JP2015143597A - water heater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water heater capable of switching over between a two-stage compression operation and a single-stage compression operation in response to a required boiling temperature of hot water or a heating capacity.SOLUTION: A water heater comprises: a first refrigerating cycle A forming a refrigerant channel by connecting together a first compressor 2A, a four-way valve 3A, a first condenser 4A2 disposed to be able to implement heat exchange with a first water-heat exchanger 4A, a first expansion valve 5A, and a first air-heat exchanger 6A by a first refrigerant pipe 7A; and a second refrigerating cycle B forming a refrigerant channel by connecting together a second compressor 2B, a second condenser 4B2 disposed to be able to implement heat exchange with a second water-heat exchanger 4B, a second expansion valve 5B, and a second air-heat exchanger 6B disposed in parallel to the first air-heat exchanger 6A leeward in an air blow direction by a second refrigerant pipe 7B. The water heater is configured to be able to switch over between a second-stage compression operation in which the first condenser 4A2 is connected in series to the second condenser 4B2 when the first compressor 2A and the second compressor 2B are connected to each other so as to be able to perform two-stage compression, and a single-stage compression operation in which the first condenser 4A2 and the second condenser 4B2 operate individually when the first compressor 2A and the second compressor 2B operate individually.

Description

  Embodiments described herein relate generally to a heat pump hot water supply apparatus.

  Conventionally, as an example of this type of hot water supply apparatus, a two-stage compression refrigeration cycle apparatus including a plurality of, for example, two refrigeration cycles (heat pump cycles) is known (see, for example, Patent Document 1).

  This two-stage compression refrigeration cycle apparatus has two-stage compression operation in which two compressors are connected in series and refrigerant is compressed by two compressors, and two compressors are connected in parallel to each other. It is configured to be able to switch between single-stage compression and parallel operation, and a heat exchanger that acts as a common condenser and evaporator is used during both operations.

Japanese Patent Laid-Open No. 04-257661

  However, in such a conventional two-stage compression refrigeration cycle apparatus, when a common heat exchanger is used by a two-stage compressor, the refrigerant during low-capacity operation of single-stage compression and large-capacity operation of two-stage compression is used. It may be difficult to ensure balance.

  Further, when frost is generated in the air heat exchanger acting as an evaporator during the heating operation, the heating operation is stopped for the defrosting operation. For this reason, there exists a subject that the heating effect reduces.

  The problem to be solved by the present invention is to provide a hot water supply apparatus capable of switching between a two-stage compression operation and a single-stage compression operation in accordance with required hot water boiling temperature and heating capacity.

  A hot water supply apparatus of an embodiment includes a first compressor, a four-way valve, a first condenser that is arranged to exchange heat with a first water passage that allows water to be supplied from a first water heat exchanger, a first throttle mechanism, A first refrigeration cycle in which a first air heat exchanger is connected by a first refrigerant pipe to form a refrigerant flow path for circulating the refrigerant, and a second compressor and a second water heat exchanger are used to feed water from the second water heat exchanger. A second condenser, a second throttle mechanism, and a second air heat exchanger arranged in parallel with the first air heat exchanger on the leeward side in the blowing direction are arranged as a second refrigerant. And a second refrigeration cycle in which a refrigerant flow path for circulating the refrigerant is formed by piping.

  And when the 1st compressor and the 2nd compressor are connected so that 2 stage compression is possible, the 1st condenser and the 2nd condenser are connected in series, the 2nd stage compression operation, the 1st compressor and the 1st compressor When the two compressors are individually operated, the first condenser and the single stage compression operation in which the second condenser is also individually operated can be switched.

The refrigeration cycle block diagram of the hot water supply apparatus which concerns on embodiment. The refrigerating cycle figure which shows the effect | action at the time of the two-stage compression operation of the hot water supply apparatus shown in FIG. The refrigeration cycle figure which shows the effect | action at the time of single stage compression operation in the case of carrying out the hot water supply operation of the 1st, 2nd refrigeration cycle of the hot water supply apparatus shown in FIG. The refrigerating cycle figure which shows the effect | action at the time of a single stage compression operation in case one side of the 1st, 2nd freezing cycle of the hot-water supply apparatus shown in FIG.

  Hereinafter, embodiments will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected to the same or an equivalent part in several drawings.

  Drawing 1 is a refrigeration cycle lineblock diagram of a hot-water supply device concerning an embodiment. As shown in FIG. 1, the hot water supply device 1 includes a plurality of, for example, a first refrigeration cycle A and a second refrigeration cycle B.

  The first refrigeration cycle A is disposed in a heat exchangeable manner with the first water passage 4A1 through which water is supplied from the discharge port 2A1, the four-way valve 3A, and the first water heat exchanger 4A of the first compressor 2A. A refrigerant that circulates the refrigerant by connecting the condenser 4A2, the first expansion valve 5A as an example of the first throttle mechanism, the first air heat exchanger 6A, and the suction port 2A2 of the first compressor 2A1 through the first refrigerant pipe 7A. A flow path is formed.

  The second refrigeration cycle B includes a refrigerant outlet 2B1 of the second compressor 2B and a second water passage 4B1 through which water is supplied from the second water heat exchanger 4B. The second expansion valve 5B, the second air heat exchanger 6B, and the suction port 2B2 of the second compressor 2B, which are examples of the second throttle mechanism, are connected by the second refrigerant pipe 7B to circulate the refrigerant. Is forming. The first and second air heat exchangers 6A and 6B are constituted by, for example, multi-row type find-and-tube heat exchangers.

  The first water passage 4A1 of the first water heat exchanger 4A and the second water passage 4B1 of the second water heat exchanger 4B are connected in series by a water supply pipe 8.

  The water supply pipe 8 includes an upstream pipe 8A connected to the water inlet of the first water passage 4A1 and a downstream water supply pipe 8B connected to the outlet of the second water passage 4B1. A water supply circulation pump 9 is interposed in the middle of the downstream side water supply pipe 8B. By this feed water circulation pump 9, the feed water is heated up to a required temperature by sequentially passing through the first and second water passages 4A1, 4B1 of the first and second water heat exchangers 4A, 4B and repeatedly circulating them. .

  And the hot water supply apparatus 1 is the 1st, 2nd compressor connection pipe | tube 10 which connects 3 A of valves and the suction inlet 2B2 of the 2nd compressor 2B, the exit of 2nd condenser 4B2, and the entrance of 1st condenser 4A1. The first and second condenser connecting pipes 11 connected in series, the inlet side connecting pipe 12 connecting the inlet sides of the first and second air heat exchangers 6A and 6B, and the first and second air heats. An outlet side connecting pipe 13 for connecting the outlet sides of the exchangers 6A and 6B is provided.

  For this purpose, the first and second air heat exchangers 6A and 6B are connected in parallel by the inlet side connecting pipe 12 and the outlet side connecting pipe 13 to form a parallel circuit. Therefore, the first and second air heat exchangers 6A and 6B are arranged in parallel with each other at a predetermined interval, and the first air heat exchanger 6A is arranged on the upstream side in the blowing direction of the blower 14 including, for example, a suction fan. And the 2nd air heat exchanger 6B is arrange | positioned in the downstream of this 1st air heat exchanger 6A.

  Further, a two-stage compression on-off valve 15 is interposed in the middle of the first and second compressor connection pipes 10, and a condenser on-off valve 16 is provided in the middle of the first and second condenser connection pipes 11. It is intervening.

  Further, an inlet-side opening / closing valve 17 is interposed in the middle of the inlet-side connecting pipe 12, and an outlet-side opening / closing valve 18 is interposed in the middle of the outlet-side connecting pipe 13.

  The hot water supply device 1 is provided with a two-phase refrigerant outlet pipe 19 that connects the refrigerant outlet side of the first condenser 4A2 to the refrigerant inlet side of the second air heat exchanger 6B. In the middle of the two-phase refrigerant outlet pipe 19, a flow rate adjustment valve 20, a gas-liquid separator 21, and a liquid side on-off valve 22 are sequentially inserted in this order from the upstream side to the downstream side in the refrigerant circulation direction.

  The gas-liquid separator 21 connects the other end of the injection pipe 23 whose one end is connected to the gas refrigerant outlet to an intermediate portion between the four-way valve 3A and the second compressor 2B in the first refrigerant pipe 7A. An injection opening / closing valve 24 is interposed in the middle of the injection pipe 23. Further, in the middle of the first refrigerant pipe 7A, a first condenser on-off valve 25 is interposed at an intermediate part between the connection part with the injection pipe 23 and the refrigerant inlet of the first condenser 4A2.

  Further, the first refrigerant pipe 7A is provided with a first air heat exchanger on / off valve 28 on the downstream side of the first condenser 4A2.

  The second refrigerant pipe 7B is provided with a second condenser on-off valve 26 on the downstream side of the second condenser 4B2, and on the downstream side of the second air heat exchanger 6B. An on-off valve 27 is interposed.

  And each said on-off valve, ie, the two-stage compression on-off valve 15, the condenser on-off valve 16, the inlet side on-off valve 17, the outlet side on-off valve 18, the liquid side on-off valve 22, the injection on-off valve 24, the first condenser on-off The valve 25, the second condenser on / off valve 26, the second air heat exchanger on / off valve 27, and the first air heat exchanger on / off valve 28 are constituted by, for example, electromagnetic valves, and are connected to the controller 29 via signal lines (not shown). Are electrically connected to each other and controlled to be opened and closed by a controller 29.

  The first and second expansion valves 5A and 5B and the flow rate adjusting valve 20 are electrically operated valves such as a PMV (pulse motor valve), and are electrically connected to the controller 29 via a signal line (not shown). The opening degree is controlled by the controller 29. Further, the controller 29 is electrically connected to an inverter (not shown) of the feed water circulation pump 9 and the blower 14 through a signal line (not shown) to control ON / OFF, rotation speed, etc. of the feed water circulation pump 9 and the blower 14. Is done.

  The controller 29 includes, for example, a microprocessor and the like, and includes a ROM in which various control programs to be described later are recorded, a CPU for executing the control program, a RAM for configuring a work area and a temporary storage at the time of execution, and the like. doing.

  The controller 29 has a function of reading an operation signal from a driving operation unit (not shown) and detection signals from various sensors such as a temperature sensor and controlling the operation of the entire hot water supply device 1 based on these read signals. ing.

  The controller 29 stores various control programs for controlling the operation of the hot water supply device 1 in the ROM, and includes a control program for controlling at least a two-stage compression operation and a single-stage compression operation. .

  In the two-stage compression operation shown in FIG. 2, the first and second refrigeration cycles A and B are performed when the operation request from a driving operation unit (not shown) is to increase the boiling temperature of hot water at a low outside air temperature. The two compressors 2A and 2B are connected in series to perform a two-stage compression operation, and the first condenser 4A2 of the first water heat exchanger 4A and the second condenser 4B2 of the second water heat exchanger 4B. Are connected in series to increase the boiling temperature of hot water.

  In the single-stage compression operation, when the operation request from the operation operation unit is an improvement in the heating capacity of the hot water supply device 1, the first and second refrigeration cycles A and B are separately supplied with hot water as shown in FIG. The operation for improving the heating capacity and the operation for defrosting the first refrigeration cycle A and the hot water supply operation for the second refrigeration cycle B, as shown in FIG. 4, and the displacement volume being smaller than those of the first compressor 2A There is an operation in which only the second refrigeration cycle B having the second compressor 2B is operated and the operation of the first refrigeration cycle A is stopped to efficiently perform the low capacity operation.

  FIG. 2 is a refrigeration cycle diagram during the two-stage compression operation. During this two-stage compression operation, the controller 29 operates (ON) the first and second compressors 2A, 2B, and further, the two-stage compression on-off valve 15, the condenser on-off valve 16, the liquid side on-off valve 22, The inlet side opening / closing valve 17 and the outlet side opening / closing valve 18 are each opened.

  On the other hand, the first and second air heat exchanger on / off valves 28 and 27 and the first and second condenser on / off valves 25 and 26 are closed by the controller 29.

  Thus, in FIG. 2, the refrigerant circulates in the refrigerant flow path indicated by the solid line in the direction of the solid arrow, and the refrigerant flow path indicated by the broken line is closed.

  That is, the first and second compressors 2A and 2B are connected in series by the first and second compressor connecting pipes 10, and the first and second condensers 4A2 and 4B2 are connected to each other by the first and second condensers. The tubes 11 are connected in series. 2 to 4, white arrows indicate the direction of water supply or circulation.

  Further, both inlet sides of the first and second air heat exchangers 6A and 6B are connected by the inlet connecting pipe 12 and both outlet sides thereof are connected by the outlet connecting pipe 13. For this purpose, the first and second air heat exchangers 6A and 6B are connected in parallel.

  On the other hand, in FIG. 2, the refrigerant flow paths indicated by broken lines, that is, from the outlet sides of the first and second condensers 4A2 and 4B2 to the inlet sides of the first and second air heat exchangers 6A and 6B, Part of the refrigerant flow path from the outlet side of the two-air heat exchanger 6B to the suction port side of the second compressor 2B is closed.

  Thereby, the high-temperature and high-pressure gas refrigerant compressed by the first compressor 2A and discharged from the discharge port 2A1 passes through the four-way valve 3A and the first and second compressor connecting pipes 10 into the second compressor 2B. The air is sucked in from the suction port 2B2, further compressed by the second compressor 2B, becomes a high-temperature and high-pressure gas refrigerant and is discharged from the discharge port 2B1, and the second and first water heat exchangers 4B and 4A are connected in series. Sequentially flows into the connected second and first condensers 4B2 and 4A2, where the latent heat of condensation is dissipated to the water flowing sequentially through the second and first water passages 4B1 and 4A1.

  Thereby, the water flowing sequentially through the second and first water passages 4B1 and 4A1 connected in series is heated in two stages. And since it heats with the high-temperature / high pressure gas refrigerant | coolant compressed by 2 steps | paragraphs, the boiling temperature of hot water can be raised.

  On the other hand, the liquid refrigerant condensed and liquefied by radiating heat in the first and second condensers 4A2 and 4B2 is reduced in pressure through the two-phase refrigerant outlet pipe 19 while the flow rate is controlled by the flow rate adjusting valve 20, and then the medium temperature and medium pressure gas is discharged. It becomes a liquid two-phase refrigerant and flows into the gas-liquid separator 21, where it is gas-liquid separated.

  Here, the gas-phase gas refrigerant separated from the gas and liquid flows into the first and second compressor connecting pipes 10 through the injection pipe 23, where they merge with the high-temperature and high-pressure gas refrigerant discharged from the first compressor 2A. Then, it is injected into the second compressor 2B.

  On the other hand, the liquid refrigerant separated by the gas-liquid separator 21 flows into the first and second air heat exchangers 6A and 6B connected in parallel and flows in parallel, and here, due to the latent heat of evaporation of the liquid refrigerant. Each of them evaporates, absorbs heat from the outside air, vaporizes, and is sucked into the first compressor 2A. This gas refrigerant is compressed again by the first compressor 2A, further compressed by the second compressor 2B, and compressed in two stages, and the above-described operation is repeated.

  Therefore, according to this two-stage compression operation, the gas refrigerant is compressed in two stages by the two first and second compressors 2A and 2B, so that the first and second water heat exchangers are converted from the second compressor 2B. The temperature and pressure of the gas refrigerant sequentially flowing into the first and second condensers 4A2 and 4B2 of 4A and 4B can be increased as compared with the case of one-stage compression.

  Further, the high-temperature and high-pressure gas refrigerant heats the water in the second water passage 4B1 and the first water passage 4A1 connected in series by the second and first condensers 4B2 and 4A2, respectively. The boiling temperature of water (hot water) discharged from the water passage 4B1 can be increased. That is, such a two-stage compression operation can perform a high compression operation such as a high-temperature water heating operation at a low outside air temperature.

  Further, by injecting the gas refrigerant separated by the gas-liquid separator 21 into the second compressor 2B through the injection pipe 23, only the liquid refrigerant is supplied to the first and second air heat exchangers 6A, 6B. Therefore, the heat absorption amount in the first and second air heat exchange increases, and the efficiency is improved. In addition, since the gas refrigerant separated into gas and liquid is caused to flow into the second compressor 2B, the influence of an increase in pressure loss due to an increase in the inflow of gas refrigerant is affected by both the first compressor 2A and the second compressor 2B. Since it does not receive, it can prevent the efficiency fall of the hot-water supply apparatus 1 whole.

  FIG. 3 is a refrigeration cycle diagram showing the operation of the single-stage compression two-unit parallel operation of the hot water supply apparatus 1 when the first and second refrigeration cycles A and B are individually operated for hot water supply.

  In this single-stage compression two-unit parallel operation, the first and second compressors 2A and 2B are operated by the controller 29, the second condenser on-off valve 26, the second air heat exchanger on-off valve 27, the first condensation The open / close valve 25 and the first air heat exchanger open / close valve 28 are opened.

  On the other hand, the condenser open / close valve 16, the liquid side open / close valve 22, the inlet side open / close valve 17, the outlet side open / close valve 18, and the injection open / close valve 24 are closed by the controller 29.

  As a result, in FIG. 3, the refrigerant circulates in the refrigerant flow path indicated by the solid line in the direction of the solid arrow, and the refrigerant flow path indicated by the broken line is closed.

  For this purpose, the first and second refrigeration cycles A and B are individually operated, and the first condenser 4A2 and the second condenser 4B2 of the first and second water heat exchangers 4A and 4B are also individually operated. Is done.

  For this reason, in the first refrigeration cycle A, the high-temperature and high-pressure gas refrigerant compressed by the first compressor 2A flows into the first condenser 4A2 of the first water heat exchanger 4A through the four-way valve 3A. Then, the latent heat of condensation is released to heat the water in the first water passage 4A1 and boil it to hot water.

  The liquid refrigerant radiated and liquefied by the first condenser 4A2 is decompressed while being controlled in flow rate by the first expansion valve 5A and flows into the first air heat exchanger 6A, where it evaporates due to the latent heat of vaporization of the liquid refrigerant. Then, it absorbs heat from the outside air, becomes a gas refrigerant, is sucked into the first compressor 2A, is compressed again here, and thereafter the water flowing through the first water passage 4A1 is heated by repeating the above-described operation. Boil in hot water.

  On the other hand, in the second refrigeration cycle B, as in the first refrigeration cycle A, the high-temperature and high-pressure gas refrigerant compressed by the second compressor 2B is converted into the second condenser 4B2 of the second water heat exchanger 4B. The latent heat of condensation is discharged here, and the water in the second water passage 4B1 is heated and boiled into hot water.

  The liquid refrigerant liquefied by radiating heat in the second condenser 4B2 is sucked into the second compressor 2B again through the second expansion valve 5B → the second air heat exchanger 6A in substantially the same manner as in the first refrigeration cycle A. Here, after being compressed again, the above operation is repeated to heat the water in the second water channel and bring it to hot water.

  Therefore, according to this single-stage operation, that is, the single-stage two-unit parallel hot water supply operation, the first and second water heat exchangers 4A and 4B of the first and second refrigeration cycles A and B are connected. Since the water (hot water) in the water channels 4A1 and 4B1 is individually heated and boiled up to the hot water, it is possible to increase the amount of hot water and the amount of hot water to be heated. That is, the heating capacity of the hot water supply device 1 can be improved.

  FIG. 4 is a refrigeration cycle diagram showing an operation when one of the first and second refrigeration cycles A and B, for example, A is defrosted and the other B is hot water supplied.

  That is, in the single-stage compression operation, when the first and second refrigeration cycles A and B are both hot-watered as shown in FIG. When the frost is generated in the first and second air heat exchangers 6A and 6B of B, the controller 29 so that the refrigerant circulates through the four-way valve 3A of the first refrigeration cycle A in the direction of the broken line arrow in FIG. This is an operation method in the case where the reverse defrosting operation is performed by switching by the above. For this reason, the opening / closing control of each opening / closing valve is controlled in the same manner as in the operation method of FIG.

  Therefore, the second refrigeration cycle B is operated for hot water supply in the same manner as the embodiment shown in FIGS. For this purpose, the high-temperature and high-pressure gas refrigerant compressed by the second compressor 2B circulates in the direction of the solid line arrow in FIG. 4, and the second condenser 4B2 of the second water heat exchanger 4B causes the second water passage 4B1. Heat the water and boil it in hot water.

  On the other hand, in the first refrigeration cycle A, the high-temperature and high-pressure gas refrigerant compressed by the first compressor 2A circulates in the direction of the dashed arrow in the direction opposite to the hot water supply operation indicated by the solid line arrow direction. It flows into the heat exchanger 6A, where the latent heat of condensation is released to heat the first air heat exchanger 6A. Thereby, the frost adhering to 6 A of 1st air heat exchangers can be defrosted by heating-melting.

  Moreover, since this 1st air heat exchanger 6A exists in the ventilation direction upstream of the air blower 14 with respect to the 2nd air heat exchanger 6B arranged in parallel with this, it was heated by the 1st air heat exchanger 6A. Hot air is blown against the second air heat exchanger 6B to heat it.

  For this reason, since the 2nd air heat exchanger 6B can be heated, the frost adhering to this 2nd air heat exchanger 6B can also be heated and defrosted.

  Thereby, in the 2nd freezing cycle B, it is not necessary to perform a reverse defrost operation. Therefore, the four-way valve 3A can be omitted to reduce the number of parts, and the configuration of the refrigeration cycle can be simplified and the cost can be reduced.

  And in this hot water supply device 1, the excluded volume of the first compressor 2A is 0.5 to 0.7 times the excluded volume of the second compressor 2B, and the compression capacity of the first compressor 2A is the second. Lower than compressor 2B.

  For this reason, only the first refrigeration cycle A provided with the first compressor 2A is operated for hot water supply, and the operation of the second refrigeration cycle B is stopped, whereby the hot water supply operation is performed easily and efficiently with low capacity. be able to.

  As mentioned above, although several embodiment of this invention was described, these embodiment is shown as an example and is not intending limiting the range of this invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and changes can be made without departing from the scope of the present invention. These embodiments and modifications thereof are included in the scope and gist of the present invention, and are included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 1 ... Hot-water supply apparatus, A ... 1st freezing cycle, B ... 2nd freezing cycle, 2A ... 1st compressor, 2B ... 2nd compressor, 3A ... Four-way valve, 4A ... 1st water heat exchanger, 4B ... 1st 2 water heat exchangers, 4A1 ... first water passage, 4B1 ... second water passage, 4A2 ... first condenser, 4B2 ... second condenser, 5A ... first expansion valve (first throttle mechanism), 5B ... first 2 expansion valve (second throttle mechanism), 6A ... first air heat exchanger, 6B ... second air heat exchanger, 7A ... first refrigerant pipe, 7B ... second refrigerant pipe, 21 ... gas-liquid separator, 23 ... injection tube, 29 ... controller.

Claims (6)

A first condenser, a four-way valve, a first water passage that feeds water from the first water heat exchanger, and a first condenser, a first throttle mechanism, and a first air heat exchanger that are arranged so as to be able to exchange heat. A first refrigeration cycle in which a refrigerant flow path for circulating the refrigerant by connecting with the first refrigerant pipe is formed;
Air is sent to the second compressor, the second water passage that allows water to be supplied from the second water heat exchanger, and the second condenser, the second throttle mechanism, and the first air heat exchanger that are arranged to exchange heat. A second refrigeration cycle in which a second air heat exchanger arranged in parallel on the leeward side of the direction is connected by a second refrigerant pipe to form a refrigerant flow path for circulating the refrigerant,
A two-stage compression operation in which the first condenser and the second condenser are connected in series when the first compressor and the second compressor are connected to be capable of two-stage compression;
A single-stage compression operation in which when the first compressor and the second compressor are individually operated, the first condenser and the second condenser are also individually operated; and
A hot water supply device that is configured to be switchable. 2. The hot water supply apparatus according to claim 1, wherein the hot water boiling temperature is switched to the two-stage compression operation when raising the boiling temperature of the hot water. During the two-stage compression operation, the first and second air heat exchangers are connected in parallel, and a gas-liquid separator that separates the gas-liquid refrigerant from the second condenser is the second condenser, The gas-phase refrigerant that is inserted between the first and second air heat exchangers and separated by the gas-liquid separator is injected into the suction port side of the first and second compressors. The hot water supply apparatus according to claim 2, wherein 2. The hot water supply apparatus according to claim 1, wherein when the heating capacity is increased, the first and second refrigeration cycles are switched to a single-stage compression operation in which the hot water supply operation is performed individually. The hot water supply apparatus according to claim 1, wherein during the single-stage compression operation, the second refrigeration cycle is operated for hot water supply, and the first refrigeration cycle is operated for defrosting by switching the four-way valve. The hot water supply apparatus according to claim 1, wherein excluded volumes of the first compressor and the second compressor are different.

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