JP2012237492A - Storage type water heater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a storage type water heater capable of shortening a heating-up period during a heat-retaining operation, while avoiding the device efficiency of a heat pump from decreasing during the heat-retaining operation that keeps warm the water to be heated.SOLUTION: The storage type water heater includes a heating means for heating bathtub water, and a heat retaining means for raising a temperature of the bathtub water using the heating means if the temperature of the bathtub water drops. The heating means includes a stored hot water reheating operation for causing a heat exchange between high-temperature water stored in a hot water storage tank 10 and the bathtub water when a heat pump unit 60 is stopped, and a direct heat-pump reheating operation for causing a heat exchange between the heated high-temperature water and the bathtub water by means of the heat pump unit 60 when the heat pump unit 60 is in operation. In the event that the bathtub water cannot be heated to a predetermined target temperature within an upper limit of heat-retaining time by the direct heat-pump reheating operation, the heat retaining means raises the temperature of the bathtub water using the stored hot water reheating operation.

Description

  The present invention relates to a hot water storage type water heater.

  Some conventional hot water storage hot water heaters perform a hot water reheating operation when the temperature of the hot water output from the heat pump does not reach a predetermined temperature, and perform a direct reheating operation of the heat pump when the predetermined temperature is reached. It has been. In addition, in a conventional hot water storage type water heater, the reheating time is calculated from the bath setting temperature at the start of reheating, the current hot water temperature, the amount of hot water, the hot water temperature in the hot water tank, etc., and the calculated reheating time is calculated. In addition, it is known to select either a hot water reheating operation or a heat pump direct reheating operation depending on whether or not the time is enough for the heat pump to produce sufficient capacity (see, for example, Patent Document 1).

Japanese Patent Application Laid-Open No. 2007-113836

  In a conventional hot water storage type hot water heater, the hot water reheating operation has a problem that although the heating capacity of the bath water is high, a large amount of medium-temperature water is generated in the hot water storage tank, and the equipment efficiency is lowered. Further, the direct heat pumping operation has a problem that there is no generation of intermediate temperature water in the hot water storage tank and the equipment efficiency is high, but the heating capacity of the bathtub water is low. In order to solve these problems, in the conventional hot water storage type hot water heater, whether the hot water from the heat pump is below a predetermined temperature, or the bath set temperature at the start of reheating, the current hot water temperature, the hot water volume, the hot water in the hot water storage tank The reheating time is calculated from the temperature, etc., and it is determined whether or not it is longer than the time that the heat pump can produce sufficient capacity, and the operation is performed by switching between the hot water reheating operation or the heat pump direct reheating operation.

  However, in the above-described conventional technique, the reheating operation to be performed is selected from the viewpoint of the efficiency of the heat pump. For this reason, when a heat pump direct reheating operation with a low bath water heating capacity is selected when performing a heat insulation operation for holding the bath temperature for a predetermined time, the bath temperature is low and the heat dissipation of the bath water is large. It is assumed that the target temperature is not reached within a predetermined time due to a large drop in bath water, or because the outside air temperature is low and direct reheating of the heat pump does not exhibit sufficient capacity. In this case, there is a possibility that it takes a long time to raise the temperature of the bath water to the target temperature, and there is a problem that convenience for the user is deteriorated.

  The present invention has been made to solve the above-described problems. In the heat retaining operation for retaining the heating target water, the temperature increase time in the heat retaining operation is shortened while suppressing a decrease in the equipment efficiency of the heat pump. It is an object of the present invention to provide a hot water storage type hot water heater capable of such a thing.

  A hot water storage type water heater according to the present invention has a hot water storage tank for storing hot water heated using a heat pump, and a water circulation circuit connected to a tank in which water to be heated is stored, and the water circulation circuit The heating target water circulating means for circulating the heating target water using the heating means, the heating means for heating the heating target water flowing in the water circulation circuit, the temperature detection means for detecting the temperature of the heating target water, and when the temperature of the heating target water is lowered And a heat retaining means that raises the temperature of the water to be heated using the heating means, and the heating means includes high temperature water stored in the hot water storage tank and water to be heated flowing in the water circulation circuit while the heat pump is stopped. The hot water storage reheating means for exchanging heat and the heat pump directly exchanging heat between the high temperature water heated using the heat pump and the water to be heated flowing in the water circulation circuit during the operation of the heat pump. The heat retaining means includes a hot water reheating means when the water to be heated cannot be heated to a predetermined target temperature within a predetermined time by the heat pump direct reheating means. The temperature is raised.

  According to the present invention, it is possible to provide a hot water storage type hot water heater capable of shortening the temperature raising time in the heat insulation operation while suppressing the decrease in the equipment efficiency of the heat pump in the heat insulation operation for keeping the water to be heated. It becomes possible.

It is a block diagram of the hot water storage type water heater in Embodiment 1 of this invention. It is a circuit block diagram at the time of the boiling independent operation | movement of the hot water storage type water heater in Embodiment 1 of this invention. It is a circuit block diagram at the time of the heat pump direct reheating operation of the hot water storage type water heater in Embodiment 1 of the present invention. It is a circuit block diagram at the time of the hot water storage reheating operation of the hot water storage type hot water heater in Embodiment 1 of the present invention. It is a flowchart which switches the heat pump direct reheating operation and hot water reheating operation of the hot water storage type hot water supply apparatus in Embodiment 1 of this invention. It is a flowchart which switches the heat pump direct reheating operation and hot water reheating operation of the hot water storage type hot water supply apparatus in Embodiment 1 of this invention.

  Embodiments of the present invention will be described below with reference to the drawings. In addition, the same code | symbol is attached | subjected to the element which is common in each figure, and the overlapping description is abbreviate | omitted.

Embodiment 1 FIG.
FIG. 1 is a configuration diagram of a hot water storage type water heater 100 according to Embodiment 1 of the present invention. A hot water storage type water heater 100 shown in FIG. 1 includes a hot water storage tank unit 1 and a heat pump unit 60 configured to use a heat pump cycle. The two units 1 and 60 are connected by a heat pump inlet pipe 41 and a heat pump outlet pipe 42. The hot water storage tank unit 1 has a control unit 70 built therein. Operations of various valves, pumps and the like provided in the hot water storage tank unit 1 and the heat pump unit 60 are controlled by a control unit 70 electrically connected thereto. Hereinafter, each component of the hot water storage type water heater 100 will be described.

  The heat pump unit 60 functions as a heating means for heating (boiling) the low temperature water led from the hot water storage tank unit 1. The heat pump unit 60 includes a compressor 61, a heating heat exchanger 62, an expansion valve 63, and an air heat exchanger 64 connected in a ring shape with a refrigerant circulation pipe 65 to constitute a refrigeration cycle (heat pump cycle). The boiling heat exchanger 62 is for exchanging heat between the refrigerant flowing through the refrigerant circulation pipe 65 constituting the heat pump cycle and the low-temperature water led from the hot water storage tank unit 1. The HP outlet side thermistor 66 is a temperature sensor for detecting the temperature of the high-temperature water heated by the boiling heat exchanger 62, and is provided in the heat pump outlet pipe 42. In order to obtain high-temperature water by the heat pump unit 60, it is preferable that the heat pump cycle is operated at a pressure exceeding the critical pressure using carbon dioxide as a refrigerant.

  On the other hand, the hot water storage tank unit 1 incorporates the following various parts and piping. The hot water storage tank 10 is for storing hot water. A hot water supply pipe 2 for supplying city water is connected to the lower part of the hot water storage tank 10, and a hot water supply pipe 3 for supplying the stored hot water to the outside of the hot water heater is connected to the upper part of the hot water storage tank 10. ing. In addition, the hot water heated by the heat pump unit 60 is introduced into the hot water storage tank 10 from the upper part of the tank, and the low temperature water is introduced from the lower part of the tank through the water supply pipe 2, thereby Hot water is stored so that a temperature difference occurs in the lower part. Moreover, the remaining hot water thermistors 11 and 12 for detecting the temperature distribution of the hot water in the hot water storage tank 10 are attached to the surface of the hot water storage tank 10 at different mounting heights. Based on the temperature distribution acquired by the remaining hot water thermistors 11 and 12, the amount of hot water in the hot water storage tank 10 is grasped, and the start and stop of the hot water boiling operation in the hot water storage tank 10 by the heat pump unit 60 is controlled. Is done.

  The hot water storage tank unit 1 includes a circulation pump 21 and a use side heat exchanger 22. The circulation pump 21 is a pump for circulating hot water through various pipes to be described later in the hot water storage tank unit 1. The use-side heat exchanger 22 uses the high-temperature water supplied from the hot water storage tank 10 and the heat pump unit 60 to heat the secondary-side heating target water (tub circulation water, heating circulation water, etc.). It is an exchanger. In the present embodiment, as a secondary side configuration of the use side heat exchanger 22, a bathtub water circulation circuit 51 that circulates hot water in the bathtub 50 will be described as an example. The use side heat exchanger 22 is installed in the middle of the bathtub water circulation circuit 51. Further, a secondary circulation pump 52 for circulating the bathtub water and a bathtub outlet side thermistor 53 for detecting the temperature of the bathtub water discharged from the bathtub 50 are installed in the middle of the bathtub water circulation circuit 51. Yes.

  Next, the valves and piping included in the hot water storage tank unit 1 will be described. The hot water tank unit 1 has a three-way valve 31 and a four-way valve 32. The three-way valve 31 is a flow path switching means having two inlets (a port and b port) through which hot water flows and one outlet (c port) through which hot water flows out. Either the a port or the b port The hot water path can be switched so that hot water flows in from the water. The four-way valve 32 is a flow path switching means having two inlets (b port and c port) through which hot water flows in and two outlets (a port and d port) through which hot water flows out. , A-b route, a-c route, and cd route are configured to be switchable.

  The hot water storage tank unit 1 includes a tank lower pipe 40, the heat pump inlet pipe 41, the heat pump outlet pipe 42, a tank upper pipe 43, a tank return pipe 44, and a use side heat exchanger primary side (heat source side) inlet pipe 45. The use side heat exchanger has a primary side outlet pipe 46 and a bypass pipe 47. Further, the circulation pump 21 is installed between the connection portion with the bypass pipe 47 on the first heat pump inlet pipe 41 and the three-way valve 31.

  The tank lower pipe 40 is a flow path that connects the first lower part of the hot water storage tank 10 and the a port of the three-way valve 31. The heat pump inlet pipe 41 is a flow path that connects the c port of the three-way valve 31 and the inlet side of the heat pump unit 60, and the heat pump outlet pipe 42 connects the outlet side of the heat pump unit 60 and the c port of the four-way valve 32. The tank upper pipe 43 is a flow path that connects the d port of the four-way valve 32 and the upper part of the hot water storage tank 10, and the tank return pipe 44 is the a port of the four-way valve 32 and the center of the hot water storage tank 10. It is the flow path which connects the return port provided between the part and the lower part. The use side heat exchanger primary side inlet pipe 45 branches from between the hot water storage tank upper part of the tank upper pipe 43 and the four-way valve 32 and is connected to the primary side inlet of the use side heat exchanger 22. The use side heat exchanger primary side outlet pipe 46 is a flow path that connects the primary side outlet of the use side heat exchanger 22 and the b port of the three-way valve 31. Further, the bypass pipe 47 is a flow path that branches from between the outlet side of the circulation pump 21 and the inlet side of the heat pump unit 60 in the heat pump inlet pipe 41 and is connected to the b port of the four-way valve 32.

  In the hot water storage type water heater 100 according to the present embodiment, the three-way valve 31 is controlled according to the operation state shown in FIGS. Thus, the hot water passage in the hot water storage tank unit 1 is switched and used. More specifically, the “first flow path configuration” that can be selected by the three-way valve 31 means that the first lower part of the hot water storage tank 10 and the heating heat exchanger 62 connect the tank lower pipe 40 and the heat pump inlet pipe 41. The “second flow path configuration” means that the use side heat exchanger primary side outlet pipe 46 and the heating heat exchanger 62 are connected via the heat pump inlet pipe 41. It is a flow path form that communicates.

  Furthermore, in the hot water storage type hot water heater 100 of the present embodiment, the following two first and second flow path configurations are controlled by controlling the four-way valve 32 in accordance with the operation states shown in FIGS. Switch between and use. More specifically, the “first flow path configuration” that can be selected by the four-way valve 32 is a flow path configuration in which the heating heat exchanger 62 and the tank upper pipe 43 communicate with each other via the heat pump outlet pipe 42. That is, the “second flow path configuration” is a flow channel configuration in which the bypass pipe 47 and the tank return pipe 44 communicate with each other.

  FIG. 2 is a circuit configuration diagram of the hot water storage type water heater 100 according to Embodiment 1 of the present invention at the time of a single heating operation. In addition, the boiling-up single operation here is a thing in which the boiling-up operation which uses the heat pump unit 60 to boil the water in the hot water storage tank 10 is performed independently. At the time of this single heating operation, the three-way valve 31 is controlled so that the first flow path configuration is selected. Accordingly, the tank lower pipe 40 and the heat pump inlet pipe 41 communicate with each other, and the flow path from the usage side heat exchanger 22 is blocked by closing the usage side heat exchanger primary side outlet pipe 46 side. Moreover, at the time of a boiling independent operation, the four-way valve 32 is controlled so that the said 1st flow path form is selected. Thereby, the heat pump outlet pipe 42 and the tank upper pipe 43 communicate with each other, and the flow paths on the tank return pipe 44 side and the bypass pipe 47 side are closed.

  The boiling-up single operation is executed by starting the operation of the circulation pump 21 and the heat pump unit 60 in a state where the three-way valve 31 and the four-way valve 32 are controlled as described above. As a result, the low-temperature water flowing out from the first lower part of the hot water storage tank 10 is guided to the heat pump unit 60 via the tank lower pipe 40, the three-way valve 31, the circulation pump 21 and the heat pump inlet pipe 41, and heat exchange for boiling is performed. After being heated in the vessel 62 to become hot water, it flows into the hot water storage tank 10 from the upper part of the hot water storage tank 10 through the heat pump outlet pipe 42, the four-way valve 32 and the tank upper pipe 43 and is stored. By performing such boiling-up single operation, high temperature water is stored from the upper layer inside the hot water storage tank 10, and this high temperature water layer gradually becomes thicker.

  FIG. 3 is a circuit configuration diagram of the hot water storage hot water supply apparatus 100 according to Embodiment 1 of the present invention during a direct heat pump operation. The heat pump direct reheating operation here is an operation in which high-temperature water boiled using the heat pump unit 60 and bathtub water are heat-exchanged in the use-side heat exchanger 22 to heat the bathtub water. It is. During the direct heat pump operation, the second flow path configuration of the three-way valve 31 is controlled to be selected. As a result, the use side heat exchanger primary side outlet pipe 46 and the heat pump inlet pipe 41 communicate with each other, and the flow path on the tank lower pipe 40 side is closed. Further, during direct heat pump operation, the four-way valve 32 is controlled so that the first flow path configuration is selected. Thereby, the heat pump outlet pipe 42 and the tank upper pipe 43 communicate with each other, and the flow paths on the tank return pipe 44 side and the bypass pipe 47 side are closed.

  The heat pump direct recharging operation is executed by starting the operation of the circulation pump 21 and the heat pump unit 60 in a state where the three-way valve 31 and the four-way valve 32 are controlled as described above. As a result, the medium-temperature water flowing out from the use side heat exchanger primary side outlet pipe 46 is led to the heat pump unit 60 via the three-way valve 31, the circulation pump 21, and the heat pump inlet pipe 41, and is heated for heating. Heated at 62. The high-temperature water that has become hot due to heat exchange is led to the use-side heat exchanger 22 via the heat pump outlet pipe 42, the four-way valve 32, and the tank upper pipe 43, and is heat-exchanged with the bath water to become medium-temperature water. On the other hand, in the path on the bathtub 50 side, the hot water stretched on the bathtub 50 circulates in the bathtub water circulation circuit 51 by operating the secondary circulation pump 52. As a result, the heat of the high-temperature water flowing through the primary side of the use side heat exchanger 22 is transmitted to the hot water flowing through the secondary side of the use side heat exchanger 22, and the hot water stretched in the bathtub 50 is warmed. As described above, in the direct heat pump operation, since the high-temperature water stored in the hot water storage tank 10 is not used, intermediate hot water is not generated in the hot water storage tank. In addition, the heat pump direct reheating operation is configured to be automatically performed by the control unit 70 by detecting the temperature drop of the hot water stretched on the bathtub 50 by the bathtub outlet side thermistor 53. In addition, the user can press the button installed on the remote controller or the like to perform the operation at an arbitrary timing.

  Next, FIG. 4 is a circuit configuration diagram at the time of hot water reheating operation of hot water storage type water heater 100 in the first embodiment of the present invention. The hot water reheating operation here is an operation in which the hot water stored in the hot water storage tank 10 and the bathtub water are heat-exchanged by the use-side heat exchanger 22 to heat the bathtub water. During this hot water reheating operation, the three-way valve 31 is controlled so that the second flow path configuration is selected. As a result, the use side heat exchanger primary side outlet pipe 46 and the heat pump inlet pipe 41 communicate with each other, and the tank lower pipe 40 side is closed and the flow path from the first lower part of the hot water storage tank 10 is blocked. The four-way valve 32 is controlled so that the second flow path configuration is selected. Thereby, the circulation pump 21 and the tank return pipe 44 communicate with each other through the bypass pipe 47, and the flow paths on the heat pump outlet pipe 42 side and the tank upper pipe 43 side are closed.

  The hot water reheating operation is executed by starting the operation of the circulation pump 21 and the secondary side circulation pump 52 in a state where the three-way valve 31 and the four-way valve 32 are controlled as described above. In addition, in this hot water storage reheating operation state, the operation of the heat pump unit 60 is stopped. As a result, the high temperature water flowing out from the upper part of the hot water storage tank 10 is guided to the use side heat exchanger 22 via the tank upper pipe 43 and the use side heat exchanger primary side inlet pipe 45, and between the hot water and the bath water. Heat exchange takes place at. The low temperature water that has become low temperature by heat exchange passes through the use side heat exchanger primary side outlet pipe 46, the three-way valve 31, the heat pump inlet pipe 41, the circulation pump 21, the bypass pipe 47, the four-way valve 32, and the tank return pipe 44. Then, the hot water storage tank 10 is returned to the hot water storage tank 10 through a return port provided in the lower part of the hot water storage tank 10. According to such a circulation path, since hot water stored in the hot water storage tank 10 is used, intermediate hot water is generated in the hot water storage tank 10. On the other hand, in the path on the bathtub 50 side, the hot water stretched on the bathtub 50 circulates in the bathtub water circulation circuit 51 by operating the secondary circulation pump 52. As a result, the heat of the high-temperature water flowing through the primary side of the use side heat exchanger 22 is transmitted to the hot water flowing through the secondary side of the use side heat exchanger 22, and the hot water stretched in the bathtub 50 is warmed. The hot water reheating operation is configured to be automatically performed by the control unit 70 by detecting the temperature drop of the hot water stretched on the bathtub 50 by the bathtub outlet side thermistor 53. In addition, the user can press the button installed on the remote controller or the like to perform the operation at an arbitrary timing.

  Next, an example of characteristic control of the hot water storage type water heater 100 according to the first embodiment will be described with reference to FIG. FIG. 5 is a flowchart for switching between the heat pump direct reheating operation and the hot water reheating operation in Embodiment 1 of the present invention. First, in step S1, a bath water heat retention operation is performed to keep the bath temperature at a set bath temperature (for example, 42 ° C.), and the process proceeds to step S2. In step S2, it is determined whether or not a predetermined time (for example, 10 minutes) has elapsed since the secondary circulation pump 52 was turned off. As a result, if 10 minutes have not elapsed since the secondary circulation pump was turned off, the process returns to step S2.

  On the other hand, in step S2, if 10 minutes have elapsed since the secondary circulation pump was turned off, the process proceeds to the next step S3. In step S3, the secondary circulation pump 52 is turned on. In step S4, it is determined whether or not the bathtub temperature detected by the bathtub outlet-side thermistor 53 is lower than a predetermined heating start temperature (for example, a set bath temperature minus 0.5 ° C.). As a result, if the establishment of the bath temperature <the set bath temperature−0.5 ° C. is not recognized, the process proceeds to step S8 described later. On the other hand, if the establishment of the bath temperature <the set bath temperature−0.5 ° C. is recognized in step S4, the process proceeds to step S5. In step S5, it is determined whether or not a heat pump direct chase prohibition flag, which will be described later, is OFF. As a result, if the heat pump direct chase prohibition flag is OFF, the process proceeds to step S6. In step S6, a direct heat pump operation is performed, and the process proceeds to step S7. In step S7, it is determined whether or not the bathtub temperature detected by the bathtub outlet side thermistor 53 is higher than a predetermined target temperature (for example, a set bathtub temperature plus 0.5 ° C.). As a result, when it is recognized that the bath temperature> the set bath temperature + 0.5 ° C., the process proceeds to step S8. In step S8, the secondary-side circulation pump 52 is turned OFF, each chasing operation is stopped, and END is reached. On the other hand, if the heat pump direct reheating prohibition flag is ON in step S5, the process proceeds to step S9. In step S9, the hot water reheating operation is performed, and the process proceeds to step S7.

  On the other hand, when the establishment of the bathtub temperature> the set bath temperature + 0.5 ° C. is not recognized in step S7, the process proceeds to step S10. In step S <b> 10, it is determined whether or not a heat retention upper limit time (for example, 15 minutes) has elapsed since the heat pump direct reheating operation or the hot water reheating operation. As a result, if the heat retention upper limit time has not elapsed since the heat pump direct reheating operation or the hot water reheating operation, the process returns to step S7 again. On the other hand, if the heat retention upper limit time has elapsed from the direct heat pump driving operation or the hot water storage driving operation, the process proceeds to step S11. In step S11, the heat pump direct reheating prohibition flag is set to ON, and the process proceeds to step S8.

  According to the hot water storage type water heater 100 of the present embodiment described above, when the bath water heat insulation operation for maintaining the bath temperature set by the user for a predetermined time is performed, first, the heat pump direct follow-up with low bath water heating capability is performed. Since the sowing operation is carried out, medium-temperature water is not generated in the hot water storage tank 10, and the equipment efficiency can be kept high. In addition, while the bath temperature can reach the predetermined target temperature within the heat retention upper limit time by the heat pump direct chasing operation, the bath water heat retaining operation using the heat pump direct chasing operation is performed. It is possible to repeatedly perform operation with high equipment efficiency while satisfying.

  Further, according to the hot water storage type water heater 100 of the present embodiment, when the bathtub temperature cannot reach the predetermined target temperature within the heat retention upper limit time due to the direct reheating operation of the heat pump, Hot water reheating operation with high heating capacity is selected. Thereby, although the apparatus efficiency is lowered due to the generation of the medium-temperature water in the hot water storage tank, it is possible to satisfy the requirement for the heat retention upper limit time.

  In addition, during the bath water heat insulation operation, once the hot water storage reheating operation is selected, the heat pump direct reheating is not selected again. When the bath water heat insulation operation is performed the next time (for example, the next day), the bath water condition is different from the previous bath water heat insulation operation (for example, the previous day). The above operation is performed.

Next, with reference to FIG. 6, another example of characteristic control of hot water storage type water heater 100 in the first embodiment will be described. FIG. 6 is a flowchart for switching between the heat pump direct reheating operation and the hot water reheating operation in Embodiment 1 of the present invention. First, in steps S21 to S24, processing similar to that in steps S1 to S4 is performed. In step S24, when establishment of bathtub temperature <set bathtub temperature−0.5 ° C. is not recognized, the process proceeds to step S28 described later. On the other hand, if the establishment of the bath temperature <the set bath temperature−0.5 ° C. is recognized in step S24, the process proceeds to step S25. In step S25, the bathtub temperature detected by the bathtub outlet side thermistor 53 is a predetermined determination temperature (for example,
It is determined whether it is less than the set bath temperature minus 1.0 ° C). As a result, if it is recognized that the bath temperature <the set bath temperature−1.0 ° C., the process proceeds to step S26. In step S26, the hot water reheating operation similar to that in step S9 is performed, and the process proceeds to step S27. On the other hand, if the establishment of the bath temperature <the set bath temperature−1.0 ° C. is not recognized, the process proceeds to step S29. In step S29, the same direct heat pump operation as in step S6 is performed, and the process proceeds to step S27.

  In step S27, it is determined whether or not the bathtub temperature detected by the bathtub outlet side thermistor 53 is larger than the set bathtub temperature plus 0.5 ° C. As a result, if it is recognized that the bath temperature> the set bath temperature + 0.5 ° C., the process proceeds to step S28. In step S28, the secondary side circulation pump 52 is turned OFF, each reheating operation is stopped, and END is reached. On the other hand, if the establishment of the bathtub temperature> the set bathtub temperature + 0.5 ° C. is not recognized in step S27, the process proceeds to step S30. In step S30, it is determined whether or not a heat retention upper limit time (for example, 15 minutes) has elapsed since the heat pump direct reheating operation or the hot water reheating operation. As a result, when the heat retention upper limit time has not elapsed since the heat pump direct reheating operation or the hot water reheating operation, the process returns to step S27 again. On the other hand, if the heat retention upper limit time has elapsed from the direct heat pump driving operation or the hot water storage driving operation, the process proceeds to step S27.

  According to the hot water storage type water heater 100 of the present embodiment described above, even when the bathtub water heat retention operation is performed to maintain the bathtub temperature set by the user for a predetermined time, even if the bathtub temperature is low, the predetermined bath temperature is low. When the temperature is within the temperature range that can be raised to the target temperature (the set bath temperature is a range from -0.5 ° C to -1.0 ° C), a heat pump direct reheating operation with low bath water heating capability is implemented. Is done. Thereby, it is possible to maintain high device efficiency while satisfying the requirement of the heat retention upper limit time. On the other hand, when the bath temperature belongs to a temperature range in which the bath heating capacity is required to be high (the set bath temperature is less than -1.0 ° C.), the hot water reheating operation with high bath water heating capability is performed. To be implemented. Thereby, although the medium efficiency water is generated in the hot water storage tank, there is a decrease in equipment efficiency, but it is possible to satisfy the requirement of the heat retention upper limit time.

  By the way, in Embodiment 1 mentioned above, the bathtub water reheating operation which repels bathtub water was demonstrated as an example of the heating operation which heats heating object water. However, the heating operation of the present invention is not limited to this, and may be, for example, a heating operation using heating circulation water as heating target water.

  In Embodiment 1 described above, the heat pump cycle is a supercritical heat pump cycle in which the pressure of the refrigerant is equal to or higher than the critical pressure, but may be a heat pump cycle that is equal to or lower than a general critical pressure. In this case, chlorofluorocarbon, ammonia, or the like may be used as the refrigerant.

10 Hot water storage tank 22 Use side heat exchanger 50 Bathtub
51 Bath Water Circulation Circuit (Water Circulation Circuit)
52 Secondary circulation pump (water circulation means)
53 Bathtub side thermistor (temperature detection means)
60 Heat pump unit (heating means)
70 Control unit (selection means)
100 Hot water storage water heater

Claims (3)

A hot water storage tank for storing hot water heated using a heat pump;
A water circulation means having a water circulation circuit connected to the tank in which the water to be heated is stored, and circulating the water to be heated using the water circulation circuit;
Heating means for heating water to be heated flowing in the water circulation circuit;
Temperature detecting means for detecting the temperature of the water to be heated;
A heat retaining means for increasing the temperature of the water to be heated using the heating means when the temperature of the water to be heated is lowered,
The heating means includes
Hot water replenishing means for exchanging heat between the hot water stored in the hot water storage tank and the water to be heated flowing in the water circulation circuit while the heat pump is stopped;
A heat pump direct replenishing means for exchanging heat between the high-temperature water heated using the heat pump and the water to be heated flowing in the water circulation circuit during the operation of the heat pump;
The heat retaining means raises the temperature of the water to be heated using the hot water storage reheating means when the heat target water cannot be heated to a predetermined target temperature within a predetermined time by the heat pump direct reheating means. A hot water storage water heater characterized by that. The heat retaining means includes
Determining means for determining whether the temperature of the water to be heated is lower than a predetermined heating start temperature at each predetermined timing during the heat retention operation;
When it is determined that the temperature of the water to be heated is lower than the heating start temperature, a selection unit that selects one of the heat pump direct reheating unit and the hot water storage replenishing unit, and
The selection means preferentially selects the heat pump direct reheating means, and when the heating target water cannot be raised to the target temperature within a predetermined time using the heat pump direct reheating means, The hot water storage type hot water supply apparatus according to claim 1, wherein the hot water storage reheating means is selected in the selection after the next time during the heat insulation operation. The heat retaining means includes
Determining means for determining whether the temperature of the water to be heated is lower than a predetermined heating start temperature at each predetermined timing during the heat retention operation;
When it is determined that the temperature of the water to be heated is lower than the heating start temperature, a selection unit that selects one of the heat pump direct reheating unit and the hot water storage replenishing unit, and
When the temperature of the heating target water belongs to a temperature range from the heating start temperature to a predetermined determination temperature lower than the heating start temperature, the selection unit selects the heat pump direct reheating means, and the heating target water 2. The hot water storage type hot water supply apparatus according to claim 1, wherein when the temperature of the hot water belongs to a temperature range lower than the determination temperature, the hot water storage reheating unit is selected.

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