than those parameters provided by the utility source  24  through the power monitor  25  and line  28 , that operation of the RMC  26   a  provides substantially no increase in “wear” or damage. Meanwhile, because the PM  25  may be available when using the RMC  26   a  circuit for measurement, continual monitoring is possible. That is, with an RMC  26   a  available, the PM  25  may still provide monitoring of the lines  28 ,  22 , and the apparatus  14  when the RMC  26   a  is inactive. Power is being delivered by the power relay  20  to the apparatus  14  and the PM  20  can monitor parameters. 
     On the other hand, the RMC  26   a  may operate as a measurement device  26  taking measurements whenever no operational power goes to the appliance  14 . When the RMC  26   a  provides “power off monitoring,” it saves many cycles on the PR  20 , and prevents arc damage by eliminating the need to operate the PR  20  unnecessarily. That is, for example, the power relay  20  may remain in the normally closed position  28  while operational, and simply open to the normally open pole  30  and the resistance measurement circuit  26  when a desire or instruction is received from the processor  21  to shut power off for power conservation. The EPMU  26  and controller  12  provide an override by the PR  20  of those instruction when warranted. Thus, mechanical wear and aging, as well as contact arc damage are reduced by use of an RMC  26   a.    
     The RMC  26   a  monitors  114  the electrical parameter desired to be measured when the acting as an EPMU  26 , even when the open condition of the PR  20  renders the PM  25  otherwise unavailable for measurements. That is, the PM  25  is disconnected from the line  22  and appliance  14  anytime the PR  20  moves to the normally open pole  30 . With the RMC  26   a  available as an EPMU  26 , no need exists for putting the PR  20  into the normally closed position  28  or pole  28  just for monitoring during energy conservation. This reduces by orders of magnitude the number of times contacts in the PR  20  must connect and disconnect, and therefore greatly extends its life. Meanwhile, the capability of the controller  12  and its PR  20  to override a power conservation condition is virtually unlimited. 
     The monitoring  114  by the RMC  26   a  (and any EPMU  26 ) results in reporting  115 , by the RMC  26   a  data to the processor  21 . Data include values of parameters at any suitable sampling speed. All may be input  115  (reported  115 ) to the processor  21 . 
     The processor  21  infers  116  as discussed hereinabove the state  89  of the appliance  14  in operation  68 , based on the value or values (a series of measurements over a period of time of the parameter of interest) provided to the processor  21  by any EPMU  26 . By “reporting”  115  regularly, the EPMU  26  provides data for an inference,  116  by the processor  21 , of the current state  89 . This may be done by observing events affecting measurements of parameters themselves. It may be done by tracking changes in the state  89 . Measurements of parameters in the current state  89  to the. Measurements of those parameters may be compared with those of different state  89 . Alternatively, the change in state  89  may be inferred by the fact that any changes occurred, and by a knowledge of a previous data histories of states  89  stored by the processor  21  for purposes of programmed calculations. 
     Thus, as illustrated in  FIG. 3 , a process  100  for inferring  116  a state  89  of the operation  68  of the appliance  14  provides an answer to the question  117  or test  117  of what that state  89  is. If the state  89  is the lower heating unit on  92  (LHU on  92 ) then the process  110  may return back to the RMC  26   a  powering  113  and monitoring  114  the electrical parameter of interest. Meanwhile, if the state  89  is off  90  then the process  110  may return back to its beginning with monitoring  111  by the optional PM  25 . 
     However, if the upper heating unit on condition  90  (UHU on  90 ) exists then the processor  21  instructs  118  the power relay  20  to close, move the switch  32  to the normally closed pole  28 . This instruction  118  amounts to an override  118  of any previous instruction that may have opened the switch  32  in the PR  20  in response to a request for power shedding, scheduled and programmed conservation programmed into the processor  21 . 
     Referring to  FIG. 5 , monitoring  121  by the PM  25  is not optional in this embodiment, applicable to either of the CD circuit  26   b  or the TD circuit  26   c.  Either of those configurations  26   b,    26   c,  runs parallel to the PR  20 . The PM  25  may report  122  to the processor  21  the value of any measured parameter in the EPMU  26 , operating it, as an EPMU  26 . As described with respect with  FIG. 4 , the processor  21  infers  123  a state  89  of the appliance  14 . If the upper heating unit  18  is in the on condition  90 , the processor  125  may instruct the power relay  20  to override whatever instructions the processor  21  has provided as far as power conservation. On the other hand, any other state  89  may still support monitoring  121  by the PM  25  with the PR  20  open (off). 
     Referring to  FIG. 6 , while continuing to refer generally to  FIGS. 1 through 6 , a chart  130  includes an abscissa  131  or x axis  131  representing time  131 . Meanwhile, the y axis  132  or ordinate  132  represents a parameter “R” which may be any suitable parameter. In this instance, the letter ‘R’ is used because one parameter measured may often be resistance. Measuring resistance is cheap, easy, and ubiquitous. In the chart, a trace  133  represents the values of  134 ,  137  of the measured parameter  132 . That is, the axis  132  represents a value  132  of the parameter  132 . 
     The trace  133  has several portions, including a first state portion  134  representing a value in one particular state  89 . Switching by the PR  20  or either of the thermostats  17 ,  19 , will typically cause a transient condition  135 . A transient  135 , typically (resistance, voltage, or current) will spike, drop off, or both. This artifact  135  may be captured because the EPMU  26  in accordance with the invention may monitor at substantially any practical periodicity or frequency desired. The trace  133  may be monitored, recorded, and stored by the processor  21  for comparisons later. A transient  135  may often be easily detected, since they typically last for a small fraction of a second to leave data points in the record. 
     Meanwhile, resistance in each of the heating elements  16 ,  18  or heating units  16 ,  18  is simply an electrical phenomenon in materials. Thus, the transient  135  will typically end with a cold rise  136  or rise  136  in resistance as any heating unit  16 ,  18  begins to warm. This typically lasts for a matter of several seconds, about five to ten, typically. The drop in resistance due to current passing from a hot heating element  16 ,  18  to the opposite, colder element  18 ,  16  may provide an artifact  135  lasting several seconds and often easily detected by the EPMU  26  in any of the configurations  26   a,    26   b,    26   c.    
     Ultimately, the value  132  of the parameter  132  represented on the axis  132  will be reflected in a steady state portion  137  of the trace  133 . Comparing the value of the trace  134  to the value of the trace  137  may actually be sufficient to detect which of the elements  16 ,  18  was previously active and which is presently active. However, the fact that a switching transient  135  exists, and the fact that the rise  136  from the lower resistance to the higher resistance as either element  16 ,  18  heats up, is not only detectable, but lasts for several seconds, enough to take several measurements by an EPMU  26 . It also signals a change. 
     In reflecting on an apparatus and method in accordance with the invention, a system  10  may be considered to be a controller  12  operating between a utility source  24  and an appliance  14 . In other contexts, a system  10  may be considered to be the source  21 , controller  12 , and appliance  14 . Typically, communications over links  36   a,    36   b,    36   c  between communication devices  34 ,  38   a,  and the like provide services beyond or separate from those provided by or required a controller  12 . Accordingly, they may be used, but are not necessary for operation of the controller  12 . Similarly, the PM  25  is useful for many purposes, and is unnecessary for certain embodiments of an EPMU  26 , as discussed hereinabove. The controller  12  adapts to whatever the condition of the line  28  presents from the utility A/C source  24 . 
     It is acknowledged that the EPMU  26  is not required to monitor and control the power relay  20 . That is not the point. The PR  20  operated in accordance with the invention may detect and respond to a threat of a cold water discharge whether the PR  20  or appliance  14  is on or off. A cold water discharge means discharge through the outlet  48   b  of water at a sufficiently low temperature to be undesirable, uncomfortable, unacceptable, or the like for the user of the appliance  14 . In each embodiment, a system  10  or a controller  12  in accordance with the invention provides both detection of, and response to a cold water event (e.g., the heater  18  turning on). One purpose or point is to provide or permit conservation measures but override them when appropriate. A controller  12  in accordance with the invention may prevent or eliminate a cold water discharge by “off” state  94  monitoring, while still taking advantage of any energy conservation mechanisms implemented “electrically upstream.” 
     Because the EPMU  26 , whether implemented in an RMC  26   a  CD  26   b,  or a TD  26   c  need only typically operate at about three to five volts and a trickle of current on the order of milliamps. A classical “555 timer” may be used to measure resistance. A distinct native controller  13  is unnecessary. However, as more devices of all types are connected to electronic controllers, a native controller  13  may be electronic. On the other hand, any functionality or structure that operates as a native controller  13  may simply be built into the thermostats  17 ,  19  and the switches therein operated to turn current off and on into the heating units  16 ,  18 . Thus, the native controller  13  may be regarded as simply a schematic representation of the fact that an appliance  14  has some mechanism for control which may be electronic, but which may be thermomechanical as described hereinabove. 
     It is significant that the controller  12  operates regardless of the state  89  of the utility source  24  and the appliance  14 . The controller  12  may provide monitoring during any state  89  and a change of that state  89  if conservation processes and connections need to be suspended in order to remediate a cold water event in the appliance  14 . Thus, a system  10 , and particularly a controller  12  and appliance  14  obtain the maximum benefit of any conservation measures effected by a utility  40  by itself, or by request to the controller  12 , while remediating a cold water event. One valuable tool for that is the EPMU  26  and its ability to continually monitor the state  89  of the appliance  14 , whether or not operational power (e.g., operating voltage and current) are provided to the appliance  14 . A system  12  or controller  12  in accordance with the invention provides a simple, robust, long-lived operation for itself and a controlled appliance  14 . Meanwhile, a home owner, for example, or other owner may set the set points for the thermostats  17 ,  19  with no need to program the controller  12 . 
     This ability to detect the state of a device  14  such as the appliance  14 , of which a water heater  14 , is a typical example is capable of determining the state  89  in an unpowered condition. It provides important information, historical information, and values of parameters that can be processed in many ways to determine patterns, condition, state  89 , and the like. Thus, the controller  12  allows the processor  21  to determine when to connect and disconnect power to the end device  14  in use. The system  12  or controller  12  can respond to some grid events like frequency distortions even without communication to a utility  40 . Meanwhile, remote commands may be administered by a utility  40  or communication links  36   a,    36   b,    36   c  regardless of the state  89  of the appliance  14 . Communication devices  34 ,  38  may also support downloads of commands, updates to software requests, telemetry data, identification of states  89 , and the like. Meanwhile, both incoming lines  28  and outgoing lines  22  may be monitored for classic electrical parameters such as voltage, current, power, frequency, and so forth. 
     The concept of a double throw relay  20  as the power relay  20  provides an extra pole  30  through which an RMC  26   a  may operate as an EPMU  26 . A single pole relay may also be used with a CD  26   b  or a TD  26   c.  The bottom line for overriding the state  89  is detecting when a cold water event has occurred, activating the upper heating unit  18 . 
     Any thermal appliance has a certain amount of electrical “inertia.” It typically does not shut down instantly no matter what the impetus for change. The liquid in a tank  11  of an appliance  14  has a massive thermal inertia that requires minutes and sometimes hours to change. Thus, detecting a cold water event rapidly through the thermostat  17 ,  19  is comparatively much slower than simply detecting rapidly the state  89 . In a system  10  in accordance with the invention, the state  89  can be determined in a fraction of a second and the controller  12  can respond similarly. Processing speed through the processor  21  becomes trivial in the timeline of control. Other mechanisms are up to orders of magnitude less precise in measurement and time of response. Prior art systems typically could only respond with a detection time of about five minutes compared to the controller  12  responding in less than a minute, typically seconds. With stored data in the processor  21  sub-second response times are reasonable. Meanwhile, the lifetime of the controller  12 , particularly that of the power relay  20  is extended by orders of magnitude. Typically, cycle-number-based lifetimes of a power relay  20  in a system  12  in accordance with the invention may increase by 2400. Meanwhile, all of these benefits are accomplished with no compromise to the load-shedding capability of a utility  40  on its own, or through a request to the controller  12 . 
     The present invention may be embodied in other specific forms without departing from its fundamental functions or essential characteristics. The described embodiments are to be considered in all respects only as illustrative, and not restrictive. All changes which come within the meaning and range of equivalency of the illustrative embodiments are to be embraced within their scope.