JP2003279136A - Heat pump water heater - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat pump water heater causing no lowering of the temperature of hot water in the upper part of a hot water storage tank even just after starting operation. <P>SOLUTION: This heat pump water heater returns water in the hot water storage tank 1 to the upper part of the hot water storage tank 1 via water supply return pipes 5 and 11 by heating the water by introducing the water to a heat pump unit 30 via a water supply forward pipe 4 by a supply water circulating pump 6. When a detecting temperature of a supply water return temperature 33 is lower than a detecting temperature of an upper temperature sensor 41 of the hot water storage tank 1, since a three-way valve 8 is switched to the bypass pipe 10 side, only hot water is supplied to the upper part of the hot water storage tank 1 so that the temperature of the hot water of the upper part in the hot water storage tank 1 is not lowered. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat pump water heater for heating water in a hot water storage tank with a heat pump.

[0002]

2. Description of the Related Art Conventionally, a heat pump water heater has been known in which heat of the atmosphere is drawn by a heat pump to heat water in a hot water storage tank. This heat pump water heater is highly efficient because it draws heat from the atmosphere, and is expected to spread in the future as an environment-friendly device that can realize energy saving. In recent years, a refrigeration cycle using carbon dioxide as a refrigerant, which has an extremely low global warming potential and ozone depletion potential, has been developed.
It has become possible to heat water to a high temperature of about 90 ° C., and a coefficient of performance COP of 3 or more can be secured, further increasing the practicality. In addition, a device equipped with an automatic hot water refilling function for the bathtub and a heat retaining function for the bathtub water has been commercialized, and the convenience is increasing.

FIG. 7 is a system configuration diagram of such a conventional heat pump water heater. When the faucet (not shown) leading to the hot water outlet pipe 3 is opened, or the hot water electromagnetic valve (not shown) for supplying hot water to the bathtub is opened, the water from the water supply source passes through the water supply pipe 2. Water is supplied to the hot water storage tank 1, and the high-temperature water in the hot water storage tank 1 is discharged from the hot water discharge pipe 3. On the other hand, the water in the hot water storage tank 1 is
After being guided to the heat pump unit 30 through the water supply outflow pipe 4 connected to the bottom of the hot water storage tank 1 and being heated to a high temperature by removing heat from the carbon dioxide refrigerant by the water supply heat exchanger 7 in the heat pump unit 30, the water supply return pipe 5 Is returned to the upper part of the hot water storage tank 1. The hot water storage tank 1 is provided with an upper temperature sensor 41, a middle temperature sensor 42, and a lower temperature sensor 43 for detecting the temperature of the water in the hot water storage tank 1.

Next, the refrigerant cycle of the heat pump unit 30 will be described. The carbon dioxide refrigerant in the refrigerant passage 18 draws heat from the atmosphere sent to the atmospheric heat exchanger 20 by the fan 19. Then, it is compressed by the compressor 17 and brought into a high temperature and high pressure state. Next, heat is supplied to the water from the hot water storage tank 1 by the feed water heat exchanger 7, and the expansion valve 21
The adiabatic expansion is performed to return to the low temperature and low pressure state, and the cycle ends. With the above configuration, high efficiency can be realized by heating the water in the hot water storage tank 1 with the heat pump unit 30.

[0005]

However, in the above-mentioned conventional heat pump water heater, when the water supply circulation pump 6 starts the operation and starts the heating operation of the water in the hot water storage tank 1, the compression in the heat pump unit 30 is started. The warm-up operation for several minutes is required to start the operation of the machine 17, and the heating capacity is not fully exhibited during this period. Since the water supply circulation pump 6 starts operating in this state, the water having a low temperature which is not sufficiently heated is supplied to the upper part of the hot water storage tank 1 through the water supply return pipe 5, and the upper part of the hot water storage tank 1 is supplied. However, there was a problem that the temperature of the high temperature water was lowered.
As a countermeasure against this, it is conceivable to delay the start of operation of the water supply circulation pump 6, but in that case, the heat pump unit 30 will be in an empty state and the refrigeration cycle will fail.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a heat pump water heater which does not reduce the temperature of the high temperature water in the upper part of the hot water storage tank immediately after the start of operation. To provide.

[0007]

[Means for Solving the Problem and Its Action / Effect] In order to achieve the above object, in Claim 1, a hot water storage tank is provided.
A heat pump unit equipped with a water supply heat exchanger for heating water in the hot water storage tank, a water feed pipe for guiding the water in the hot water storage tank to the heat pump unit, and water heated by the heat pump unit as the hot water storage In a heat pump water heater having a water supply return pipe for returning to the upper part of the tank and a water supply circulation pump for circulating the water in the hot water storage tank with the heat pump unit, the water supply return pipe and the water supply forward pipe are connected to each other. And a three-way valve at the connection between the water supply return pipe and the bypass pipe. Therefore, if the three-way valve is switched to the bypass pipe side from the start of the operation of the heat pump unit to the completion of the warm-up operation, water that is not sufficiently heated and has a low temperature will be heated again in the heat pump unit. Therefore, the temperature of the high temperature water in the upper part of the hot water storage tank is not lowered.

According to a second aspect of the present invention, there is provided a hot water storage tank, a heat pump unit provided with a water feed heat exchanger for heating water in the hot water storage tank, and a water feed pipe for guiding the water in the hot water storage tank to the heat pump unit. In a heat pump water heater provided with a water supply return pipe for returning water heated by the heat pump unit to the upper part of the hot water storage tank, and a water supply circulation pump for circulating water in the hot water storage tank between the heat pump unit, A bypass pipe connecting the water supply return pipe and the middle and lower parts of the hot water storage tank is provided, and a three-way valve is provided at a connection portion between the water supply return pipe and the bypass pipe. Therefore, if the three-way valve is switched to the bypass pipe side from the start of the operation of the heat pump unit to the completion of the warm-up operation, water that is not sufficiently heated and has a low temperature will be stored in the middle of the hot water tank (or Since it is returned to the lower part, the temperature of the high temperature water in the upper part of the hot water storage tank is not lowered.

In claim 3, claim 1 or claim 2
In the heat pump water heater described in (1), the reheating water exchanger upstream of the three-way valve is provided with a reheating heat exchanger for reheating the bath water. Therefore, when heating the bathtub water or keeping it warm, the bathwater is heated by operating the water supply circulation pump and passing the water guided from the hot water storage tank and heated by the heat pump unit through the heating bath heat exchanger. be able to.

According to a fourth aspect of the present invention, in the heat pump water heater according to the first to third aspects, the water supply return pipe upstream of the three-way valve is provided with a water supply return temperature sensor for detecting a water supply return temperature. The three-way valve is switched based on the detection information of the feed water return temperature sensor. Therefore, when it is detected that the temperature of the water heated by the heat pump unit becomes high,
If the three-way valve is switched from the bypass pipe side route to the water supply return pipe side route, only the water heated to high temperature by the heat pump unit will be returned to the upper part of the hot water storage tank, so Does not lower the temperature of hot water.

According to a fifth aspect of the present invention, in the heat pump water heater according to the fourth aspect, the feed water return temperature sensor is located downstream of the additional heating heat exchanger. Therefore, it is possible to detect that the temperature of the water heated by the heat pump unit has decreased due to the additional operation of the bath water,
At this time, if the three-way valve is switched to the bypass pipe side, the water having a low temperature returns through the bypass pipe, so that the temperature of the high temperature water in the upper part of the hot water storage tank is not lowered.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a system configuration diagram of a first embodiment of a heat pump water heater according to the present invention. The water in the hot water storage tank 1 is guided by the water supply circulation pump 6 to the heat pump unit 30 through the water supply outflow pipe 4 connected to the bottom of the hot water storage tank 1, and is converted from the carbon dioxide refrigerant by the water supply heat exchanger 7 in the heat pump unit 30. After removing heat and being heated to a high temperature, it is returned to the upper part of the hot water storage tank 1 through the water supply return pipe 5. A feed water return temperature sensor 33 for detecting the feed water return temperature is provided downstream of the feed water heat exchanger 7, and a three-way valve 31 is provided further downstream thereof. The bypass pipe 32 branched by the three-way valve 31 communicates with the water supply outflow pipe 4. Further, the hot water storage tank 1 is provided with an upper temperature sensor 41, a middle temperature sensor 42, and a lower temperature sensor 43 for detecting the temperature of the water in the hot water storage tank 1. Since the refrigerant cycle of the heat pump unit 30 is the same as that of the conventional example described in FIG. 7, the description thereof is omitted here.

FIG. 4 shows an operation control flow of the above-mentioned three-way valve 31. First, it is confirmed whether or not the boiling operation of the water in the hot water storage tank 1 is in progress (step S1). If it is being boiled, the feed water return temperature heated by the heat pump unit 30 is confirmed by the feed water return temperature sensor 33 and compared with the tank upper temperature detected by the upper temperature sensor 41 of the hot water storage tank 1 (step S2). When the water supply return temperature is lower than the tank upper temperature, the three-way valve 31 is switched to the bypass pipe 32 side to perform heating again (step S4). If the water return temperature is higher than the tank upper temperature,
The three-way valve 31 is switched to the path on the hot water storage tank 1 side, and heated water is supplied to the upper part of the hot water storage tank (step S
3). In this way, since only high-temperature water heated above the temperature of the upper part of the tank is supplied to the upper part of the hot water storage tank 1, the temperature of the high temperature water in the upper part of the hot water storage tank 1 is not lowered.

FIG. 2 is a system configuration diagram of the second embodiment of the heat pump water heater of the present invention. The water in the hot water storage tank 1 is guided by the water supply circulation pump 6 to the heat pump unit 30 through the water supply outflow pipe 4 connected to the bottom of the hot water storage tank 1, and is converted from the carbon dioxide refrigerant by the water supply heat exchanger 7 in the heat pump unit 30. After removing heat and being heated to a high temperature, it is returned to the upper part of the hot water storage tank 1 through the water supply return pipes 5 and 11. A feed water return temperature sensor 33 for detecting the feed water return temperature is provided downstream of the feed water heat exchanger 7, and a three-way valve 8 is provided further downstream thereof. One downstream path of the three-way valve 8 is connected to a water supply return pipe 11 that communicates with the upper portion of the hot water storage tank 1, and the other downstream path is connected to a bypass pipe 10 that communicates with the middle portion (may be the lower portion) of the hot water storage tank 1. Has been done. Other configurations are shown in FIG.
Since it is the same as that of the first embodiment described above, the description thereof will be omitted here.

FIG. 5 is an operation control flow of the above-mentioned three-way valve 8. First, it is confirmed whether or not the boiling operation of the water in the hot water storage tank 1 is in progress (step S1). If it is being boiled, the feed water return temperature heated by the heat pump unit 30 is confirmed by the feed water return temperature sensor 33 and compared with the tank upper temperature detected by the upper temperature sensor 41 of the hot water storage tank 1 (step S2). When the water supply return temperature is lower than the tank upper temperature, the three-way valve 8 is switched to the bypass pipe 10 side to supply water to the low temperature portion near the middle portion (or lower portion) of the hot water storage tank 1 (step S4 '). If the water supply return temperature is equal to or higher than the tank upper temperature, the three-way valve 8 is switched to the path on the water supply return pipe 11 side, and heated water is supplied to the upper part of the hot water storage tank 1 (step S3 ′). Since only high temperature water heated above the temperature of the upper part of the tank is supplied to the upper part of the hot water storage tank 1,
The temperature of the high temperature water in the upper part of the hot water storage tank 1 is not lowered.

FIG. 3 is a system configuration diagram in the third embodiment of the heat pump water heater of the present invention. The main difference from the second embodiment shown in FIG. 2 is that an additional heating heat exchanger 9 is provided upstream of the three-way valve 8 of the feed water return pipe 5, and the additional heating heat exchanger 9 and the three-way valve 8 are provided. The point is that the water supply return temperature sensor 34 is provided between the two. In FIG. 3, the water in the bathtub 16 is additionally heated by the additional heating heat exchanger 9 and kept warm. That is, the hot water circulating bath 14 guides the hot water in the bathtub 16 to the hot water heating heat exchanger 9 through the bath metal fitting 15 and the hot water return pipe 12, where it is heated by hot water heating, and then through the hot water forward pipe 13 to the hot water bath. It is configured to return to the inside of 16. When the bath temperature sensor 23 provided in the additional heating return pipe 12 detects the preset temperature of the bath, the additional heating circulation pump 14 stops and the additional heating operation ends. In this example, since the bath water can be heated by heating with the heat pump, high efficiency can be achieved and the heating time can be shortened.

FIG. 6 is an operation control flow at the time of the above-described additional heating operation. First, it is confirmed whether or not a reheating switch such as an operation remote controller (not shown) is operated to generate a reheating request (step S11). When the additional heating request is generated, the additional heating circulation pump 14 is operated to guide the water in the bath 16 to the additional heating heat exchanger 9 (step S12). At the same time, the operation of the water supply circulation pump 6 is started, the water in the hot water storage tank 1 is heated by the heat pump unit 30, and then the water is guided to the additional heating heat exchanger 9 to add heat to the bath water in the additional heating heat exchanger 9 to add additional heat. Burn (step S13).

Next, after the water is heated by the heat pump unit 30, the water temperature in the feed water return pipe, which has been deprived of heat by the additional heat exchanger, is confirmed by the feed water return temperature sensor 34,
The temperature is compared with the tank upper temperature detected by the upper temperature sensor 41 of the hot water storage tank 1 (step S14). When the water supply return temperature is lower than the tank upper temperature, the three-way valve 8 is switched to the bypass pipe 10 side to supply water to the low temperature portion near the middle part of the hot water storage tank 1 (step S16). When the water supply return temperature is equal to or higher than the tank upper temperature, the three-way valve 8 is switched to the path on the water supply return pipe 11 side, and heated water is supplied to the upper part of the hot water storage tank 1 (step S15). In this way, since only high-temperature water heated above the temperature of the upper part of the tank is supplied to the upper part of the hot water storage tank 1, the temperature of the high temperature water in the upper part of the hot water storage tank 1 is not lowered.

This additional heating operation is continued until the bath water has boiled to the set temperature, and when it has boiled to the set temperature (step S17), the additional heating circulation pump 14 is stopped (step S).
18), the water supply circulation pump 6 is also stopped (step S1)
9). Next, the three-way valve 8 is switched to the bypass pipe 10 side and stands by (step S20).

In this embodiment, in step S14, the return water temperature and the tank upper temperature are compared and the three-way valve 8 is switched. The return water temperature is correlated with the temperature detected by the bath temperature sensor 23 during the additional heating operation. Since there is a relationship, the temperature detected by the bath temperature sensor 23 may be used instead.

[Brief description of drawings]

FIG. 1 is a system configuration diagram of a first embodiment of a heat pump water heater of the present invention.

FIG. 2 is a system configuration diagram of a second embodiment of the heat pump water heater of the present invention.

FIG. 3 is a system configuration diagram of a heat pump water heater according to a third embodiment of the present invention.

FIG. 4 is an operation control flow of the three-way valve 31.

[Fig. 5] Operation control flow of the three-way valve 8

[Fig. 6] Operation control flow during additional heating operation

FIG. 7 is a system configuration diagram of a conventional heat pump water heater.

[Explanation of symbols]

1 ... Hot water storage tank 2 ... Water pipe 3… Swimming pipe 4 ... Water supply outflow pipe 5, 11 ... Water supply return pipe 6 ... Water circulation pump 7 ... Water heat exchanger 8, 31 ... 3-way valve 9 ... Additional heat exchanger 10, 32 ... Bypass pipe 12 ... Reheating tube 13 ... Reheating tube 14 ... Additional circulation pump 15. Bathtub circulation fittings 16 ... Bathtub 17 ... Compressor 18 ... Refrigerant path 19 ... fan 20 ... Atmosphere heat exchanger 21 ... Expansion valve 23 ... Bath temperature sensor 30 ... Heat pump unit 33, 34 ... Water supply return temperature sensor 41 ... Upper temperature sensor 42 ... Central temperature sensor 43 ... Lower temperature sensor

Claims (5)

[Claims] 1. A hot water storage tank, a heat pump unit equipped with a feed water heat exchanger for heating water in the hot water storage tank, a water feed pipe for guiding the water in the hot water storage tank to the heat pump unit, and the heat pump. In a heat pump water heater comprising a water supply return pipe for returning water heated by a unit to the upper part of the hot water storage tank, and a water supply circulation pump for circulating water in the hot water storage tank with the heat pump unit, A heat pump water heater comprising a bypass pipe that connects the pipe and the water supply outflow pipe, and a three-way valve at a connection portion between the water supply return pipe and the bypass pipe. 2. A hot water storage tank, a heat pump unit equipped with a feed water heat exchanger for heating water in the hot water storage tank, a water feed pipe for guiding the water in the hot water storage tank to the heat pump unit, and the heat pump. In a heat pump water heater comprising a water supply return pipe for returning water heated by a unit to the upper part of the hot water storage tank, and a water supply circulation pump for circulating water in the hot water storage tank with the heat pump unit, A heat pump water heater comprising a bypass pipe that connects the pipe to the middle and lower parts of the hot water storage tank, and a three-way valve provided at a connection portion between the water supply return pipe and the bypass pipe. 3. The water supply return pipe upstream of the three-way valve,
The heat pump water heater according to claim 1 or 2, further comprising a reheating heat exchanger for reheating the bath water. 4. The water supply return pipe upstream of the three-way valve,
The heat pump water heater according to claim 1, further comprising a water supply return temperature sensor for detecting the water supply return temperature, and switching the three-way valve based on detection information of the water supply return temperature sensor. . 5. The heat pump water heater according to claim 4, wherein the water supply return temperature sensor is located downstream of the additional heat exchanger.