Patent Description:
Heating, ventilation, and air conditioning (HVAC) technologies have been developed for conditioning indoor air with the goal of effectively and efficiently providing comfort for occupants and/or satisfactory ambient conditions for property. Chilled beams are a heating and cooling technology that can utilize heated or chilled water to condition indoor air. Water is passed through a finned-tube coil of pipe which exchanges heat with the surrounding air through radiation and convection. A chilled beam may be mounted to the ceiling of a room.

There are two types of chilled beams: passive and active. With passive chilled beams, as the cold water passes through the coil, the coil cools and the air around it becomes denser and moves down toward the floor. This convective heat transfer allows warmer air to rise toward the ceiling to replace the cold air in a continuing cycle. As cold water is pumped through the beam it allows the cycle to continue.

The active chilled beams make use of ventilation air that has been preconditioned by a Dedicated Outdoor Air System (DOAS). Energy Recovery Ventilators (ERVs) are a special type of DO AS, which make use of the energy recovery process by exchanging the energy contained in the exhausted building air and use it to condition the incoming, outdoor air. An ERV is a type of air-to-air heat exchanger that not only transfers sensible heat but also latent heat. Since both temperature and moisture are transferred, ERVs can be considered as total enthalpy exchange devices.

The ERV technology has demonstrated an effective means of reducing energy costs and has allowed for the downsizing of chillers and boilers. Additionally, these systems allow for the indoor environment to maintain a more comfortable humidity level.

Various ERV manufacturers are using enthalpy wheels in combination with desiccant wheels and cooling coils to obtain very low humidity levels. These ERVs are able to provide ventilation air that can provide all of the latent cooling (moisture removal) that is needed for humidity control. If the humidity is controlled, then the cooling coil only needs to do sensible cooling (temperature reduction). If the cooling coil does not condense any moisture, then no condensate is produced, and there is no need for a condensate pan and condensate drainage system. The ventilation air from the ERV can be used in a chilled beam to induce the air flow that is required across the dry, cooling coil. This eliminates the need for a fan. With no fans and no compressors in the rooms, this system is much quieter.

An active beam accepts dry air from the ERV through a supply duct. This supply air is then forced through nozzles in order to create high velocity air streams which reduces the pressure, inducing room air up through the heating/cooling coil. This induced air then mixes with the supply air and is discharged back into the space.

The water temperature supplied to the chilled beams must be a few degrees higher than the air dew point to avoid any condensation on the coil. A typical chiller discharge temperature is between <NUM> and <NUM> (average <NUM>). To avoid condensation on the coil, the typical entering water temperature to the chilled beams normally needs to be controlled between <NUM> and <NUM> (average <NUM>).

In "Cooling Unit and Method" (International Publication No. <CIT>) Long et al. describe a cooling unit including a heat exchanger having an inlet for receiving coolant from a coolant supply and an outlet to exhaust coolant to a coolant return. The cooling unit has an input line in fluid communication with the coolant supply and the inlet of the heat exchanger, an output line in fluid communication with the outlet of the heat exchanger and the coolant return, a transfer line comprising a component configured to allow fluid communication from the output line to the input line, and a controller configured to control a flow rate of coolant delivered by the transfer line.

In "Chilled Beam Module, System and Method" (<CIT>) Fischer et al. describe a multiple-zone chilled beam air conditioning system that includes a pump serving each zone that both recirculates water within a chilled-beam module and chilled beam and circulates water in and out of a chilled water distribution system through one or more valves to control the temperature of the wafer delivered to the chilled beams.

The invention at hand relates to a system and apparatus for conditioning of indoor air, in particular in form of a control system for controlling liquid flow from a supply into a conditioning load such as chilled beam and a corresponding method of controlling flow of a liquid from a liquid supply system into a conditioning load.

Chilled beams are a technology being used as part of HVAC systems throughout the world. Chilled beams typically use cooled and heated water to cool or heat, respectively, a conditioned space. The cold and hot water supplies used to fuel chilled beams are typically shared among a number of conditioning loads that may include fan coils, chilled beams and other devices and these may be divided among several conditioned spaces within an indoor environment. These conditioned spaces may have different heating and cooling needs depending, for example, on the number of people in the space, the facing of the conditioned space relative to uncontrolled sources (e.g., radiant heat from the sun), personal preferences, and the like.

The task to be solved by the invention at hand is to optimize the flow of cooling agents and to provide a method for the regulation thereof.

This task is solved by providing a control system according to claim <NUM> and a method according to claim <NUM>.

Aspects of the invention relate to a control system that is used with a single chilled beam, thus allowing each chilled beam to be independently controlled reducing the time it takes to achieve and maintain comfortable conditions in all conditioned spaces serviced by a HVAC system.

When operating in a cooling mode the water input to a chilled beam may be just above the dew point to maximize the rate of cooling while preventing condensation on the chilled beam and the associated need for collection and draining or, if draining is not provided or ineffective, water damage to the facility. As the dew point will depend on the ambient conditions of each chilled beam, the cold water provided by the chiller in an HVAC system generally cannot simultaneously be near the dew point of all chilled beams requiring cooling.

The control system has a recirculation pump that recirculates a portion of the return water from the chilled beam. During cooling operation, the return water may be warmer than the input water to the chilled beam if the return water has absorbed heat from the conditioned space. The recirculated portion of the return water is combined with water from the cold-water supply in proportions suitable to provide both a desired flow rate and a desired water temperature. In the case of cooling, the pumped portion of the water returned from the chilled beam warms the cold water from the supply. This combined water is provided to the input of the chilled beam.

The control system includes a control valve that restricts flow of the cold-water supply in the control system. The temperature of the combined water (i.e., the water from the supply and the recirculated water) is monitored to determine whether more or less water from the cold water supply is needed to achieve the desired input water temperature to the chilled beam. The control valve is opened or closed with variable degree to increase or decrease, respectively, the amount of supply water.

The control system includes a control module to control the recirculation pump and the control valve based on inputs from the user and various sensors. Example inputs used for control include a setpoint temperature for the conditioned space, an actual temperature of the conditioned space, an indication of moisture content in the air, the temperature of liquid entering into the chilled beam, an operating mode for the control system (e.g., heating, cooling).

One aspect relates to a control system for controlling liquid flow from a supply into a chilled beam. The control system comprises a supply input port; a load return port; a recirculation pump for pumping liquid from a pump input port to a pump output port, the pump input port connected to receive a first portion of liquid flowing from the load return port; a junction configured to combine liquid flowing from the pump output port with liquid flowing from the supply input port; a load input port configured to receive such combined liquid from the junction; a supply return port connected to receive a remaining portion of the liquid flowing from the load return port; a control valve to restrict flow of liquid between the supply input port and the supply return port; a sensor; and a control module to control the control valve based at least in part on a measurement from the sensor.

In some embodiments of the control system the control module is configured to receive an ambient temperature in a conditioned space and a setpoint temperature, and to control the control valve based on the setpoint temperature and the ambient temperature. The sensor may be a temperature sensor that measures a load input temperature of the combined liquid, and the control module may be configured to control the control valve based on a target liquid temperature and the load input temperature. The control module may be further configured to receive an indication of moisture content of air in the conditioned space, determine a dew point from the indication of moisture content and the ambient temperature, and determine the target liquid temperature based on the dew point, the setpoint temperature, and the ambient temperature.

In some embodiments of the control system the junction is a second junction and the control system further comprises a first junction to split flow from the load return port into the first portion and the remaining portion; and a check valve connected between the supply return port and the first junction, the check valve oriented to allow liquid to flow through the check valve to the supply return port. The control valve may be connected between the supply input port and the second junction.

In some embodiments of the control system the junction is a second junction and the control system further comprises a first junction to split flow from the load return port into the first portion and the remaining portion; and a check valve connected between the supply input port and the second junction, the check valve oriented to allow liquid to flow from the supply input port through the check valve. The control valve may be connected between the supply return port and the first junction.

In some embodiments of the control system the recirculation pump is a fixed speed pump.

In some embodiments of the control system the supply input port is a first supply input port, the supply return port is a first supply return port, and the control valve is a first control valve, and the control system further comprises a second supply input port; a second supply return port; and a second control valve connected between the second supply return port and the pump input port to restrict flow of liquid between the second supply input port and the second supply return port.

Another aspect relates to a control system for controlling liquid flowing from a supply into a chilled beam, the control system comprising a supply input port; a load return port; a first junction to split flow from the load return port into a first portion and a second portion; a recirculation pump for pumping liquid from a pump input port to a pump output port, the pump input port configured to receive the first portion from the first junction; a supply return port configured to receive the second portion; a second junction to combine flow from the supply input port and the pump output port; a load input port configured to receive such combined flow from the second junction; a control valve to control flow of liquid between the supply input port and the supply return port; a sensor; and a control module to control the control valve based at least in part on a measurement from the sensor.

In some embodiments of the control system the supply input port is a first supply input port, the supply return port is a first supply return port, and the control valve is a first control valve, the system further comprising a second supply input port; a second supply return port; and a second control valve connected between the second supply return port and the first junction to restrict flow of liquid between the second supply input port and the second supply return port. The first control valve may connected between the first supply input port and the second junction, and the control system may further comprise a first check valve connected between the first supply return port and the first junction, the first check valve oriented to allow liquid to flow through the first check valve to the first supply return port; and a second check valve connected between the second supply input port and the second junction, the second check valve oriented to allow liquid to flow from the second supply input port through the second check valve. The sensor may be a liquid temperature sensor positioned to measure a load input temperature of liquid flowing from the second junction to the load input port. The control system may further comprise an ambient temperature sensor and a humidity sensor to measure ambient conditions, wherein the control module is further configured to receive a setpoint temperature; determine a dew point from measurements from the ambient temperature sensor and the humidity sensor, determine a target load input temperature based on the dew point, the load input temperature, and the setpoint temperature, and control the control valve to achieve the target load input temperature at the temperature sensor.

Another aspect relates to a method of controlling flow of a liquid from a liquid supply system into a conditioning load, the method comprising receiving a supply input flow from the liquid supply system at a supply input port; receiving load return flow from the conditioning load at a load return port; dividing the load return flow into a recirculation flow and a supply return flow; pumping the recirculation flow into a junction; discharging the supply return flow to the liquid supply system through a supply return port; forming a load input flow by combining, in the junction, the supply input flow with the recirculation flow; delivering the load input flow to the conditioning load through a load input port; measuring a load input temperature of the liquid of the load input flow; and controlling a control valve to restrict the supply input flow and the supply return flow based at least in part on the load input temperature.

In some embodiments the pumping is performed by a fixed speed pump for pumping only the recirculation flow.

In some embodiments a temperature of the liquid of the supply input flow is less than an ambient temperature of an indoor space conditioned by the conditioning load, and the method further comprises measuring a dew point temperature near the conditioning load; and determining a target load input temperature as the dew point plus a positive margin temperature, wherein the controlling the control valve comprises reducing the control valve's resistance to flow if the load input temperature is higher than the target load input temperature and increasing the control valve's resistance to flow if the load input temperature is less than the target load input temperature.

In some embodiments the method further comprises receiving a setpoint temperature specifying what ambient temperature is desired in an indoor space conditioned by the conditioning load; measuring the ambient temperature in the indoor space; and determining a target load input temperature based at least in part on the setpoint temperature and the ambient temperature, wherein controlling the control valve comprises adjusting the control valve's resistance to flow so as to cause a temperature difference between the target load input temperature and the load input temperature to decrease. The temperature of the liquid of the supply input flow may be less than an ambient temperature of an indoor space conditioned by the conditioning load, and the method may further comprise determining a temperature of the supply input flow, wherein the pumping is started when the target load input temperature is above the temperature of the supply input flow.

Some embodiments relate to a control system that uses only a single control valve and a single, fixed-speed pump to vary the relative amounts of the recirculation flow through the pump and the flow from the liquid supply to achieve a desired temperature for the liquid flowing into a chilled beam. Another embodiment relates to a control system that uses only a single control valve and a single, fixed-speed pump to vary the relative amounts of the recirculation flow through the pump and the flow from the liquid supply to achieve a desired flow rate for the liquid flowing into the chilled beam.

The foregoing is a non-limiting summary of the invention, which is defined by the attached claims.

Chilled beams in combination with an ERV are starting to be used to overcome problems with conventional HVAC systems. Compared to conventional HVAC systems, a system with chilled beams and an ERV can provide much better humidity control, improved indoor air quality, significantly lower energy costs, much quieter living spaces, and reduced maintenance costs. The inventors have recognized and appreciated that a reason the chilled beams and ERV system is not being used more is because of the complicated designs and high costs for the systems that control the chilled beams. Some aspects of the disclosure relate to a control system design that will allow chilled beam and ERV systems to be more economically viable.

The inventors have recognized and appreciated the difficulties in adapting chilled beam system designs for each new installation (e.g., in a building or other facility to have conditioned air). Particularly existing chilled beam control systems can require large, expensive hardware and complicated software control schemes that are difficult to design, install, and tune, driving up installation costs and limiting the viability of the technology. These designs can still have significant limitations that affect comfort such as the inability to provide heating and cooling simultaneously at different chilled beams, and the inability to provide maximum cooling rates in conditioned spaces having different dew point temperatures.

Some embodiments are directed to a control system that controls the flow of cooling or heating liquid from one or more liquid supply systems to a chilled beam (or other suitable conditioning load). The control system may pump a portion of the flow that has already passed through the chilled beam and combine it with liquid from the supply to achieve a flow into the chilled beam that has a desired input temperature (which may be determined, for example, from the ambient conditions and a user specified setpoint temperature). A control valve and recirculation pump may be controlled to vary the relative amounts of the recirculation flow and supply flow to achieve the desired temperature for the liquid flowing into the chilled beam. If a control system is provided with each chilled beam as opposed to using a single control system to control a zone, the need for secondary piping can be eliminated as well as any need for reverse return piping or balancing valves. (Eliminating such piping can significantly reduce design, engineering, and installation costs. ) Further, because each chilled beam may be independently controlled, the control system for each chilled beam can be immediately responsive to the specific heating and cooling demands of its chilled beam rather than having to prioritize competing demands as may be the case in zone-based control systems that serve multiple conditioning loads (e.g., multiple chilled beams).

<FIG> show embodiments of a single supply control system. The features and concepts introduced with respect to the single supply control systems may also be applicable to the two-supply control system later discussed with reference to <FIG>.

Referring now to <FIG>, a control system <NUM> for controlling liquid flow from a supply into a chilled beam or other suitable conditioning load is shown. Control system <NUM> has a supply input port <NUM> and supply return port <NUM>. When connected to a liquid supply system a relatively larger liquid pressure may be connected to input port <NUM> and a relatively lower liquid pressure connected to port <NUM>. Liquid supply systems are discussed further herein, for example, in connection with <FIG>, <FIG>, <FIG>, and <FIG>.

Control system <NUM> has load input port <NUM> and load return port <NUM>. The input and return ports of a chilled beam or other conditioning load may be connected to ports <NUM> and <NUM>, respectively.

Ports <NUM>, <NUM>, <NUM>, and <NUM> and all ports internal to the control system for handling liquid are of a type suitable for requirements of a particular embodiment of control system <NUM>. Those of skill in the art appreciate that the appropriate materials for a port may depend on many factors such as the anticipated liquid pressure, the volume of liquid flow, and requirements of other components in the system. Ports may be of a type that allow for normal connecting and disconnecting (e.g., pipe connector, pipe fitting, hose clamps, couplings), or may be permanently attached such as by soldering, welding, or even continuous conduit. The latter may be practical, for example, in embodiments where control system <NUM> is assembled with the conditioning load or liquid supply system. The choice of the type of port connection may consider factors such as where the connection will take place and how likely it is that the port needs to be disconnected in the future to support, for example, maintenance of the system.

Control system <NUM> has a recirculation pump <NUM>. Pump <NUM> has a pump input port <NUM> and a pump output port <NUM>. Pump <NUM> pumps liquid from pump input port <NUM> to pump output port <NUM>. Pump input port <NUM> is connected to a first junction <NUM> and pump output port <NUM> is connected to second junction <NUM>. Pump <NUM> may be a single (fixed) speed pump, or a multi- or variable-speed pump in some embodiments. Pump <NUM> may be sized to pump only a fraction of the flow rate associated with an attached conditioning load since only a portion of the flow returning from the load is pumped by pump <NUM>.

In some embodiments, pump <NUM> is a fixed speed pump sized such that the flow rate of liquid through load input port <NUM> is within a target flow rate range or approximately a target flow rate for the conditioning load over a range of positions for control valve <NUM>. This target or target range for the flow rate may be specified by the conditioning load's manufacture or determined by its construction.

A first junction <NUM> splits liquid received from load return port <NUM>; a first portion is directed to pump input port <NUM> for recirculation while a second portion is returned to the liquid supply system via supply return port <NUM>. While junction <NUM> is illustrated by a T-type fitting in <FIG>, it should be appreciated that any suitable device for splitting the liquid may be used.

A second junction <NUM> combines liquid received from supply input port <NUM> and pump output port <NUM> and provides the combined liquid to load input port <NUM>. While junction <NUM> is illustrated by a T-type fitting in <FIG>, it should be appreciated that any suitable device for combining the liquid may be used.

It is noted that in some embodiments junctions <NUM> and <NUM> are made from the same type of component (e.g., a T-type fitting) which may be able to provide both splitting of a liquid flow and combining a liquid flow. In some other embodiments, junctions <NUM> and <NUM> use different component types. The use of different component types for junctions <NUM> and <NUM> may be to provide better performance of the splitting and combining functions of the respective junctions. Second junction <NUM> may, for example include a mixer such as a static helical mixer that improves mixing of the combined flows (this may be beneficial in some embodiments to achieve an accurate temperature reading of the combined flow).

Control system <NUM> may include a control valve <NUM> for restricting flow of liquid between supply input port <NUM> and supply return port <NUM>. Control valve <NUM> has a first port <NUM> and a second port <NUM>. In control system <NUM>, control valve <NUM> is connected between supply input port <NUM> and junction <NUM>. Control valve <NUM> is adjustable from completely closed to completely opened through intermediate positions. If control valve <NUM> is completely closed, flow of liquid is prevented between ports <NUM> and <NUM>. If control valve <NUM> is completely open, control valve <NUM> presents its minimum restriction to the flow of liquid. The intermediate positions provide intermediate levels of restriction to the flow of liquid between ports <NUM> and <NUM>. In some embodiments control valve <NUM> can assume discrete intermediate positions (e.g., in some embodiments utilizing digital control), while in some other embodiments control valve <NUM> can be continuously controlled in intermediate positions between open and closed (e.g., in some embodiments utilizing analog control).

While the direction of liquid flow in control valve <NUM> may not be directly controlled by control valve <NUM>, a check valve <NUM> may be provided to prevent reverse flow in control system <NUM>. Reverse flow might otherwise occur for example, if the pressure at supply return port <NUM> is greater than the pressure at supply input port <NUM>. Check valve <NUM> has an input port <NUM> and an output port <NUM>. Check valve <NUM> prevents flow from output port <NUM> to input port <NUM> but allows flows from input port <NUM> to output port <NUM>. Check valve <NUM> is connected between supply return port <NUM> and first junction <NUM>. In control system <NUM>, check valve <NUM> is oriented to allow liquid to flow through check valve <NUM> to supply return port <NUM>. If control system <NUM> is connected to a load such as a chilled beam, which does not allow a net flow of liquid between load input port <NUM> and load return port <NUM> this orientation of check valve <NUM> will further ensure that flow through control valve <NUM> is from first port <NUM> to second port <NUM>. <FIG> shows another embodiment, control system <NUM>, where the position of control valve <NUM> and check valve <NUM> are switched. (The descriptions of embodiments of control system <NUM> otherwise applying equally to control system <NUM>. ) Note that the direction of check valve <NUM> is such as to allow flow in the direction from supply input port <NUM> to supply output port <NUM>. As will be discussed in connection with <FIG>, both configurations may be used simultaneously in two supply control systems.

Control system <NUM> further comprises a sensor <NUM>. Sensor <NUM> may be used to determine the temperature of the liquid entering the load through load input port <NUM>. In some embodiments sensor <NUM> is a temperature sensor that measures the liquid combined at second junction <NUM> and conveyed to load input port <NUM>; such a temperature sensor may, for example, be placed inside the hydraulic conveyance (e.g., pipe) between second junction <NUM> and load input port <NUM> as indicated in <FIG>. In some embodiments a Pete's plug is used to allow a temperature sensor such as a thermistor or thermocouple to be inserted into the conduit. In some embodiments a T-shaped fitting may be used to accommodate a temperature sensor. In some embodiments sensor <NUM> includes a flow meter for measuring the flow rate of the liquid entering the load through load input port <NUM> and control module <NUM> controls control valve <NUM> and pump <NUM> to achieve a target load flow rate.

It should be appreciated that the illustration of sensor <NUM> in <FIG> as a temperature sensor between second junction <NUM> and load input port <NUM> is illustrative of some embodiments. The temperature of the liquid flowing out of load input port <NUM> may be measured in other ways. For example, <FIG> shows a control system <NUM> where sensor <NUM> includes temperature sensors <NUM> and <NUM> and flow meters <NUM> and <NUM>. (The descriptions of embodiments of control systems <NUM> and <NUM> otherwise applying equally to control system <NUM>. ) Flow meters <NUM> and <NUM> measure the rate of liquid flowing through the respective meter. Flow meters <NUM> and <NUM> are connected in a suitable way; for example, each flow meter may be connected in line so that all liquid flowing through the relevant pipe also passes through the flow meter. In this example, temperature sensor <NUM> and flow meter <NUM> are provided between supply input port <NUM> and junction <NUM> to measure the temperature and flow rate of the liquid entering from supply input port <NUM>. Another temperature sensor <NUM> and flow meter <NUM> measure the temperature and flow rate of the recirculated liquid and are provided between recirculating pump <NUM> and junction <NUM>.

The temperature of the liquid flowing to load input port <NUM>, Tin can be estimated from these measurements as Tin = ( T<NUM>F<NUM> + T<NUM> F<NUM>)/(F<NUM> + F<NUM>), where T<NUM> and T<NUM> are the temperature measurements of temperature sensors <NUM> and <NUM>, respectively, and F<NUM> and F<NUM> are the flow rate measurements of flow meters <NUM> and <NUM>, respectively.

It should be appreciated that other positions and configurations of temperature sensors and flow meters in the control system may also be used to estimate the temperature of the liquid flowing to load input port <NUM>. Refer momentarily to <FIG>, which shows an embodiment, control system <NUM>, as part of a conditioning system <NUM>. In <FIG> five liquid flows are labelled within control system <NUM>, namely (i) supply input flow <NUM>, (ii) recirculation flow <NUM>, (iii) load input flow <NUM>, (iv) load return flow <NUM>, and (v) supply return flow <NUM>. The flow rates associated with these flows are se are abbreviated F<NUM>, F<NUM>, F<NUM>, F<NUM>, and F<NUM> respective.

Assuming liquid does not leave the load (e.g., the chilled beam does not leak), there is no net flow on the load ports <NUM> and <NUM>, thus F<NUM> = F<NUM>. This also implies that there will be no net flow to the supply ports <NUM> and <NUM>, thus F<NUM> = F<NUM>. By Kirchhoff's law we see that F<NUM> = Fi9i + F<NUM>,and F<NUM> = F<NUM> + F<NUM>. Further, assuming the internal piping of the control system is well insulated and that the devices within the control system do not affect the liquid temperature it becomes clear that the temperature of recirculation flow <NUM>, load return flow <NUM>, and supply return flow <NUM> are the same. In some embodiments, the temperature of the liquid provided by a liquid supply system <NUM> (or any suitable liquid supply system) to supply input port <NUM> may be a fixed value controlled by liquid conditioner <NUM>. Thus, control system <NUM> may be able to assume the temperature of supply input flow <NUM> is equal to such fixed value, though, in some embodiments, liquid supply system <NUM> provides a temperature measurement of the supply liquid to control system <NUM> via a data port (such as data port <NUM>, <FIG>). Accordingly, temperature sensor <NUM> may not be installed or required.

It should be clear that multiple sensor configurations can be used to estimate the temperature of the liquid flowing to load input port <NUM>. The use of temperature sensors and flow meters at various points within control system <NUM>, may be desired, for example, to provide greater visibility on the overall performance and improve the efficacy of the chilled beam and the control system. For example, the temperature drop of the liquid between entering a chilled beam through load input port <NUM> and exiting the beam to load return port <NUM> along with the flow rate is indicative of the amount of heat transfer occurring on the chilled beam. (An experimental example is discussed in connection with <FIG>. ) As another example, in some embodiments, measurement of the temperature of supply input flow <NUM> may be used to improve the effectiveness of the control module algorithms (e.g., pump <NUM> may be turned off if supply input flow alone will provide improved performance over combining it with recirculation flow).

Returning to <FIG>, control system <NUM> may include power port <NUM> which may be connected to a power source <NUM>. Power port <NUM> may receive electrical power needed to operate control system <NUM>. While power port <NUM> is shown connected to control module <NUM>, it should be appreciated that power may be provided to various other components of control system <NUM> directly or through control module <NUM>. In some embodiments, power is provided for internally by control system <NUM>. For example, control system <NUM> may be battery powered, include a generator, or use a suitable combination of battery storage, generators, and external power sources.

Control system <NUM> may include control module <NUM>. Control module <NUM> may control control valve <NUM> and recirculation pump <NUM> based on various inputs such as from sensor <NUM>, user interface <NUM> ambient sensor <NUM>, and remote commands received from data port <NUM>.

Some embodiments of control module <NUM> are described, for example, in connection with <FIG>. In some embodiments control module <NUM> includes data port <NUM> for communicating with other devices such as a control and monitoring center, other control systems, and the like.

In some embodiments, control module <NUM> has a user interface port <NUM> for connecting to a user interface such as user interface <NUM>. A user interface <NUM> may provide an interface for a user of the conditioned space to control control system <NUM>. User interface <NUM> may allow a user to, among other things, indicate whether conditioning of the air in a conditioned space is desired, the type of conditioning (e.g., heating or cooling), a setpoint temperature specifying a desired temperature in the conditioned space, and to create a schedule for operation of control system <NUM>. User interface <NUM> may also present information about the status of control system <NUM>, the conditioned space, and the like to the user. In some embodiments, user interface <NUM> is a computer or other electronic device with any suitable combination of user interface devices such as a display, keypad, haptic feedback, speaker, microphone, touch screen, mouse, trackball, and other types of user interface devices.

Control module <NUM> may have an ambient sensor port <NUM> for connecting an ambient sensor such as ambient sensor <NUM>. Ambient sensor <NUM> may measure the ambient conditions of in a conditioned space. For example, ambient sensor <NUM> may measure the temperature (e.g., "room" or"air" temperature), the humidity, the relative humidity, the dew point temperature, or other conditions in a conditioned space. In some embodiments multiple ambient sensors are used, for example, a first set of one or more sensors may be used to measure conditions such as dew point at or near the chilled beam while a second set of one or more sensors may be used to measure a temperature representative of the conditioned space.

It should be appreciated that any suitable hydraulic conveyance may be used between the various hydraulic components of control system <NUM>. If hydraulic conveyances are circular in cross-section, the internal diameter may be between <NUM> and <NUM> metre (e.g., about <NUM>, <NUM>, <NUM>, <NUM>, <NUM> metre diameter, or any combination of ranges such between <NUM> mtr to <NUM> mtr. For example, <NUM>, <NUM>, <NUM>, or <NUM> mtr. nominal pipe diameter may be used. Control system <NUM> may be designed such that the total length of its hydraulic conveyances is the least practical in view of considerations such as proper operation, the ease of repair. In some embodiments the total length of hydraulic conveyances is less than <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> equivalent internal diameters of the hydraulic conveyance. For example, an embodiment with <NUM> metre pipe may have a total length of hydraulic conveyances less than <NUM> metre.

Having discussed embodiments of a control system with reference to <FIG>, the use of the control system as part of a conditioning system is discussed with references to <FIG>. While <FIG> refer to control system <NUM>, it should be appreciated that other embodiments (e.g., control systems <NUM>, <NUM>, <NUM>) or aspects of other embodiments of the control system may be used with the described conditioning systems. The examples in <FIG> are exemplary and the control system may be used in other conditioning systems and with other liquid supply systems.

<FIG> shows conditioning system <NUM> using a control system <NUM>. Conditioning system <NUM> includes a liquid supply system <NUM>, a conditioned space <NUM>, an air supply system <NUM>, control system <NUM> and conditioning load <NUM> (among other elements).

Conditioning system <NUM> is a system for conditioning one or more conditioned spaces such as conditioned space <NUM>. Conditioned space <NUM> is a volume where one or more environmental parameters such as temperature and humidity are to be controlled by conditioning system <NUM>. Examples of volumes that may be suited for conditioning include but are not limited to the rooms of a house, condo, hotel, or office; retail space; or office buildings; commercial real estate, industrial buildings; factories; hangers; boats, aircraft, vehicles, and other indoor environments.

Liquid supply system <NUM> provides conditioned liquid. Liquid supply system <NUM> may be referred to as a "two-pipe system". A liquid conditioner <NUM> conditions liquid to have desired characteristics (e.g., to have a particular temperature or to be within a specific temperature range). Pump <NUM> pump the conditioned liquid through liquid supply system <NUM>. Liquid conditioner <NUM> may include a chiller and/or a boiler, though any suitable device for conditioning the liquid may be used. The liquid may be water, water with additives to improve performance (e.g., to reduce the risk of freezing), or any other suitable liquid. Liquid returns to liquid conditioner <NUM> via a liquid return pipe <NUM>. Liquid supply pipe <NUM> and liquid return pipe <NUM> are connected to the supply input port <NUM> and supply return port <NUM>, respectively, of control system <NUM>. Supply pipe <NUM> and return pipe <NUM> may be similarly connected to any number of control systems similar or identical to control system <NUM>, or any other devices that may utilize the conditioned liquid provided by liquid supply system <NUM>. To illustrate this concept a control system <NUM> and load <NUM> are also shown connected to liquid supply system <NUM>. For simplicity only control system <NUM> and load <NUM> are shown; they may have additional components and may be in conditioned space <NUM> or another conditioned space. In some embodiments, <NUM>, <NUM>, or even <NUM>,<NUM> of additional devices may be connected, however, in some embodiments of conditioning systems <NUM>, control system <NUM> may be the only device connected to liquid supply system <NUM>.

In some embodiments liquid supply system <NUM> may be a "cold" liquid supply system or a "hot" liquid supply system. A cold supply system may utilize a chiller for liquid conditioner <NUM> to cool the liquid, for example, to a temperature between above <NUM> and about <NUM>. The temperature may be a fixed value (e.g., <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) to within a tolerance (e.g., degree or two) though requirements may differ with different embodiments. Similarly, a hot supply system may utilize a boiler to heat a liquid, for example, to a temperature between about <NUM> and <NUM>. The temperature may be a fixed value (e.g., <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) to within a tolerance (e.g., a few degrees) though requirements may differ with different embodiments. It may not be critical that the temperature of a liquid from a supply source be known or tightly controlled as some embodiments control system <NUM> can dynamically adapt to respond to changing supply conditions.

Liquid supply pipe <NUM> and liquid return pipe <NUM> may each terminate after connection of all devices to liquid supply system <NUM>, though in some cases they are connected together to provide a complete flow path even when all connected devices are not using liquid from the system. In some cases, a bypass (not shown) is used to prevent deadheading pump <NUM>.

Conditioning load <NUM> is located at/in conditioned space <NUM>. Load <NUM> may be a chilled beam, fan coil unit, another device for heat transfer with conditioned space <NUM>, or any other suitable device. In some embodiments, load <NUM> is a two-port device with an input which receives liquid; the liquid flows through piping within load <NUM> allowing energy transfer with conditioned space <NUM> and exits via a return port. The piping may be coiled to increase the amount of energy transfer that takes place prior to returning the liquid flow. Control system <NUM> is connected to load <NUM> by load input port <NUM> and load return port <NUM>. Control system <NUM> may be designed to match the requirements of load <NUM>. For example, load <NUM> may be a chilled beam designed to receive about <NUM> to. <NUM> cubic metre per minute of liquid. The pipes, pump, and ports of control system <NUM> may be selected for the efficient operation of such a chilled beam.

In some embodiments air supply system <NUM> provides air to load <NUM>. For example, load <NUM> may be an active chilled beam where the air supplied by air supply system <NUM> enhances air flow past the coil of the active chilled beam. Air flow over piping in load <NUM> may enhance energy transfer between the load and conditioned space as well as improve distribution of conditioned air in conditioned space <NUM>. In some embodiments air supply system <NUM> provides air to load <NUM> via an air duct <NUM>. In some other embodiments, air supply system <NUM> provides increased air flow over load <NUM> without a duct. Air supply system <NUM> may be a dedicated outdoor air system (DOAS) and may feature an energy recovery ventilator (ERV). It is noted that some systems, such as those utilizing a passive chilled beam may be designed to operate without an air supply system.

Ambient sensor <NUM> is provided in conditioned space <NUM> to measure one or more properties in conditioned space <NUM>. In some embodiments, ambient sensor <NUM> is positioned proximal to load <NUM>, though ambient sensor <NUM> may be positioned anywhere in conditioned space <NUM>. As discussed below in connection with <FIG>, control module <NUM> may use ambient sensor <NUM> as an input for control decisions. In some embodiments, multiple ambient sensors may be used to sense the condition of the air at different locations, such conditions to be used as further inputs to the control decision process or simply provided for informational purposes.

In some embodiments, control module <NUM> varies the relative amounts of recirculation flow <NUM> and supply input flow <NUM> that are mixed to form load input flow <NUM> by controlling control valve <NUM> and recirculation pump <NUM>. Control module <NUM> may control pump <NUM> and control valve <NUM> to achieve a target condition, such as the temperature of load input flow <NUM> or the flow rate of load input flow <NUM>, or the ambient temperature in conditioned space <NUM>. One or more target conditions may be determined based on inputs received by control module <NUM>. For example, in a cooling mode (e.g., liquid conditioner <NUM> being a chiller) with recirculation pump <NUM> turned on, control module <NUM> may open control valve <NUM> more to allow more supply input flow <NUM> (e.g., cold water) to mix with recirculation flow <NUM> reducing the temperature of load input flow <NUM>. As a result of the flow rate of supply input flow <NUM> increasing the pressure differential across pump <NUM> may also increase resulting in a reduction in the flow rate of recirculation flow <NUM>. Similarly, if control valve <NUM> is closed more to reduce the temperature of load input flow <NUM>, supply input flow rate <NUM> may decrease and recirculation flow <NUM> may increase. The heating mode may be analogous. In some embodiments of control system <NUM>, even as control valve <NUM> varies position the flow rate of load input flow <NUM> is relatively constant (e.g., within <NUM>%, <NUM>%, <NUM>% or <NUM>% of the maximum or minimum flow rate) because of an inverse relationship between supply input flow <NUM> and recirculation flow <NUM> as control valve <NUM> position is changed.

<FIG> shows a conditioning system <NUM> using a control system <NUM>. This system is similar to conditioning system <NUM> in <FIG> except that another liquid supply system design has been provided. Liquid supply system <NUM> may be referred to as a diverter-tee system as it features diverter tees, such as diverter tee <NUM>, that restrict flow in order to provide a pressure differential between supply input port <NUM> and supply return port <NUM> that is suitable for operation of control system <NUM> and load <NUM>. This allows liquid supply pipe <NUM> of liquid supply system <NUM> to connect in sequence to both the supply input and return ports of a device before connecting to another device. One or more devices such as control system <NUM> may be connected to liquid supply system <NUM>. A simplified illustration of a control system <NUM> with a load <NUM> is shown to illustrate the connection of additional devices in conditioning system <NUM>. A diverter tee <NUM> providing a suitable pressure drop for the operation of control system <NUM>. While diverter tees <NUM> and <NUM> are illustrated at the return connection, it should be appreciated that diverter tees may be located either or both the input and return branches. It is noted that pipe <NUM> forms a loop, thus the sequence of attaching a number of devices may significantly impact the total length of pipe <NUM>. An advantage of liquid supply system <NUM> over system <NUM> is significantly less pipe may be needed to connect the same number of devices to supply system <NUM>.

A third example of a conditioning system utilizing control system <NUM> is shown in <FIG>. Conditioning system <NUM> has a liquid supply system <NUM> which has a chiller <NUM>, boiler <NUM> and a pump <NUM>. Chiller <NUM> cools the liquid in supply system <NUM> and boiler <NUM> heats the liquid in supply system <NUM>. Liquid supply system is connected to devices such as control system <NUM> in ways similar to those discussed in connection with conditioning system <NUM> (<FIG>). Such a system allows a single supply control system such as control system <NUM> to be used for both heating and cooling. Valves <NUM>, <NUM>, <NUM>, and <NUM> may be used to control whether liquid cooled by chiller <NUM> or liquid heated by boiler <NUM> flows through the piping of liquid supply system <NUM>. An operator, for example, may open valves <NUM> and <NUM> and close valves <NUM> and <NUM> during periods of time requiring cooling in conditioned space <NUM>, and switch the configuration of the valves for periods of time requiring heating in conditioned space <NUM>. This may be done, for example, once a year with the disconnected device powered down during the dormant period. In some other embodiments, valves <NUM>, <NUM>, <NUM>, and <NUM> are appropriately replaced with <NUM> -way valves. While liquid supply system <NUM> is illustrated as a two-pipe system, it should be appreciated that a similar configuration could be achieved by adapting the diverter tee liquid supply system <NUM> to have valves to select between multiple liquid conditioners such as a boiler and a chiller.

A disadvantage of the single supply control systems described with reference to <FIG> is that the control system can only heat or cool to the temperature of the liquid made available at supply input port <NUM> by the connected liquid supply system. If some devices connected to a single liquid supply system require hot liquid (for heating) and others require cool liquid (for cooling) not all conditioning demands can be simultaneously met. Similarly, a control system may be trying to provide cooling through a chilled beam at one time of day and heating at another and unless the liquid supply system changes to meet such need (a solution that may not be practical) only heating or cooling will be available, but not both.

Introduced in <FIG> are two-supply control systems for controlling conditioning loads such as a chilled beam. Two-supply control systems may be connected to a "cold" liquid supply system and a "hot" liquid supply system so that cooling and heating is available at any time for the conditioned space being managed by the control system.

<FIG> shows a two-supply control system <NUM> according to some embodiments. Note that the designation of "first" and "second" with respect to the supply ports, the control valves and check valves is not an indication of priority, precedence, or order. The purpose is merely to distinguish between elements.

In control system <NUM> first supply input port <NUM> and first supply return port <NUM> may be connected to a first liquid supply system. Second supply input port <NUM> and second supply return port <NUM> may be connected to a second liquid supply system. When connected to their respective liquid supply systems, a relatively larger liquid pressure may be exerted at input ports <NUM> and <NUM> relative to the respective return ports <NUM> and <NUM>.

Control system <NUM> includes first control valve <NUM> having ports <NUM> and <NUM>, and second control valve <NUM> have ports <NUM> and <NUM>. First control valve <NUM> and second control valve <NUM> may be similar to embodiments of control valve <NUM> described with reference to <FIG>.

Control system <NUM> also includes first check valve <NUM> having input ports <NUM> and output port <NUM>, and second check valve <NUM> have input port <NUM> and output port <NUM>. First check valve <NUM> and second check valve <NUM> allow flow of liquid from their respective input ports to their respective output ports and prevent flow in the opposite direction. Check valves <NUM> and <NUM> may be similar to embodiments of check valve <NUM> described with reference to <FIG>.

In control system <NUM>, first control valve <NUM> may be connected between first supply input port <NUM> and junction <NUM> and first check valve <NUM> may be connected between junction <NUM> and first supply return port <NUM>. First check valve <NUM> may be oriented to allow flow of liquid out of port <NUM>. This configuration is similar to the configuration of control valve <NUM> and check valve <NUM> in control system <NUM>, described with reference to <FIG>.

In control system <NUM>, second control valve <NUM> is connected between first junction <NUM> and second supply return port <NUM> and second check valve <NUM> is connected between second supply input port <NUM> and second junction <NUM>. Second check valve may be oriented to allow flow of liquid into control system <NUM> from port <NUM>. This configuration of control valve <NUM> and check valve <NUM> is similar to the configuration of control valve <NUM> and check valve <NUM> in control system <NUM>, described with reference to <FIG>.

Control system <NUM> may be configured to permit flow of liquid from only one of the two supplies at any given time. This may be achieved by assuring that at least one of the control valves <NUM> and <NUM> is always closed. (Which valve is closed can be switched by first completely closing both control valves.

<FIG> shows a conditioning system <NUM> according to some embodiments. Conditioning system <NUM> includes two-supply control system <NUM> connected to a load <NUM> for conditioning conditioned space <NUM>. Conditioning system <NUM> also includes cold water supply system <NUM> and hot water supply system <NUM>.

Cold water supply system <NUM> includes a chiller <NUM> for cooling water. A pump <NUM> for pumping the cold water to the devices along cold-water supply pipe <NUM>. The cold water returns to chiller <NUM> along cold-water return pipe <NUM>. Similarly, hot water supply system <NUM> includes a boiler <NUM> for heating water and a pump <NUM> for pumping the hot water to the devices along hot water supply pipe <NUM>. The hot water returns along hot water return pipe <NUM>.

Although only one device (i.e., control system <NUM>) is shown connected to supply systems <NUM> and <NUM> it should be appreciated that any number of devices may be connected to such liquid supply systems as was discussed previously, for example, in connection with liquid supply system <NUM> of <FIG>.

First supply input port <NUM> of control system <NUM> is connected to cold water supply pipe <NUM> of cold-water supply system <NUM>; first supply return port <NUM> is connected to cold water return pipe <NUM>. Similarly, second supply input port <NUM> is connected to hot water supply pipe <NUM> of hot water supply system <NUM> and second supply return port <NUM> is connected to hot water return pipe <NUM>.

<FIG> shows the flow of liquid within control system <NUM>. Included are the same flows of liquid as were discussed with reference to the single supply control system <NUM> in <FIG>, namely (i) supply input flow <NUM>, (ii) recirculation flow <NUM>, (iii) load input flow <NUM>, (iv) load return flow <NUM>, and (v) supply return flow <NUM>. The operation of these flows is identical to the earlier discussion except that supply input flow <NUM> originates from port <NUM> or port <NUM> and supply return flow <NUM> is returned to port <NUM> or port <NUM>. Specifically, first supply input flow 191A and second supply input flow 191B combine to form supply input flow <NUM>; and supply return flow <NUM> is divided into first supply return flow <NUM> A and second supply return flow 195B.

In some embodiments, only one of first supply input flow <NUM> A and second supply input flow <NUM> IB has a non-zero flow rate at any given time. Similarly, only one of first supply return flow <NUM> A and second supply return flow 195B has a non -zero flow rate at any given time.

These conditions may be achieved by ensuring that at any time at least one of the control valves (<NUM> or <NUM>) is closed. Assuming no loss of liquid in the load (i.e., F<NUM> = F<NUM>), the return flow rates will equal the input flow rates of the respective supply. That is, using the same notation adopted earlier F191A = F195A and F191B = F195B.

While control system <NUM> has only been shown in conditioning system <NUM> with a four-pipe liquid supply system (i.e., two two-pipe liquid supply systems) it should be appreciated that any suitable liquid supply system may be used. For example, diverter tee type liquid supply systems may be used.

A method <NUM> of controlling flow of a liquid from a liquid supply system into a conditioning load is discussed with reference to <FIG>. Some of the embodiments of the described control systems may be used to implement method <NUM>. In discussing some of the steps of method <NUM>, reference is made to control system <NUM> in <FIG>, however, this is simply an example, and method <NUM> may be implemented using other control system embodiments or in other suitable ways.

Method <NUM> begins at step <NUM> where supply input flow is received at a supply input port. For example, in <FIG>, supply input flow <NUM> is received through supply input port <NUM>. The supply liquid flow may be received from a liquid supply system such as liquid supply system <NUM>.

At step <NUM>, method <NUM> receives a load return flow at a load return port. For example, in <FIG>, load return flow <NUM> is received through load return port <NUM>. The load return flow may be received from a conditioning load such as load <NUM>.

At step <NUM>, method <NUM> divides the return liquid into a recirculation flow and a supply return flow. For example, in <FIG>, junction <NUM> divides load return flow <NUM> into recirculation flow <NUM> and supply return flow <NUM>.

At step <NUM>, method <NUM> pumps the recirculation flow into a junction. For example, in <FIG>, recirculation pump <NUM> pumps recirculation flow <NUM> into junction <NUM>.

At step <NUM>, method <NUM> discharges the supply return flow through a supply return port. For example, in <FIG>, supply return flow is discharged through supply return port <NUM> back to liquid supply system <NUM>.

At step <NUM>, method <NUM> forms a load input flow by combining in the junction the supply input flow with the recirculation flow. For example, in <FIG>, supply input flow <NUM> and recirculation flow <NUM> are combined injunction <NUM> to form load input flow <NUM>.

At step <NUM>, method <NUM> delivers the load input flow to the conditioning load through a load input port. For example, in <FIG>, load input flow <NUM> is delivered to load <NUM> via load input port <NUM>.

At step <NUM>, method <NUM> measures a load input temperature of the load input flow. For example, in <FIG>, sensor <NUM> measures the temperature of load input flow <NUM>. It should be appreciated that the temperature of the load input flow may be measured less directly, for example, if the flow rates and temperatures of the supply input flow and the recirculation flow are known, the temperature of the load input flow can be calculated.

At step <NUM>, method <NUM> controls a control valve to restrict the supply of liquid based at least in part on the load input temperature. For example, in <FIG>, control module <NUM> provides a control signal to control valve <NUM> causing control valve <NUM> to restrict the rate of supply input flow <NUM>.

Having discussed primarily the mechanical operation of embodiments of a control system, some additional aspects of some embodiments of control module <NUM> are discussed with reference to control system <NUM> in <FIG>. Control system <NUM> is a two-supply control system like control system <NUM> in <FIG>. It should be clear however that the control module <NUM> can be used in or easily adapted for use in a single supply control system such as those discussed in connection with <FIG>.

Control module <NUM> may receive input signals from sensor <NUM>, ambient sensor <NUM>, user interface <NUM> and via data port <NUM>. Control module <NUM> may be configured to send control signals to first control valve <NUM>, second control valve <NUM>, and recirculation pump <NUM>. Control module <NUM> may also send information such as the input signals, control signals, and status of control system <NUM> to other devices via data port <NUM>.

Control module <NUM> may include a plurality of modules such as memory <NUM>, processor <NUM>, power supply <NUM>, communications module <NUM>, and input/output (I/O) modules <NUM>.

Processor <NUM> may be configured to implement control algorithms in response to input signals received by control module <NUM>. Processor <NUM> may be operatively connected to memory <NUM> and other modules of control module <NUM>. Processor <NUM> may be any suitable processing device such as for example and not limitation, a central processing unit (CPU), digital signal processor (DSP), field programmable gate array (FPGA), application specific integrated circuit (ASIC), or any suitable processing device. In some embodiments, processor <NUM> comprises one or more processors, for example, processor <NUM> may have multiple cores and/or multiple microchips.

Memory <NUM> may be integrated into processor <NUM> and/or may include "off-chip" memory that may be accessible to processor <NUM>, for example, via a memory bus (not shown). In some embodiments, memory <NUM> stores software modules that when executed by processor <NUM> perform desired functions; in some embodiments memory <NUM> stores an FPGA configuration file for configuring processor <NUM>. Memory <NUM> may be any suitable type of non-transient, computer-readable storage medium such as, for example and not limitation, RAM, ROM, EEPROM, PROM, volatile and non-volatile memory devices, flash memories, or other tangible, non-transient computer storage medium.

Power supply <NUM> provides the power signals for the operation of control module <NUM> and other electrical devices in control system <NUM>. Power supply <NUM> may use power source <NUM> to facilitate generation of such power signals, though other sources of power may be used. For example, power source <NUM> may provide a 120V AC power signal to control system <NUM>. Power supply <NUM> may convert the provided AC signal into DC voltage signals suitable for operation of various components of control system <NUM> - control module <NUM> may require <NUM>. 3V and/or 5V, control valves <NUM> and <NUM> may require 24V, and recirculation pump may require 12V. Thus, power supply <NUM> may convert the 120V AC power signal into these various DC voltage signals, or any other signals based on the requirements of a particular embodiment.

Communications module <NUM> may be any suitable combination of hardware and software configured to generate and receive communication signals over data port <NUM>. Data port <NUM> may include a wired data port, a wireless data port, or both. Data port <NUM> may provide a connection to a network such as a LAN, WAN, the internet, and/or another device using any suitable communications protocol. Communications module <NUM> may be configured to communicate with other control systems, a centralized control and monitoring center, or any other device. For example, multiple controls systems may be connected together and to a control and monitoring center to facilitate data logging, reconfiguration of the connected control systems and the like. In some embodiments, multiple control systems are daisy chained together; to facilitate this port <NUM> may include two or more physical connectors to allow each control system to be connected by cable into the next. Other suitable network topologies may also be used.

I/O <NUM> may include digital I/O <NUM>, relay <NUM>, analog-to-digital converter <NUM> (ADC <NUM>), digital-to-analog converter / pulse width modulator <NUM> (DAC/PWM <NUM>), and amplifier <NUM>. I/O <NUM> permits signaling with other devices and sensors connected to control module <NUM>. I/O <NUM> is not limited to these types of input and output, and the discussion of the use of I/O <NUM> is exemplary and other input/output mechanisms may be used in other embodiments.

Digital I/O <NUM> allows for digital signaling of input and/or output signals. For example, sensor <NUM>, ambient sensor <NUM>, or user interface <NUM> may utilize digital communication protocols that utilize digital EO <NUM>.

Relay <NUM> may be used to facilitate the use of a low voltage digital EO (e.g., <NUM> V, 5V) to control a higher voltage signal. For example, recirculation pump <NUM> may require a 12V power signal drawing <NUM> Amp of current to run the pump. A digital EO pin may only be able to provide, say, a <NUM> V signal with a 15mA maximum current. The use of a properly configured relay <NUM> can allow such a digital I/O pin to control a much higher voltage and current power signal to pump <NUM>.

ADC <NUM> allows analog signal to be processed digitally by converting such signals into a sequence of digital bits. For example, sensor <NUM> may be a thermistor which has a resistance that varies predictably with temperature. A suitable circuit (e.g., voltage divider) and ADC <NUM> may be used to convert a voltage measurement into a digital signal. The digital signal may then be processed by processor <NUM> (or otherwise) to determine the temperature from the thermistor. As another example, sensor <NUM> may be a thermocouple whose voltage may be converted to a digital signal directly by ADC <NUM> or after a suitable signal conditioning circuit (e.g., amplification, low pass filtering).

DAC/PWM <NUM> represent two forms of outputting an analog voltage signal. Digital -to-analog converters may convert digital inputs into analog outputs with discrete increments (though such increments may be below the noise floor in some cases). Pulse width modulation (PWM) may simulate an analog voltage level by switching between digital values at high frequency. The time average voltage value controlled by varying the duty cycle. Low pass filtering can be used to remove the high frequency switching content leaving the time average voltage signal level. DACs or PWMs may, for example, be used to provide an analog output signal for controlling the control valves <NUM> and <NUM>.

Amplifier <NUM> may increase the voltage or current of a low power signal, such as a signal output by digital I/O <NUM> or DAC/PWM <NUM>. For example, control valve <NUM> may require an analog voltage input between <NUM> and <NUM> volts to vary the valve position from completely closed (e.g., at 2V) to completely open (e.g., at 10V). A PWM signal may be generated by a <NUM>. 3V digital device (logic <NUM> at <NUM> V, logic <NUM> at <NUM> V) - thus the time average voltage of the PWM signal can only be between <NUM> and <NUM> volts. To use the PWM signal to control valve <NUM>, amplifier <NUM> may be configured to multiply the input voltage by a little over <NUM> and the resultant signal used for control.

Control module <NUM> may send or receive signals to sensors and actuators associated with control system <NUM> as well as provide electrical power to such devices. Though, in some embodiments power may be provided directly by power source <NUM> or another source. Signal channels <NUM>, <NUM>, <NUM>, and <NUM> may facilitate signaling with first control valve <NUM>, second control valve <NUM>, recirculation pump <NUM>, and sensor <NUM>, respectively. In some embodiments, signal channels <NUM>-<NUM> may also provide power to the respective sensors and actuators. In some cases, the control signal and power may be the same signal. For example, if pump <NUM> is a fixed speed pump, the control signal may simply be providing the power needed to run the pump. Signal channels <NUM>-<NUM> may be wired or wireless signal channels, or any suitable type of signal channel.

Attention is now turned to method <NUM>, shown in <FIG>, for controlling a control system for conditioning indoor air in a conditioned space using a conditioning load such as a chilled beam, fan coil, or the like. Method <NUM> may be implemented in any suitable combination of software and hardware. For example, method <NUM> may be implemented in control module <NUM> to control control system <NUM>. Method <NUM> is described in connection with reference to control system <NUM> (<FIG>), however, it should be appreciated that method <NUM> may be used to control any suitable two-source control system such as control system <NUM> shown in <FIG>.

Method <NUM> is a control loop that may repeat indefinitely. All paths in the flow diagram return to the first step, step <NUM>, thus completing a loop. For simplicity "stop" conditions have not been shown. If desired, a stop condition may be suitably implemented, for example as an interrupt or as part of "mode" determination. Of course, loss of power may inherently stop method <NUM> when implemented in an electrical device. It is noted that method <NUM> may have "memory" in the sense that earlier loops can affect the current loop.

At step <NUM>, method <NUM> obtains sensor and user inputs. Sensor inputs obtained may include measurements from sensor <NUM>, ambient sensor <NUM>, and other suitable, available sensor inputs. User inputs may include a setpoint temperature, an operating mode, and the like. User inputs may be input by a user via user interface <NUM> or provided from a device connected via data port <NUM>. Such user inputs may be calculated based on other earlier user inputs - for example, in the case where a user has programmed a conditioning schedule.

Also, at step <NUM>, the operating mode is determined. Operating modes may include cooling, heating, standby or other suitable modes. Some embodiments may allow the user to set the operating mode while in others the operating mode may be determined based on the sensor inputs and user inputs (e.g., the temperature in the conditioned space, the setpoint temperature). Similarly, in some embodiments the user may additionally be able to specify that the mode be determined automatically based on the sensor inputs and other user inputs. A "reset" mode (for simplicity not shown) may restart method <NUM> by returning it to "start" and potentially resulting in reinitialization of various variables to their initial start conditions (i.e., deleting memory of earlier loops of method <NUM>).

At step <NUM>, it is determined if the operating mode has changed in the current loop of method <NUM> as compared to the immediately preceding loop of method <NUM>. Specifically, step <NUM> would determine "yes" if the present mode changed relative to the mode of the immediately
preceding loop and "no" if the present mode did not change relative to the mode of the immediately preceding loop. For example, at step <NUM> method <NUM> would determine "yes" if the mode changed from "cooling" in the immediately preceding loop of method <NUM> to "heating" in the present loop of method <NUM>. The first loop through method <NUM> (i.e., the initial loop) may be handled in any suitable way, for example, by assuming the value of the preceding loop to be "standby" as part of the initialization process for method <NUM>.

If "yes" is determined at step <NUM>, method <NUM> proceeds to step <NUM> where any control variables are set to initial values or other suitable values. Control variables may include quantities that change from loop to loop in method <NUM>. For example, as discussed below, method <NUM> may utilize one or more integral control variables that accumulate over each loop of method <NUM> and such integral control variables may be reset at this step.

After step <NUM>, or if "no" is determined at step <NUM>, method <NUM> continues to step <NUM> where a leg of the flow diagram is selected based on the current mode. Three modes are shown in the embodiments of method <NUM> illustrated in the flow diagram: standby, cooling, and heating.

If it is determined at step <NUM> that the current mode is standby, method <NUM> proceeds to step <NUM> where the heating and cooling control valves are both closed and the recirculation pump is turned off. For the purposes of illustration it is assumed here (and in the discussion of steps <NUM>-<NUM>) that a "cold" liquid supply system is connected to first supply ports <NUM> and <NUM> and a "hot" liquid supply system is connected to second supply ports <NUM> and <NUM> of control system <NUM> (<FIG>). Thus, first control valve <NUM> may be referred to as the "cooling control valve", and second control valve <NUM> may be referred to as "heating control valve". Thus, with reference to control system <NUM>, at step <NUM> first control valve <NUM> and second control valve <NUM> may be closed by sending appropriate signals via signal channels <NUM> and <NUM> respectively. Similarly, recirculation pump <NUM> may be turned off by providing an appropriate signal via signal channel <NUM>. (The same signal channels may be used for control at other steps in method <NUM> as well.

If it is determined at step <NUM> that the current mode is cooling, method <NUM> proceeds to step <NUM>. At step <NUM> the heating control valve is closed. Closing the heating control valve prevents the flow of hot liquid into the control system and potentially mixing with the cold liquid. When the heating control valve is already closed at this step the method may proceed immediately to step <NUM>. In some embodiments it may be assumed that the heating control valve is already closed under certain circumstances. For example it may be appropriate to assume so if the mode of the immediately preceding loop of method <NUM> was cooling since the heating control valve can only be un-closed in heating mode and it must have been closed for the preceding loop to continue past step <NUM>.

If the heating control valve is not initially completely closed at this step, method <NUM> may pause until the heating control valve has completely closed or has had sufficient time to completely close in response to a suitable "close" control signal. In some embodiments the heating control valve provides a feedback signal as to the current valve position in which case method <NUM> may proceed to step <NUM> when such feedback signal indicates the heating control valve is completely closed. In some embodiments, the heating control valve is configured to receive a control signal specifying the valve position but does not provide direct feedback as to the actual valve position. The time to reach the valve position specified by the control signal may be non-trivial and thus method <NUM> may pause to allow sufficient time for the valve to close so as to avoid the possibility of both the cooling control valve and the heating control valve being open (and the potentially wasteful mixing of the hot and cold supply liquids). The amount of time to pause may be a fixed value, for example, the amount of time it takes to change the control valve position from completely open to completely closed. In some other embodiments, method <NUM> estimates the valve position based on the prior control signals to the valve, time, and known closing characteristics of the valve. For example, a control valve may require <NUM> seconds to go from completely open to completely closed. If the last heating control valve control signal was"<NUM>% open" and that signal was maintained for <NUM> minutes, method <NUM> can reasonably assume the heating control valve reached the <NUM>% open position within that time. Accordingly, assuming the valve has a linear rate of closure, waiting <NUM> or more seconds (i.e., <NUM>% of <NUM> seconds) after the "close" control signal was sent may be a sufficient amount of time to wait to conclude the heating control valve is completely closed (despite the lack of direct feedback on the valve position).

Step <NUM> is largely to improve efficiency by avoiding the mixing of hot and cold liquid. Some embodiments may proceed to step <NUM> before the heating control valve is completely closed (e.g., to improve overall system response time). Thus in some embodiments method <NUM> may proceed to step <NUM> immediately after sending the close signal to the heating control valve, after a predetermined amount of time (that may be less than the amount of time required to close the valve), or after the valve is reported or calculated to be substantially closed (e.g., <NUM>% closed (<NUM>% open); <NUM>% closed (<NUM>% open)).

After step <NUM>, method <NUM> proceeds to step <NUM> where the target load input temperature is determined. The target load input temperature is the target temperature for the liquid entering the conditioning load. For example, with reference to control system <NUM>, the target load input temperature is the temperature of the liquid flowing into the load, i.e., load input flow <NUM>, at load input port <NUM>. The target load input temperature may be determined based on the setpoint temperature (e.g., the desired ambient temperature in the conditioned space), the current temperature of the conditioned space (e.g., obtained from ambient sensor <NUM>), elapsed time, information from prior loops of method <NUM>, and the like. Any suitable control scheme may be used to determine the target load input temperature, for example, a proportional controller ("P controller"), a proportional-integral controller ("PI controller"), a proportional-integral-differential controller ("PID controller"), and the like may be used. In some embodiments a physics-based model of the conditioning system is used to determine the target load input temperature. In some embodiments an error signal used for control is calculated as the signed difference between the actual ambient temperature and the setpoint temperature.

In some embodiments the target load input temperature is constrained between the dew point temperature of the air plus some margin to prevent condensation, and the setpoint temperature. Advantageously if the load does not produce any condensate, costs associated with including a condensate pan or condensate drainage system are eliminated as well as the associated risks of water damage and mold. In some embodiments the setpoint temperature is constrained to be above the dew point temperature plus margin temperature. In some embodiments the margin is between -<NUM> and -<NUM>. The dew point temperature of the air may be provided by ambient sensor <NUM> or calculated based on measurements of ambient sensor <NUM> (e.g., from air temperature and relative humidity measurements). For example, ambient sensor <NUM> may include temperature and relative humidity sensors. Dew point can be calculated using a suitable formula from the measured temperature and relative humidity.

Having determined the target load input temperature, method <NUM> continues to step <NUM> where the cooling control valve position is determined and set. The recirculation pump may also be controlled. The cooling control valve may be set based on the load input temperature, the target load input temperature, elapsed time, information from prior loops of method <NUM>, and the like. The load input temperature may be measured, for example, by sensor <NUM>. Control schemes similar to those used for determining the target load input temperature at step <NUM> may be used to determine the cooling control valve position (e.g., P, PI, PID controllers; model based). An appropriate signal may be sent to the cooling control valve to set the determined valve position. In some embodiments an error signal used for control is calculated as the signed difference between the load input temperature and the target load input temperature. The range of the cooling control valve position may be, for example, from <NUM>% open (i.e., fully closed) to <NUM>% open (i.e., fully opened).

In some embodiments at step <NUM> the recirculation pump is turned on (or kept on). Such control methodology for the recirculation pump may be used, for example, if the recirculation pump is a fixed speed pump and the temperature of the cold supply liquid is unknown. In some other embodiments of method <NUM>, the recirculation pump is controlled based on the inputs and the target load input temperature. For example, in some embodiments if the temperature of the cold supply liquid is above the target load input temperature the pump is turned/kept off, and if the temperature of the source cold liquid is below the target load input temperature the pump is turned on.

If it is determined at step <NUM> that the current mode is heating, method <NUM> proceeds to step <NUM>. At step <NUM> the cooling control valve is closed. Considerations for closing the cooling valve are analogous to closing the heating control valve at step <NUM> while in the cooling mode.

After step <NUM>, method <NUM> proceeds to step <NUM> where the target load input temperature is determined. The considerations and methods of determining the target load input temperature at step <NUM> are analogous to those at step <NUM> for cooling, however the lower bound temperature may not be critical since condensation on the load may not be a risk during heating, particularly if the setpoint temperature is well above the dew point. In one embodiment the control system is limited to setting the target load input temperature between the setpoint temperature and the nominal temperature of the hot liquid supply.

Having determined the target load input temperature, method <NUM> proceeds to step <NUM> where the heating control valve position is determined and set. The pump is also controlled. The considerations and methods for determining the heating control valve position and controlling the pump are largely analogous to those discussed in connection with step <NUM> for the cooling mode.

After completing step <NUM> in standby mode, step <NUM> in cooling mode, or step <NUM> in heating mode method <NUM> returns to step <NUM> and the process repeats.

It should be clear that method <NUM> may also be used to control a single-source control system such as controls system <NUM>, <NUM>, <NUM>, and <NUM> (<FIG>). These control systems represent a special case where only "cooling" or "heating" mode is available at any given time.

In the case where a conditioning system, such as conditioning system <NUM> (<FIG>), may, for example, be seasonally switched between cooling and heating, method <NUM> may be used but the cooling control valve and the heating control valve may be treated as the same valve (e.g., control valve <NUM> in <FIG>) and thus the closing of the off-mode valve at steps <NUM> and <NUM> may be skipped. (Care may need to be taken to avoid allowing the mode to be set to the unavailable mode.

It should be appreciated that other control methods may be implemented in control module <NUM> and the discussed embodiments of method <NUM> are examples. In other embodiments the steps of method <NUM> may be performed in different orders, some steps may be omitted, and other steps may be added.

Turning now to <FIG>, a flow diagram <NUM> for an embodiment which utilizes proportional controllers is illustrated. Flow diagram <NUM> can represent an embodiment of steps <NUM>, <NUM> and <NUM> of method <NUM>, an embodiment of steps <NUM>, <NUM> and <NUM> of method <NUM>, or as part of another control method or as part of control module <NUM>. At box <NUM> a setpoint temperature <NUM> is obtained, for example, from a user interface <NUM> (discussed earlier; see e.g., <FIG>). Combiner <NUM> subtracts the ambient temperature <NUM> in the conditioned space from the setpoint temperature <NUM> creating an error signal <NUM>. Target load input temperature controller <NUM> scales and shifts error signal <NUM> to produce a target load input temperature <NUM>. For example, the offset may be the setpoint temperature and the scaling factor may be determined by experiment or in another suitable way. In some embodiments a dew point temperature measurement <NUM> may also be used to determine the target load input temperature. Combiner <NUM> subtracts the measured load input temperature <NUM> from target load input temperature <NUM> to produce error signal <NUM>. Valve and pump controller <NUM> produces a control valve control signal by scaling and shifting error signal <NUM>. For example, assume the valve position is represented by a voltage between 2V and 10V, with 2V representing fully closed and 10V representing fully open, the offset may be 2V and the scaling factor may be determined by experiment. Assume in this embodiment that valve and pump controller simply turns on or leaves the recirculation pump on. The valve and pump control signals <NUM> affect the control valve and pump resulting in the liquid flow that occurs in the control system and the load (see box <NUM>). This in turn affects the conditioned space (box <NUM>). The feedback to combiner <NUM> and combiner <NUM> is facilitated by boxes <NUM> and <NUM>, respectively. Box <NUM> represents a sensor that measures the temperature of the liquid flowing into the load such as sensor <NUM>, and box <NUM> represents a sensor measuring a representative temperature of the conditioned space such as ambient sensor <NUM> (both discussed earlier; see e.g., <FIG>).

Attention is now turned to <FIG> which shows an indoor environment <NUM> in a conditioning system <NUM> has been implemented according to some embodiments. In this example, indoor environment <NUM> has two conditioned spaces, namely, conditioned space <NUM> and conditioned space <NUM>. Conditioning system <NUM> has been configured with a cold-water supply system <NUM> and a hot water supply system <NUM> having chiller <NUM> and boiler <NUM>, respectively. Also shown in <FIG> are supply pumps <NUM> and <NUM> for the cold water and hot water supply systems <NUM> and <NUM>, respectively. Supply pump <NUM> pumps cold water from chiller <NUM> through cold water supply pipe <NUM>. This water returns to chiller <NUM> via the cold- water return line <NUM>. Similarly, supply pump <NUM> pumps hot water from boiler <NUM> through hot water supply pipe <NUM>. This water returns to boiler <NUM> via the hot water return line <NUM>.

Connected to hot and cold-water supply systems <NUM> and <NUM> are control systems 501A, <NUM> IB, and 501C. The control systems in this embodiment are two-supply control systems such as control systems <NUM>, and <NUM> discussed with reference to <FIG> and <FIG>. In this example embodiment, cold water supply system <NUM> is connected to the first supply input ports 110A, 110B, and <NUM> IOC; and first supply return ports <NUM> A, <NUM> IB, and 111C of the respective control systems. Hot water supply system <NUM> is connected to the second supply input ports 112A, 112B, and 112C; and second supply return ports 113A, 113B, and 113C of the respective control systems.

Connected to the control systems are conditioning loads <NUM> A, <NUM> IB, and 231C, respectively via the respective load input ports <NUM> A, 115B, and 115C and the respective load return ports 116A, 116B, and 116C.

Controls systems <NUM> A and 501B and their respective loads are in conditioned space <NUM>. Control system 501C and its load 231C is in conditioned space <NUM>. Each control system may be installed along with its respective load in the ceiling or wall of the associated conditioned space, hung from the ceiling, or placed in another suitable location in the conditioned space.

Conditioned space <NUM> may, for example, be a relatively large room requiring two loads while conditioned space <NUM> may be relatively smaller requiring only a single load to meet the heating and cooling needs of the room.

In this embodiment, the control systems are daisy chained to one another via their data ports. As illustrated, control systems <NUM> IB and 501C both have data ports with two connectors to facilitate wired communication. Specifically, data port 174A of control system 501A is connected to data port 174B1 of control system <NUM> IB; data port 174B2 of control system <NUM> IB is connected to data port 174C1 of control system 501C; and finally data port 174C2 of control system <NUM> IB is connected to a control and monitoring center <NUM>. Center <NUM> may be a computer system that allows for controlling and monitoring all aspects of conditioning system <NUM>. Center <NUM> may be local to indoor environment <NUM> or may be connected to via the internet or other network. Any suitable data may be communicated between each of the control systems and center <NUM>. In some embodiments, center <NUM>, for example, logs the performance of the control systems; this data may be analyzed and used to update control parameters such as control coefficients used by the control modules.

In conditioned space <NUM> a user interface <NUM> IB is connected to control system <NUM> IB via UI port <NUM> IB. User interface commands such as setting the setpoint temperature or the mode of operation (e.g., cooling, heating, standby) may be communicated to both control systems <NUM> A and <NUM> IB so that these control systems are always working together to condition space <NUM>. The settings entered through UI <NUM> IB may be communicated from control system <NUM> IB to control system <NUM> A via the connection between data ports 174B1 and 174A.

Control system 501A has ambient sensors 182A1 and 182A2 connected via ambient sensor port 172A. Control system <NUM> IB has ambient sensor 182B connected via ambient sensor port 172B. In some embodiments, ambient sensor 182A1 is positioned on, in, or proximal to load <NUM> A so as to provide accurate dew point temperature estimates at load <NUM> A. Similarly, ambient sensor 182B may be positioned on, in, or proximal to load <NUM> IB, again with the goal of providing accurate dew point temperature measurements at load <NUM> IB. On the other hand, ambient sensor 182A2 may be used to measure the ambient temperature used by both the control modules of control systems 501A and 501B. In this case ambient sensor 182A2 may be positioned at a suitable location in conditioned space <NUM>. Example locations for sensor 182A2 include on a wall, table, at a location unlikely to receive direct sunlight. In some embodiments, ambient sensor 182A2 has a wireless connection to port <NUM> A to enable the sensor to be positioned with a greater amount of flexibility. The ambient temperature measured by ambient sensor 182A2 may be communicated from control system 501A to control system 501B via the connection of data ports <NUM> A and 174B2 allowing both systems to utilize the same ambient temperature measurement for control.

Conditioned space <NUM> may be conditioned by control system 501C and load 231C independent from the conditioning of conditioned space <NUM>. UI 181C, connected to control system 501C via UI port 171C, may allow the user to configure control system 501C, for example, by setting the setpoint temperature. Ambient sensor 182C is connected to control system 501C via ambient sensor port 172C.

Experiments were conducted with a conditioning system to verify operational aspects of some embodiments. Some example results are presented with reference to <FIG> which shows a conditioning system <NUM> with a control system <NUM>, cold water supply system <NUM>, and chilled beam <NUM>. For simplicity a single supply system connected to a cold-water supply is shown. For the experiments, a hot water supply system was also connected to a second set of supply ports (not shown) on control system <NUM>. Control system <NUM> was instrumented with temperature sensors <NUM>, <NUM>, and <NUM>; and flow meters <NUM> and <NUM>. (Other components are as described elsewhere by the same reference number. ) Control system <NUM> was connected to cold water supply system <NUM> via ports <NUM> and <NUM>. Cold water supply system <NUM> included a chiller <NUM>, a pump <NUM>, and cold-water supply pipe <NUM> and cold water return pipe <NUM>. Chiller <NUM> was configured to provide cold water at about <NUM>.

Temperature sensor <NUM> measured the temperature of the water entering the load <NUM> through load input port <NUM>. Temperature sensor <NUM> measured the temperature of the water entering supply input port <NUM>. Temperature sensor <NUM> measured the temperature of the water entering load return port <NUM>. Flow meter <NUM> measured supply input flow <NUM> coming through supply input port <NUM>. Flow meter <NUM> measured load return flow <NUM>.

Control system <NUM> was run and an actual test result is illustrated. With recirculation pump <NUM> running ambient sensor <NUM> measured the temperature and relative humidity of conditioned space <NUM> as <NUM> and <NUM>%, respectively. This corresponds to a dew point of about <NUM>. Control valve <NUM> was partially open resulting in a measured supply input flow <NUM> of <NUM> cubic metre per minute (M<NUM>/M) at flow meter <NUM>. The temperature of the supply water at temperature sensor <NUM> was measured as <NUM> (close to the nominal <NUM>). At the same time flow meter <NUM> measured load return flow <NUM> as <NUM><NUM>/M. The temperature of the water entering the chilled beam was measured by temperature sensor <NUM> as <NUM> (-<NUM> above the dew point) while the temperature of the water existing the beam was measured by temperature sensor <NUM> as <NUM>. The temperature change from the input to the return port of the chilled beam is <NUM>, which is within the typical range for a variety of commercially available chilled beams).

These measurements imply a recirculation flow <NUM> of <NUM><NUM>/M. These particular measurements were reasonably self-consistent. For example, the temperature of load input flow <NUM> can be estimated in two ways - the direct measurement from temperature sensor <NUM> (<NUM>) and by a weighted average of the temperatures and flow rates of supply input flow <NUM> and recirculation flow <NUM>. Assuming the temperature of recirculation flow <NUM> is the same as load return flow <NUM> we calculate a load input flow temperature of <NUM> (i.e., ((<NUM> X <NUM>) + (<NUM> X <NUM>)) / (<NUM> + <NUM>)).

An energy balance around control system <NUM> should indicate that the energy input from the water supply <NUM> should equal energy output to the chilled beam <NUM>. The energy, Q, in Joules/hr, can be expressed as Q = <NUM> x F x DT, where A is the flow rate in cubic metres per minute, and AT is the change in temperature from the return to the input in degrees Celsius. (The constant <NUM> relates to the choice of units and has the unit Joules minute per cubic metres hour Celsius. ) We calculate the energy from the supply system as <NUM> Joules/hr (i.e., <NUM> X <NUM> X (<NUM>- <NUM>)) and the energy to the chilled beam as <NUM> Joules /hr (i.e., <NUM> X <NUM> X (<NUM>- <NUM>)). These numbers are equivalent within the measurement error of our sensors. (Note, the energy exchange in the control system is negligible for our purposes compared to that in the chilled beam.

Having thus described several aspects of at least one embodiment of this invention, it is to be appreciated that various alterations, modifications, and improvements will readily occur to those skilled in the art, as long as they fall within scope of the invention which is defined by the appended claims. Accordingly, the foregoing description and drawings are by way of example only.

It should be appreciated that the connections between the hydraulic components shown in the drawings and described with reference to embodiments of control systems, liquid supply systems, conditioning systems, and the like may be achieved by any suitable pipe, hose, tube, conduit, or other mechanism for conveying liquid under pressure. Where such connections have been described as a specific hydraulic conveyance (e.g., liquid supply "pipe" <NUM>, <FIG>) it should be appreciated that other embodiments may use hose, tube, conduit, or any other suitable hydraulic conveyance.

It should be appreciated that all mechanical and end electrical equipment will have functional limitations. Generally, the ideal behavior has been described so as to not unnecessarily distract from the general operation and description of the embodiments. Those of skill in the art will recognize and appreciate the need to consider both ideal and non-ideal behavior in designing specific embodiments just as with any electrical or mechanical device.

It should also be appreciated that in describing the operation of valves such as control valves <NUM> and <NUM> variations of "close" and "open" (e.g., closed, closing, opened, opening) generally refer to the change in the control valve's resistance to flow relative to its current position and do not mean "completely closed" (whereby flow is prevent) or "completely open" (allowing maximum flow) unless it is clear from the context that that is the intended meaning.

It should also be appreciated that the descriptions of components having the same name or same reference number appear in multiple drawings (e.g., control valve <NUM>, first control valve <NUM>, second control valve <NUM>) so as to avoid having to describe the common aspects of a component multiple times. It should be clear to those of skill in the art whether such descriptions made with reference to one embodiment are applicable to another embodiment. The above-described embodiments of the present invention can be implemented in any of numerous ways. For example, the embodiments may be implemented using hardware, software or a combination thereof. When implemented in software, the software code can be executed on any suitable processor or collection of processors, whether provided in a single computer or distributed among multiple computers.

Further, it should be appreciated that a computer may be embodied in any of a number of forms, such as a rack-mounted computer, a desktop computer, a laptop computer, or a tablet computer. Additionally, a computer may be embedded in a device not generally regarded as a computer but with suitable processing capabilities, including a Personal Digital Assistant (PDA), a smart phone or any other suitable portable or fixed electronic device.

Such computers may be interconnected by one or more networks in any suitable form, including as a local area network or a wide area network, such as an enterprise network or the Internet. Such networks may be based on any suitable technology and may operate according to any suitable protocol and may include wireless networks, wired networks or fiber optic networks.

Also, the various methods or processes outlined herein may be coded as software that is executable on one or more processors that employ any one of a variety of operating systems or platforms. Additionally, such software may be written using any of a number of suitable programming languages and/or programming or scripting tools, and also may be compiled as executable machine language code or intermediate code that is executed on a framework or virtual machine.

In this respect, the invention may be embodied as a computer readable medium (or multiple computer readable media) (e.g., a computer memory, one or more floppy discs, compact discs, optical discs, magnetic tapes, flash memories, circuit configurations in Field Programmable Gate Arrays or other semiconductor devices, or other tangible computer storage medium) encoded with one or more programs that, when executed on one or more computers or other processors, perform methods that implement the various embodiments of the invention discussed above. The computer readable medium or media can be transportable, such that the program or programs stored thereon can be loaded onto one or more different computers or other processors to implement various aspects of the present invention as discussed above.

In this respect, it should be appreciated that one implementation of the above-described embodiments comprises at least one computer-readable medium encoded with a computer program (e.g., a plurality of instructions), which, when executed on a processor, performs some or all of the above-discussed functions of these embodiments. As used herein, the term "computer-readable medium" encompasses only a computer-readable medium that can be considered to be a machine or a manufacture (i.e., article of manufacture). A computer-readable medium may be, for example, a tangible medium on which computer-readable information may be encoded or stored, a storage medium on which computer-readable information may be encoded or stored, and/or a non-transitory medium on which computer-readable information may be encoded or stored. Other non-exhaustive examples of computer-readable media include a computer memory (e.g., a ROM, a RAM, a flash memory, or other type of computer memory), a magnetic disc or tape, an optical disc, and/or other types of computer-readable media that can be considered to be a machine or a manufacture.

The terms "program" or "software" are used herein in a generic sense to refer to any type of computer code or set of computer-executable instructions that can be employed to program a computer or other processor to implement various aspects of the present invention as discussed above. Additionally, it should be appreciated that according to one aspect of this embodiment, one or more computer programs that when executed perform methods of the present invention need not reside on a single computer or processor, but may be distributed in a modular fashion amongst a number of different computers or processors to implement various aspects of the present invention.

Typically, the functionality of the program modules may be combined or distributed as desired in various embodiments.

Such relationships may likewise be achieved by assigning storage for the fields with locations in a computer-readable medium that conveys relationship between the fields.

Also, the invention may be embodied as a method, of which an example has been provided. The acts performed as part of the method may be ordered in any suitable way.

Accordingly, embodiments may be constructed in which acts are performed in an order different than illustrated, which may include performing some acts simultaneously, even though shown as sequential acts in illustrative embodiments.

For the purposes of describing and defining the present disclosure, it is noted that terms of degree (e.g., "substantially," "slightly," "about," "comparable," etc.) may be utilized herein to represent the inherent degree of uncertainty that may be attributed to any quantitative comparison, value, measurement, or other representation. Such terms of degree may also be utilized herein to represent the degree by which a quantitative representation may vary from a stated reference (e.g., about <NUM>% or less) without resulting in a change in the basic function of the subject matter at issue. Unless otherwise stated herein, any numerical values appearing in this specification may be modified by a term of degree thereby reflecting their intrinsic uncertainty.

Claim 1:
A control system for controlling liquid flow from a supply into a chilled beam, the control system comprising:
a supply input port (<NUM>);
a load return port (<NUM>);
a recirculation pump (<NUM>) for pumping liquid from a pump input port (<NUM>) to a pump output port (<NUM>), the pump input port connected to receive a first portion of liquid flowing from the load return port;
a junction (<NUM>) configured to combine liquid flowing from the pump output port with liquid flowing from the supply input port;
a load input port (<NUM>) configured to receive such combined liquid from the junction;
a supply return port (<NUM>) connected to receive a remaining portion of the liquid flowing from the load return port;
a control valve (<NUM>) located either in line with the supply input port or in line with the supply return port, the control valve configured to restrict flow of liquid between the supply input port and the supply return port;
a sensor (<NUM>) configured to measure a load input temperature of the combined liquid; and
a control module (<NUM>) to control the control valve based at least in part on a measurement from the sensor.