JP2004177115A - Heat pump water heater - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stabilize the temperature of coming hot water even when selecting operation seeking hot water supplying load and economy, miniaturize a hot water storage tank and save energy. <P>SOLUTION: This heat pump water heater comprises a water circuit connected with a water heat exchanger 13 for heat exchange between a condenser 2 in a cooling medium circuit and itself while circulating hot water from the lower part of the hot water storage tank 5 to the upper part thereof and a mixing valve 17 for mixing the hot water taken out of the upper part of the hot water storage tank 5 with running water to selectively control the temperature of the hot water. When a hot water amount detecting means 35 detects that the remaining amount of the hot water in the hot water storage tank 5 is a preset value or smaller, a compressor 1 in a cooling medium circuit is operated for highly efficient reheating by a heat pump. <P>COPYRIGHT: (C)2004,JPO

Description

  The present invention relates to a heat pump water heater.

  A first conventional example of a conventional heat pump water heater is shown in FIG. 13, that is, a refrigerant circuit including a compressor 1, a condenser 2, a pressure reducing device 3, and an evaporator 4, a hot water tank 5, a circulation pump 6 A hot water supply circuit to which a heat exchange section for exchanging heat with the condenser 2 is connected; a heater 7 provided at an upper portion in the hot water storage tank 1; and an upper portion and a central portion of the hot water storage tank 5. A hot water control device 8 and an electric opening / closing valve 9 are used. The whole inside of the hot water storage tank 5 is heated to low-temperature hot water by the heat pump operation by the compressor 1, and the upper part of the hot water storage tank 5 is heated by the heater 7 at midnight. Heat to hot water.

  Normally, the electric on-off valve 9 is closed and the low-temperature hot water is used from the center of the hot water storage tank 5 via the hot water control device 8, and when high-temperature hot water is required, the electric on-off valve 9 is opened to open the high-temperature hot water. Is used via the hot and cold water control device 8 (for example, see Patent Document 1).

FIG. 14 shows a second conventional example using a general electric water heater. A hot water controller 8 is provided at the outlet of the hot water tank 5 and a heater 10 built in the hot water tank 5 is used. The hot water and the water supplied from the pressure reducing valve 11 are mixed at an appropriate temperature by the hot water controller 8 and then poured into a bathtub (for example, see Patent Document 2).
JP-A 1-225838 JP-A-4-6345

  However, in the first conventional example, when hot water is discharged, the hot water remains in the pipe up to the terminal (faucet) after the hot water is stopped, and the hot water is radiated from the pipe as time passes to lower the temperature.

  That is, since heat radiation loss occurs, it is necessary to increase the heat radiation amount. In addition, when the terminal mixes high-temperature hot water and city water to obtain an appropriate temperature, it takes time to adjust the temperature and wastes the high-temperature water.

  Therefore, as the capacity of the hot water tank increases, the energy required for boiling increases. Therefore, there were problems in terms of installation space, energy saving, and convenience when tapping.

  Further, in the second conventional example, since the water in the entire hot water storage tank 5 is heated to uniform hot water by the heater 10, and the hot water is stored, heat radiation from the hot water storage tank 5 becomes large with respect to a small amount of hot water supply load, resulting in wasteful energy consumption. It becomes.

  The present invention solves such a conventional problem, and has an object to reduce the size of a hot water tank and save energy.

  In order to achieve the above object, the present invention provides a refrigerant circulation circuit having a compressor, a water heat exchanger disposed for hot water circulation of a hot water storage tank and performing heat exchange between the refrigerant circulation circuit on the way. A connected water circulation path, a circulation pump for forcibly circulating the hot water from the lower part of the hot water tank to the upper part of the hot water tank in the water circulation path, and storing the hot water heated by the water heat exchanger in a temperature stratified manner from above the hot water tank, A hot water level detecting means for detecting a remaining hot water level by a vertical temperature distribution of hot water stored in the hot water storage tank, and a mixing valve for performing optional hot water temperature adjustment by mixing hot water taken out from an upper part of the hot water storage tank and tap water. And when the hot water level detecting means detects that the remaining hot water level in the hot water storage tank has decreased to a predetermined value, the compressor of the refrigerant circuit is driven to perform additional cooking.

  Therefore, it is possible to perform rational boiling according to the amount of remaining hot water in the hot water storage tank.

  As is clear from the above description, according to the heat pump water heater of the present invention, a stable tap water temperature can be obtained even when the operation pursuing the hot water supply load and economy is selected, and the heat loss of the piping system to the terminal equipment is obtained. Therefore, the size of the hot water storage tank can be reduced and energy saving can be achieved. In addition, since it is possible to rationally boil the water according to the amount of remaining hot water in the hot water storage tank, it is possible to promote further energy saving.

  An embodiment of the present invention is directed to a water circulation circuit having a refrigerant circulation circuit having a compressor and a water heat exchanger arranged for hot water circulation of a hot water storage tank and performing heat exchange with the refrigerant circulation circuit on the way. A circulating pump for forcibly circulating hot water from the lower part of the hot water tank to the upper part of the hot water tank in the water circulation path, and for storing the hot water heated by the water heat exchanger from the upper part of the hot water tank in a temperature stratified manner; A hot water level detecting means for detecting a remaining hot water level based on a vertical temperature distribution of stored hot water, and a mixing valve for adjusting a desired hot water temperature by mixing hot water taken out from an upper part of the hot water storage tank and tap water. When the hot water level detecting means detects that the remaining hot water level in the hot water storage tank has decreased to a predetermined value, the compressor of the refrigerant circuit is driven to perform reheating.

  Therefore, even if the operation pursuing the hot water supply load and economy is selected, a stable tapping temperature can be obtained, and the heat loss of the piping system to the terminal device can be reduced to reduce the size of the hot water tank and save energy. is there.

  In addition, since high-efficiency heat pump reheating is performed according to the amount of remaining hot water in the hot water tank, reliable hot water supply and power saving can be realized.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Example 1)
In FIG. 1, reference numeral 1 denotes a compressor, 2 denotes a condenser, 3 denotes a decompression device, and 4 denotes an evaporator. The compressor 1, the condenser 2, the decompression device 3, and the evaporator 4 are connected in order, and a refrigerant circulation circuit is provided. Is composed.

  5 is a hot water storage tank, 12 is a circulation pump for forcibly circulating the hot water under the hot water storage tank 5 to the upper part, 13 is a water heat exchanger, and exchanges heat with the condenser 2.

  The circulation pump 12 and the water heat exchanger 13 form a water circulation path that connects the lower part and the upper part of the hot water storage tank 5. Reference numeral 14 denotes a temperature detector, which is provided at the outlet of the water heat exchanger 13 and detects a medium temperature to generate a signal. Reference numeral 15 denotes hot water temperature setting means for setting the boiling hot water temperature and having a plurality of signals.

  Reference numeral 16 denotes a rotation speed controller which controls the rotation speed of the circulation pump 12 so that the signal of the temperature detector 14 matches the signal of the hot water temperature setting means 15. A mixing valve 17 mixes hot water taken out from the upper part of the hot water storage tank 5 with water depressurized by the pressure reducing valve 11 and supplied to the lower part of the hot water storage tank 5 to arbitrarily adjust the hot water temperature.

  Next, the operation of the above configuration will be described. When the hot water supply load is large, the hot water temperature setting means 15 sets the boiling of the high-temperature hot water, and when the hot water supply load is small, the medium hot water is set for the boiling. Then, the high-temperature and high-pressure superheated gas discharged from the compressor 1 flows into the condenser 2, where it heats the water sent from the circulation pump 12 and flowing into the water heat exchanger 13. At that time, it is condensed and liquefied by the heat radiation action and flows into the pressure reducing device 3, where the pressure is reduced and flows into the evaporator 4.

  Then, it absorbs atmospheric heat to evaporate and return to the compressor 1. On the other hand, the water flowing out from the lower part of the hot water tank 5 flows into the water heat exchanger 13 via the circulation pump 12, is heated by the heat of condensation of the refrigerant, and is stored in the upper part of the hot water tank 5. By repeating this operation, the whole hot water is gradually stored from above in the hot water storage tank 5.

  In this case, when the high-temperature hot water boiling operation is performed in a place where the remaining hot water of the previous day has been heated by the heat pump, the high-temperature hot water is stored above the remaining hot water of the previous day. That is, hot water layers having different temperatures are stored in the hot water storage tank 5. In other words, a temperature stratified type hot water is stored.

  When the hot water is to be discharged from the hot water storage tank 5, the mixing valve 17 mixes the high-temperature hot water in the upper part of the hot water storage tank 5 with the tap water, lowers the hot water temperature used in the terminal and sends it to the terminal equipment. Is stable.

  Therefore, even if the remaining hot water temperature and the boiling temperature are different, it is possible to select an operation pursuing hot water supply load and economy. In addition, since heat loss in the piping system to the terminal device is reduced, the size of the hot water storage tank is reduced and energy saving is achieved. Further, it is not necessary to adjust the hot water temperature at the terminal, and the convenience is improved.

(Example 2)
In FIG. 2, components having the same configuration and operation as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted. Numeral 18 denotes hot water amount detecting means, which is provided in a plurality of numbers in the vertical direction of the hot water storage tank 5 and detects a vertical temperature distribution of hot water in the hot water storage tank and issues a signal based on a state of the remaining hot water amount. Reference numeral 19 denotes a controller which sets the temperature of the hot water temperature setting means 15 based on a signal from the hot water quantity detecting means 18.

  The operation of the above configuration will be described. Immediately before the start of the boiling operation, the controller 19 sets the set temperature of the hot water setting means 15 from the remaining hot water state detection signals of the plurality of hot water detecting means 18 provided in the hot water tank 5.

  That is, when the remaining hot water amount immediately before the start of operation is larger than the previous day's remaining hot water amount, it is considered that the hot water supply load is small, and the temperature setting of the hot water temperature setting means 15 is lowered. Conversely, when the amount of remaining hot water is small, the temperature setting is increased.

  The control of the set temperature of the hot water temperature setting means 15 by the controller 19 is performed by changing the temperature set by the initial hot water temperature setting means 15 (for example, changing the temperature setting of 65 ° C. to 50 ° C.). Alternatively, the setting temperature of the hot water setting means 15 may be automatically determined based on the hot water amount detected by the hot water amount detecting means 18.

  Then, the boiling operation is started, and the rotation speed controller 16 controls the rotation speed of the circulating pump 12 so that the signal from the temperature detector 14 coincides with the signal from the hot water temperature setting means 15 to boil to the set temperature. Thereafter, the temperature is lowered to an appropriate temperature by the mixing valve 17 and sent to the terminal device.

  Therefore, even if the remaining hot water temperature and the boiling temperature are different, the hot water temperature at the terminal is stable, so that the hot water temperature can be automatically set according to the amount of hot water used.

(Example 3)
In FIG. 3, components having the same configuration and operation as those of the first and second embodiments are denoted by the same reference numerals, and description thereof is omitted.

  Reference numeral 20 denotes a plurality of mixing valves, each of which mixes hot water taken out of the hot water storage tank 5 and water supplied to a lower portion of the hot water storage tank 5 to arbitrarily adjust the hot water temperature.

  The operation of the above configuration will be described. When the hot water heated in the hot water storage tank 5 is discharged at the same time under different conditions such as a kitchen and a bath reheating, a plurality of mixing valves 20 are provided according to a request from a terminal. Adjust to the hot water temperature and supply.

  Therefore, even if tapping and stopping of tapping are performed at different terminal temperatures at each terminal, the tapping temperature is stabilized, and convenience is improved.

(Example 4)
In FIG. 4, components having the same configurations and operations as those of the first to third embodiments are denoted by the same reference numerals, and description thereof is omitted.

  Reference numeral 21 denotes hot water temperature setting means for setting the hot water temperature of the terminal. Reference numeral 22 denotes a controller, which sends a signal to the mixing valve 17 to match the signal of the hot water temperature setting means 21 gradually from the hot water signal from the hot water temperature setting means 21 at the time of hot water supply.

  The operation of the above configuration will be described. Hot water temperature setting means 21 sets the hot water temperature of the terminal. Immediately after the tapping, the controller 22 sends a signal of the hot water slightly higher than the signal of the tapping temperature setting means 21 to the mixing valve 17, and then sends a signal that matches the signal of the tapping temperature setting means 21. Therefore, the temperature of hot water to be discharged from the terminal is quickly increased.

(Example 5)
In FIG. 5, components having the same configuration and operation as those of the first to fourth embodiments are denoted by the same reference numerals, and description thereof is omitted.

  A heater 23 is provided downstream of the water heat exchanger 13. Reference numeral 24 denotes hot water amount detecting means, which is provided in the hot water storage tank 5 in plurality. Reference numeral 25 denotes a heating controller, which energizes the heater 23 in response to a signal from the hot water amount detecting means 24.

  Reference numeral 26 denotes a time integrating means, which receives a signal from the hot water amount detecting means 24 and integrates the energizing time of the heater 23. 27 is a storage means for storing the previous time integrating means 26. Reference numeral 28 denotes a hot water amount comparing means, which compares the signal of the hot water amount detecting means 24 immediately before and immediately before the start of the operation, and transmits a change amount signal of the hot water amount exceeding a certain temperature. 29 is an operation time control means for setting the energization time of the heater 23 from the storage means 27 and the hot water amount comparison means 28.

  The operation of the above configuration will be described. Immediately before the start of the boiling operation, the hot water amount detecting means 24 detects the remaining hot water amount in the hot water storage tank 5 and sends a signal to the hot water amount comparing means 28. Then, the last remaining hot water amount is compared with the current remaining hot water amount, and a signal is transmitted to the operation time control means 29.

  Further, the storage unit 27 transmits a signal of the previous energization time of the heater 23 to the operation time control unit 29. Then, the operating time control means 29 sets the energizing time of the heater 23 at the time of the current boiling operation from the signals of the storage means 27 and the hot water amount comparing means 28.

  That is, the remaining hot water amount is compared with the previous day and today, and if the remaining hot water amount is large, the energization time of the heater 23 is set to be short. Conversely, if the amount of remaining hot water is small, the energization time is set longer. Then, the boiling operation is started, and the heated hot water is sequentially stored from the upper part of the hot water storage tank 5 by the heat pump using the compressor 1.

  Then, when the hot water is stored up to the position of the hot water amount detecting means 24, the hot water amount detecting means 24 sends a signal to the heating controller 25, and the heater 23 is energized.

  The time accumulating means 26 accumulates the energizing time of the heater 23 and is energized until the energizing time set by the operating time control means 29.

  The hot water is stored in the hot water tank 5 at different temperature layers. The mixing valve 17 mixes the hot water taken out from the upper part of the hot water tank 5 and the water supplied to the lower part of the hot water tank 5, and the hot water used in the terminal. And send it to the terminal equipment, so that a stable tapping temperature can be obtained.

  Further, since the amount of boiling water can be varied according to the amount of hot water used, power consumption can be reduced.

(Example 6)
In FIG. 6, components having the same configuration and operation as those of the first to fifth embodiments are denoted by the same reference numerals, and description thereof is omitted.

  Numeral 30 denotes reheating operation means for manually setting the reheating operation. An operation controller 31 performs a combined operation of the compressor 1 and the heater 23 in response to a signal from the reheating operation means 30.

  The operation of the above configuration will be described. When a large amount of hot water is urgently needed, the operation controller 31 receives a signal from the reheating operation means 30 and energizes the compressor 1 and the heater 23 to perform a combined operation. Therefore, the reheating operation can be performed with a high heating capacity.

  Also, even if reheating is performed at a temperature different from the remaining hot water temperature in the hot water storage tank 5, the mixing valve 17 is lowered to the hot water temperature used at the terminal and sent to the terminal equipment at the time of tapping, so that the boiling time is increased. And stabilization of tapping temperature.

(Example 7)
In FIG. 7, components having the same configurations and operations as those of the first to sixth embodiments are denoted by the same reference numerals, and description thereof is omitted.

  A mixing valve 32 mixes hot water taken out of the hot water storage tank 5 and water supplied to the lower part of the hot water storage tank 5, adjusts the hot water temperature arbitrarily, and transmits a signal by detecting the temperature.

  An operation controller 33 compares a signal of the mixing valve 32 with a signal of the tapping temperature setting means 21 to energize the compressor 1 and the heater 23.

  The operation of the above configuration will be described. When the tapping is started, the mixing valve 32 detects the tapping temperature and sends a signal to the operation controller 33.

  The operation controller 33 compares the signal of the mixing valve 32 with the signal of the tapping temperature setting means 21.

  When the remaining hot water amount decreases and the hot water temperature starts to decrease, the signal of the mixing valve 32 transmits a signal lower in temperature than the signal of the hot water temperature setting means 21. Recognizing this, the operation controller 33 energizes the compressor 1 and the heater 23 to perform the combined operation.

  Therefore, the reduction of the remaining hot water amount is automatically detected, and the reheating operation is automatically performed with a high heating capacity, so that it is possible to improve convenience and prevent running out of hot water.

(Example 8)
In FIG. 8, components having the same configurations and operations as those of the first to seventh embodiments are denoted by the same reference numerals, and description thereof is omitted.

  A controller 34 detects a signal from the mixing valve 32 and switches the signal of the hot water temperature setting means 15 to be equal to the signal of the hot water temperature setting means 21.

  In the above configuration, the outlet medium temperature of the water heat exchanger 13 is detected by the temperature detector 14, and the rotation speed controller 16 controls the rotation speed of the circulation pump 12 so that the signal thereof matches the signal of the hot water temperature setting means 15. Perform reheating operation while controlling.

  When tapping is started during the reheating operation, the mixing valve 32 detects the tapping temperature and sends a signal to the controller 34.

  Here, the controller 34 compares the signal of the mixing valve 32 with the signal of the tapping temperature setting means 21. Then, when the remaining hot water amount decreases and the hot water temperature starts to drop, controller 34 switches the signal of hot water temperature setting means 15 to match the signal of hot water temperature setting means 21.

  Therefore, the rotation speed controller 16 controls the rotation speed of the circulation pump 12 so that the outlet medium temperature of the water heat exchanger 13 matches the signal of the hot water temperature setting means 21. Thereby, the hot water boiled in the water heat exchanger 13 has the same temperature as the hot water to be discharged, and is directly discharged.

(Example 9)
In FIG. 9, components having the same configuration and operation as those of the first to eighth embodiments are denoted by the same reference numerals, and description thereof is omitted.

  Reference numeral 35 denotes hot water amount detecting means, which is provided in the hot water storage tank 5 and detects a temperature to transmit a signal. An operation controller 36 energizes the compressor 1 in response to a signal from the hot water amount detecting means 35, and performs an independent operation using a heat pump.

  In the above configuration, when the hot water is discharged from the hot water storage tank 5, the hot water level is pushed upward, and when the hot water level reaches the position of the hot water level detecting means 35, the hot water level detecting means 35 sends a signal to the operation controller 36 and the compressor 1 is energized, and an independent operation is performed by a heat pump.

  Then, since the mixing valve 17 is sent to the terminal device after being lowered to the hot water temperature to be used, the tapping temperature is stabilized even if the remaining hot water temperature and the reheating temperature are different. Therefore, it becomes possible to perform the reheating operation with power saving.

(Example 10)
In FIG. 10, components having the same configuration and operation as those of the first to ninth embodiments are denoted by the same reference numerals, and description thereof is omitted.

  Reference numeral 37 denotes a heater, which is provided in the middle of the hot water supply circuit above the water heat exchanger 13 and the hot water storage tank 5, and is constituted by a plurality of heaters and the like, and its output can be varied. Reference numeral 38 denotes a first temperature detector, which is provided at the outlet of the water heat exchanger 13, detects the temperature of the medium flowing therethrough, and generates a signal.

  Reference numeral 39 denotes a second temperature detector, which is provided at the outlet of the heater 37, detects the temperature of the medium flowing therethrough, and generates a signal. Reference numeral 40 denotes a rotation speed controller that controls the rotation speed of the circulation pump 12 in response to a signal from the first temperature detector 38. Reference numeral 41 denotes a controller, which controls the output of the heater 37 in response to a signal from the second temperature detector 39.

  In the above configuration, the first temperature detector 38 detects the hot water temperature of the heat pump, that is, the hot water temperature of the outlet of the water heat exchanger 13 at the time of the combined operation of the heat pump operation and the heater. The heat is then sent to 40, where the number of revolutions of the circulation pump 12 is controlled so that the temperature of the hot water from the heat pump becomes a predetermined temperature.

  During the operation, when the outlet temperature of the heater 37 rises, the second temperature detector 39 detects the temperature of the hot water, sends a signal to the controller 41, and reduces the output of the heater 37. Therefore, the boiling water temperature of the heat pump in the combined operation is the same as that of the single operation of the heat pump, so that the boiling operation can be performed with high efficiency.

(Example 11)
11, components having the same configuration and operation as those of the first to tenth embodiments are denoted by the same reference numerals, and description thereof is omitted.

  Reference numeral 42 denotes an open / close valve, which is provided in the hot water supply circuit of the circulation pump 12 and the water heat exchanger 13. Reference numeral 43 denotes a controller which closes the on-off valve 42 when the operation of the compressor 1 is stopped.

  In the above configuration, immediately after the operation is stopped, the hot water between the outlet of the water heat exchanger 13 and the hot water storage tank 5 that has become hot during operation is radiated and the temperature is reduced, and the density is increased. A force is generated, and the hot water tends to flow backward from the upper portion of the hot water storage tank 5.

  However, since the controller 43 closes the on-off valve 42 when the operation is stopped, natural circulation can be prevented. As a result, the hot water in the hot water storage tank 5 flows back to the hot water supply circuit and does not radiate heat.

(Example 12)
12, components having the same configuration and operation as those of the first to eleventh embodiments are denoted by the same reference numerals, and description thereof is omitted.

  Reference numeral 44 denotes a heat source, which is provided in the hot water tank 5 or provided in a water circulation path communicating the upper part and the lower part of the hot water tank 5. Reference numeral 45 denotes hot water amount detecting means, which is provided in the hot water storage tank 5 and detects a temperature to generate a signal. Reference numeral 46 denotes a human body recognizing means, which is provided in the bathroom and recognizes the human body and counts the number of persons to generate a signal. Reference numeral 47 denotes an operation controller which controls the operation of the heat source 44 and the circulation pump 12 based on signals from the hot water amount detecting means 45 and the human body recognizing means 46.

  In the above configuration, when the remaining hot water reaches the position of the hot water detecting means 45 after the hot water is discharged from the hot water storage tank 5, the hot water detecting means 45 sends a signal to the operation controller 47. The human body recognizing means 46 is provided in the bathroom, counts the number of bathers, and sends a signal to the operation controller 47.

  Then, the operation controller 47 selects whether or not to perform the reheating operation based on the signal of the human body recognizing unit 46 when receiving the signal of the hot water amount detecting unit 45. For example, if the person is the last bather, the remaining amount of hot water at the position of the hot water amount detecting means 45 is sufficient, so that the reheating operation is not performed. Therefore, wasteful reheating operation can be prevented, so that power consumption can be saved, and the operation of boiling the hot water tank can be performed during the late night hours to promote the leveling of the power load.

  The last bather is determined by initially inputting the expected number of bathers.

  As described above, according to the present invention, it is possible to provide a heat pump water heater capable of obtaining a stable tap water temperature, and is suitable for, for example, a home kitchen or a bath.

FIG. 1 is a configuration diagram of a heat pump water heater showing a first embodiment of the present invention. Configuration diagram of a heat pump water heater showing a second embodiment of the present invention Configuration diagram of a heat pump water heater showing a third embodiment of the present invention Configuration diagram of a heat pump water heater showing a fourth embodiment of the present invention Configuration diagram of a heat pump water heater showing a fifth embodiment of the present invention Configuration diagram of a heat pump water heater showing a sixth embodiment of the present invention Configuration diagram of heat pump water heater showing embodiment 7 of the present invention Configuration diagram of a heat pump water heater showing embodiment 8 of the present invention Configuration diagram of a heat pump water heater showing a ninth embodiment of the present invention Configuration diagram of a heat pump water heater showing embodiment 10 of the present invention Configuration diagram of heat pump water heater showing embodiment 11 of the present invention Configuration diagram of a water heater showing a twelfth embodiment of the present invention Configuration diagram of conventional heat pump water heater Configuration diagram of conventional water heater

Explanation of reference numerals

DESCRIPTION OF SYMBOLS 1 Compressor 5 Hot water storage tank 12 Circulation pump 13 Water heat exchanger 17 Mixing valve 35 Hot water level detection means

Claims (1)

A refrigerant circuit having a compressor, a water circuit arranged for hot water circulation of a hot water storage tank and connecting a water heat exchanger for performing heat exchange with the refrigerant circuit in the middle thereof, and a hot water tank in the water circuit A circulation pump for forcibly circulating hot water from the lower part to the upper part of the tank and storing the hot water heated by the water heat exchanger in a temperature stratified manner from above the hot water storage tank, and a vertical direction of the hot water stored in the hot water storage tank. And a mixing valve for mixing hot water taken out from the upper part of the hot water tank and tap water to perform any hot water temperature adjustment, and the remaining hot water amount in the hot water tank is predetermined. A heat pump water heater in which the compressor in the refrigerant circuit is driven to perform reheating when the hot water amount detecting means detects that the temperature has decreased to a value.

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