JP2012026626A - Hot water storage type water heater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hot water storage type water heater that prevents hot water of high temperature from flowing backward from a heating means to a hot water storage tank after operation of the heating means stops.SOLUTION: After an operating heat pump unit 1 is stopped, a selector valve 29 is positioned at an intermediate point between a first state in which water flows to a lower part of a hot water storage tank 21 from a heat pump supply pipe 26 through a bypass pipe 28 for a specified period, and a second state in which water flows to the upper part of the hot water storage tank 21 from the heat pump supply pipe 26. Consequently, the hot water of high temperature having been heated in a coolant-water heat exchanger 12 of the heat pump unit 1 is prevented from flowing back to the lower part of the hot water storage tank 21 to raise the temperature of water in the lower part of the hot water storage tank 21. The temperature of water supplied to the heat pump unit 1 is prevented from increasing to reduce COP of the heat pump unit 1.

Description

  The present invention relates to a heat pump type water heater for boiling hot water by a heat pump unit and storing the hot water.

  Conventionally, in this type, when a hot water supply operation is performed, a user opens the hot water tap so that the hot water in the hot water storage tank is pushed out toward the hot water discharge pipe by the water supply pressure from the water supply pipe. The high-temperature water of about 70 to 90 ° C. pushed out from the water and the water from the branch pipe were mixed by the hot water supply mixing valve so as to reach the hot water temperature set by the user using the remote controller, and hot water was supplied through the hot water supply pipe.

  At this time, the water to be supplied is divided into a hot water mixing valve and a lower part of the hot water storage tank, and the pipe connected to the lower part of the hot water storage tank branches to a bypass circuit with the heat pump unit on the way. Except during the heating operation, a lower part of the hot water storage tank and a bypass circuit for the heat pump unit were formed. (For example, patent document 1).

JP 2007-155171 A

  By the way, in this conventional type, during the hot water supply operation, in addition to the path from the water supply, a reverse flow path from the water supply to the switching valve, the hot water outlet of the heat pump unit, the refrigerant-water heat exchanger, the water supply port of the heat pump unit, and the lower part of the hot water storage tank When the hot water supply operation is performed in a state where the temperature of the refrigerant-water heat exchanger of the heat pump unit is high just after the boiling operation is finished, the water heated by the high-temperature refrigerant-water heat exchanger is Backflows up and raises the temperature of the water below the hot water storage tank.

  For this reason, there has been a problem that the temperature of the water supply to the heat pump unit rises, leading to a decrease in the COP of the heat pump unit and a decrease in the hot water supply mode test COP.

  In order to solve the above-mentioned problems by focusing attention on this point, the present invention is particularly configured as claimed in claim 1 including a hot water storage tank, a compressor, a refrigerant-water heat exchanger, an expansion valve, and an evaporator. A heating means for heating the hot water taken out from the lower part, an outflow pipe for sending the hot water from the hot water storage tank to the heating means, an inflow pipe for sending the hot water generated by the heating means to the upper part of the hot water storage tank, A bypass pipe that branches off from the inflow pipe and sends the hot water to the lower part of the hot water storage tank, a water supply pipe having one end connected to the bypass pipe, and a flow of the hot water that passes through the inflow pipe In a hot water storage type hot water supply apparatus comprising a switching valve that can be set to a first state that switches to the pipe side and a second state that switches to the upper side of the hot water storage tank, the heating means stops operating. A predetermined time from Up to per to, those having a control unit for controlling the intermediate position between the first and second states the position of the switching valve.

  Further, in the hot water storage type hot water supply apparatus according to claim 2, in particular, a hot water storage tank, a compressor, a refrigerant-water heat exchanger, an expansion valve, and an evaporator are provided, and hot water taken out from the lower part of the hot water storage tank is provided. A heating means for heating; an outflow pipe for sending the hot water from the hot water storage tank to the heating means; a heat exchanger inlet temperature detecting means provided in the outflow pipe; and the hot water generated by the heating means for the hot water storage tank An inflow pipe that is sent to the upper part of the pipe, a bypass pipe that is branched from the inflow pipe and that sends the hot water to the lower part of the hot water storage tank, a water supply pipe having one end connected to the bypass pipe, and the inflow pipe In a hot water storage type hot water supply apparatus provided with a switching valve that can be set to a first state in which the flow of the warm water passing therethrough is switched to the bypass pipe side and a second state in which the hot water tank is switched to an upper side of the hot water storage tank, The heating means A control unit that controls the position of the switching valve to an intermediate position between the first state and the second state until the detected temperature of the heat exchanger inlet temperature detecting means becomes equal to or lower than a predetermined temperature after It is provided.

  According to the first aspect of the present invention, after the heat pump unit is changed from the operating state to the stopped state, the position of the switching valve is moved to the heat pump forward pipe for a predetermined time until the temperature of the refrigerant-water heat exchanger decreases from the high temperature to the low temperature. From the first state where the flow path is switched to the lower part of the hot water storage tank through the bypass pipe and the second state where the flow path is switched from the heat pump forward pipe to the upper part of the hot water storage tank The reverse flow path from the water supply to the switching valve, the heat pump forward pipe of the heat pump unit, the refrigerant-water heat exchanger, the heat pump return pipe of the heat pump unit, the lower part of the hot water storage tank can be shut off by the switching valve, and the refrigerant-water heat exchanger The heat pump unit prevents the hot water heated by the water from flowing back to the lower part of the hot water tank and raising the temperature of the water in the lower part of the hot water tank. The temperature of the water is lowered and the COP of the heat pump units elevated, thereby preventing the deterioration of the hot water supply mode test COP.

  According to the hot water storage type hot water supply apparatus of the second aspect of the present invention, after the heat pump unit is switched from the operating state to the stopped state, the temperature detected by the heat exchanger inlet temperature sensor is lowered to the predetermined temperature. Until the temperature of the refrigerant-water heat exchanger decreases from a high temperature to a low temperature, the first state of switching the flow path from the heat pump forward pipe to the lower part of the hot water storage tank via the bypass pipe, and the heat pump forward pipe to the hot water storage tank Since it controls so that it may become a middle position with the 2nd state which switches to a flow path in the upper part of water, it is a switching valve from a water supply, a heat pump forward pipe of a heat pump unit, a refrigerant-water heat exchanger, a heat pump return pipe of a heat pump unit, The reverse flow path at the bottom of the hot water storage tank can be blocked by the switching valve, and the high-temperature water heated by the refrigerant-water heat exchanger flows back to the bottom of the hot water storage tank. Te to prevent the raise the temperature of the hot water storage tank bottom water, decrease in COP of the heat pump unit temperature of the feed water rises to the heat pump unit, thereby preventing the deterioration of the hot water supply mode test COP.

The schematic block diagram of the hot water storage type hot-water supply apparatus which shows one Embodiment of this invention. The flowchart figure of the same embodiment.

Next, a first embodiment to which the present invention is applied will be described with reference to FIG.
The hot water storage type hot water supply apparatus A according to this embodiment includes a heat pump unit (heating means) 1, a hot water storage tank unit 2, a hot water supply control unit 3, and the like.
In this embodiment, the hot water taken out from the lower part of the hot water storage tank 21 to be described later is low temperature water (low temperature water; for example, about 5 to 20 ° C.), and the hot water heated by the heat pump unit 1 is high temperature water (high temperature). For example, about 70 to 90 ° C.).

The heat pump unit 1 includes a compressor 11, a refrigerant-water heat exchanger 12 as a condenser, an expansion valve 13 as a decompressor, and a heat pump circuit 15 including a forced air-cooled evaporator 14. And a heat pump control unit 5 that drives and controls the heat pump circuit 15.
In the heat pump circuit 15, for example, carbon dioxide is used as a refrigerant to constitute a supercritical heat pump cycle.
Further, since carbon dioxide is used as the refrigerant, it is possible to boil low temperature water to a high temperature of about 90 ° C. without an electric heater.

In the heat pump unit 1, a heat pump return pipe (outflow pipe) 25 extending from the hot water storage tank unit 2 described later is connected to one end of a flow path provided separately from the heat pump circuit 15 of the refrigerant-water heat exchanger 12. The heat pump return pipe 25 is provided with a heat exchanger inlet temperature sensor T1.
The other end of the refrigerant-water heat exchanger 12 is connected to a heat pump forward pipe (inflow pipe) 26 extending from the hot water storage tank unit 2 described later. The heat pump outlet pipe 26 is provided with a heat exchanger outlet temperature sensor T2. It has been.
Further, the heat pump unit 1 is provided with an outside air temperature sensor T3 for detecting the temperature of the outside air.

The refrigerant-water heat exchanger 12 employs a counter flow system in which the refrigerant and heated water (low temperature water) face each other, and the refrigerant is supercritical during heat exchange by the supercritical heat pump cycle. Since it is condensed in the state, the water to be heated can be efficiently heated to a high temperature.
Further, the expansion valve described above so that the temperature difference between the temperature of the heat exchanger inlet temperature sensor T1 on the inlet side of the refrigerant-water heat exchanger 12 and the temperature of the heat exchanger outlet temperature sensor T2 on the outlet side becomes constant. 13 or by controlling the compressor 11, the COP (energy consumption efficiency) is reduced when the inlet temperature of the refrigerant-water heat exchanger 12 of the water to be heated (low temperature water) is a low temperature of about 5 to 20 ° C. It is possible to heat the water to be heated with a high efficiency of 3.0 or more.

The hot water storage tank unit 2 has a hot water storage tank 21 that is elongated in the vertical direction (vertical direction). The hot water storage pipe 21 communicates with the interior of the hot water storage tank 21 at the upper part thereof and the hot water supply pipe 24 at the lower part thereof. It is connected.
The water supply pipe 24 is connected to a water pipe so that water (tap water) is supplied. The water supply pipe 24 includes a pressure reducing valve 36 and a water supply pipe 24 for reducing the water supply pressure from the water pipe to a predetermined pressure. A water supply temperature sensor 37 for detecting the temperature of the flowing water is provided, and a check valve 49 is further provided on the downstream side of the connection portion with the branch pipe 30 branched from the water supply pipe 24.

The hot water storage tank 21 is provided with a hot water storage temperature sensor T4 including a plurality of temperature sensors arranged in the vertical direction.
The hot water storage temperature sensor T4 detects the temperature distribution in the vertical direction in the hot water storage tank 21 and detects how much heat remains in the hot water storage tank 21.

Further, the hot water storage tank 21 is connected so that the end of the heat pump return pipe 25 is communicated with the inside of the hot water storage tank 21 at the lower part and the end of the heat pump forward pipe 26 is communicated with the upper part.
In addition, a circulation pump 27 is provided in the heat pump return pipe 25, and the water to be heated (low temperature water) in the hot water storage tank 21 is exchanged between the refrigerant and the water through the heat pump return pipe 25 by the driving force of the circulation pump 27. It is sent to the vessel 12 and sent out from the refrigerant-water heat exchanger 12 via the heat pump forward pipe 26.
In addition, in this embodiment, although the circulation pump 27 is provided in the heat pump unit 1 side, it is not limited to this, You may provide in the hot water storage tank unit 2 side.

Further, a bypass pipe 28 is connected to the hot water storage tank 21.
One end of the bypass pipe 28 is connected to the heat pump forward pipe 26 via a switching valve 29, and the other end is connected to the vicinity of the hot water storage tank 21 of the water supply pipe 24.
The switching valve 29 is composed of, for example, an electromagnetic three-way valve, and a first state in which the flow path is switched from the heat pump forward pipe 26 to the lower part of the hot water storage tank 21 via the bypass pipe 28 (to the bypass side), and the heat pump forward pipe 26. Can be set to the second state in which the flow path is switched to the upper part of the hot water storage tank 21 (to the boiling side).

The hot water discharge pipe 23 is connected to a branch pipe 30 branched from the water supply pipe 24 via a hot water supply mixing valve 31.
This hot-water supply mixing valve 31 is a valve that mixes high-temperature water taken out through the hot-water supply pipe 23 and water (tap water) from the branch pipe 30, and the hot-water supply setting set by the user with the remote controller 4 described later. The mixing ratio is controlled so that the temperature is reached.
A hot water supply pipe 32 is connected to the hot water supply mixing valve 31, and a hot water supply temperature sensor T5 for detecting the temperature of the hot water mixed by the hot water supply mixing valve 31 and a hot water supply flow rate sensor for detecting the flow rate of hot water. 34 is provided.
Further, a hot water tap 35 is provided at the end of the hot water supply pipe 32, and this hot water tap 35 is provided in a kitchen, a bathroom, a bathroom, and the like. The hot water discharge pipe 23 is provided with a pressure relief valve 38 for releasing the pressure of the hot water storage tank 21.

Moreover, the hot water storage type hot water supply apparatus A of this embodiment is provided with a bathtub B.
In the bathtub B, one end of the bath return pipe 41 and one end of the bath return pipe 42 are connected to each other.
Further, a bath heat exchanger 43 made of a stainless steel tube for heating the hot water stored in the bathtub B is provided in the upper portion of the hot water storage tank 21, and the bath heat exchanger 43 is moved to the entrance of the bath heat exchanger 43. The other end of the pipe 41 is connected, and the other end of the return pipe 42 is connected to the outlet.
In addition, the bath pipe 41 has a bath temperature sensor T6 for detecting the temperature of hot water flowing from the bathtub B to the bath heat exchanger 43, and a bath circulation for circulating hot water between the bath B and the bath heat exchanger 43. The pump 48 is provided, and the bath return pipe 42 is provided with a bath return temperature sensor T7 that detects the temperature of hot water flowing from the bath heat exchanger 43 to the bathtub B.
By operating the bath circulation pump 48, hot water stored in the bathtub B is sent to the bath heat exchanger 43, and the hot water is heated in the bath heat exchanger 43, so that the hot water in the bathtub B can be kept warm. There is a catch-up.

Further, the bath pipe 41 is connected to the hot water supply pipe 32 through a hot water filling pipe 44.
The hot water filling pipe 44 includes a hot water filling valve 45 for starting / stopping hot water filling to the bathtub B, a bath flow counter 46 for counting the amount of hot water filling to the bathtub B, and hot water in the bathtub B to the hot water supply pipe. A check valve 47 is provided to prevent backflow to 32.
Thus, when filling the bathtub B, the hot water valve 45 is opened so that hot water set at a desired bath temperature by the remote controller 4 to be described later is supplied from the hot water supply mixing valve 31 to the hot water pipe 44 and the bath. It is supplied to the bathtub B through the forward pipe 41.

The hot water storage tank unit 2 is provided with a hot water supply control unit 3.
The hot water supply control unit 3 includes a CPU (Central Processing Unit), a storage device, an input / output device, and the like, acquires temperature information from various temperature sensors T1 to T7, and the circulation pump 27 and the bottom circulation pump 48. It controls output, switching of the flow path of the switching valve 29, mixing ratio of the hot water supply mixing valve 31, opening and closing of the hot water filling valve 45, and the like.

The remote controller 4 includes a hot water supply temperature setting switch 4a for setting the hot water supply temperature, a bath temperature setting switch 4b for setting the bath temperature, and a hot water amount setting switch provided in the remote controller 4 for hot water having the set bath temperature. The bath automatic switch 4c for filling the hot water with the amount of hot water set in (not shown) and keeping it warm for a predetermined time, the reheating switch 4d for reheating, and the hot water in the hot water storage tank 21 in the daytime time zone. In addition, a heating switch 4e for boiling a certain amount, a display unit 4f comprising a liquid crystal display panel for displaying the hot water supply temperature, the amount of remaining hot water in the hot water storage tank 21 and the like, a speaker for buzzer sound and voice guidance (not shown) A remote control unit (not shown) for comprehensively controlling them is provided.
The remote controller 4 is connected to the hot water supply control unit 3 by wire or wirelessly, and information set by the remote control 4 is sent to the hot water supply control unit 3.

Next, operation control of the hot water storage type hot water supply apparatus A of the present embodiment will be described.
First, the boiling operation of the hot water storage type hot water supply apparatus A will be described.
When the hot water supply control unit 3 detects that the necessary amount of heat does not remain in the hot water storage tank 21 on the next day based on the hot water storage temperature sensor T4 in the midnight electric power time zone, the heating pump control unit 5 starts boiling. Issue a command.
Upon receiving this command, the heat pump control unit 5 starts driving the circulation pump 27 after starting the compressor 11.

At this time, the switching valve 29 is in a second state, that is, in a state where the flow path is switched to the boiling side (upper side of the hot water storage tank 21), and low temperature water of about 5 to 20 ° C. The extracted low-temperature water is sent to the refrigerant-water heat exchanger 12 through the heat pump return pipe 25 and heated to a high temperature of about 70 to 90 ° C. The high-temperature water sent from the refrigerant-water heat exchanger 12 to the heat pump forward pipe 26 is put into the hot water storage tank 21 from the upper part of the hot water storage tank 21.
Incidentally, in the hot water storage tank 21, for example, high temperature water is stored in the upper part and low temperature water is stored in the lower part. This is caused by a difference in specific gravity due to the temperature difference, forming a temperature boundary layer and a high temperature with a low specific gravity. Since water is located in the upper part and low-temperature water having a higher specific gravity is located in the lower part, they do not mix with each other.

Thereafter, when the hot water supply control unit 3 detects that the necessary amount of heat has been stored based on the temperature distribution information of the hot water storage tank 21 obtained from the hot water storage temperature sensor T4, it issues a boiling stop command to the heat pump control unit 5. Then, the compressor 11 is stopped and the circulation pump 27 is stopped, and the boiling operation is finished.

In addition, during the hot water supply operation, the user opens the hot water tap 35 so that the hot water in the hot water storage tank 21 is pushed out toward the hot water discharge pipe 23 by the supply water pressure from the water supply pipe 24.
The hot water of about 70 to 90 ° C. pushed out from the hot water storage tank 21 and the water from the branch pipe 30 are mixed in the hot water supply mixing valve 31 so that the hot water temperature set by the user with the remote controller 4 is reached. Hot water is supplied through.

Next, the control for preventing the high-temperature water from flowing backward from the refrigerant-water heat exchanger 12 to the lower part of the hot water storage tank 21 after the heat pump unit 1 is stopped from the operating state as immediately after the boiling operation is finished is shown in FIG. This will be described with reference to the flowchart of FIG.
First, when the heat pump unit 1 is changed from the operating state to the stopped state (S1), the hot water supply control unit 3 starts a timer (not shown) provided in the hot water supply control unit 3 (S2), and the switching valve 29 is set to the heat pump. An intermediate position between the first state where the flow path is switched from the forward pipe 26 to the lower part of the hot water storage tank 21 via the bypass pipe 28 and the second state where the flow path is switched from the heat pump forward pipe 26 to the upper part of the hot water storage tank 21. Control to be (S3)

Thus, the switching valve 29 blocks the reverse flow path from the water supply to the switching valve 29, the heat pump forward pipe 26 of the heat pump unit 1, the refrigerant-water heat exchanger 12, the heat pump return pipe 25 of the heat pump unit 1, and the lower part of the hot water storage tank 21. Is.
This prevents high-temperature water heated by the refrigerant-water heat exchanger 12 from flowing back to the lower part of the hot water storage tank 21 and increasing the temperature of the water in the lower part of the hot water storage tank 21, thereby supplying water to the heat pump unit 1. This prevents the temperature of the heat pump unit 1 from decreasing and the hot water supply mode test COP from decreasing.

  Next, it is detected whether the heat pump unit 1 is restarted (S4). When the heat pump unit 1 is restarted, the switching valve 29 is controlled to be in a normal position (S5), and then the heat pump unit 1 is restarted. Start. (S6)

  When the heat pump unit 1 is not restarted in (S4), it is determined whether a predetermined time has elapsed since the timer started (S7). If the predetermined time has not elapsed, the process returns to (S4) and the predetermined time has elapsed. If so, it is determined that the temperature of the refrigerant-water heat exchanger 12 has already dropped and high-temperature water does not flow back from the refrigerant-water heat exchanger 12 to the lower part of the hot water storage tank 21, and the timer timing is ended (S8). ) And (S5).

  As described above, after the heat pump unit 1 is stopped from the operating state, the position of the switching valve 29 is bypassed from the heat pump forward pipe 26 for a predetermined time until the temperature of the refrigerant-water heat exchanger 12 falls from high temperature to low temperature. Control is performed so as to be in an intermediate position between the first state where the flow path is switched to the lower part of the hot water storage tank 21 via the pipe 28 and the second state where the flow path is switched from the heat pump forward pipe 26 to the upper part of the hot water storage tank 21. As a result, the switching valve 29 blocks the reverse flow path from the water supply to the switching valve 29, the heat pump forward pipe 26 of the heat pump unit 1, the refrigerant-water heat exchanger 12, the heat pump return pipe 25 of the heat pump unit 1, and the lower part of the hot water storage tank 21. Therefore, the high-temperature water heated by the refrigerant-water heat exchanger 12 flows back to the lower part of the hot water storage tank 21 to change the temperature of the water in the lower part of the hot water storage tank 21. And prevented from being allowed to rise, the temperature of the water supply to the heat pump unit 1 is raised lowering of COP of the heat pump unit 1, thereby preventing the deterioration of the hot water supply mode test COP.

  In the present embodiment, the position of the switching valve 29 is switched from the heat pump forward pipe 26 to the lower part of the hot water storage tank 21 via the bypass pipe 28 for a predetermined time after the heat pump unit 1 is stopped from the operating state. Control is performed so that the first state and the second state where the flow is switched from the heat pump forward pipe 26 to the upper part of the hot water storage tank 21 are switched, but the present invention is not limited to this, and the heat pump unit 1 is in an operating state. After entering the stop state, the temperature of the hot water flowing back from the refrigerant-water heat exchanger 12 to the lower part of the hot water storage tank 21 is determined based on the temperature detected by the heat exchanger inlet temperature sensor T1, and the heat pump unit 1 is changed from the operation state to the stop state. After that, the position of the switching valve 29 is bypassed from the heat pump forward pipe 26 until the temperature detected by the heat exchanger inlet temperature sensor T1 decreases to a predetermined temperature. The intermediate position between the first state where the flow path is switched to the lower part of the hot water storage tank 21 via the hot pipe 28 and the second state where the flow path is switched from the heat pump forward pipe 26 to the upper part of the hot water storage tank 21. It may be controlled.

  As a result, after the heat pump unit 1 is stopped from the operating state, the position of the switching valve 29 is changed until the temperature detected by the heat exchanger inlet temperature sensor T1 is lowered to a predetermined temperature, that is, the temperature of the refrigerant-water heat exchanger 12. Until the temperature drops from high temperature to low temperature, the first state in which the flow path is switched from the heat pump forward pipe 26 to the lower part of the hot water storage tank 21 via the bypass pipe 28, and the flow path is switched from the heat pump forward pipe 26 to the upper part of the hot water storage tank 21. By controlling so as to be in an intermediate position with respect to the second state, the switching valve 29 from the water supply, the heat pump forward pipe 26 of the heat pump unit 1, the refrigerant-water heat exchanger 12, the heat pump return pipe 25 of the heat pump unit 1, the hot water storage Since the reverse flow path of the lower part of the tank 21 is blocked by the switching valve 29, the high-temperature water heated by the refrigerant-water heat exchanger 12 is The temperature of the water in the lower part of the hot water storage tank 21 is prevented from flowing back to the lower part of the hot water tank 21 and the temperature of the water supply to the heat pump unit 1 is increased to lower the COP of the heat pump unit 1 and the hot water supply mode. This prevents a decrease in the test COP.

DESCRIPTION OF SYMBOLS 1 Heating means 3 Control part 11 Compressor 12 Refrigerant-water heat exchanger 13 Expansion valve 14 Evaporator 21 Hot water storage tank 24 Water supply pipe 25 Outflow pipe 26 Inflow pipe 28 Bypass pipe 29 Switching valve

Claims (2)

  A hot water storage tank, a compressor, a refrigerant-water heat exchanger, an expansion valve, and an evaporator; heating means for heating hot water taken out from a lower portion of the hot water storage tank; and the hot water from the hot water storage tank to the heating means. An outflow pipe to be sent, an inflow pipe for sending the hot water generated by the heating means to the upper part of the hot water storage tank, a bypass pipe which is branched from the inflow pipe and sends the hot water to the lower part of the hot water storage tank, and one end A water supply pipe connected to the bypass pipe, a first state where the flow of the hot water passing through the inflow pipe is switched to the bypass pipe side, and a second state where the hot water tank is switched to the upper side of the hot water storage tank In a hot water storage type hot water supply apparatus including a switchable valve, the position of the switch valve is changed between the first state and the second state until a predetermined time elapses after the heating unit stops operating. Control to the middle position Hot water storage type hot water supply apparatus characterized by comprising a that controller.   A hot water storage tank, a compressor, a refrigerant-water heat exchanger, an expansion valve, and an evaporator; heating means for heating hot water taken out from a lower portion of the hot water storage tank; and the hot water from the hot water storage tank to the heating means. An outflow pipe to be sent, a heat exchanger inlet temperature detection means provided in the outflow pipe, an inflow pipe for sending the hot water generated by the heating means to the upper part of the hot water storage tank, and a branch from the inflow pipe. A first state in which the bypass pipe for sending the hot water to the lower part of the hot water storage tank, a water supply pipe having one end connected to the bypass pipe, and the flow of the hot water passing through the inflow pipe to the bypass pipe side And a switching valve that can be set to a second state for switching to the upper side of the hot water storage tank, the heat exchanger inlet temperature detection after the heating means has stopped operating Mean temperature of detection There decreased below a predetermined temperature, the hot water storage type hot-water supply apparatus characterized by comprising a control unit for controlling the position of the switching valve in an intermediate position between said first and second states.

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