Recirculation fluid heating system

Abstract

To provide a device for heating fluid and a related method.SOLUTION: In an idle mode, a pump draws out liquid from a reservoir, and the liquid circulates in a heater and returns to the reservoir. A control device actuates the heater so as to heat the liquid to a first set temperature, and a temperature within the reservoir becomes stable at the first set temperature. In a supply mode, part or all of the heated liquid flows from an outlet to a fixture. Cold liquid is supplied from a supply source to the reservoir and a mixture of the liquid is received by an inlet of the heater. A control device controls a ratio of the cold liquid to the liquid from the reservoir in the mixture so as to maintain the heater at set heating speed while maintaining a temperature of the liquid released from the heater outlet at a set temperature or a temperature near the set temperature.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] [CROSS-REFERENCE TO RELATED APPLICATIONS] This application is a continuation of U.S. Provisional Patent Application No. 62 / 515,831, filed June 6, 2017. The disclosure of which is incorporated herein by reference. Let's say.

[0002] [Field of the Invention] The present invention relates to an apparatus and related method for heating a fluid. [Background technology]

[0003] In many applications, it is desirable to heat a liquid to a particular operating temperature. For example: The piping systems used to supply drinking water generally consist of water utility connections, wells, or is a water source such as a water tank and a water heater to provide hot water for bathing, washing hands, laundry, etc. and a heater for heating a portion of the water.

[0004] There are two main types of liquid heaters used in the aforementioned piping systems: tank and The "-type" heater heats a tank filled with water and stores a reserve of hot water at the required temperature. To do this, a heat source such as an oil or gas burner or an electrical resistance element is used. The fixture intermittently draws hot water from the top of the tank while cold water is drawn from the supply into the tank. Typically, the heat source is drawn from the tank during periods of peak demand. It is not possible to heat water fast enough to replace all of the hot water. During periods of demand, hot water reserves may be depleted, reducing the temperature of the water supplied to fixtures. Because tanks are pressure vessels that are heated, they usually have a built-in pressure regulator to prevent steam explosions in the event of a malfunction. This is a large factory-built unit with safety features to prevent the tank itself from being damaged. This makes the tank expensive, and the costs of transporting and installing the tank also tend to increase. Heat loss from the tank to the surrounding air typically occurs when hot water is drawn from the fixture. It consumes energy even when it's not there.

[0005] An "instantaneous" heater uses water from a source as it is delivered to the fixture. The instantaneous heater is designed to heat water from the flow and does not store a large amount of heated water. a heat source such as a burner and heat exchanger, electrical resistance, or flow The instantaneous heater has electrodes configured to conduct an electric current into the water. This reduces transportation and installation costs. However, instantaneous heaters Typically, they must heat at a rate sufficient to heat the maximum flow of water during periods of peak demand. This tends to increase the size and cost of the heater. The heating rate may be limited by the available power source, for example, the available electrical power. Summary of the Invention [Problem to be solved by the invention]

[0006] However, further improvements are desired. [Means for solving the problem]

[0007] According to one aspect of the present invention, there is provided a liquid heating system. The stem preferably includes a reservoir and a source of coolant in communication with the reservoir. The system preferably has an inlet connected to a reservoir and one that uses heated fluid. or a heater having an outlet connected to a plurality of fixtures. The system preferably includes a heated liquid return valve connected between the outlet of the heater and the reservoir. The system preferably includes a pump connected in series with the heater. The pump draws liquid from the reservoir and moves the liquid in a predetermined downstream direction. and pumped through the heater and return connection to the reservoir. The system applies heat to the liquid flowing from the inlet to the outlet to bring the liquid at the outlet to a set temperature. A control is provided which is operable to operate the heater to provide The connection and pump desirably allow liquid flow from the heater outlet to the reservoir. constructed and arranged to prevent fluid flow from the reservoir through the return connection to the fixture The system according to this aspect of the invention includes a connection between the source of chilled liquid and the inlet of the heater. The cooling system may include a chilled liquid suction connection, and the control device may prevent chilled liquid flow through the suction connection. Operable to activate the chilled liquid suction connection to shut off or to supply chilled liquid flow. This allows a mixture of cold liquid and liquid from the reservoir to be supplied to the inlet of the heater. The control device may be adapted to control the temperature of the heater inlet. The ratio of the cold liquid (i) from the cold liquid suction connection to the liquid (ii) entering the , heating the heater while maintaining the liquid discharged from the heater at or near the set temperature. The rate may be operable to maintain the rate at or near a set heating rate. As will be described below, some systems according to this aspect of the invention may be used under various flow conditions. This can provide useful heating performance.

[0008] According to a further aspect of the present invention, there is provided a heating unit for use in a fluid system. The heating unit according to this aspect of the invention preferably comprises a frame and a heater mounted on the frame. These components preferably have an inlet and an outlet. an assembly including a heater and an outlet end connection connected to the outlet of the heater; an outlet end connection assembly including a reservoir return connection point and a fixture connection point; and an inlet end connection defining a reservoir draw connection communicating with the inlet of the reservoir. The frame-mounted components further include a pump connected in series with the heater. The pump may pump the liquid from the inlet end connection through the heater to the outlet end connection. and the outlet end connection assembly is operable to connect the heater outlet to the reservoir return connection. Allows fluid flow from the reservoir return connection to the heater outlet and fixture connection points. The unit according to this aspect of the invention may be arranged to prevent liquid flow to the Preferably, the liquid flowing from the inlet to the outlet is maintained at a set temperature. The present invention further comprises a control device operable to operate to supply heat to the The unit of this aspect may be used, for example, in the configuration of the above-mentioned system. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic diagram showing, in cross section, a portion of a heating unit and system according to one embodiment of the present invention; [Figure 2] 2 is a diagram illustrating a control regime that can be used in the units and system of FIG. 1. [Figure 3] FIG. 2 is a view similar to FIG. 1 showing a unit and system according to another embodiment of the invention. [Figure 4] 1 and 3, showing a unit and system according to yet another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] A modular heating unit 10 (FIG. 1) according to one embodiment of the present invention includes a A frame 12 is provided for mounting components. The frame 10 includes structural elements 14 that are used to support other components described below. The cover 16 is a structural element that cooperates with the cover to define the housing. The other components of the unit 10 are partially or wholly enclosed within the housing. and secured to the frame by conventional elements (not shown). The unit 10 reduces the need for on-site work at the location where the unit is installed. Therefore, it is preferable that the components be pre-assembled by mass production in a factory, for example.

[0011] The unit 10 includes a heater 18 having an inlet 20 and an outlet 22. 18 is constructed and arranged to heat the liquid flowing from the inlet 20 to the outlet 22 . Heater 18 is what is commonly referred to in the art as an "instantaneous" heater. One form of instantaneous heater is an ohmic heater. Ohmic heaters heat a liquid by directing an electric current through the liquid itself. That is, the liquid is heated by converting electrical energy into heat within the liquid. Some particularly desirable ohmic heaters are described in U.S. Pat. Nos. 7,817,906 and 7,817,906. 9,587,853 and International Patent Application Publication No. 2018 / 08577 No. 3, the disclosures of which are incorporated herein by reference. Other types of instantaneous heaters may be used. For example, heater 18 may be an electric It may be a resistance heater or a combustion heater. Electric resistance heaters are Conducting an electric current through a solid heating element electrically isolated from the liquid and radiating heat from the heating element The combustion heater is configured to transfer heat to the liquid. The heater 18 is preferably is the unit of what is referred to herein as the "heating rate" when the heater is operating. configured to vary the amount of heat delivered to the liquid per time within a non-zero range of values; Such a change may be continuous or stepwise. However, if the variation is stepwise, the stepwise variation should preferably be approximated as a continuous variation. The process should include a number of steps that can be implemented.

[0012] The outlet end connection 24 comprises a pipe 26 connected to the outlet 22 of the heater. A connecting pipe 27 extends from the pipe 26 to a fixture connection point 28. Another branch pipe 30 extends from pipe 26 to reservoir return connection point 32. A check valve 34 is provided in the branch pipe 30. A check valve is attached from the heater outlet 22 to the reservoir return connection point 32. It allows flow in one direction but blocks flow in the other.

[0013] An inlet end connection 36 is provided between the reservoir draw connection point 38 and the inlet 20 of the heater 18. A pump 40 is connected to the inlet end connection. The pump is connected in series with the heater 18. The pump draws liquid from the reservoir and The liquid is drawn from the connection 38 and pumped into the inlet of the heater, thereby forcing the liquid into a forward flow. In this embodiment, pump 38 is constructed and arranged to move the , it is preferable that the pump is a relatively low output pump.

[0014] A chilled water suction connection pipe 42 extends from the chilled liquid supply connection point 45 to the inlet end connection 36. A throttle valve 44 is attached to the cold water suction connection pipe 42. The valve 44 Actuated by an actuator, such as a knob-driven or motor-driven actuator The actuator closes the valve 44 in the full position (where the valve completely blocks flow through the cold water inlet 42). closed position, fully open position (where the valve provides low resistance to flow through the chilled water inlet), or in an intermediate position This allows the flow resistance within the cold water inlet to be varied.

[0015] The modular heating unit 10 flows through the heater outlet 22 to the fixture connection point 27. The system further includes a temperature sensor 50 in thermal communication with the liquid. Preferably, the temperature sensor is Adjacent to the outlet, for example, at the outlet of the heater or somewhat upstream of the outlet, specifically, The valve is located between the operating element of the turbine and the outlet, or in the pipe 26 at the outlet end connection 24. By placing a temperature sensor close to the heater's operating element, changes in heater operation can be This minimizes the time required for the temperature sensor to respond.

[0016] The unit 10 further includes a controller 52. The controller 52 controls the temperature of the outlet liquid. The control unit is connected to the temperature sensor 50 to receive information from the heater. A controller is coupled to the heater 18 to detect and adjust the heating rate. A control device is connected to the pump 40 to turn the pump on and off, and a control device opens and closes the valve 44. 4 to an intermediate position. , configured to perform the control operations described below. The control device comprises analog electronic elements, It may comprise digital or mixed electronic components, optical components, mechanical components The control device may also include a control circuit, as described below. One or more programmable digital microphones programmed to perform the control operations The program is hard-wired into the circuit. or may be stored in one or more memories (not shown) incorporated in the controller. The controller may store the set temperature and the temperature during production. The temperature may have a preset heating rate permanently stored in the and a user-adjustable knob (not shown) for adjusting one or both of the powers. The controller typically generates logic level signals and other components necessary to operate the controller. A conventional interface driver circuit (not shown) is used to convert between the It also includes conventional analog-to-digital and digital-to-analog converters. The unit 10 is fitted with suitable power supply connections for supplying power to other elements of the system. If the heater is a combustion heater, it is preferred that a suitable The appropriate fuel connections are provided within the unit 10. The power supply and fuel for the heater are The supply connection may be connected to a drive circuit of the control device. Although shown as having a unitary structure, it contains many components that perform various functions as described below. The control device may be housed within a housing defined by the frame 10. Although the device is shown as being compatible with the control system, some or all of the components may be controlled by the control system. The connections between the elements of the control device and the control device and the unit may be located outside the device. Connections between the other elements of 10 may be through any communication medium.

[0017] Unit 10 also has a backup system to ensure safety in the event of component malfunction. The unit may include a backup element (not shown). A fuse for cutting off power to the heater 18 if the temperature rises above a safety threshold. elements such as pull links or other thermally responsive elements, and safety valves to relieve excess pressure within the heater. It is preferable to have a full valve.

[0018] A heated fluid supply system according to a further embodiment of the present invention comprises a unit 10 . The system shown in FIG. 1 may be used, for example, to provide heated drinking water in a building or vehicle. The system includes a source of chilled water 60. The source 60 is located in the piping system. Pressures commonly used in construction, e.g., about 40 to about 125 pounds per square inch or about 27 5 - Arranged to supply chilled water under pressure of about 860 kPa. For example, chilled liquid The source may be a connection to a public water supply system or may be a source commonly used in the local area. The system may also be powered by a well pump and pressure tank. a reservoir 6 in the form of a pressure vessel such as a tank capable of withstanding the applied pressure; 2. The tank 62 has a supply port 64. The supply port 64 has a check valve. A valve 67 is connected to the source 60, which allows cold water from the source to flow to the bottom or bottom of the tank. The water flows into the tank in its vicinity, but the water cannot flow out of the tank. The supply 60 is connected to the cold water suction connection pipe 42 of the unit 10 at connection point 45. are.

[0019] The tank 62 has a hot water outlet port 66. The hot water outlet port 66 is connected to the unit 1. 0 is connected to the inlet end connection 36 at the reservoir draw connection point 38. Tubing 68 is connected to outlet end connection 24 of unit 10 at connection point 32. The return flow tube passes through the wall of the tank 62 and exits below the top of the tank and at port 66. It terminates below and above the bottom of the tank.

[0020] Most preferably, the reservoir or tank 62 does not include an internal heating source. For example, tank 62 is preferably an "unfired" type pressure vessel.

[0021] The outlet end connection 24 is connected to the hot water pipe in the building or vehicle at connection point 28, 72 in the building using hot water. As such, examples of fixtures include a shower head 72a, a washing machine 72b, and a drinking water preparation device 72c. 2c. In addition, some or all of these fixtures may be connected to other piping ( The cooling water supply 60 may be connected to a cold water source 60 by a cooling water supply 62 (not shown).

[0022] In operation, a method of supplying a heated fluid according to a further aspect of the present invention comprises: Tank 62 and the pipes and connections are maintained under pressure by source 60 .

[0023] The controller 52 measures the temperature of the water (leaving the heater) measured by the sensor 50. Monitor and adjust the heating rate to maintain this temperature at the set point. The coolant intake valve 44 is also adjusted to maintain the coolant intake valve 44 at 400°C. This control scheme is shown in FIG. The water flowing into the heater is at the inlet temperature. The heater 18 is heated by the flow rate through the heater. The temperature of the water is increased by an amount equal to the heating rate divided by the The difference between the set point temperature and the outlet temperature is the temperature error signal. This temperature error signal is then converted into a temperature transfer function S T The processed error signal is also The heating rate is increased when the outlet temperature decreases, or vice versa. The heating rate is adjusted according to the processed error signal to decrease as the temperature increases. The transfer function is a proportional component, which is commonly referred to in the control system industry. , an integral component, and a differential component.

[0024] The controller also monitors the heating rate provided by the heater 18 and adjusts the heating rate. This is subtracted from the set heating rate to produce the heating rate error. Transfer function S H to yield a processed error signal. Again, the transfer function is , preferably includes one or more of a proportional component, an integral component, and a derivative component. If the heating rate is less than the set heating rate, the controller activates the valve actuator 46, which Therefore, it is advisable to open the cold water intake valve 44 gradually to reduce the flow resistance through the valve 44 .

[0025] Under idle conditions, water is not drawn from the system by fixture 72 (Figure 1). There is little or no pressure differential across the refrigerant intake valve 44, thereby allowing for constant flow regardless of whether the valve is open or closed. Under this condition, there is essentially no flow through the coolant suction connection 42. The water is drawn from the tank through the hot water outlet 66, the heater 18, the outlet end connection 24, and the tubing 68. The water is then circulated through the heater and back to the tank. The temperature of the water near the top of the tank is equal to the temperature of the water near the top of the tank. Initially, this temperature is much lower than the set temperature, and the controller will operate the heater 18 at a high heating rate. As the heating operation continues, heated water accumulates near the top of the tank, The inlet temperature is gradually increased within a preset tolerance from the set point, and the heating rate is reduced to zero. If the heating rate remains at zero for a certain interval, the controller will The pump and heater are turned off for an interval, for example, from a few minutes to 30 minutes, and then At the end of the interval, the pump 40 is turned on and the heater 18 is not turned on, and the sensor 5 0 to resume monitoring the outlet temperature. If the water has been circulating for a period of time, e.g., several minutes, If the temperature remains below the set temperature by more than a predetermined tolerance after cycling, the controller While maintaining operation of the pump 40, the heater 18 is turned on. If the heater 18 stops, If the circulating water temperature is at or within the set temperature tolerance while With the pump still stopped, the pump is also stopped and another stop interval is waited, and then the The steps above are repeated until the water near the top of the tank 62 is at or near the set temperature. Unless water is drawn from the system, the controller will not activate the heater and pump. Typically, the hot water near the top of the tank is It cools quickly by conductive and convective heat transfer to the cooler water near the bottom of the tank. , in most cases until the tank 62 is substantially filled with hot water at a temperature close to the set temperature. Once the tank is filled with hot water, the pump and heater will be running continuously. Once the tank is substantially full, the heater is operated intermittently to compensate for heat loss from the tank. That would be good.

[0026] When one or more of the fixtures are opened and hot water is drawn from the system, the system is in supply mode. In this mode of operation, chilled water from the source 60 is drawn through the chilled liquid intake port 64. The water flows into the bottom of the tank and also through valve 44 into inlet end connection 36, thereby Thus, the pump 40 pumps a mixture of hot and cold water drawn from the tank to the inlet of the heater. This tends to reduce the outlet temperature measured by sensor 50, The control system will respond by increasing the heating rate. If the temperature exceeds the set heating rate, the controller activates the actuator to throttle the valve 44. 46, thereby reducing the flow resistance between the refrigerant suction connection 42 and the inlet end connection 36. This increases the resistance, thereby reducing the cold water flow through valve 44 and opening port 64 at the bottom of the tank. This increases the cold water flow through the tank in the water supplied by the pump 40. Increasing the proportion of hot water drawn from the top increases the inlet temperature. tends to reach an equilibrium condition, the heater is operated at a set heating rate, and the outlet temperature is set In other words, the flow rate through the heater varies with the demands of the fixture 72. The control unit controls the reservoir for cold water at the cold water inlet connection supplied from the heater inlet. This adjusts the rate at which hot water is drawn from the heater inlet. The nozzle temperature is adjusted so that at the prevailing flow rate the heater operates at the set heating rate. This will result in an outlet temperature equal to the set point temperature.

[0027] Preferably, the set heating rate is the maximum heating rate that the heater will provide or the maximum heating rate. If the fixture draws only a moderate hot water flow, the valve 44 will be fully This opens the system so that all of the hot water leaving the system is replaced by water passing through the cold water inlet. Under these conditions, the system can operate for an infinite period of time, specifically It operates for a theoretically infinite period of time so as not to deplete the hot water stored in tank 62. Under these operating conditions, the heater will continually operate at a heating rate less than the set heating rate. If a fixture draws a large amount of hot water from the system, valve 44 will be partially closed, allowing a large amount of hot water to flow. A quantity of hot water is drawn from the tank and returned to the tank through inlet port 64 at the bottom of the tank. However, if the heater is maintained below the set heating rate, As long as the valve 44 is not fully closed, the heater 18 will not fully close. The system operates to extend the time for which hot water at the set temperature is continuously supplied. Below, the heater 18 operates to slow the depletion of the tank 62. In this example, water flows from reservoir 62 to fixture 72 only through heater 18 and from inlet 20. It flows only downstream through the heater towards the outlet 22 .

[0028] Many features of the heater described above with reference to FIG. The end connection 24 may be connected to a reservoir or tank 62, in which case the hot water is The hot and cold liquids are returned to the reservoir at or near the bottom of the reservoir. This allows for better mixing within the tank 62. This allows for a uniform temperature distribution within the tank 62. In one such configuration, the return fluid connection point 24 of the outlet end connection 24 is For example, a check valve 67 is connected to the cold water inlet port 64 of the tank between the check valve 67 and the cold water inlet port. It may be continued.

[0029] Control schemes other than the temperature regulation feedback control system described above may also be used. A system according to a further embodiment of the present invention (FIG. 3) is similar to the system described above in connection with FIGS. 104 and a temperature sensor associated with the coolant inlet pipe 142. 102. A flow sensor 106 and a temperature sensor 108 are connected to the inlet end connection 136. The area 101 is connected to a reservoir 162 and is used to The outlet end connection is connected to the pressure sensor 103 and the flow sensor 104. All of these sensors are connected to the control device 152. However, a throttle valve 144 is provided between the coolant inlet pipe 142 and the inlet end connection 136. The valve 144 is controlled by an actuator connected to a controller 152. Other throttle valves and actuators connected to the control device 162 are connected to the outlet end connection 1 24 between the heater outlet 122 and the return flow connection to the reservoir 162. A check valve is provided at the connection between the outlet end connection and the building's hot water piping 170. , to prevent backflow of water from the piping and fittings 172.

[0030] In this embodiment, reservoir 162 is an unpressurized and unburned container. The pump is provided with a cover 163 to prevent contamination of the stored water. The reservoir is loosely fitted to communicate with the atmosphere. The reservoir is opened via a float valve 167 operated by a float 169 located in 162. The valve 167 opens when the water level in the reservoir drops. It closes when the water level rises, allowing the water to flow adjacent to the bottom of the reservoir, if necessary. to allow water to enter from any point and maintain a substantially constant level of water in the reservoir. It has become like this.

[0031] In operation, the controller 152 activates the pump 40 to pump water into the heater 118. The controller adjusts the valve 111 in response to the pressure detected by the sensor 103. Adjust the operating speed of the pump 140 to thereby maintain a constant pressure at the outlet end connection. During idle operation, there is no demand from fixtures 172, so flow sensor 119 detects the flow of 70 indicates zero flow through the outlet end connection to throttle valve 1. 11 is kept open and throttle valve 144 is closed while circulating liquid through the heater. To achieve this, the pump 140 is operated at a relatively low power. , simply recirculates the water through the heater and reservoir. The heater is operated in response to the flow rate detected by the sensor 106 and the water temperature detected by the sensor 108. Set the heating rate to -140, which will allow the heater to raise the temperature of the circulating water to the set temperature. To raise.

[0032] When one or more of the fixtures 172 are opened and draw hot water, the flow to the fixture is detected by the sensor 119. In response, the control device enters an active supply mode. The controller sets the heating rate of the heater 118 to the set heating rate and the pump 140 The pumping power delivered by the Valve 111 is closed to maintain the pressure detected by sensor 103 at the desired level. The throttle valve 111 setting required to maintain the That is, as demand increases, valve 111 gradually closes, allowing the flow of heat from heater 118 to the reservoir. This reduces the amount of heated water returning to 162. Valve 111 responds to demand from the fixture. Opening and closing changes the total flow rate through the heater. If fixture 172 draws water moderately, The control device 110 detects the flow rate of the chilled water detected by the sensor 104 and the flow rate of the chilled water detected by the sensor 106. By summing the detected hot water flow rate with the total flow rate, the dominant flow rate and the setting At a constant heating rate, the water leaving the heater is mixed with hot and cold water to achieve the set temperature. The throttle valve 144 is adjusted to deliver a mixture of hot and cold water. is supplied to a heater, and the mixture is heated to a set temperature by the heater, The system will be able to provide water at the set temperature for an extended period of time.

[0033] Under some operating conditions, for example, the water from reservoir 162 may be heated to a temperature higher than the set point. If the mixture is at a much lower temperature, the controller 144 determines whether the mixture is to be heated to the set temperature. Before the heating rate is reached, the valve 144 is fully closed. If the set heating rate is If the applied heating rate is less than the set heating rate, the controller Under other operating conditions, for example, fixture 172 draws water at a low rate and If the water drawn from reservoir 172 is at or near the set temperature, it will heat at the set rate. The operation of the heater prevents the water passing through the heater 118 even when the valve 144 is fully open. Under this condition, the controller 110 controls the temperature of the given The heating rate is reduced below the set rate.

[0034] The sensors and control systems used in the above embodiments may be modified. For example, the flow-sensing control scheme described with reference to FIG. 3 uses a pressurized reservoir similar to that of FIG. Conversely, the temperature sensing feedback described with reference to FIG. The control system may be used in the pumping system described with reference to FIG.

[0035] When the system of FIG. 3 is under idle conditions, the controller controls the pump 140 and heater 1 18 is stopped for the stop interval and then the pump is restarted. If the temperature of the water drawn from the bar is at or near the set temperature after the pump restarts If not, the controller may shut down the pump for a further shut down interval. The controller maintains operation of the pump and starts the heater.

[0036] In the system described above, the flow is controlled in part by an adjustable valve. These are in addition to other elements that can cause variable flow, e.g., cold water intakes, reservoirs, etc. A variable speed pump associated with the bar withdrawal connection and the return connection to the reservoir Also, in the above embodiment, the flow through the cold water inlet connection may be replaced by: The cold water inlet of the reservoir can be cooled by throttling or pumping the connection. For example, in the embodiment described with reference to FIG. 4 is provided in a connection to the cold water inlet 64 of the reservoir rather than the cold water inlet connection 44. In this configuration, closing the throttle valve increases the flow of cold water through the inlet connection. In a further configuration, the throttle valve 44 is relocated to the reservoir outlet connection 38, It may also be adapted to control hot water from reservoir 62. Any of these configurations The ratio of water from the reservoir to water from the cold water inlet connection is controlled to feed the mixture into the heater. The pump is connected downstream of the outlet of the heater. or may be incorporated into the heater.

[0037] In the above discussion, the set temperature is treated as a constant value. The set temperature may be varied, for example, a first relatively low set temperature when water is not flowing to the fixture. A first set temperature may be set and a second, higher set temperature may be set when water flows to the fixture. In this configuration, the temperature of the water in the reservoir stabilizes at a first setpoint temperature and then rises to a second, higher setpoint. This configuration not only reduces heat loss from the reservoir, but also provides a This configuration variation reduces the maximum flow rate delivered to the fixture at higher set points. The first low setting is used when low demand is expected, e.g., only at night in a typical residential building. The temperature may be set.

[0038] A system according to a further embodiment of the present invention (FIG. 4) is substantially similar to the system of FIGS. However, the outlet end connection 224 is connected to the heater outlet 222 and the three outlet connection ports. Each outlet connection has a manifold connected to types 227a, 227b, and 227c. The pipe 227 is equipped with the corresponding shut-off valves 201a, 201b, and 201c. 01a, 201b, and 201c are solenoid mechanisms or motors that can open and close the shutoff valves. The manifold 226 has an actuator such as a motor mechanism. The connection point is connected to a branch pipe 230 which leads to a return conduit 268 extending into the reservoir 268. It continues.

[0039] The inlet end connection 236 again includes a pump 240 and is connected to the reservoir draw connection 23 8 to the hot water outlet port 266 of the reservoir. is again connected to the inlet end connection via a throttle valve 246. Type 203 is the junction between the reservoir drawer connection point 238 and the inlet end connector and cold water inlet. At a point between the two, the inlet end connector 236 is connected. Between the junction with the pipe 203 and the junction with the cold water inlet 242, an inlet end connector The check valve allows flow in the upward direction as shown in Figure 4. The bypass pipe is connected to the outlet connecting pipe at a point downstream of the valve 201c. The bypass control valve 205 communicates with one of the outlet connection pipes 227 at the The bypass control valve 205 is connected to the associated actuator. A recirculation shutoff valve 215 is provided at the branch port of the outlet end connection structure to the inlet end connection structure. The control device controls the backflow from the manifold 226 to the reservoir. Valve 215 is closed to prevent this and is opened to allow this flow. The valve actuators are connected to a controller 205, which operates all of these valves. It can be done.

[0040] In this embodiment, the outlet end connection 224 does not include a check valve. 240 operates continuously whenever the recirculation shutoff valve 215 is open, and 63. Maintaining a pressure in the outlet end connection that is higher than the pressure in 63, thereby It is adapted to prevent flow to the outlet end connection.

[0041] The control device 252 includes a signal receiver 253, such as a wireless receiver or a network-enabled The receiver may be, for example, an internet-enabled receiver.

[0042] Each of the outlet connection pipes 227 is connected to a different fixture through an appropriate individual connection line. In this case, different fixtures require hot water at different temperatures. The pipe 227c is adapted to be delivered to a fixture 272c, e.g., to come into contact with a person's skin. The shower head or sink used is connected to the first minimum use temperature, for example, about 10 Requires hot water between 5-110°F (40-43°C). Outlet connection pipe 227b is connected to the second High temperature dishwashers, e.g., requiring hot water at 140-160°F (60-71°C). The outlet connection pipe 227c is connected to the fixture 172b, such as a washing machine or a vacuum cleaner. 3. Higher operating temperatures, e.g., 190-200°F (88-93°C) hot water required. Each fixture is connected to a corresponding transmitter 211. The transmitter 211 transmits a signal in a form that can be received by the receiver 253. and associated with pre-coded codes pointing to special fixtures requiring hot water. Identify the equipment that will be used.

[0043] In idle mode, the controller 252 controls the outlet valves 201a-201c and the bypass valve 201a-201c. 5 is kept closed and recirculation shutoff valve 215 is opened, which allows water to flow into manifold 22 6 to reservoir 262. In idle mode, the controller maintain the water temperature at a first operating temperature corresponding to the minimum water temperature required by some of the fixtures installed. Similar to the previous approach, the heater heats the water in the reservoir 262 to a first use temperature, It operates to maintain the water at this temperature. If one of the fixtures requests hot water, transmits a signal through the associated transmitter 211. If this signal is If the controller indicates that water should be supplied, the controller sets the set temperature of the heater 218. The temperature sensor 250 detects the temperature emitted from the heater 218 and adjusts the temperature to the second or third operating temperature. When the water being served indicates that it has reached the new setpoint temperature, the control unit notifies the fixture that sent the signal. The associated outlet connection pipe will be opened. For example, if fixture 272a sends a signal If so, the heater increases the set temperature to the third use temperature and then opens the valve 201a. The apparatus operates the recirculation valve 215 to maintain the temperature of the water in the reservoir 262 at the first use temperature. The system will shut off the fixture 272a when it no longer needs water. It will remain in this state until it sends another signal indicating that it is not providing water to one of the fixtures. If another fixture sends a further signal while the other fixture is still supplying the water, the control unit will close the other outlet valve. The controller may simply ignore this further signal or queue this request. However, if the first fixture 272 is not available at this time, If water is requested, the control device maintains outlet valve 201c in a closed position and bypass control valve 202c is closed. This requirement is met by opening 05, which allows water at the first operating temperature to flow into the heater. The water will be supplied to fixture 272c from the reservoir without passing through the

[0044] Once the fixture that originally requested the water has sent a signal indicating that the request has been fulfilled, , the controller 252 returns the set temperature to the first operating temperature and resumes idle mode operation. .

[0045] The term "pipe" as used in this disclosure means a pipe capable of transporting flowing liquid under pressure. It should be understood that the term "pipe" includes any element of non-circular cross section. Structures such as flexible hoses, conduits and tubes, and general rigid pipes of circular cross section This will include:

[0046] The systems, units and methods according to the invention may be applied to heating fluids other than water. Also, the terms "cold" and "hot" may be used interchangeably within the scope of the present invention. The temperature range is not limited to that used in ordinary piping systems. In industrial systems that handle liquids such as metals or molten salts, the "cold" liquid is heated to temperatures of several hundred degrees Celsius. A "hot" liquid may be at a temperature, or even higher.

[0047] In the following paragraphs, some additional aspects of the present invention are described.

[0048] a reservoir; a coolant supply source in communication with the reservoir; and a level coolant supply adjacent the top of the reservoir. Inlet connected to the reservoir via a reservoir drawer connection that communicates with the reservoir via a a heater having a heater element and an outlet connected to one or more fixtures; a heated liquid return connection below the level of the reservoir draw connection, a heated liquid return connection in communication with the reservoir to return the heated liquid to the reservoir; A heater is installed to supply heat to the liquid flowing from the inlet to the outlet to bring the liquid to a set temperature. and a controller operable to operate the heater; The pump and connections are designed so that fluid from the reservoir is only drawn through the reservoir outlet connection. flow through the heater and from the heater to the reservoir only through the reservoir return connection. 1. A liquid heating system constructed and arranged to:

[0049] 1. A method of operating a heated liquid supply system, comprising: (a) In idle mode, fluid is drawn from the reservoir to the inlet of the heater. Activate the heater to heat the body, return the fluid to the reservoir, and controlling the operation of the heater so that the temperature reaches a first set temperature; (b) in a supply mode, to supply a mixture of chilled liquid and liquid from the reservoir; A liquid is drawn from the reservoir into the heater and a cold liquid at a temperature lower than the first set temperature is drawn. into the reservoir and a heater is configured to heat the mixture to a set temperature equal to or greater than the first set temperature. and controls the flow rate from the reservoir in the mixture so that the heater operates at the set heating rate. The ratio of the liquid (i) to the cold liquid (ii) is controlled, and at least a portion of the heated mixture is and A method comprising:

[0050] Draws fluid from reservoir to heater in both idle and supply modes The step of drawing includes drawing the liquid from adjacent the top of the reservoir. The method according to claim 0049.

[0051] (a) a reservoir; (b) a source of coolant in communication with the reservoir; (c) having an inlet connected to a reservoir and an outlet connected to one or more fixtures; A heater and (d) a coolant intake connection connected between a coolant source and the inlet of the heater; (e) a return connection connected between the heater outlet and the reservoir; (f) a pump connected in series with the heater to draw liquid from the reservoir; The liquid is passed in a predetermined downstream direction through the heater and the reservoir return connection to the reservoir. A pump that can deliver (g) Activating the heater to supply heat to the liquid flowing from the inlet to the outlet, a control device operable to vary the amount of heat supplied to the liquid within a range of heating rates; A device comprising: a cooling liquid suction device for a liquid (ii) from a reservoir supplied to the inlet of the heater; Control the rate of cold liquid (i) from the inlet connection, which is then released from the outlet of the heater. The heating rate of the heater is set to a set heating rate or a control device operable to maintain the sensor in proximity thereto; A liquid heating system comprising:

[0052] The heater is connected to the reservoir adjacent the top of the reservoir. The system described in

[0053] Although the present invention has been described above with reference to particular embodiments, these embodiments are not intended to limit the scope of the present invention. It is to be understood that the appended claims are merely illustrative of the principles and applications of the present invention. Many modifications may be made to the exemplary embodiments without departing from the spirit and scope of the invention as described. It is to be understood that modifications may be made and other arrangements may be devised.

Claims

1. (a) a reservoir; (b) a source of coolant in communication with the reservoir; (c) having an inlet connected to the reservoir and an outlet connected to one or more fixtures; A heater that (d) a heated liquid return connection connected between the outlet of the heater and the reservoir; Department and (e) a pump connected in series with the heater for drawing liquid from the reservoir; and directing the liquid in a predetermined downstream direction through the heater and the return connection to the reservoir. a pump capable of delivering the fluid to the reservoir; (f) a liquid flowing from the inlet to the outlet to bring the liquid at the outlet to a set temperature; a controller operable to operate the heater to provide heat to a body, The return connection and the pump transfer fluid from the outlet of the heater to the reservoir. allowing fluid flow and preventing fluid flow from the reservoir through the return connection to the fixture. a control device constructed and arranged to A liquid heating system comprising:

2. The system of claim 1 , wherein the return connection comprises a check valve.

3. The reservoir is closed to maintain the liquid in the reservoir at superatmospheric pressure.

3. The cooling system of claim 2, wherein the cooling liquid source is configured to provide cooling liquid under pressure. system.

4. The reservoir is opened to the atmosphere, thereby allowing the liquid in the reservoir to be at atmospheric pressure. The system of claim 1 ,

5. The pump is adapted to pump liquid through the heater and to the one or more fixtures. The system of claim 4 , wherein the system is operable.

6. Detecting activation of one or more of the fixtures that draw liquid from the outlet of the heater. The control device further includes a demand-type sensor that operates to A first pumping power is applied to the circulation pump to pump liquid into the heater when the heater is not operating. and operating the pump and receiving a first pumping power when one or more of the fixtures are operating. and a second pumping power operable to operate the circulation pump at a second pumping power higher than the first pumping power. The system of claim 5 .

7. The system of claim 1 , wherein the reservoir is unburned.

8. The reservoirs include stacked reservoirs, collapsible reservoirs, and field-assembled reservoirs.

8. The system of claim 7, wherein the sensor is selected from the group consisting of a sensor bar.

9. The control device controls the heater in response to the temperature detected by the sensor. Operable to vary the amount of heat supplied to the liquid within a range of non-zero heating rates. The system of claim 1 .

10. a coolant intake connection connected between the coolant source and the inlet of the heater; and the control device controls the cooling liquid suction connection to provide a cooling liquid flow through the suction connection. a cooling unit operable to actuate the cooling unit, thereby discharging the cold liquid and the liquid from the reservoir.

10. The system of claim 9, wherein a mixture of

11. The control device controls the liquid supplied from the reservoir to the inlet of the heater (ii) ) to control the ratio of the cold liquid (i) from the cold liquid suction connection to the the heater while maintaining the liquid discharged from the heater at or near the set temperature.

11. The method of claim 10, operable to maintain a heating rate at or near a set heating rate. The system described.

12. a temperature sensor operable to detect the temperature of liquid exiting the outlet of the heater; the control device controls the heater to maintain the temperature at the set temperature, to the heater to control the ratio in response to the heating rate provided by the heater.

12. The method of claim 11, wherein the heating rate is adjustable by adjusting the heating rate provided by the heating rate adjusting means. system.

13. The control system responds to control inputs representing conditions applied to one or more of the fixtures.

10. The system of claim 1, operable to change the set point temperature accordingly.

14. The control system controls each of the fixtures that draw liquid from the outlet of the heater. and a control input value representative of the operation of the control unit, operable to vary the set temperature. Item 1. The system according to item 1.

15. a temperature sensor operable to detect the temperature of the liquid exiting the heater; The control system is configured to detect when the temperature detected by the sensor is at or near the set temperature. and shutting off the pump and the heater when the heater is not providing heat.

10. The system of claim 1, wherein the system is operable to:

16. a temperature sensor operable to detect the temperature of liquid flowing from the reservoir to the heater; the control system further comprises a temperature sensor, and the temperature detected by the sensor is set to the set temperature. and operable to shut off the pump and the heater when the temperature is at or near The system of claim 1 .

17. The control system may be configured to initiate a predetermined shutdown period regardless of the temperature detected by the sensor. After a period of time, the pump is started again, and then, depending on the temperature detected by the sensor, (i) keeping the pump running and turning on the heater, or (ii) 17. A system according to claim 15 or 16, operable to stop the pump again.

18. detecting activation of one or more of the fixtures that draw liquid from the outlet of the heater; a demand-type sensor operable to increase the set temperature in response to detecting a demand. This allows the heater to reach a temperature higher than the temperature of the liquid stored in the tank.

10. The system of claim 1, wherein the system supplies heated liquid to the fixture.

19. 1. A heating unit for use in a liquid heating system, comprising: (a) a frame; (b) a component attached to the frame, (i) a heater having an inlet and an outlet; (ii) an outlet end connection assembly connected to the outlet of the heater; an outlet end connection assembly including a reservoir return connection point and a fixture connection point; (iii) defining a reservoir draw connection point in communication with the inlet of the heater; an inlet end connection; (iv) a pump connected in series with the heater, the pump moving a liquid Operable to pump air from said inlet end connection through said heater to said outlet end connection and the outlet end connection assembly connects the outlet of the heater to the reservoir return. allowing fluid flow from the reservoir return connection point to the outlet of the heater; and a pump positioned to prevent liquid flow to the fixture connection point. (vi) a temperature controller for controlling a temperature of a fluid passing through the outlet from the inlet to the outlet to maintain the fluid at a set temperature; a control device operable to operate the heater to supply heat to a liquid flowing through the and, a component including: A heating unit comprising:

20. The outlet end connection is reversed between the outlet of the heater and the reservoir return connection.

20. The unit of claim 19, comprising a stop valve.

21. The frame defines a housing, and the heater and the pump are disposed within the housing. and the connection points are accessible from outside the housing. The unit described in.

22. 20. A method of assembling a heated liquid supply system, comprising the steps of: The reservoir return connection point and the reservoir draw-out connection point are connected to a reservoir formed separately from the unit. and the fixture connection point of the unit is adapted to use a heated liquid. and connecting the one or more fixtures.

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