JP2007198671A - Water heater - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water heater capable of improving a coefficient of the performance (COP) of a heat pump by lowering a water temperature even if the temperature of water (water supply temperature) distributed to a water heat exchanger of the heat pump is high. <P>SOLUTION: A supply water temperature Tw is detected by a supply water temperature sensor 20 when operating the heat pump HP, a first valve 13 is closed, and a second valve 14 is opened to distribute all of the water taken out of a hot water storage tank 6 by the operation of a water supply pump 8 from the downstream side of a water supply pipe conduit 7 to a bypass pipe conduit 12, when the detected supply water temperature Tw is over a prescribed temperature upper limit value Tws, and the water (water of temperature lower than non-cooled water) after cooled by the heat exchanging portion 12a of the bypass pipe conduit 12 is distributed to the water heat exchanger 2. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a hot water supply apparatus using a heat pump as a heat source.

  This type of hot water supply apparatus includes a heat pump having at least a compressor, a water heat exchanger, an expansion valve, and an air heat exchanger, a hot water storage tank, and a water supply pump. The water heat exchanger of the heat pump is for exchanging heat between the refrigerant and water, the water inlet of the water heat exchanger is connected to the lower part of the hot water storage tank via the water supply pump, and the hot water outlet is the hot water storage tank Connected to the top of the.

  This hot water supply device operates a heat pump and operates a water supply pump to send water in a hot water storage tank to a water heat exchanger of the heat pump, thereby heating the water with refrigerant heat to store hot water after heating. Can be sent to the tank. Since a predetermined amount of hot water or hot water and water is stored in the hot water storage tank when the hot water in the hot water storage tank is taken out through a pipe connected to the upper part of the hot water tank, an amount of water corresponding to the amount of hot water taken out is stored. (Tap water) is taken into the hot water storage tank through a pipe line connected to the lower part of the hot water storage tank.

The heat pump generally uses a compressor whose rotation speed can be controlled and an electronic expansion valve whose opening degree can be controlled. The refrigerant discharge temperature from the compressor, the outside air temperature, the water inlet temperature to the water heat exchanger, and The capacity adjustment of the heat pump is performed by varying the rotation speed of the compressor and the opening of the expansion valve based on the temperature of the hot water from the water heat exchanger.
Japanese Patent No. 3601369

  When the hot water is taken out from the hot water storage tank, the water (tap water) corresponding to the amount taken out is taken into the hot water storage tank, and the water is drawn out from the hot water storage tank and heated by the water heat exchanger of the heat pump. It is structured to be sent to the tank. In short, the temperature of the water fed into the water heat exchanger of the heat pump depends on the temperature of the water (tap water) taken into the hot water storage tank.

  The temperature of the water fed into the water heat exchanger of the heat pump (incoming water temperature) is preferably the upper limit temperature ≧ the incoming water temperature, considering the coefficient of performance (COP) of the heat pump. However, since the temperature of the water (tap water) varies depending on the season and installation environment, it is actually impossible to set the temperature of water entering the water heat exchanger to the upper limit value ≥ the water temperature. When the temperature of water entering the vessel exceeds the upper limit, the enthalpy required for water heating is insufficient and the coefficient of performance (COP) of the heat pump is lowered.

  The present invention was created in view of the above circumstances, and the object of the present invention is to reduce the temperature of the water fed to the water heat exchanger of the heat pump even when the temperature of the water (incoming water temperature) is high. An object of the present invention is to provide a hot water supply device capable of improving the coefficient of performance (COP) of a heat pump.

  In order to achieve the above object, the present invention connects a heat pump having at least a compressor, a water heat exchanger, an expansion valve, and an air heat exchanger, and a lower portion thereof to a water inlet of the water heat exchanger via a water inlet line. And a hot water storage tank whose upper portion is connected to the hot water outlet of the water heat exchanger via the hot water outlet pipe, and water in the hot water tank is sent to the water inlet of the water heat exchanger, and the water heat exchanger A hot water pump for feeding hot water after being heated in the hot water storage tank from the hot water outlet, and one end connected to the upstream side of the water inlet pipe and the other end connected to the downstream side of the water inlet pipe. It is characterized by comprising a bypass line for lowering the temperature of the water sent from the tank to the water inlet line and returning the water after the temperature reduction to the water inlet line.

  According to this hot water supply apparatus, when all of the water drawn from the hot water storage tank by the operation of the water supply pump is sent to the water heat exchanger through the water inlet pipe, the enthalpy required for water heating is insufficient and the coefficient of performance (COP of the heat pump) ) May decrease, the coefficient of performance (COP) of the heat pump can be improved by lowering the incoming water temperature fed into the hydrothermal exchanger using the bypass line.

  According to the present invention, the coefficient of performance (COP) of the heat pump can be improved by lowering the temperature of the water fed to the water heat exchanger of the heat pump even when the temperature of the water (incoming water temperature) is high.

  The above object and other objects, structural features, and operational effects of the present invention will become apparent from the following description and the accompanying drawings.

[First Embodiment]
1 to 3 show a first embodiment of the present invention. 1 is a circuit configuration diagram of a hot water supply apparatus, FIG. 2 is a control system diagram of the hot water supply apparatus shown in FIG. 1, and FIG. 3 is a flowchart relating to incoming water temperature control.

  First, the circuit configuration of the hot water supply apparatus will be described with reference to FIG. In the figure, HP is a heat pump, 6 is a hot water storage tank, 7 is a water inlet line, 8 is a water supply pump, 9 is a hot water outlet line, 10 is a water intake line, 11 is a hot water outlet line, 12 is a bypass line, Reference numeral 13 is a first valve, 14 is a second valve, and 15 is a backflow prevention valve.

The heat pump HP includes a variable capacity compressor 1 capable of controlling the number of revolutions, a water heat exchanger 2 that performs heat exchange between the refrigerant and water, an electronic expansion valve 3 that can control the opening degree, and air. It has at least a heat exchanger 4 and a blower 5 for an air heat exchanger, and uses carbon dioxide (CO ₂ ) as a refrigerant.

  A discharge temperature sensor 16 for detecting the refrigerant discharge temperature Td from the compressor 1 is provided at or near the discharge port (no symbol) of the compressor 1, and the air heat exchanger 4 or the vicinity thereof. Is provided with an outside air temperature sensor 17 for detecting the outside air temperature Ta, and a water inlet temperature sensor for detecting the water inlet temperature Twi to the water heat exchanger 2 at or near the water inlet 2a of the water heat exchanger 2. 18 and a hot water temperature sensor 19 for detecting the hot water temperature Two from the water heat exchanger 12 is provided at or near the hot water outlet 2b of the water heat exchanger 2.

  The hot water storage tank 6 stores a predetermined amount of hot water or hot water and water in a full state. One end of the water inlet pipe 7 is connected to the lower part of the hot water storage tank 6, and the other end is connected to the water inlet 2 a of the heat exchanger 2. The water supply pump 8 is provided in the vicinity of the hot water storage tank in the water inlet pipe 7. One end of the hot water outlet 9 is connected to the hot water outlet 2 b of the heat exchanger 2, and the other end is connected to the upper part of the hot water storage tank 6. The water intake conduit 10 is for taking water (tap water) into the hot water storage tank 6, and the hot water extraction conduit 11 is for taking out hot water in the hot water storage tank 6.

  One end of the bypass pipe 12 is connected to the upstream side of the water inlet pipe 7 (downstream side of the water supply pump 8), and the other end is connected to the downstream side of the water inlet pipe. This bypass pipe 12 has a heat exchanging part 12a installed on the downstream side of the air heat exchanger 4 in the wind direction, and in the illustrated example, the heat exchanging part 12a is arranged between the air heat exchanger 4 and the blower 5. ing.

  The first valve 13 is composed of an electromagnetic on-off valve, and is provided between the one end connection position and the other end connection position of the bypass pipe 12 in the water inlet pipe 7. The second valve 14 is composed of an electromagnetic on-off valve and is provided on the upstream side of the bypass conduit 12. The first valve 13 and the second valve 14 are water passages from the hot water storage tank 6 to the water inlet 2 a of the water heat exchanger 2, “flow passages only through the water intake conduit 7” and “water intake conduit 7. , Means for switching to any one of “a flow path sequentially passing through the bypass conduit 12 and the water inlet conduit 7”.

  The backflow prevention valve 15 includes a check valve and is provided on the downstream side of the bypass conduit 12. The backflow prevention valve 15 serves to regulate the flow of water in the bypass conduit 12 in a direction from one end connection location to the other end connection location.

  In addition, a water supply temperature for detecting a temperature (water supply temperature) Tw of water fed from the hot water storage tank 6 to the water inlet pipe 7 between the water supply pump 8 in the water inlet pipe 7 and one end connection portion of the bypass pipe 12. A sensor 20 is provided.

  In the hot water supply apparatus shown in FIG. 1, the heat pump HP is operated, and the water supply pump 8 is operated to feed the water in the hot water storage tank 6 into the water heat exchanger 2 of the heat pump HP, whereby the water is generated by the refrigerant heat. The heated hot water can be fed into the hot water storage tank 6.

  Next, the control system of the hot water supply apparatus shown in FIG. 1 will be described with reference to FIG. In the figure, 21 is a main control circuit, 22 is a compressor drive circuit, 23 is an expansion valve drive circuit, 24 is a blower drive circuit, 25 is a pump drive circuit, 26 is a valve drive circuit, and 27 is a tapping temperature setting device.

  The main control circuit 21 has a microcomputer configuration, and the memory includes its discharge temperature Td, outside air temperature Ta, incoming water temperature Twi, outgoing hot water temperature Two, and preset hot water temperature Swo, and the rotation speed and expansion valve of the compressor 1 as appropriate. A program for performing operation control (including capacity adjustment) of the heat pump HP while varying the opening degree of 3, a program for performing incoming water temperature control described later, data necessary for each control, and the like are stored. In the main control circuit 21, detection signals from the discharge temperature sensor 16, the outside air temperature sensor 17, the incoming water temperature sensor 18, the outgoing hot water temperature sensor 19 and the feed water temperature sensor 20, and the hot water temperature set by the hot water temperature setting device 27 (setting) A signal related to the tapping temperature) Swo is input.

  Based on the control signal from the main control circuit 21, the compressor drive circuit 22 sends a drive signal corresponding to the set target rotational speed to the motor 1a for compressor operation. Based on the signal from the main control circuit 21, the expansion valve drive circuit 23 sends a drive signal corresponding to the set opening change amount to the expansion valve operating motor 3a. The blower drive circuit 24 sends a predetermined drive signal to the blower operation motor 5a based on the signal from the main control circuit 21. Based on the signal from the main control circuit 21, the pump drive circuit 25 sends a drive signal corresponding to the set rotational speed to the pump operation motor 8a. Based on the signal from the main control circuit 21, the valve drive circuit 26 sends a predetermined open signal or close signal to the first valve operating solenoid 13a and the second valve operating solenoid 14a, respectively.

  Next, with reference to FIG. 3, the incoming water temperature control method executed by the hot water supply apparatus shown in FIG. 1 will be described.

  At the start of operation of the heat pump HP, the first valve 13 is open and the second valve 14 is closed (see step ST1 in FIG. 3). In this valve open / closed state, a “flow path that passes only through the water intake pipe 7” is selected as the water flow path from the hot water storage tank 6 to the water inlet 2a of the water heat exchanger 2; All of the water drawn from the hot water storage tank 6 is sent to the water heat exchanger 2 through the incoming water line 7, and the water is heated by the refrigerant heat, and the heated hot water is sent to the hot water storage tank 6 through the hot water outlet line 9. It is.

  After starting the operation of the heat pump HP, the feed water temperature sensor 20 detects the feed water temperature Tw, and determines whether or not the detected feed water temperature Tw exceeds a predetermined temperature upper limit value Tws (see step ST2 in FIG. 3). When the feed water temperature Tw is equal to or lower than a predetermined temperature upper limit value Tws, the valve open / closed state in step ST1 is maintained.

  When it is determined in step ST2 that the feed water temperature Tw exceeds the predetermined temperature upper limit value Tws, the first valve 13 is closed and the second valve 14 is opened (see step ST3 in FIG. 3). In this valve open / closed state, the “flow path that passes through the water intake line 7, the bypass line 12, and the water intake line 7 in order” is selected as the water flow path from the hot water storage tank 6 to the water inlet 2 a of the water heat exchanger 2. Therefore, all of the water drawn from the hot water storage tank 6 by the operation of the water supply pump 8 is sent from the downstream side of the water inlet pipe 7 to the bypass pipe 12 and from the bypass pipe 12 to the downstream side of the water inlet pipe 7. Returned to The bypass pipe 12 has a heat exchanging part 12a installed on the downstream side of the air direction of the air heat exchanger 4, and the temperature of the water fed into the bypass pipe 12 is lowered by heat radiation in the heat exchanging part 12a. The water after the temperature drop is returned to the downstream side of the water inlet pipe 7, and water having a temperature lower than that of uncooled water is sent to the water heat exchanger 2.

  For example, the temperature upper limit value Tws of the feed water temperature Tw that can be handled by adjusting the capacity of the heat pump HP is 15 ° C., and the feed water temperature Tw exceeds 15 ° C. Even when (COP) decreases, the coefficient of performance (COP) of the heat pump can be improved by reducing the incoming water temperature Twi fed into the hydrothermal exchanger 2 using the bypass pipe 12. The heat exchange section 12a installed on the downstream side of the air heat exchanger 4 in the wind direction can be expected to have a corresponding cooling effect, so that the water heat exchanger 2 can be used even in the summer or installation environment where the feed water temperature Tw tends to be high. It is sufficiently possible to lower the incoming water temperature Twi fed to the temperature to the temperature upper limit value Tws or less. It is also possible to adjust the amount of decrease in the incoming water temperature Twi fed into the water heat exchanger 2 by varying the amount of heat released in the heat exchange part 12a of the bypass pipe 12 according to the form of the heat exchange part 12a. .

  Thereafter, it is determined whether or not the feed water temperature Tw detected by the feed water temperature sensor 20 has become equal to or lower than a predetermined temperature upper limit value Tws (see step ST4 in FIG. 3). When it is determined in step ST4 that the feed water temperature Tw is equal to or lower than the predetermined temperature upper limit value Tws, the process proceeds to step ST1, where the first valve 13 is opened again and the second valve 14 is closed. Take control.

  According to the first embodiment, during operation of the heat pump HP, the feed water temperature sensor 20 detects the feed water temperature Tw, and when the detected feed water temperature Tw exceeds the predetermined temperature upper limit value Tws, the first valve 13 is closed. Then, the second valve 14 is opened and all of the water drawn from the hot water storage tank 6 by the operation of the water supply pump 8 is sent to the bypass line 12 from the downstream side of the water inlet line 7, and the heat exchange part of the bypass line 12 The water after being cooled at 12a (water having a temperature lower than that of uncooled water) is fed into the water heat exchanger 2.

  Therefore, if all the water drawn from the hot water storage tank 6 by the operation of the water supply pump 8 is sent to the water heat exchanger 2 through the water inlet pipe 7, the enthalpy necessary for water heating is insufficient and the coefficient of performance (COP of the heat pump) ) Is lowered, the coefficient of performance (COP) of the heat pump can be improved by lowering the incoming water temperature Twi fed into the water heat exchanger 2 using the bypass pipe 12.

  In the first embodiment, the water flow path from the hot water storage tank 6 to the water inlet 2a of the water heat exchanger 2 is referred to as “flow path only through the water intake line 7” and “water intake line 7 and bypass line. As shown in FIG. 4, the first valve 13 and the second valve 14 are shown as means for switching to any one of “a flow path that sequentially passes 12 and the water inlet pipe 7”. Alternatively, a flow path switching valve 28 provided at one end connection position of the bypass pipe line 12 may be used. The flow path switching valve 28 is composed of an electromagnetic three-way switching valve. By switching the flow path switching valve 28 to the inlet pipe 7 side (see the solid line) in the step ST1 by the valve drive circuit 26, “only through the water pipeline 7 is passed. “Flow path” can be selected, and the flow path switching valve 28 is switched to the bypass pipe line 12 side (see the broken line) in step ST3, thereby sequentially passing through the “water inlet pipe line 7, the bypass pipe line 12, and the water inlet pipe line 7”. Can be selected.

[Second Embodiment]
5 to 7 show a second embodiment of the present invention. 5 is a circuit configuration diagram of the hot water supply apparatus, FIG. 6 is a control system diagram of the hot water supply apparatus shown in FIG. 5, and FIG. 7 is a flowchart relating to incoming water temperature control.

  The second embodiment is different from the first embodiment in that the first valve 13 is excluded from the water inlet pipe 7 and only the second valve operating motor 14a is driven by the valve drive circuit 26. And the opening and closing of only the second valve 14 is controlled based on the feed water temperature Tw detected by the feed water temperature sensor 20. Since other configurations are the same as those of the first embodiment, the same reference numerals are used and the description thereof is omitted.

  Here, with reference to FIG. 7, the incoming water temperature control method performed with the hot-water supply apparatus shown in FIG. 5 will be described.

  At the start of operation of the heat pump HP, the second valve 14 is closed (see step SE1 in FIG. 7). In this valve open / closed state, a “flow path that passes only through the water intake pipe 7” is selected as the water flow path from the hot water storage tank 6 to the water inlet 2a of the water heat exchanger 2; All of the water drawn from the hot water storage tank 6 is sent to the water heat exchanger 2 through the water inlet pipe 7. The water sent to the water heat exchanger 2 is heated by the refrigerant heat, and the heated hot water is sent to the hot water storage tank 6 through the hot water discharge pipe 9.

  After the operation of the heat pump HP is started, the feed water temperature Tw is detected by the feed water temperature sensor 20, and it is determined whether or not the detected feed water temperature Tw exceeds a predetermined temperature upper limit value Tws (see step SE2 in FIG. 7). When the feed water temperature Tw is equal to or lower than the predetermined temperature upper limit value Tws, the valve open / closed state in step SE1 is maintained.

  When it is determined in step SE2 that the feed water temperature Tw exceeds the predetermined temperature upper limit value Tws, the second valve 14 is opened (see step SE3 in FIG. 7). In this valve open / closed state, as a water flow path from the hot water storage tank 6 to the water inlet 2 a of the water heat exchanger 2, “a flow path only through the water intake line 7” and “a water intake line 7, a bypass line 12, and Since both of “the flow path sequentially passing through the water inlet pipe 7” are selected, a part of the water drawn from the hot water storage tank 6 by the operation of the water supply pump 8 is sent to the water heat exchanger 2 through the water inlet pipe 7. In addition, the remaining portion is fed into the bypass conduit 12 from the downstream side of the water inlet conduit 7 and returned from the bypass conduit 12 to the downstream side of the water inlet conduit 7. The bypass pipe 12 has a heat exchanging part 12a installed on the downstream side of the air direction of the air heat exchanger 4, and the temperature of the water fed into the bypass pipe 12 is lowered by heat radiation in the heat exchanging part 12a. The water after the temperature drop is returned to the downstream side of the inlet pipe 7 and merges with the uncooled water, and the water having a lower temperature than the uncooled water (joined water) is sent to the water heat exchanger 2. .

  For example, the temperature upper limit value Tws of the feed water temperature Tw that can be handled by adjusting the capacity of the heat pump HP is 15 ° C., and the feed water temperature Tw exceeds 15 ° C. Even when (COP) is lowered, the coefficient of performance (COP) of the heat pump can be improved by lowering the incoming water temperature Twi fed into the water heat exchanger 2 using the bypass pipe 12. The heat exchange section 12a installed on the downstream side of the air heat exchanger 4 in the wind direction can be expected to have a corresponding cooling effect, so that the water heat exchanger 2 can be used even in the summer or installation environment where the feed water temperature Tw tends to be high. It is sufficiently possible to lower the incoming water temperature Twi fed to the temperature to the temperature upper limit value Tws or less. Further, the ratio of the amount of water flowing into the “flow path that passes only through the water inlet pipe 7” and “the flow path that passes through the water inlet pipe 7, the bypass pipe 12, and the water inlet pipe 7 in order” is varied at the branching point or the like. Thereby, it is also possible to adjust the temperature drop amount of the water sent to the water heat exchanger 2 after joining.

  Thereafter, it is determined whether or not the feed water temperature Tw detected by the feed water temperature sensor 20 has become equal to or lower than a predetermined temperature upper limit value Tws (see step SE4 in FIG. 7). If it is determined in step SE4 that the feed water temperature Tw is equal to or lower than the predetermined temperature upper limit value Tws, the process proceeds to step SE1 to close the second valve 14 again, and thereafter, the same incoming water temperature control is performed.

  According to the second embodiment, during operation of the heat pump HP, the feed water temperature sensor 20 detects the feed water temperature Tw, and when the detected feed water temperature Tw exceeds the predetermined temperature upper limit value Tws, the feed water pump 8 is operated. A part of the water drawn out from the hot water storage tank 6 is sent to the water heat exchanger 2 through the inlet pipe 7, and the remaining part is sent from the downstream side of the inlet pipe 7 to the bypass pipe 12. The water that has been cooled in step 1 is combined with uncooled water, and water having a temperature lower than that of uncooled water (joined water) is sent to the water heat exchanger 2.

  Therefore, if all the water drawn from the hot water storage tank 6 by the operation of the water supply pump 8 is sent to the water heat exchanger 2 through the water inlet pipe 7, the enthalpy necessary for water heating is insufficient and the coefficient of performance (COP of the heat pump) ) Is lowered, the coefficient of performance (COP) of the heat pump can be improved by lowering the incoming water temperature Twi fed into the water heat exchanger 2 using the bypass pipe 12.

  Further, the ratio of the amount of water flowing into the “flow path that passes only through the water inlet pipe 7” and “the flow path that passes through the water inlet pipe 7, the bypass pipe 12, and the water inlet pipe 7 in order” is varied at the branching point or the like. Thereby, the temperature fall amount of the water by the bypass line 12 and the temperature fall amount of the water sent to the water heat exchanger 2 after joining can be adjusted.

[Third Embodiment]
FIG. 8 shows a third embodiment of the present invention. 5 is a circuit configuration diagram of the hot water supply apparatus, FIG. 6 is a control system diagram of the hot water supply apparatus shown in FIG. 5, and FIG. 7 is a flowchart relating to incoming water temperature control.

  The third embodiment is different from the first embodiment in that the first valve 13 is excluded from the inlet pipe 7, the second valve 14 is excluded from the bypass pipe 12, and the hot water storage tank 6 is used. That is, the water supply temperature sensor 20 for detecting the temperature (water supply temperature) Tw of the water fed into the water pipe 7 is excluded, and the valve drive circuit 26 is excluded from the control system (not shown). Since other configurations are the same as those of the first embodiment, the same reference numerals are used and the description thereof is omitted.

  Here, the incoming water temperature control method executed by the hot water supply apparatus shown in FIG. 8 will be described.

  Since the hot water supply apparatus shown in FIG. 8 does not have the flow path switching valve as in the first and second embodiments, the water flow path from the hot water storage tank 6 to the water inlet 2a of the water heat exchanger 2 is “input”. Both “the flow path passing only through the water conduit 7” and “the flow path passing through the water inlet conduit 7, the bypass conduit 12, and the water intake conduit 7” are always selected.

  Therefore, at the time of operation of the heat pump HP, a part of the water drawn out from the hot water storage tank 6 by the operation of the water supply pump 8 is sent to the water heat exchanger 2 through the water inlet conduit 7, and the rest is the water inlet conduit 7. It is sent from the downstream side to the bypass conduit 12 and returned from the bypass conduit 12 to the downstream side of the water inlet conduit 7. The bypass pipe 12 has a heat exchanging part 12a installed on the downstream side of the air direction of the air heat exchanger 4, and the temperature of the water fed into the bypass pipe 12 is lowered by heat radiation in the heat exchanging part 12a. The water after the temperature drop is returned to the downstream side of the inlet pipe 7 and merges with the uncooled water, and the water having a lower temperature than the uncooled water (joined water) is sent to the water heat exchanger 2. .

  For example, the temperature upper limit value Tws of the feed water temperature Tw that can be handled by adjusting the capacity of the heat pump HP is 15 ° C., and the feed water temperature Tw exceeds 15 ° C. Even when (COP) is lowered, the coefficient of performance (COP) of the heat pump can be improved by lowering the incoming water temperature Twi fed into the water heat exchanger 2 using the bypass pipe 12. The heat exchange section 12a installed on the downstream side of the air heat exchanger 4 in the wind direction can be expected to have a corresponding cooling effect, so that the water heat exchanger 2 can be used even in the summer or installation environment where the feed water temperature Tw tends to be high. It is sufficiently possible to lower the incoming water temperature Twi fed to the temperature to the temperature upper limit value Tws or less. Further, the ratio of the amount of water flowing into the “flow path that passes only through the water inlet pipe 7” and “the flow path that passes through the water inlet pipe 7, the bypass pipe 12, and the water inlet pipe 7 in order” is varied at the branching point or the like. Thereby, it is also possible to adjust the temperature drop amount of the water sent to the water heat exchanger 2 after joining.

  According to the third embodiment, at the time of operation of the heat pump HP, a part of the water drawn from the hot water storage tank 6 by the operation of the feed water pump 8 is sent to the water heat exchanger 2 through the water inlet pipe 7 and the remaining part is discharged. Water that has been sent from the downstream side of the inlet pipe 7 to the bypass pipe 12 and cooled by the bypass pipe 12 is merged with uncooled water, so that water at a lower temperature than the uncooled water (combined water) ) Is fed into the water heat exchanger 2.

  Therefore, if all the water drawn from the hot water storage tank 6 by the operation of the water supply pump 8 is sent to the water heat exchanger 2 through the water inlet pipe 7, the enthalpy necessary for water heating is insufficient and the coefficient of performance (COP of the heat pump) ) Is lowered, the coefficient of performance (COP) of the heat pump can be improved by lowering the incoming water temperature Twi fed into the water heat exchanger 2 using the bypass pipe 12.

  Further, the ratio of the amount of water flowing into the “flow path that passes only through the water inlet pipe 7” and “the flow path that passes through the water inlet pipe 7, the bypass pipe 12, and the water inlet pipe 7 in order” is varied at the branching point or the like. Thereby, the temperature fall amount of the water by the bypass line 12 and the temperature fall amount of the water sent to the water heat exchanger 2 after joining can be adjusted.

  Further, since the flow path switching valve as in the first and second embodiments is not required, the circuit configuration can be simplified by eliminating the valve and the valve driving circuit, and the program for controlling the incoming water temperature and the series based on the program Can be made unnecessary.

It is a circuit block diagram of the hot water supply apparatus which shows 1st Embodiment of this invention. FIG. 2 is a control system diagram of the hot water supply device shown in FIG. 1. It is a flowchart which concerns on incoming water temperature control. It is a circuit block diagram which shows the partial modification of 1st Embodiment. It is a circuit block diagram of the hot water supply apparatus which shows 2nd Embodiment of this invention. FIG. 6 is a control system diagram of the water heater shown in FIG. 5. It is a flowchart which concerns on incoming water temperature control. It is a circuit block diagram of the hot water supply apparatus which shows 3rd Embodiment of this invention.

Explanation of symbols

  HP ... heat pump, 1 ... compressor, 2 ... water heat exchanger, 2a ... water inlet, 2b ... outlet port, 3 expansion valve, 4 ... air heat exchanger, 6 ... hot water storage tank, 7 ... water inlet line, 8 ... Water supply pump, 9 ... Hot water supply line, 12 ... Bypass line, 12a ... Heat exchange section, 13 ... First valve, 14 ... Second valve, 15 ... Backflow prevention valve, 20 ... Feed water temperature sensor, 21 ... Main control circuit , 22: compressor driving circuit, 23: expansion valve driving circuit, 25: pump driving circuit, 26: valve driving circuit, 28: flow path switching valve.

Claims (5)

A heat pump having at least a compressor, a water heat exchanger, an expansion valve and an air heat exchanger;
A hot water storage tank whose lower part is connected to the water inlet of the water heat exchanger via the water inlet pipe and whose upper part is connected to the outlet of the water heat exchanger via the hot water outlet;
A water supply pump for sending the water in the hot water storage tank to the water inlet of the water heat exchanger, and for sending the hot water heated by the water heat exchanger from the hot water outlet into the hot water storage tank;
One end is connected to the upstream side of the water inlet pipe, and the other end is connected to the downstream side of the water inlet pipe. The temperature of the water sent from the hot water storage tank to the water inlet pipe is lowered to reduce the temperature of the water. A bypass line for returning to the water intake line,
A water heater characterized by that. The bypass pipe has a heat exchange section installed on the downstream side of the air direction of the air heat exchanger, and a backflow prevention valve that regulates the flow of water in the bypass pipe in a direction from one end connection location to the other end connection location. ,
The hot water supply apparatus according to claim 1. A valve provided in the bypass line;
A water supply temperature sensor for detecting the temperature of the water sent from the hot water storage tank to the inlet pipe,
Valve control means for closing the valve when the feed water temperature is equal to or lower than a predetermined temperature upper limit value and opening the valve when the feed water temperature exceeds the predetermined temperature upper limit value;
The hot-water supply apparatus of Claim 1 or 2 characterized by the above-mentioned. Switch the flow path of water from the hot water storage tank to the inlet of the water heat exchanger to one of the flow path passing through the water intake pipe only, or the flow path passing through the water intake pipe, the bypass pipe, and the water intake pipe in order. Flow path switching means;
A water supply temperature sensor for detecting the temperature of the water sent from the hot water storage tank to the inlet pipe,
When the feed water temperature is less than or equal to the predetermined upper temperature limit, the water flow path from the hot water storage tank to the water heat exchanger inlet is switched to a flow path that passes only the water intake pipe, and the feed water temperature reaches the predetermined upper temperature limit. A flow path control means for switching the flow path of the water from the hot water storage tank to the water inlet of the water heat exchanger when it exceeds the flow path through the water intake line, the bypass line, and the water intake line in order.
Further comprising valve control means,
The hot-water supply apparatus of Claim 1 or 2 characterized by the above-mentioned. The flow path switching means comprises a first valve provided between one end connection position and the other end connection position of the bypass pipe in the water inlet pipe, and a second valve provided in the bypass pipe,
The flow path control means opens the first valve when the feed water temperature is equal to or lower than a predetermined temperature upper limit value, closes the second valve, and closes the first valve when the feed water temperature exceeds the predetermined temperature upper limit value. And opening the second valve,
The hot water supply apparatus according to claim 4.

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