JP2014043962A - Heat pump water heater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect abnormality in a heat pump at low costs by using an electric current detecting device without using a pressure switch and a pressure detecting device.SOLUTION: A heat pump water heater has a heat pump unit 100 having a refrigerant circuit in which a compressor 1, a refrigerant-water heat exchanger 2, a pressure reducing valve device 3 and an air-refrigerant heat exchanger 4 are circularly connected through refrigerant piping 5, and a tank unit 200 having a warm water tank 20, a warm water circulating device 21 and the like. A control portion 13 executes an abnormality determination mode during a period from start of the compressor 1 to the lapse of a predetermined time. In the abnormality determination mode, an electric current in the compressor is detected by an electric current detecting device 8 while keeping a rotational frequency of the compressor 1 and an opening of the pressure reducing valve device 3 at respective predetermined constant values. If the electric current in the compressor is at an abnormality determination value or higher, the compressor is determined to have abnormality, and the compressor 1 is stopped.

Description

  The present invention relates to a heat pump water heater equipped with a heat pump unit.

  As a prior art, for example, a heat pump water heater as described in Patent Document 1 is known. A conventional water heater includes a pressure switch or a pressure detection device. For example, when the pressure of the refrigerant circuit becomes equal to or higher than an abnormality determination value due to blockage of the refrigerant circuit, the compressor of the heat pump unit is stopped. Yes.

  Further, as another conventional technique, a heat pump water heater as described in Patent Document 2 is known. In this prior art, when the current value energized to the compressor of the heat pump unit becomes equal to or higher than the abnormality determination value after the specified time has elapsed after the compressor is started, the compressor is stopped. It is configured. After starting the compressor, the pressure of the refrigerant circuit is maintained at an appropriate high pressure value by the operation of the pressure reducing valve device. However, if an abnormality occurs in the pressure reducing valve device, the current value may continue to increase with the pressure of the refrigerant circuit. is there. In another conventional technique, when the current value continues to increase with the pressure, an abnormality of the pressure reducing valve device is detected by the current detection means.

Japanese Patent No. 4874138 JP 2010-71603 A

  In the prior art described in the above-mentioned Patent Document 1, the pressure switch and the pressure detection device are expensive parts, so that there is a problem that the product cost increases. On the other hand, in the prior art described in Patent Document 2, when the current value of the compressor increases, this state is detected as an abnormality of the pressure reducing valve device. For this reason, if the current value increases due to the load of the compressor, the operation of the pressure reducing valve device, etc., even if the pressure reducing valve device is in a normal state, there is a possibility that it is erroneously determined to be abnormal, and there is a problem that the determination accuracy is lowered.

  The present invention has been made to solve the above-described problems, and a first object of the present invention is to use a current detection device to detect a malfunction of a heat pump without using a pressure switch and a pressure detection device. It is providing the heat pump water heater which can detect this at low cost.

  In addition, a second object of the present invention is to employ an abnormality determination mode in which the compressor and the pressure reducing valve device are maintained in a constant operating state, thereby stably detecting an abnormality of the heat pump and having a high reliability. The purpose is to provide a water heater.

  The heat pump water heater according to the present invention has a refrigerant circuit in which a compressor, a refrigerant water heat exchanger, a pressure reducing valve device, and an air refrigerant heat exchanger are connected in an annular shape, and heats the water by the refrigerant water heat exchanger. The value of the current flowing through the compressor, the heat pump that generates the hot water, the hot water tank that stores the hot water heated by the heat pump, the hot water circulation device that circulates water between the refrigerant water heat exchanger and the hot water tank A current detection device for detecting the compressor current and a control device for controlling the operation of the compressor based on the compressor current, during a period until a preset time elapses from the start of the compressor, An abnormality judgment mode is held in which the rotation speed of the compressor and the opening of the pressure reducing valve device are held at a constant value. When the compressor current exceeds the abnormality judgment value during the abnormality judgment mode, the compressor current is reduced. The compressor is judged to be abnormal It is configured to stop.

  According to the present invention, at the start of operation of the compressor, the abnormality determination mode is held in which the rotation speed of the compressor and the opening degree of the pressure reducing valve device are maintained at a constant value. Therefore, an expensive pressure switch or pressure detection device is used. Even without this, it is possible to detect a clogging of the refrigerant circuit, an abnormality of the decompression device, and the like using a relatively inexpensive current detection device. Therefore, a highly reliable heat pump water heater can be realized at low cost. In addition, since the compressor current level is determined with the heat pump operating conditions constant, the compressor current level can be determined stably without receiving disturbance due to fluctuations in the operating state. Can be detected with high accuracy.

It is a block diagram which shows the heat pump water heater by Embodiment 1 of this invention. In Embodiment 1 of this invention, it is a timing chart which shows the operating state of the compressor and pressure-reduction valve apparatus in abnormality determination mode. In Embodiment 2 of this invention, it is a timing chart which shows the operating state of the compressor in a malfunction determination mode, a pressure-reduction valve apparatus, and a circulation pump. In Embodiment 3 of this invention, it is a characteristic diagram which shows the relationship between outside temperature and abnormality determination value. In Embodiment 4 of this invention, it is a characteristic diagram which shows the relationship between discharge refrigerant | coolant temperature and abnormality determination value. In Embodiment 5 of this invention, it is a characteristic diagram which shows the relationship between outside temperature and determination mode continuation time. In Embodiment 6 of this invention, it is a characteristic diagram which shows the relationship between discharge refrigerant | coolant temperature and determination mode continuation time.

Embodiment 1 FIG.
Hereinafter, the first embodiment of the present invention will be described with reference to FIGS. 1 and 2. In each drawing used in this specification, common elements are denoted by the same reference numerals, and redundant description is omitted. FIG. 1 is a configuration diagram illustrating a heat pump water heater according to Embodiment 1 of the present invention. As shown in this figure, the heat pump water heater of this embodiment includes a heat pump unit 100 and a tank unit 200.

  The heat pump unit 100 includes a refrigerant circuit in which a compressor 1, a refrigerant water heat exchanger 2, a pressure reducing valve device 3 and an air refrigerant heat exchanger 4 are annularly connected via a refrigerant pipe 5, a fan 6 and a fan motor 7. It has. The compressor 1 circulates the refrigerant in the refrigerant circuit, and the refrigerant water heat exchanger 2 exchanges heat by exchanging heat between the refrigerant flowing on the primary side and the water flowing on the secondary side. It is for heating. Further, the pressure reducing valve device 3 reduces the temperature of the refrigerant flowing into the air refrigerant heat exchanger 4 to a low temperature and a low pressure by depressurizing (expanding) the refrigerant according to the opening degree. The pressure reducing valve device 3 is constituted by an electronically controlled expansion valve or the like, and its opening degree is controlled by a control unit 13 described later. On the other hand, the air refrigerant heat exchanger 4 heats the refrigerant by exchanging heat between the outside air (air) and the refrigerant. The fan 6 is driven by the fan motor 7 and is driven by the air refrigerant heat exchanger 4. It is what cools.

  The heat pump unit 100 includes a sensor system including various detection devices and sensors, and a control unit 13 that controls the operation of the heat pump unit 100. First, the sensor system will be described. The current detection device 8 detects a compressor current that is a value of a current flowing through the compressor 1. The feed water temperature sensor 9 detects the temperature of the water flowing into the secondary side of the refrigerant water heat exchanger 2, and the boiling temperature sensor 10 is the hot water flowing out from the secondary side of the refrigerant water heat exchanger 2. Detect temperature. The outside air temperature sensor 11 detects the temperature of outside air around the heat pump unit 100. Furthermore, the refrigerant temperature sensor 12 detects the temperature of the refrigerant discharged from the compressor 1 as the discharged refrigerant temperature.

  The control unit 13 includes a storage circuit, an input / output port, and an arithmetic processing circuit, and a detection device and a sensor constituting a sensor system are connected to the input side of the control unit 13, respectively. Various actuators including the compressor 1, the pressure reducing valve device 3, and the fan motor 7 are connected to the output side of the control unit 13. The control unit 13 is configured to perform data communication with the control unit 25 mounted on the tank unit 200. Thereby, the control part 13 can control the rotation speed of the compressor 1, the opening degree of the pressure-reduction valve apparatus 3, and the rotation speed of the fan motor 7 based on the output of a sensor system | strain, and the information on the tank unit 200 side. .

  On the other hand, the tank unit 200 supplies water (hot water) between the hot water tank 20 that stores hot water heated by the heat pump unit 100 (refrigerant water heat exchanger 2) and between the refrigerant water heat exchanger 2 and the hot water tank 20. A hot water circulation device 21 that circulates and a control unit 25 are provided. The hot water circulation device 21 includes a feed pipe 22 that connects a lower part of the hot water tank 20 and the secondary side inlet of the refrigerant water heat exchanger 2, a secondary side outlet and the hot water tank of the refrigerant water heat exchanger 2. 20 is provided with a return pipe 23 that connects the upper part of 20 and a circulation pump 24 provided in the middle of the feed pipe 22, for example. The controller 25 is configured to control at least the operation of the circulation pump 24. In the following description, the control unit 13 is referred to as a heat pump side control unit 13 and the control unit 25 is referred to as a tank side control unit 25 as necessary.

(Boiling operation)
Next, the boiling operation which is one of the basic operations of the heat pump water heater will be described.
The boiling operation is performed in cooperation with the control units 13 and 25 when a request for heating (boiling) water in the hot water tank 20 is generated on the tank unit 200 side, for example. In this case, the heat pump side control unit 13 executes the rotational speed control of the compressor 1, the opening degree control of the pressure reducing valve device 3 and the rotational speed control of the fan motor 7, and the temperature detected by the boiling temperature sensor 10 is the target. The rotational speed of the circulation pump 24 is controlled so as to coincide with the boiling temperature.

  More specifically, the rotational speed of the compressor 1 is controlled based on the outputs of the outside air temperature sensor 11, the feed water temperature sensor 9, and the like, and the opening degree of the pressure reducing valve device 3 is the outside air temperature sensor 11, the refrigerant temperature sensor 12, etc. Is controlled based on the output of. The rotational speed control of the circulation pump 24 may be executed by the heat pump side control unit 13 via the tank side control unit 25, or may be directly executed by the heat pump side control unit 13.

  In the boiling operation, when the circulation pump 24 is operated, water staying in the lower part of the hot water tank 20 is introduced into the refrigerant water heat exchanger 2 through the feed pipe 22, and this water is supplied to the refrigerant water heat exchanger 2. Is heated to become hot water. The hot water flowing out from the refrigerant water heat exchanger 2 is stored in the hot water tank 20 via the return pipe 23.

(Abnormality judgment control)
Next, the operation after starting the operation of the water heater will be described. The following operation is realized by the control of the control units 13 and 25. After the operation of the water heater is started, as described above, the boiling operation is executed based on the request on the tank unit 200 side or the like. However, before the boiling operation is started, an abnormality of the heat pump 100 is detected. Shifts to the abnormality judgment mode. FIG. 2 is a timing chart showing operating states of the compressor and the pressure reducing valve device in the abnormality determination mode in the first embodiment of the present invention. As shown in this figure, the abnormality determination mode is performed during a period from when the compressor is started until a preset time elapses. This implementation period is set in advance as a minimum time necessary for detecting, for example, blockage of the refrigerant circuit, abnormality of the pressure reducing valve device 3, and the like.

  During the execution of the abnormality determination mode, the rotation speed of the compressor 1 and the opening degree of the pressure reducing valve device 3 are held at preset constant values, and the compressor current is detected by the current detection device 8 in this state. To do. Here, when the refrigerant circuit is blocked or the decompression device is abnormal, the compressor current tends to increase. Therefore, during the abnormality determination mode, the rotation speed of the compressor 1 is kept as low as possible, and the opening degree of the pressure reducing valve device 3 is kept as large as possible. It is preferable to keep the machine current small. Thereby, a big difference can be produced in the compressor current between the normal time and the abnormal time, and the above determination accuracy can be improved.

  If the compressor current exceeds the abnormality determination value during the abnormality determination mode, it is determined that the compressor current is abnormal, that is, the refrigerant circuit is blocked, the pressure reducing valve device 3 is abnormal, or the like. Then, the compressor 1 is stopped. When it is determined that the compressor current is abnormal, after the compressor 1 is stopped, the abnormality determination mode is performed again to repeat the operation of determining the compressor current, and the abnormality determination is repeated a plurality of times. In this case, all the devices constituting the heat pump unit 100 may be stopped. In this case, the devices to be stopped include at least the compressor 1, the refrigerant water heat exchanger 2, the pressure reducing valve device 3, and the air refrigerant heat exchanger 4. The operation of the fan motor 7 may be continued.

  According to the above control, even if it is determined that the compressor current is abnormal, the abnormality determination mode is performed again to re-determine the compressor current. It is possible to suppress erroneous determination and improve the determination accuracy. In addition, when the abnormality determination is continuous, the heat pump unit 100 can be completely stopped to protect each device mounted on the unit.

  On the other hand, when the compressor current in the abnormality determination mode is held below the abnormality determination value, the heat pump unit 100 including the compressor 1 and the pressure reducing valve device 3 is normally operated when the execution period has elapsed. It determines with operating, and complete | finishes abnormality determination mode. Then, while continuing the operation of the compressor 1, the operation proceeds to the boiling operation based on a request (instruction) on the tank unit 200 side. As a result, when it is determined that the compressor current is normal, the operation automatically shifts to the boiling operation, so that the start delay of the boiling operation due to the abnormality determination can be minimized, and the convenience of the user is improved. Can be improved.

  As described above in detail, according to the present embodiment, when the operation of the compressor 1 is started, the abnormality determination mode for holding the rotation speed of the compressor 1 and the opening of the pressure reducing valve device 3 at a constant value is performed. Even without using an expensive pressure switch or pressure detection device, it is possible to detect the blockage of the refrigerant circuit, the abnormality of the decompression device, or the like using the relatively inexpensive current detection device 8. Therefore, a highly reliable heat pump water heater can be realized at low cost. Moreover, since the magnitude of the compressor current is determined with the operating condition of the heat pump unit 100 being constant, the magnitude of the compressor current can be stably determined without receiving disturbance due to fluctuations in the operating state. The abnormality of the heat pump unit 100 can be detected with high accuracy.

  In the first embodiment, the case where the abnormality determination value is set as a constant value is exemplified. However, the present invention is not limited to this, and as shown in Embodiments 3 and 4 described later, the abnormality determination value may be variable.

Embodiment 2. FIG.
Next, a second embodiment of the present invention will be described with reference to FIG. The present embodiment is characterized in that, in addition to the same configuration and control as in the first embodiment, the circulation pump 24 is stopped during the abnormality determination mode. FIG. 3 is a timing chart showing operating states of the compressor, the pressure reducing valve device, and the circulation pump in the abnormality determination mode in the second embodiment of the present invention. As shown in this figure, in the abnormality determination mode of the present embodiment, the rotation speed of the compressor 1 and the opening degree of the pressure reducing valve device 3 are held at preset constant values, respectively, and the circulation pump 24 is operated. In the stopped state, the current detection device 8 detects the compressor current.

  According to the present embodiment configured as described above, in addition to the same effects as those of the first embodiment, the following effects can be obtained. By stopping the circulation pump 24, the operating state of the compressor 1 is affected by the temperature of the water circulating between the hot water tank 20 and the refrigerant water heat exchanger 2, the piping structure of the hot water circulation device 21, and the piping length. It becomes difficult to receive the influence of the circulation amount of water which changes according to etc. This eliminates the need for excessive consideration of variations in the compressor current when setting the abnormality determination value, making it easy to set the abnormality determination value and improving the accuracy of determining the compressor current. .

Embodiment 3 FIG.
Next, Embodiment 3 of the present invention will be described with reference to FIG. The present embodiment is characterized in that, in addition to the same configuration and control as in the first embodiment, the abnormality determination value is changed according to the outside air temperature. FIG. 4 is a characteristic diagram showing the relationship between the outside air temperature and the abnormality determination value in Embodiment 3 of the present invention. When the outside air temperature is listed, the refrigerant temperature also increases accordingly. Therefore, in a state where the rotation speed of the compressor 1 and the opening of the pressure reducing valve device 3 are constant, the compressor current is increased due to the rise in the outside air temperature. There is a tendency to increase. Therefore, as shown in FIG. 4, the abnormality determination value is preferably set to be larger as the outside air temperature is higher. Note that the solid line in FIG. 4 illustrates the case where the abnormality determination value is increased stepwise, and the dotted line illustrates the case where the abnormality determination value is increased linearly.

  According to the present embodiment configured as described above, in addition to the same effects as those of the first embodiment, the following effects can be obtained. Even when the operating condition of the compressor 1 is kept constant, the compressor current varies depending on the outside air temperature. In this embodiment, the abnormality determination value is appropriately changed based on the outside air temperature. The temperature change of the compressor current can be compensated. Therefore, the presence / absence of an abnormality can be accurately determined even in an environment where the outside air temperature changes, and the determination accuracy can be further improved.

Embodiment 4 FIG.
Next, a fourth embodiment of the present invention will be described with reference to FIG. The present embodiment is characterized in that, in addition to the same configuration and control as in the first embodiment, the abnormality determination value is changed according to the temperature of the refrigerant discharged from the compressor 1. FIG. 5 is a characteristic diagram showing the relationship between the discharged refrigerant temperature and the abnormality determination value in Embodiment 4 of the present invention. As described above, even when the operating condition of the compressor 1 is kept constant, when the discharge refrigerant temperature rises, the compressor current tends to increase accordingly. Therefore, as shown in FIG. 5, the abnormality determination value is preferably set to be larger as the discharge refrigerant temperature is higher. Note that the solid line in FIG. 5 illustrates the case where the abnormality determination value is increased stepwise, and the dotted line illustrates the case where the abnormality determination value is increased linearly.

  Also in the present embodiment configured as described above, the abnormality determination value can be appropriately changed based on the discharge refrigerant temperature based on substantially the same principle as in the third embodiment, and this change allows the temperature of the compressor current to be changed. Changes can be compensated. Therefore, in addition to the same effects as those of the first embodiment, the presence / absence of an abnormality can be accurately determined even in an environment where the discharged refrigerant temperature changes.

Embodiment 5 FIG.
Next, a fifth embodiment of the present invention will be described with reference to FIG. In addition to the same configuration and control as in the first embodiment, the present embodiment is characterized in that the duration of the abnormality determination mode (hereinafter referred to as determination mode duration) is changed based on the outside temperature. . FIG. 6 is a characteristic diagram showing the relationship between the outside air temperature and the determination mode duration in the fifth embodiment of the present invention. As shown in this figure, in this Embodiment, it is set as the structure which increases determination mode continuation time, so that outside temperature is low. Note that the solid line in FIG. 6 illustrates the case where the abnormality determination value is increased stepwise, and the dotted line illustrates the case where the abnormality determination value is increased linearly.

  The rising speed when the compressor current increases from the start of operation of the compressor 1 tends to decrease as the outside air temperature decreases, that is, the increase tends to be slow. For this reason, even when the operating condition of the compressor 1 is kept constant, when an abnormality is determined based on the compressor current, a longer time is required as the outside air temperature is lower. Therefore, as shown in FIG. 6, the determination mode duration time is preferably set longer as the outside air temperature is lower.

  According to the present embodiment configured as described above, the determination mode duration time can be changed based on the outside air temperature. That is, even in an environment where the outside air temperature changes, the determination mode duration required for determining an abnormality can always be adjusted to an appropriate length. Therefore, in addition to the same effects as those of the first embodiment, it is possible to suppress erroneous determination due to lack of determination mode duration and the like and improve determination accuracy.

Embodiment 6 FIG.
Next, a sixth embodiment of the present invention will be described with reference to FIG. The present embodiment is characterized in that, in addition to the same configuration and control as in the first embodiment, the determination mode duration is changed based on the discharge refrigerant temperature. FIG. 7 is a characteristic diagram showing the relationship between the discharged refrigerant temperature and the determination mode duration in the sixth embodiment of the present invention. As shown in this figure, in the present embodiment, the determination mode duration is increased as the discharged refrigerant temperature is lower. Note that the solid line in FIG. 7 illustrates the case where the abnormality determination value is increased stepwise, and the dotted line illustrates the case where the abnormality determination value is increased linearly.

  When the outside air temperature is low, the refrigerant temperature also decreases accordingly. Therefore, the rate of increase when the compressor current increases from the start of operation of the compressor 1 tends to be slower as the discharged refrigerant temperature is lower. Therefore, as shown in FIG. 7, the determination mode duration time is preferably set longer as the discharged refrigerant temperature is lower.

  In the present embodiment configured as described above, the determination mode duration is appropriately changed based on the discharge refrigerant temperature and the determination mode duration required for determining an abnormality is based on the same principle as in the fifth embodiment. Can be secured stably. Therefore, in addition to the same effects as those of the first embodiment, erroneous determination can be suppressed and determination accuracy can be improved.

  In the fourth and sixth embodiments, the case where the abnormality determination value and the determination mode duration time are changed based on the discharged refrigerant temperature is exemplified. However, the present invention is not limited to this. For example, the temperature of the main body of the compressor 1 may be detected, and the abnormality determination value or the determination mode duration may be changed based on the detected temperature. In this case, the abnormality determination value is preferably configured to increase as the temperature of the compressor 1 increases, and the determination mode duration is preferably configured to increase as the temperature of the compressor 1 decreases.

  In the first to sixth embodiments, each configuration has been described individually. However, the present invention is not limited to this, and the configuration of the first to sixth embodiments is not limited to this configuration. One system may be realized by combining a plurality of configurations that can be combined. Specifically, in the present invention, the configuration for changing the abnormality determination value based on the outside air temperature or the discharge refrigerant temperature is combined with the configuration for changing the determination mode duration based on the outside air temperature or the discharge refrigerant temperature. Also good.

  In the present invention, as the heat pump unit 100, a heat pump cycle that is operated in a supercritical state where the refrigerant pressure is equal to or higher than the critical pressure may be employed, or a heat pump cycle that is operated at a pressure lower than the critical pressure is employed. May be. In this case, the refrigerant may be configured to use Freon gas, ammonia, or the like.

DESCRIPTION OF SYMBOLS 1 Compressor 2 Refrigerant water heat exchanger 3 Pressure reducing valve device 4 Air refrigerant heat exchanger 5 Refrigerant piping 6 Fan 7 Fan motor 8 Current detection device 9 Feed water temperature sensor 10 Boiling temperature sensor 11 Outside temperature sensor (outside temperature detection means)
12 Refrigerant temperature sensor (temperature detection means)
13, 25 Control unit (control device)
20 Hot water tank 21 Hot water circulation device 22 Feed pipe 23 Return pipe 24 Circulation pump 100 Heat pump unit (heat pump)
200 tank units

Claims (9)

A heat pump that has a refrigerant circuit in which a compressor, a refrigerant water heat exchanger, a pressure reducing valve device, and an air refrigerant heat exchanger are annularly connected, and generates water by heating water by the refrigerant water heat exchanger;
A hot water tank for storing hot water heated by the heat pump;
A hot water circulation device for circulating water between the refrigerant water heat exchanger and the hot water tank;
A current detection device for detecting a compressor current which is a value of a current flowing through the compressor;
A control device for controlling the operation of the compressor based on the compressor current,
During a period from the start of the compressor until a preset time elapses, an abnormality determination mode for holding the rotation speed of the compressor and the opening of the pressure reducing valve device at a constant value is performed, A heat pump water heater configured to determine that the compressor current is abnormal and stop the compressor when the compressor current becomes equal to or greater than an abnormality determination value during the abnormality determination mode.   During the abnormality determination mode, the compressor current and the opening of the pressure reducing valve device are held at constant values, and the compressor current is determined while the hot water circulation device is stopped. The heat pump water heater according to claim 1, which is configured to be executed. An outside temperature detecting means for detecting outside temperature is provided,
The heat pump water heater according to claim 1 or 2, wherein the abnormality determination value is changed based on the outside air temperature. Comprising temperature detection means for detecting the temperature of the refrigerant discharged from the compressor or the temperature of the compressor as the compressor temperature;
The heat pump water heater according to any one of claims 1 to 3, wherein the abnormality determination value is configured to change based on the compressor temperature. An outside temperature detecting means for detecting outside temperature is provided,
The heat pump water heater according to any one of claims 1 to 4, wherein the duration of the abnormality determination mode is changed based on the outside air temperature. Comprising temperature detection means for detecting the temperature of the refrigerant discharged from the compressor or the temperature of the compressor as the compressor temperature;
The heat pump water heater according to any one of claims 1 to 5, wherein the duration of the abnormality determination mode is changed based on the compressor temperature.   The structure according to any one of claims 1 to 6, wherein when the compressor current is determined to be abnormal during the abnormality determination mode, the abnormality determination mode is executed again to determine the compressor current. The heat pump water heater described.   8. The configuration is such that when the compressor current is less than the abnormality determination value during the abnormality determination mode and is determined to be normal, the operation of the compressor is continuously shifted to a boiling operation. The heat pump water heater according to any one of the above.   The heat pump water heater according to any one of claims 1 to 8, wherein when the abnormality determination mode determines that an abnormality has occurred a plurality of times in succession, the operation of the heat pump is stopped.

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