JP5094217B2 - Heat pump water heater - Google Patents

Description

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

  The heat pump hot water supply apparatus is roughly classified into a hot water storage type heat pump hot water supply apparatus as in Patent Document 1 and an instantaneous heat pump hot water supply apparatus as in Patent Document 2.

  The hot water storage type heat pump hot water supply device has a heating capacity of 4.5 to 6.0 kW, is heated to 65 to 90 ° C. hot water using cheap nighttime power at midnight, and 300 to 480 L of hot water is stored in the hot water storage tank. Store. During hot water supply during the day, water is mixed with high-temperature hot water stored in a hot water storage tank.

  On the other hand, in the instantaneous heat pump hot water supply device, the temperature of the water introduced from the water supply pipe is raised by the water heat exchanger and hot water is supplied to the use terminal as it is, thus eliminating the need for a large hot water storage tank. Until the pressure condition immediately after the start of operation of the heat pump circuit is stabilized, sufficient heat of condensation cannot be generated to warm the water. Hot water is mixed with water from the exchanger.

JP 2005-134070 A JP 2003-279133 A

  In the hot water storage type heat pump hot water supply device described in Patent Document 1, since hot water stored in the hot water storage tank is mixed with water, the hot water in the hot water storage tank having a temperature lower than the desired hot water supply set temperature is effective. It cannot be used. For example, after boiling the hot water storage tank, hot water at the required temperature can be supplied to the hot water in the hot water storage tank whose temperature has dropped below the hot water supply set temperature due to heat dissipation, etc., even though a large amount of heat remains. Cannot be done (in this way, hot water in a hot water storage tank having a large amount of heat, although the temperature is lower than the hot water supply set temperature) will be referred to as intermediate hot water.

  For this reason, reheating is necessary. Considering the efficiency at the time of boiling, the higher the incoming water temperature to the heat pump water heater, the lower the COP, which is the ratio of the water heating capacity to the power consumption of the heat pump, so-called energy efficiency. In other words, it is less energy efficient to boil hot water having a high temperature such as an intermediate hot water portion than to boil water having a low temperature such as water supplied from a water pipe. Moreover, the energy efficiency at the time of boiling falls, so that there is much amount of intermediate temperature hot water.

  Moreover, in the instantaneous heat pump hot water supply apparatus described in Patent Document 2, hot water stored in a small hot water supply tank is mixed with hot water from the water heat exchanger for a short time from the start of operation until the instantaneous circuit starts up. Hot water at a desired temperature is supplied. For this reason, the hot water in the hot water supply tank whose temperature is lower than the hot water supply set temperature cannot be used. If the effective hot water storage amount decreases due to a long time required for starting up, the temperature of the hot water in the hot water supply tank may be lower than the preset hot water supply temperature. Then, it is necessary to boil again the hot water supply tank containing the middle temperature remaining hot water which has a big calorie | heat amount. This boiling is performed after the hot water supply is stopped. The efficiency at the time of boiling is as described above.

  In addition, as with the hot water storage tank of the hot water storage type heat pump hot water supply device, for example, after boiling the hot water tank, the intermediate temperature hot water in the hot water storage tank whose temperature is lower than the set hot water temperature due to heat dissipation or the like has a large amount of heat remaining. Nevertheless, hot water at the required temperature cannot be supplied. For this reason, reheating is necessary. The efficiency at the time of boiling is as described above.

  This invention is made | formed in view of the said prior art, The objective is to reduce the amount of middle temperature remaining hot water in a heat pump hot-water supply apparatus.

The present invention relates to a compressor, a water-refrigerant heat exchanger that performs heat exchange between water and a refrigerant, a decompression device that depressurizes refrigerant from the water-refrigerant heat exchanger, and air that performs heat exchange between air and the refrigerant. A heat pump refrigerant circuit connected to a refrigerant heat exchanger, the water refrigerant heat exchanger, a hot water storage tank for storing water heat-exchanged in the water refrigerant heat exchanger, and a circulation pump for circulating water in the hot water storage tank A heat pump water heater comprising a hot water storage circuit, a tank hot water circuit for supplying hot water in the hot water storage tank from a hot water supply terminal, and an operation control means for controlling the operation of the heat pump water heater. Sometimes, the presence or absence of operation of the heat pump refrigerant circuit is determined according to a time zone .

In the above , the temperature of the hot water in the hot water storage tank from the state where hot water generated in the heat pump refrigerant circuit and hot water discharged from the hot water storage tank are mixed and supplied to the hot water supply terminal at a hot water supply set temperature. However, when the temperature is lower than the set temperature of the hot water supply, it has a control device for increasing the number of revolutions of the compressor, and the hot water generated in the heat pump refrigerant circuit is diluted with the hot water discharged from the hot water storage tank to the hot water supply terminal. It is preferable to supply.

  According to the present invention, it is possible to reduce the amount of intermediate temperature hot water in the tank.

  Hereinafter, an embodiment of a heat pump hot water supply apparatus according to the present invention will be described with reference to the drawings. The system diagram of the heat pump hot water supply apparatus 100 is shown in FIGS. The heat pump hot water supply apparatus 100 is roughly divided into a heat pump refrigerant circuit 90 and a water supply circuit 91, a hot water supply circuit 92, a bath hot water filling circuit 93, a bath reheating heating circuit 94, a bath reheating heat absorption circuit 95, and a tank boiling back circuit 96. Yes.

  Next, the configuration of each circuit will be described below.

  The heat pump refrigerant circuit 90 (FIGS. 1 and 2A) in the present embodiment includes two refrigerant circuits in order to further increase the instantaneous hot water supply capacity. A single refrigerant circuit may be used as long as the amount of heat that can maintain an appropriate amount of hot water as a hot water supply device is obtained. The refrigerant of the heat pump refrigerant circuit 90 is carbon dioxide, so that hot water can be supplied.

  In the first heat pump refrigerant circuit 90a, the compressor 1a that compresses the refrigerant into a high-temperature refrigerant, the refrigerant that has been compressed by the compressor 1a to a high temperature, and the water (water supply) supplied for hot water supply are heated. A water refrigerant heat exchanger 2 to be exchanged, an expansion valve 3a for depressurizing the refrigerant exiting the water refrigerant heat exchanger 2, and an evaporator 4a for evaporating the low-temperature and low-pressure refrigerant exiting the expansion valve 3a are connected by a refrigerant line. Configured.

  Similarly to the first refrigerant circuit 90a, the second heat pump refrigerant circuit 90b also compresses the refrigerant into a high-temperature refrigerant, the compressor 1b that is compressed by the compressor 1b, and the high-temperature refrigerant and hot water supply. A water refrigerant heat exchanger 2 that exchanges heat with water (water supply) supplied for the purpose, an expansion valve 3b that depressurizes the refrigerant that exits the water refrigerant heat exchanger 2, and a low-temperature and low-pressure refrigerant that exits the expansion valve 3b The evaporator 4b for evaporating the water is connected by a refrigerant pipe.

  The compressors 1a and 1b can be controlled in capacity by inverter control, and the rotation speed is variable from a low speed (for example, 1000 rpm) to a high speed (for example, 6000 rpm). The evaporators 4a and 4b are air refrigerant heat exchangers, and exchange heat between a large amount of outdoor air and the decompressed refrigerant by the outdoor fans 5a and 5b.

  The water-refrigerant heat exchanger 2 includes refrigerant-side heat transfer tubes 2a, 2b and water-side heat transfer tubes 2c, 2d. The refrigerant flow in the refrigerant-side heat transfer tubes 2a, 2b and the water-side heat transfer tubes 2c, 2d It is opposite to the water flow. Then, the high-temperature and high-pressure refrigerant and the low-temperature water exchange heat. That is, when the water having a low temperature passes through the water-side heat transfer tubes 2c and 2d at the inlet of the water-refrigerant heat exchanger 2 (the lower side of the water-refrigerant heat exchanger 2 in the drawing), the water-refrigerant is gradually heated. The temperature is raised to a predetermined temperature set by the control device 120 described later at the outlet of the heat exchanger 2 (upper side of the water-refrigerant heat exchanger 2 in the drawing).

  A water supply circuit 91 (FIGS. 1 and 2B) includes a water supply fitting 11 for taking in clean water from the outside, a pressure reducing valve 12 for adjusting the fetched clean water to an appropriate water pressure, and a feed water flow sensor for measuring the feed water flow rate. 13. Water refrigerant heat exchanger flow rate sensor 15 for measuring how much water supply flows to the water refrigerant heat exchanger 2, in order to prevent water from flowing back from the water refrigerant heat exchanger 2 side to the water supply fitting 11 side The check valve 14 is provided. From the water supply fitting 11 to the water-side heat transfer tubes 2c, 2d of the water refrigerant heat exchanger 2 are connected by a water pipe, and these members are provided in the water pipe.

  The hot water supply circuit 92 (FIGS. 1 and 2 (c)) includes water pipes from the water side heat transfer pipes 2c and 2d of the water / refrigerant heat exchanger 2 to the hot water supply fitting 19 connected to the hot water supply pipe outside the apparatus, members, including. Between the water-refrigerant heat exchanger 2 and the hot-water supply fitting 19, a first hot-water mixing valve 16 used for mixing hot water heated by the water-side heat transfer tubes 2c, 2d and hot water stored in the hot-water storage tank 21; The second hot water mixing valve 17 used for mixing the water supplied from the water supply circuit 91 with the hot water passing through the first hot water mixing valve 16 and the flow rate for adjusting the flow rate of the hot water passing through the second hot water mixing valve 17 A regulating valve 18 is arranged.

  A circuit from the hot water storage tank 21 through a part of the hot water supply circuit 92 to the hot water supply fitting 19 is referred to as a tank hot water supply circuit 92T. When hot water is supplied by the tank hot water supply circuit 92 </ b> T, the same amount of water that is discharged from the hot water storage tank 21 must flow from the lower portion 21 c of the hot water storage tank 21.

  One inlet of the first hot water mixing valve 16 is connected to the upper part 21 a of the hot water storage tank 21. Further, the lower part 21c of the hot water storage tank 21 is connected to the water supply circuit 91 at a point AA. The hot water storage tank 21 is used to store hot water of about 60 to 90 ° C. preheated by the water / refrigerant heat exchanger 2 of the tank boiling back circuit 96 (FIGS. 1 and 3C). The first hot water / mixing valve 16 is used to mix hot water stored in the hot water storage tank 21 with hot water supplied from the water / refrigerant heat exchanger 2 according to a command from the control device 120. Specifically, the hot water stored in the hot water storage tank 21 is mixed from the first hot water / water mixing valve 16 until the hot water heated by the water / refrigerant heat exchanger 2 is heated to a desired temperature. As a result, hot water of a predetermined temperature set by the control device 120 flows out. At this time, the water supplied from the water supply fitting 11 (all or a part thereof) is diverted at the point AA to the hot water storage tank 21 and the water refrigerant heat exchanger 2. Hot water from the water-refrigerant heat exchanger 2 and hot water from the hot water storage tank 21 are joined together by the first hot water / water mixing valve 16. Further, from the first hot water / water mixing valve 16, hot water in the hot water storage tank 21 having a low temperature and hot water heated by the water / refrigerant heat exchanger 2 are mixed as described later, and the controller 120 Hot water of a predetermined temperature set is discharged.

  One inlet of the second hot water / mixing valve 17 is connected to a water pipe. This water pipe is branched from the water supply circuit 91 (around “C” in FIGS. 2B and 2C). That is, a part of the water supplied from the water supply fitting 11 can flow. In the second hot water / mixing valve 17, the hot water mixed by the first hot / water mixing valve 16 and the water branched from the water supply circuit 91 can be mixed in accordance with a command from the control device 120. It can be said that the second hot water / water mixing valve 17 is a valve for fine adjustment of the temperature just before the hot water supply. The control device 120 opens and closes the first hot water mixing valve 16 and the second hot water mixing valve 17 in order to discharge hot water having a predetermined hot water supply temperature (about 35 to 60 ° C.) to the hot water terminal via the hot water supply fitting 19. To control.

  The bath hot water filling circuit 93 (FIGS. 1 and 3A) branches from a pipe line 19 a that connects the flow rate adjusting valve 18 of the hot water supply circuit 92 and the hot water supply fitting 19. The bath hot water filling circuit 93 includes up to a metal fitting 35 for supplying hot water from the branch portion 19a to the bathtub 36. In the piping of the bath hot water filling circuit 93, a pouring solenoid valve 31 and a flow switch 32, a bath circulation pump 33, a water level sensor 34, and a hot water inlet / outlet fitting 35 are sequentially arranged.

  The hot water solenoid valve 31 is used to guide hot water from the branch portion 19a to the bathtub 36 side. The flow switch 32 detects the flow of hot water in the bath hot water filling circuit 93. The bath circulation pump 33 is used to supply hot water from the bathtub 36 to the bath chase heat exchanger 29 during bath chase. The water level sensor 34 detects the water level of the hot water poured into the bathtub 36. The bath metal fitting 35 and the bath circulation adapter 36a attached to the bathtub 36 are connected by a water pipeline.

  The bath reheating heating circuit 94 (FIG. 1 and FIG. 3B) is a circuit for reheating the hot water in the bathtub 36 and has a bath reheating heat exchanger 29. The in-machine circulation pump 23 connected to the outlet side of the secondary refrigerant side heat transfer tube 29 a of the bath reheating heat exchanger 29 supplies water to the water side heat transfer tubes 2 c and 2 d of the water refrigerant heat exchanger 2. The water-side heat transfer tubes 2c and 2d heat water. Heated and heated water (high temperature water) passes through a follow-up electromagnetic valve 27 and a check valve 28 provided in a pipe branched from the hot water supply circuit 92. Here, while the bath reheating heating circuit 94 is in operation, the reheating electromagnetic valve 27 is in an open state.

  The high-temperature water that has passed through the check valve 28 flows into the secondary refrigerant side heat transfer tube 29 a of the bath reheating heat exchanger 29. In the bath reheating heat exchanger 29, the flow of high temperature water in the secondary refrigerant side heat transfer tube 29a and the flow of hot water in the bathtub water side heat transfer tube 29b form a counter flow. The high-temperature water that has exchanged heat with the hot water in the bathtub water-side heat transfer tube 29 b is lowered in temperature to become low-temperature water, and flows into the in-machine circulation pump 23. Thereafter, the low-temperature water is returned to the water / refrigerant heat exchanger 2 from the water pipe connected to the downstream side of the check valve 14 of the water supply circuit 91. Thereafter, water continues to circulate through the bath reheating heating circuit 94 while the bath renewal operation is continued.

  The bath reheating endothermic circuit 95 (FIGS. 1 and 3B) is a circuit for heating hot water in the bathtub 36. The bath water is supplied from the bath circulation adapter 36a provided in the bathtub 36 through the metal fitting 35. Lead to the bath heat exchanger 29. The bathtub water taken out from the bathtub 36 is guided to the bath circulation pump 33 through the water level sensor 34. The bath circulation pump 33 pressurizes the bath water and supplies it to the bath reheating heat exchanger 29 via the flow switch 32. At this time, the pouring solenoid valve 31 provided in the bath hot water filling circuit 93 is closed to guide the bath water to the bath reheating heat exchanger 29. The bath water is heated when flowing through the bath water side heat transfer tube 29 b of the bath reheating heat exchanger 29, and is returned to the bath circulation adapter 36 a via the hot water inlet / outlet fitting 37.

  The tank boiling back circuit 96 (FIGS. 1 and 3C) is a circuit that guides the hot water heated by the water / refrigerant heat exchanger 2 to the hot water storage tank 21. The tank boiling back circuit 96 includes a hot water storage tank 21, an in-machine circulation pump 23 for feeding hot water to the hot water storage tank, and a first hot water mixing valve 16. When the tank boiling back circuit 96 is operated, the reheating electromagnetic valve 27 of the bath reheating heating circuit 94 is closed. The first hot water / water mixing valve 16 allows the water / refrigerant heat exchanger 2 side and the hot water storage tank 21 to communicate with each other. The second hot water / mixing valve 17 shuts off the first hot water / mixing valve 16 and the water supply side. In this state, the in-machine circulation pump 23 is operated to supply the water in the hot water storage tank 21 from the lower part 21 c of the hot water storage tank 21 to the water refrigerant heat exchanger 2. The hot water stored in the hot water storage tank 21 is heated to about 60 to 90 ° C. by the water / refrigerant heat exchanger 2, and returned to the upper portion 21 a of the hot water storage tank 21 through the first hot water / water mixing valve 16.

  Then, hot water is stored in the upper part of the hot water storage tank 21, and low temperature hot water that is not hot is pushed out from the lower part. The hot water storage state in the hot water storage tank 21 is known as a layer separation state, and has a continuous temperature distribution from the top to high temperature, medium temperature, and low temperature. A part of the medium temperature hot water remains as a medium temperature hot water having a sufficient amount of heat but having a temperature lower than the hot water supply set temperature. The end of the boil-back is when the water refrigerant heat exchanger water outlet temperature sensor 62 reaches a predetermined temperature. Then, the medium hot water is pushed out from the lower part of the hot water storage tank 21 and the hot water is pushed out to complete the reboiling. The temperature difference in the water-refrigerant heat exchanger 2 is large at the stage where the low-temperature water is pushed out, that is, it can be boiled back in a state where the heat exchange efficiency is good. Will decline.

  When the set temperature is boiled back at 60 ° C. (or 90 ° C.), for example, most of the tank only needs to be hot water of 60 ° C. (or 90 ° C.), so the water refrigerant heat exchanger water inlet temperature sensor 61 When (or 60 ° C.) is detected, the boil-back is finished.

  In addition, when starting up the heat pump refrigerant circuit 90, the heating capability of the heat pump refrigerant circuit 90 is not sufficient. Therefore, a preheating operation is performed using the bath reheating heating circuit 94 until the water refrigerant heat exchanger 2 can heat water at a predetermined temperature. Specifically, the reheating electromagnetic valve 27 is opened, and the water / refrigerant heat exchanger 2 side of the first hot water / mixing valve 16 and the hot water storage tank 21 are shut off. The first hot water mixing valve 16 side and the water supply side of the second hot water mixing valve 17 are also shut off. In this state, the in-machine circulation pump 23 is operated so that water circulates between the water refrigerant heat exchanger 2 and the bath-heating heat exchanger 29.

  A specific operation of the control device 120 that operates the circuit will be described below. The control device 120 operates / stops the heat pump refrigerant circuit 90. Moreover, the rotational speed of compressor 1a, 1b and the opening degree of expansion valve 3a, 3b are controlled. Further, water-related devices such as the hot and cold mixing valves 16 and 17 and the flow rate adjusting valve 18 of the hot water supply circuit 92 are also controlled.

  The heat pump hot water supply apparatus 100 shown in the present embodiment is provided with compressor discharge pressure sensors 51a and 51b on the discharge side of the compressors 1a and 1b of the heat pump refrigerant circuit 90. Furthermore, the heat pump hot water supply device 100 includes a number of temperature sensors including those not shown, and these are connected to the control device 120.

  In the heat pump refrigerant circuit 90, compressor discharge temperature sensors 50a and 50b are provided on the discharge side of the compressors 1a and 1b, evaporator refrigerant inlet temperature sensors 52a and 52b are provided on the refrigerant inlet side of the evaporators 4a and 4b, and refrigerant outlet side is provided. Are provided with evaporator refrigerant outlet temperature sensors 53a and 53b, and the evaporator 4 (or the vicinity thereof) is provided with outside air temperature sensors 54a and 54b. In the water supply circuit 91, a water supply temperature sensor 60 is provided in the vicinity of the water supply fitting 11, and a water refrigerant heat exchanger water inlet temperature sensor 61 is provided upstream of the water inlet side of the water refrigerant heat exchanger 2. In the hot water supply circuit 92, a water refrigerant heat exchanger water outlet temperature sensor 62 is provided downstream of the water outlet side of the water refrigerant heat exchanger 2, and a mixing temperature between the first hot water mixing valve 16 and the second hot water mixing valve 17. A sensor 63 has a hot water supply temperature sensor 64 in the hot water supply line downstream of the second hot water / water mixing valve 17, and a plurality of tank temperature sensors 65 a, 65 b, 65 c in order from the top, changing the position on the side wall of the hot water storage tank 21. Are provided. As will be described later, the tank temperature sensor 65a serves to detect a temperature that is a prerequisite for performing the boil-back operation.

  In heat pump hot water supply apparatus 100 in which various sensors are arranged in this way, when a user sets a desired hot water supply temperature Tws using a remote controller (not shown) disposed in the house, controller 120 supplies hot water at a desired temperature. Each valve is controlled so that hot water can be supplied. That is, the control device 120 sets the target temperature Twb of the hot water supply temperature sensor 64 provided downstream of the second hot water / water mixing valve 17 to a temperature (Tws + α1) higher by α1 than the set hot water supply temperature. The target temperature Twk of the mixing temperature sensor 63 provided between the first hot water mixing valve 16 and the second hot water mixing valve 17 is set to (Tws + α1 + α2) higher by α2 than this temperature. The target temperature Twh of the water refrigerant heat exchanger water outlet temperature sensor 62 is set to a higher temperature (Tws + α1 + α2 + α3 + α4) by (α3 + α4). α4 will be described later.

  Here, α1 to α3 are set for the following reason. In this embodiment, in consideration of heat radiation in the water pipeline, the target temperature is set higher as the upstream side of the hot water supply circuit 92 becomes closer to the water refrigerant heat exchanger 2. Even if the outlet temperature of the water-side heat transfer tubes 2c, 2d of the water-refrigerant heat exchanger 2 or the mixing temperature of the hot water flowing out of the first hot / cold water mixing valve 16 fluctuates somewhat due to disturbance or the like, the desired hot water supply temperature is exceeded. Since the temperature is set slightly higher, it can be adjusted to a desired temperature by controlling the amount of water mixed with the hot water flowing into the second hot water mixing valve 17. As a result, hot water supply with little temperature fluctuation can be realized.

  The above α4 is when the temperature of the hot water in the hot water storage tank 21 becomes lower than the target value of the mixing temperature sensor 63, that is, the amount of heat remaining in the hot water storage tank 21 is low but the temperature is low. In order to use hot water effectively, it is set by the control device 120 based on the following conditions.

This will be described with reference to the flowchart of FIG. When the temperature Twu of the tank temperature sensor 65a provided in the upper part of the hot water storage tank 21 is equal to or lower than the temperature Twi of the feed water temperature sensor 60 + the correction value β (130Y), that is, it is determined that there is no heat quantity available in the hot water storage tank 21. If you want to
α4 = 0 (Formula 1)
Is set (131). Here, the correction value β is a correction value for determining the presence or absence of the amount of heat in the hot water storage tank 21.

On the other hand, when the temperature Twu of the tank temperature sensor 65a is higher than the temperature Twi of the feed water temperature sensor 60 + the correction value β (130N), that is, when the necessary amount of heat remains in the hot water storage tank 21, the following conditions are satisfied. α4 is set. When the temperature Twu of the tank temperature sensor 65a of the hot water storage tank 21 is higher than the target value Twk of the mixing temperature sensor 63 (132Y), that is, when there is hot water at a sufficiently high temperature in the hot water storage tank 21,
α4 = 0 (Formula 2)
Is set (133).

On the other hand, when the temperature Twu of the tank temperature sensor 65a is equal to or lower than the target value Twk of the mixed temperature sensor 63 (132N), that is, the temperature is not sufficiently high in the hot water storage tank 21, but the necessary amount of heat remains.
α4 = (Twk−Twu) × k (Formula 3)
Is set (134).

  Here, the coefficient k is a coefficient for setting the mixing ratio of the hot water from the water-refrigerant heat exchanger 2 and the hot water from the hot water storage tank 21. For example, when k = 0.25, the target temperature Twh of the water / refrigerant heat exchanger water outlet temperature sensor 62 is set to the target value Twk of the mixed temperature sensor 63 and the tank temperature sensor 65a as compared with the normal case of α4 = 0. The temperature difference from the temperature Twu is set to a quarter of the temperature difference.

  At this time, when the temperature of the water-refrigerant heat exchanger water outlet temperature sensor 62 is the target temperature Twh, if α3 is neglected because it is a minute amount, the equations (100) to (100) to (100) to ( 300) holds. First, the hot water (temperature Twh) from the water-refrigerant heat exchanger 2 and the hot water (temperature Twu) from the hot water storage tank 21 are mixed to obtain mixed hot water (temperature Twk). Further, as described above, the formula (200) is assumed. From these, equation (300) is obtained, and the mixing ratio of hot water from the water-refrigerant heat exchanger 2 and hot water from the hot water storage tank 21 is 4 to 1 when k = 0.25. In the figure, x represents the flow rate ratio from the water-refrigerant heat exchanger 2.

  In this way, the coefficient k is set so that the amount of hot water from the water-refrigerant heat exchanger 2 is greater than the amount of hot water from the hot water storage tank 21, so that during the hot water supply, the temperature Twu of the tank temperature sensor 65a is the water temperature sensor. Even when the temperature Twi of 60 is equal to or less than the correction value β, that is, when there is no necessary amount of heat in the hot water storage tank 21 and no hot water is supplied from the hot water storage tank 21, a temporary reduction in the amount of hot water is minimized. Can be suppressed.

  FIG. 4 is a flowchart for setting the addition value α4 to the water outlet temperature target value of the water / refrigerant heat exchanger, and FIG. 5 is a flowchart for setting the opening degree Ft of the first hot / cold water mixing valve. α4 and Ft are set independently from a predetermined temperature.

Next, the details of the opening degree control of the first hot water mixing valve 16 will be described. This will be described with reference to the flowchart of FIG. The opening degree Ft of the first hot / cold water mixing valve 16 is expressed as a ratio (%) of the flow rate on the water refrigerant heat exchanger 2 side to the total flow rate of the first hot / cold water mixing valve 16. 0% indicates the fully open degree on the hot water storage tank 21 side, and 100% indicates the fully open degree on the water refrigerant heat exchanger 2 side. First, when the temperature Twu of the tank temperature sensor 65a is equal to or lower than (temperature Twi of the feed water temperature sensor 60 + correction value β) (138Y), that is, when the necessary amount of heat is exhausted in the hot water storage tank 21, the first hot water mixing is performed. The opening degree Ft of the valve 16 is Ft = 100 (Equation 4)
(139), and the hot water supply in the hot water storage tank 21 is stopped.

  A case where the temperature Twu of the tank temperature sensor 65a is higher than the temperature Twi + correction value β of the feed water temperature sensor 60 (138N), that is, a case where there is a necessary amount of heat in the hot water storage tank 21 will be described below. When the temperature Two of the water outlet temperature sensor 62 of the water-refrigerant heat exchanger 2 is equal to or higher than the temperature Twu of the tank temperature sensor 65a at the upper part of the hot water storage tank 21 (140Y), the opening degree of the first hot water / water mixing valve 16 for each of the following conditions: Set Ft.

When the temperature Twu of the tank temperature sensor 65a is equal to or higher than the target value Twk of the mixed temperature sensor 63 (141Y), that is, when Two ≧ Twu ≧ Twk,
Ft = 100 (Formula 5)
Is set (142). At this time, since the temperature of the hot water from the water refrigerant heat exchanger 2 and the temperature of the hot water in the hot water storage tank 21 are equal to or higher than the target value of the mixing temperature, the hot water in the hot water storage tank 21 is not used and the water refrigerant heat exchanger is used. Only hot water from 2 is used, and when the temperature is higher than this target value, hot water at a desired temperature is supplied from the hot water supply port by mixing the water with the second hot water mixing valve 17 downstream. That is, there is no need to use hot water in the hot water storage tank 21.

Next, when the target value Twk of the mixed temperature sensor 63 is equal to or higher than the temperature Two of the water refrigerant heat exchanger water outlet temperature sensor 62 (143Y), that is, when Twk ≧ Two ≧ Twu,
Ft = 100 (Formula 6)
Is set (144). At this time, the temperature of the hot water from the water-refrigerant heat exchanger 2 and the temperature of the hot water in the hot water storage tank 21 are both equal to or lower than the target value of the mixing temperature. Since the temperature is higher than the temperature of hot water in the tank 21, only hot water from the water-refrigerant heat exchanger 2 is used. That is, the hot water in the hot water storage tank 21 cannot be used and cannot be used.

Next, when the target value Twk of the mixed temperature sensor 63 is lower than the temperature Two of the water refrigerant heat exchanger water outlet temperature sensor 62 (143N), that is, when Two>Twk> Twu,
Ft = (Twu−Twk) / (Twu−Two) × 100 (Expression 7)
Is set (145). At this time, hot water from the water-refrigerant heat exchanger 2 whose temperature is higher than the target value of the mixing temperature and hot water in the hot water storage tank 21 whose temperature is lower than the target value of the mixing temperature are mixed. That is, the temperature is adjusted by simmering with hot water in the hot water storage tank 21 instead of water. This is executed together with the case where the target temperature Twh of the water refrigerant heat exchanger water outlet temperature sensor 62 is set higher than usual (step 134 in FIG. 4). As a result, the hot water in the hot water storage tank 21 that has a sufficient amount of heat but has a low temperature and is difficult to use can be used effectively.

On the other hand, when the temperature Two of the water outlet temperature sensor 62 of the water-refrigerant heat exchanger 2 is lower than the temperature Twu of the tank temperature sensor 65a in the upper part of the hot water storage tank 21 (140N), the first hot water mixing valve 16 is turned on for each of the following conditions. The opening degree Ft is set. When the target value Twk of the mixed temperature sensor 63 is equal to or higher than the temperature Twu of the tank temperature sensor 65a (146Y), that is, when Twk ≧ Twu> Two,
Ft = 10 (Formula 8)
And set. At this time, the temperature of the hot water in the hot water storage tank 21 is equal to or lower than the target value of the mixing temperature, but is higher than the temperature of the hot water from the water-refrigerant heat exchanger 2, so the hot water in the hot water storage tank 21 is used preferentially. That is, even if the temperature of the hot water in the hot water storage tank 21 is low, the hot water in the hot water storage tank 21 is used until the water refrigerant heat exchanger 2 starts up. Here, the hot water on the hot water storage tank 21 side having a higher temperature than the hot water from the water refrigerant heat exchanger 2 is not flowed at all (Ft = 0%), but the hot water on the water refrigerant heat exchanger 2 side is flowed at a small flow rate (10 %) The reason for flowing is to stabilize the operation of the heat pump refrigerant circuit 90 by constantly applying a hot water supply load to the heat pump refrigerant circuit 90 even at a small flow rate. If Ft = 0% and the water in the water refrigerant heat exchanger 2 is stopped, the load for removing the heat generated in the heat pump refrigerant circuit 90 is lost, and the refrigerant side of the water refrigerant heat exchanger 2 is more than expected. This is because there is a risk that a high temperature and high pressure may occur. Therefore, the small flow rate is an amount that does not cause a problem and may be equal to or less than the amount of hot water discharged from the hot water storage tank, and here, Ft ≦ 20%.

Next, when the temperature Two of the water refrigerant heat exchanger water outlet temperature sensor 62 is equal to or higher than the target value Twk of the mixing temperature sensor 63 (148Y), that is, when Twu> Two ≧ Twk,
Ft = 100 (Formula 9)
Is set (149). At this time, similarly to the above-described steps 141Y and 142, the temperature of the hot water from the water / refrigerant heat exchanger 2 and the temperature of the hot water in the hot water storage tank 21 are equal to or higher than the target value of the mixing temperature. Hot water is not used, only hot water from the water-refrigerant heat exchanger 2 is used. When the temperature is higher than this target value, water is mixed by the second hot water mixing valve 17 downstream, so that hot water having a desired temperature is mixed. Supply.

Finally, when the temperature Two of the water refrigerant heat exchanger water outlet temperature sensor 62 is lower than the target value Twk of the mixing temperature sensor 63 (148N), that is, when Twu>Twk> Two,
Ft = (Twu−Twk) / (Twu−Two) × 100 (Equation 10)
Is set (150). At this time, the hot water storage tank 21 hot water having a temperature higher than the target value of the mixing temperature and the hot water from the water-refrigerant heat exchanger 2 having a temperature lower than the target value of the mixing temperature are mixed. For example, when the heat pump refrigerant circuit 90 starts up, the temperature of the hot water in the hot water storage tank 21 is sufficiently high, and the hot water from the water refrigerant heat exchanger 2 has not reached the predetermined target temperature Twh set by the control device 120. Executed. That is, the responsiveness is improved by using the hot water storage tank 21 until the water refrigerant heat exchanger 2 is started up. From another point of view, the hot water from the hot water storage tank 21 is warmed with hot water from the water-refrigerant heat exchanger 2.

  When operating the heat pump refrigerant circuit 90, the control device 120 controls the rotational speed of the compressors 1a and 1b. Since the heat capacity of the refrigerant circulation system including the water-refrigerant heat exchanger 2 is large, the water outlet temperature of the water-refrigerant heat exchanger 2 does not change immediately even if the rotation speed of the compressors 1a, 1b is changed. The response speed of the water outlet temperature is slow. Therefore, the discharge pressures of the compressors 1a and 1b, which are characteristics related to the water outlet temperature of the water-refrigerant heat exchanger 2 and have a fast response speed, are determined as control targets. In the instantaneous heat pump hot water supply device, there is a problem that if the heat pump refrigerant circuit 90 rises slowly, the amount of hot water supplied from the hot water storage tank increases. Therefore, the rise characteristic is improved as follows.

  The discharge pressure of the compressors 1a and 1b is higher as the water outlet temperature of the water-refrigerant heat exchanger 2 is higher. The target discharge pressure Pd0 is expressed as (Equation 11) as a function of a water outlet temperature target value Twh (= Tws + α1 + α2 + α3 + α4) of the water-refrigerant heat exchanger 2.

Pd0 = f (Twh) (Formula 11)
The rotational speeds of the compressors 1a and 1b are controlled so that the deviation ΔEpd (= Pd0−Pd) between the target discharge pressure Pd0 and the actual discharge pressure Pd becomes zero. At this time, for example, the rotational speeds of the compressors 1a and 1b are increased or decreased as a function of the deviation ΔEpd and (deviation ΔEpd−previous deviation ΔEpd).

  Even if the actual discharge pressure Pd has reached the target discharge pressure Pd0 due to the influence of the flow rate of water flowing through the heat pump refrigerant circuit 90, the water outlet temperature of the water refrigerant heat exchanger 2 is also expected to deviate from the target value. Therefore, the target discharge pressure Pd0 is corrected as needed so that the water outlet temperature of the water-refrigerant heat exchanger 2 approaches the target value Twh.

  That is, when the control device 120 controls the rotation speed of the compressors 1a and 1b, the water outlet temperature of the water-refrigerant heat exchanger 2 is determined based on the flow rate determined by the opening of the user's faucet or the like. Control is performed so as to have the value Twh. Target value Twh is set based on hot water supply temperature Tws set by the remote controller. Further, the opening degree of the expansion valve 3a is controlled so that the degree of superheat of the refrigeration cycle of the first heat pump refrigerant circuit 90a is controlled. Specifically, the opening degree of the expansion valve 3a is controlled so that the degree of superheat that is the temperature difference between the refrigerant outlet temperature and the refrigerant inlet temperature of the evaporator 4a becomes a predetermined value. The same applies to the refrigeration cycle of the second heat pump refrigerant circuit 90b.

  The state of the refrigeration cycle can be changed by changing the degree of superheat of the heat pump refrigerant circuits 90a and 90b. Therefore, the refrigeration cycle state with high energy efficiency can be maintained by controlling the opening degree of the expansion valve so as to achieve a predetermined degree of superheat.

  Hereinafter, three typical examples of the operation of the heat pump water heater 100 will be described.

  The first example relates to hot water supply at a relatively early stage (stage where there is plenty of high-temperature hot water) after the tank boiling-back operation, for example. This is when there is high hot water.

  The second example occurs, for example, when hot water is supplied several times after the tank boiling-back operation, and the hot water in the hot water storage tank 21 becomes low. This is a case where, after rising, hot water has remained in the hot water storage tank 21 after starting up, but has become hot water (intermediate hot water) whose temperature is lower than the set hot water temperature.

  The third example occurs, for example, when the heat is radiated over time after the tank boil-back operation and the temperature of the hot water in the hot water storage tank 21 is lowered, that is, when the hot water is in the middle temperature. There is no hot water in the hot water storage tank 21 at the time of start-up, and there is intermediate hot water.

  First, a case where hot water having a sufficiently high temperature is present in the hot water storage tank 21 both at the time of rising and after the rising will be described with reference to FIGS.

  When a user-desired hot water supply temperature Tws is set by a remote controller (not shown) and a faucet (not shown) connected to the hot water fitting 19 is opened, the water flowing in from the water fitting 11 by the water pressure is supplied to the pressure reducing valve 12 and Water supply flow sensor 13, check valve 14, water refrigerant heat exchanger flow sensor 15, water refrigerant heat exchanger 2, first hot / cold water mixing valve 16, second hot / cold water mixing valve 17, flow rate adjusting valve 18, and hot water supply fitting 19 are sequentially provided. After that, it flows out of the faucet. This circuit is called an instantaneous circuit. In that case, the control apparatus 120 detects a water flow with the feed water flow sensor 13 provided in the instantaneous circuit, and starts the compressors 1a and 1b of the heat pump refrigerant circuit 90.

  At this time, α4 for setting the water outlet temperature target value Twh of the water-refrigerant heat exchanger 2 is set to α4 = 0. That is, in the flowchart of FIG. 4, there is a case where there is hot water having a sufficiently high temperature in the hot water storage tank 21, that is, a case where the temperature Twu of the tank temperature sensor 65 a of the hot water storage tank 21 is higher than the target value Twk of the mixed temperature sensor 63. (132Y), α4 = 0 (131) is set, and the water outlet temperature target value Twh of the water-refrigerant heat exchanger 2 is a temperature rise amount α1 to α3 in consideration of the heat dissipation amount in each pipe with respect to the hot water supply set temperature Tws. Only is added.

  The temperature Two of hot water from the water / refrigerant heat exchanger 2 does not reach the target value Twh set by the control device 120 until the heat pump refrigerant circuit 90 starts up after the compressors 1a and 1b are started. Therefore, in the flowchart of FIG. 5, since (temperature Twu of the tank temperature sensor 65a> target value Twk of the mixing temperature sensor 63> temperature Two of the water outlet temperature sensor 62) (148N), the control device 120 performs mixing. The opening Ft of the first hot water / water mixing valve 16 is set and adjusted to (Equation 10) (step 150) so that the temperature of the temperature sensor 63 becomes the target temperature Twk (= Tws + α1 + α2). Furthermore, the control device 120 controls the amount of water mixed by the second hot water / water mixing valve 17 so that the temperature of the downstream hot water supply temperature sensor 64 becomes the target temperature Twb (= Tws + α1). Thereby, hot water of appropriate temperature is supplied to the faucet.

  As the time elapses after the compressors 1a and 1b are started, the heating capacity of the heat pump refrigerant circuit 90 gradually increases, and the temperature Two of the water outlet temperature sensor 62 of the water refrigerant heat exchanger 2 increases. At this time, since the control device 120 sets the opening degree Ft of the first hot water / water mixing valve 16 based on (Equation 10), the opening degree Ft increases. This is because the hot water in the hot water storage tank 21 has a sufficiently high temperature so that Twu can be considered constant and the target temperature Twk can also be considered constant. The numerator is constant, and Two is This is because the denominator of (Equation 10) decreases as the number increases.

  As a result, in the first hot water / water mixing valve 16, the flow rate on the water / refrigerant heat exchanger 2 side gradually increases, and the flow rate on the hot water storage tank 21 side gradually decreases. When the temperature Two of the water outlet temperature sensor 62 of the water-refrigerant heat exchanger 2 reaches the target value Twh, it can be considered that the detected value of the mixing temperature sensor 63 becomes Twk (148Y in FIG. 5), and the first hot water mixing The opening degree Ft of the valve 16 is set to 100% (149), and the supply of hot water from the hot water storage tank 21 side is stopped. At this time, hot water with a sufficiently high temperature remains in the hot water storage tank 21, and the hot water is continuously supplied only from the heat pump refrigerant circuit 90 side.

  When the hot water supply flow rate sensor 13 detects that the hot water supply terminal is closed, it is determined from the temperature of the temperature sensor 65a of the hot water storage tank 21 that hot water with a sufficiently high temperature remains in the hot water storage tank 21, and the tank The compressors 1a and 1b are stopped without performing the boil-back operation.

  Next, in the second example, hot water was hot in the hot water storage tank 21 at the time of start-up, but after heat up, a sufficient amount of heat remained in the hot water storage tank 21, but it became hot water with low temperature. The case will be described. In this case, since the operation at the time of rising is the same as that in the first example in which hot water having a sufficiently high temperature is present in the hot water storage tank 21 both at the time of rising and after the rising, the operation at the time of rising will be described. Is omitted.

  When the heat pump refrigerant circuit 90 starts up, the heating capacity gradually increases, and the detection value of the water outlet temperature sensor 62 of the water refrigerant heat exchanger 2 reaches the target value Twh, the detection value of the mixed temperature sensor 63 becomes Twk. The supply of hot water from the hot water storage tank 21 side is temporarily stopped. At this time, when the temperature Twu of the tank temperature sensor 65a in the upper part of the hot water storage tank 21 becomes equal to or lower than the target value Twk of the mixed temperature sensor 63 (132N in FIG. 4), the control device 120 of the water refrigerant heat exchanger 2 Α4 for setting the water outlet temperature target value Twh is set based on (Equation 3) (134). Thereby, the water outlet temperature target value Twh is set higher by the value α4 expressed by (Expression 3), and accordingly, the target discharge pressure Pd0 of the compressors 1a and 1b expressed by (Expression 11) is also increased. Therefore, the rotational speeds of the compressors 1a and 1b are increased so that the actual discharge pressure Pd becomes the target discharge pressure Pd0, and the water outlet temperature Two of the water-refrigerant heat exchanger 2 also increases.

  At this time, since (temperature Two of the water outlet temperature sensor 62 of the water refrigerant heat exchanger 2> target value Twk of the mixing temperature sensor 63> temperature Twu of the tank temperature sensor 65a), the opening degree of the first hot water / mixing valve 16 Ft is set to (Expression 7) (145 in FIG. 5). Thereby, hot water from the water refrigerant heat exchanger 2 having a temperature higher than the target value Twk of the mixing temperature and hot water in the hot water storage tank 21 having a temperature lower than the target value Twk of the mixing temperature are mixed, and water refrigerant heat exchange is performed. The hot water coming from the vessel 2 can be squeezed to obtain an appropriate temperature. As a result, the hot water in the hot water storage tank 21 that has a sufficient amount of heat but has a low temperature and is difficult to use can be used effectively.

  As time passes, the amount of hot water in the hot water storage tank 21 decreases, and the temperature Twu of the tank temperature sensor 65a also decreases. Each time, α4 is set based on (Expression 3) and Ft is set based on (Expression 7). Hot water in the hot water storage tank 21 having a low temperature and hot water from the water-refrigerant heat exchanger 2 set at a high temperature target value are appropriately mixed in the first hot water / water mixing valve.

  When there is no more heat available in the hot water storage tank 21 (130Y in FIG. 4, 138Y in FIG. 5), α4 is returned to 0 (131), Ft is set to 100% (139), and hot water from the hot water storage tank 21 side is returned. Stop supplying. Immediately after the hot water supply from the hot water storage tank 21 is stopped, the amount higher than the target value of the mixing temperature at the first hot water mixing valve 16 is mixed with water at the downstream second hot water mixing valve 17 to obtain a desired value. Supply hot water at a temperature of. Since α4 becomes 0, the target discharge pressure Pd0 of the compressors 1a and 1b represented by (Equation 11) also decreases, so that the actual discharge pressure Pd becomes the target discharge pressure Pd0. The rotational speed of 1b is decelerated, the water outlet temperature Two of the water refrigerant heat exchanger 2 is also lowered, and hot water is continuously supplied only from the heat pump refrigerant circuit 90 side while approaching the newly set target value Twh.

  When the water supply flow rate sensor 13 detects that the hot water supply terminal is closed, it is determined from the temperature of the temperature sensor 65a of the hot water storage tank 21 that there is no necessary amount of heat in the hot water storage tank 21, and the tank boiling back operation is performed. The temperature of the temperature sensor 65a, which is a condition for starting the tank boiling back operation, is set to a predetermined value lower than the hot water supply set temperature. If the hot water supply set temperature is 42 ° C, for example, it is set to 35 ° C. When the hot water in the hot water storage tank 21 reaches a predetermined position, the compressors 1a and 1b are stopped. As described above, hot water coming from the water / refrigerant heat exchanger 2 is squeezed by hot water in the hot water storage tank 21 instead of water, so that the intermediate hot water having a temperature lower than the set hot water temperature in the tank is effectively used. The amount of remaining hot hot water in the hot water storage tank 21 can be reduced. Therefore, it is possible to maintain high energy efficiency when the tank of the heat pump water heater is boiled back.

  Next, a case where there is hot water having a low temperature but a sufficient amount of heat remaining in the hot water storage tank 21 at the time of start-up will be described as a third example. The setting of α4 for setting the water outlet temperature target value Twh of the water refrigerant heat exchanger 2 when the heat pump refrigerant circuit 90 starts up is performed as follows. Since the temperature Twu of the tank temperature sensor 65a in the upper part of the hot water storage tank 21 is equal to or lower than the target value Twk of the mixed temperature sensor 63 (132N in FIG. 4), the control device 120 sets α4 based on (Equation 3). (134). Accordingly, the water outlet temperature target value Twh is set to a value higher by α4 expressed by (Equation 3), and the heat pump is set so that the temperature Two of hot water from the water-refrigerant heat exchanger 2 becomes the target value Twh. The rotation speed of the compressors 1a and 1b of the refrigerant circuit 90 is controlled.

  The temperature Two of hot water from the water / refrigerant heat exchanger 2 does not reach the target value Twh set by the control device 120 until the heat pump refrigerant circuit 90 starts up after the compressors 1a and 1b are started. For example, in the case of a short time after the start of the compressors 1a and 1b (target value Twk of mixing temperature sensor 63 ≧ temperature Twu of tank temperature sensor 65a> temperature Two of water refrigerant heat exchanger water outlet temperature sensor 62) (FIG. 146Y), the opening degree Ft of the first hot water mixing valve 16 is set to 10% (147), and hot water in the hot water storage tank 21 is used with priority. That is, until the water-refrigerant heat exchanger 2 starts up, even if the temperature of the hot water in the hot water storage tank 21 is low, the idea is to endure and use the hot water.

  When the heating capacity of the heat pump refrigerant circuit 90 gradually increases and the temperature Two of the hot water from the water refrigerant heat exchanger 2 becomes equal to or higher than the temperature Twu of the hot water in the hot water storage tank 21 (143Y), the first hot water mixing valve 16 is opened. The degree Ft is set to 100% (144), and only hot water from the water-refrigerant heat exchanger 2 is used. At this time, if the opening degree Ft of the first hot / cold water mixing valve 16 is suddenly changed from 10% to 100%, the water flow rate on the water / refrigerant heat exchanger 2 side rapidly increases, and the rotational speeds of the compressors 1a and 1b increase. Since the heating capacity of the heat pump refrigerant circuit 90 due to the above does not keep up and the temperature Two of the hot water from the water refrigerant heat exchanger 2 may decrease, Ft should not be decreased (or not decreased more than a predetermined ratio). Change slowly.

  Furthermore, when the temperature Two of the hot water from the water / refrigerant heat exchanger 2 becomes higher than the target value of the mixing temperature with the passage of time (143N), the opening degree Ft of the first hot water / mixing valve 16 is set to (Equation 7). (145). In other words, lukewarm with tank water instead of water. Thereby, the hot water from the water refrigerant | coolant heat exchanger 2 whose temperature is higher than the target value of mixing temperature, and the hot water in the hot water storage tank 21 whose temperature is lower than the target value of mixing temperature can be mixed. As a result, the hot water in the hot water storage tank 21 that has a sufficient amount of heat but has a low temperature and is difficult to use can be used effectively.

  As time passes, the amount of hot water in the hot water storage tank 21 decreases, and the temperature Twu of the tank temperature sensor 65a also decreases. Each time, α4 is set based on (Expression 3) and Ft is set based on (Expression 7). Hot water in the hot water storage tank 21 having a low temperature and hot water from the water-refrigerant heat exchanger 2 set at a high temperature target value are appropriately mixed in the first hot water / water mixing valve.

  When the necessary amount of heat in the hot water storage tank 21 is lost (130Y in FIG. 4, 138Y in FIG. 5), α4 is returned to 0 (131), Ft is set to 100% (139), and hot water from the hot water storage tank 21 side is returned. Stop supplying. Immediately after the hot water supply from the hot water storage tank 21 is stopped, the amount higher than the target value of the mixing temperature at the first hot water mixing valve 16 is mixed with water at the downstream second hot water mixing valve 17 to obtain a desired value. Supply hot water at the temperature of the hot water outlet. Since α4 becomes 0, the target discharge pressure Pd0 of the compressors 1a and 1b represented by (Equation 11) is also lowered, so that the actual discharge pressure Pd becomes the target discharge pressure Pd0. The rotational speed of 1b is decelerated, the water outlet temperature Two of the water refrigerant heat exchanger 2 is also lowered, and hot water is continuously supplied only from the heat pump refrigerant circuit 90 side while approaching the newly set target value Twh.

  When the water supply flow rate sensor 13 detects that the hot water supply terminal is closed, it is determined from the temperature of the temperature sensor 65a of the hot water storage tank 21 that there is no necessary amount of heat in the hot water storage tank 21, and the tank boiling back operation is performed. When the hot water in the hot water storage tank 21 reaches a predetermined position, the compressors 1a and 1b are stopped. As described above, it is possible to simmer with hot water in the hot water storage tank 21 instead of water, or to endure with the hot water until the water refrigerant heat exchanger 2 starts up even if the hot water is low. The low intermediate temperature remaining hot water can be used effectively, and the amount of intermediate temperature remaining hot water in the hot water storage tank 21 can be reduced. Therefore, it is possible to maintain high energy efficiency when the tank of the heat pump water heater is boiled back.

  In the above embodiment, the instantaneous heat pump water heater has been described as an example. The instantaneous heat pump water heater normally supplies only hot water generated in the heat pump refrigerant circuit to the hot water supply terminal when the heating capacity of the heat pump refrigerant circuit is stabilized. On the other hand, a hot water storage type heat pump water heater mixes water with hot water stored in a hot water storage tank and supplies it to a hot water supply terminal. In addition, the heating capacity of the heat pump refrigerant circuit of the instantaneous heat pump water heater is reduced, and the hot water storage tank is enlarged to always mix the hot water generated in the heat pump refrigerant circuit with the hot water stored in the hot water storage tank during hot water supply. This is called a semi-instantaneous or semi-hot water storage heat pump water heater (hereinafter referred to as a semi-instantaneous method). The present invention is also applicable to a semi-instantaneous heat pump water heater. That is, in a semi-instantaneous heat pump water heater, hot water in the hot water storage tank whose temperature is lower than the hot water set temperature is mixed with hot water from the heat pump refrigerant circuit in which the temperature target value is set high by the control device. Hot water is supplied to the proper temperature. Therefore, the middle temperature remaining hot water having a temperature lower than the set temperature of hot water supply in the tank is effectively used, and the amount of remaining middle temperature hot water in the hot water storage tank 21 is reduced, so that high energy efficiency can be maintained when the tank of the heat pump water heater is boiled back. The minimum requirement is to drain the hot intermediate hot water from the hot water storage tank for hot water supply. In the present embodiment, the middle temperature remaining hot water is discharged from the upper part of the hot water storage tank.

  As described above, according to the present embodiment, by effectively using the intermediate temperature remaining hot water, the amount of the intermediate temperature remaining hot water to be boiled back can be reduced, and the energy efficiency at the time of tank boiling back can be improved.

It is a circuit diagram of one Example of the heat pump hot-water supply apparatus which concerns on this invention. It is a circuit diagram of one Example of the heat pump hot-water supply apparatus which concerns on this invention. It is a circuit diagram of one Example of the heat pump hot-water supply apparatus which concerns on this invention. It is a flowchart figure which sets the addition value to the water outlet temperature target value of the water refrigerant heat exchanger which concerns on this invention. It is a flowchart figure which sets the opening degree of the 1st hot water mixing valve which concerns on this invention. It is a figure which shows the relationship of temperature.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1a, 1b Compressor 2 Water refrigerant | coolant heat exchanger 3a, 3b Expansion valve 4a, 4b Evaporator 13 Feed water flow rate sensor 16 1st hot water mixing valve 17 2nd hot water mixing valve 18 Flow rate adjustment valve 21 Hot water storage tank 31 Pouring solenoid valve 36 Bathtub 51a, 51b Discharge pressure sensor 60 Water supply temperature sensor 62 Water refrigerant heat exchanger water outlet temperature sensor 63 Mixed temperature sensor 64 Hot water supply temperature sensor 100 Heat pump hot water supply device 120 Control device

Claims (7)

A heat pump hot water supply device comprising a heat pump refrigerant circuit and a hot water storage tank for storing hot water heated by the heat pump refrigerant circuit, and capable of supplying hot water generated in the heat pump refrigerant circuit and hot water stored in the hot water storage tank to a hot water supply terminal In
Hot water stored in the hot water storage tank and having a temperature lower than the hot water supply set temperature and hot water higher than the hot water supply set temperature generated in the heat pump refrigerant circuit and higher than the temperature of the hot water stored in the hot water storage tank Mix hot water and supply hot water to the hot water supply terminal ,
A heat pump hot water supply comprising a control device for setting a target value of the temperature of water heated by the heat pump refrigerant circuit based on a temperature difference between the temperature of hot water stored in the hot water storage tank and a hot water supply set temperature. apparatus. In claim 1,
Even if the temperature of the hot water stored in the hot water storage tank becomes lower than the hot water supply set temperature, the boil-back operation to the hot water storage tank is not performed, and the boil-back operation is performed after the temperature falls below a predetermined value lower than the hot water supply set temperature. A heat pump hot water supply apparatus characterized by performing. In claim 2,
The boil-back operation is performed after the temperature sensor disposed at the top of the plurality of temperature sensors disposed on the side wall of the hot water storage tank has reached a predetermined value lower than the hot water supply set temperature. A heat pump hot-water supply device that is performed. In claim 1,
Hot water generated in the heat pump refrigerant circuit is lower than the hot water supply set temperature,
The hot water stored in the hot water storage tank is also lower in temperature than the hot water supply set temperature,
A heat pump hot water supply apparatus characterized by that. In claim 4,
A heat pump hot water supply apparatus, wherein hot water discharged from the hot water storage tank and hot water generated in the heat pump refrigerant circuit less than the amount of hot water are mixed. In claim 1,
From the state where hot water generated in the heat pump refrigerant circuit and hot water discharged from the hot water storage tank are mixed and supplied to the hot water supply terminal at a hot water supply set temperature, the temperature of the hot water in the hot water storage tank is the hot water supply set temperature. When it becomes below, it has a control device that increases the rotation speed of the compressor of the heat pump refrigerant circuit,
A heat pump hot water supply apparatus for supplying hot water generated in the heat pump refrigerant circuit with the hot water discharged from the hot water storage tank to the hot water supply terminal. In claim 6,
A heat pump hot water supply apparatus, wherein after the hot water supply is stopped, the hot water storage tank is boiled back.

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