JP5179345B2 - Hot water storage water heater - Google Patents

Description

  The present invention relates to a hot water storage type hot water supply apparatus provided with an indirect heat exchanger for heating an external fluid such as bath water in an upper part of a hot water storage tank for storing hot water heated by a heating means.

  Conventionally, in this type of hot water storage type hot water supply device, as shown in Patent Document 1, hot water heated by a heat pump type heating means is returned from the upper part of a hot water storage tank to store hot water in a normal boiling operation, The indirect heat exchanger provided in the upper part of the hot water storage tank allows the water in the bathtub and the like to be circulated and heated by the heat in the hot water storage tank, and the high temperature heated by the heat pump heating means below the indirect heat exchanger. An intermediate return pipe for returning hot water was connected, and the hot water temperature near the indirect heat exchanger above the intermediate return pipe was lowered to a temperature at which the efficiency of indirect heating was lowered by the hot water storage temperature sensors provided on the upper and lower sides of the hot water storage tank. Is detected, the hot water heated by the heat pump heating means is returned from the intermediate return pipe and the intermediate boiling operation is performed to raise the temperature in the vicinity of the indirect heat exchanger. It was.

JP 2008-39340 A

  However, in this conventional one, since the intermediate boiling operation is performed after detecting that the temperature in the vicinity of the indirect heat exchanger above the connection position of the intermediate return pipe has dropped, the intermediate boiling operation is started at the time of starting. There is a possibility that low temperature water exists near the intermediate return pipe or a temperature boundary layer of hot water exists.

  If hot water from the heat pump heating means flows into the water near the intermediate return pipe by the intermediate boiling operation, this water is heated before the vicinity of the indirect heat exchanger is heated. While it takes time to heat the vicinity of the exchanger, the hot water returned from the intermediate return pipe tries to rise to the upper part of the hot water tank as heat, but water is pulled from the lower part of the hot water tank to the heat pump heating means. Therefore, the hot water flow is directed downward in the hot water storage tank, and a thick temperature boundary layer with a gentle vertical temperature gradient is formed between the hot water at the top and the low temperature water at the bottom, or the temperature boundary layer itself. The heat at the upper part of the hot water storage tank diffuses into the water at the lower part of the hot water storage tank after the intermediate boiling operation is over, which deteriorates the efficiency of the hot water storage.

  In addition, when hot water from the heat pump type heating means flows into the temperature boundary layer near the intermediate return pipe by the intermediate boiling operation, the hot water returned from the intermediate return pipe is used as heat in the upper part of the hot water storage tank. However, since water is pulled from the lower part of the hot water tank to the heat pump heating means, the flow of hot water is directed downwards of the hot water tank, increasing the temperature boundary layer and reducing the vertical temperature gradient. As a result, the heat at the upper part of the hot water storage tank is easily diffused to the lower part of the hot water storage tank as time elapses after the intermediate boiling operation is finished, and the hot water storage efficiency is deteriorated.

  In order to solve the above problems, the present invention provides a hot water storage tank for storing hot water, a water supply pipe connected to the bottom of the hot water storage tank, a hot water discharge pipe connected to the top of the hot water storage tank, and hot water taken out from the lower part of the hot water storage tank. A heating circuit for returning the hot water to the upper part of the hot water storage tank, a heating means for heating the hot water provided in the middle of the heating circuit, and heating for flowing hot water in the hot water tank provided in the heating circuit to the heating circuit A circulation pump; an indirect heat exchanger provided at an upper portion in the hot water storage tank for heating an external fluid by the heat of the hot water in the hot water storage tank; and the indirect heat branched from the downstream side of the heating means of the heating circulation circuit. An intermediate return pipe connected to the intermediate portion of the hot water storage tank below the upper end of the exchanger and the hot water heated by the heating means through the heating circulation circuit to the hot water storage tank Switching means for switching between returning to the hot water tank and returning to the hot water tank intermediate part via the intermediate return pipe, and hot water storage for detecting the temperature of the hot water in the hot water tank provided in plural in the vertical direction of the side surface of the hot water tank And when the hot water storage temperature sensor located above the intermediate return pipe and in the vicinity of the indirect heat exchanger detects a temperature equal to or lower than a first predetermined temperature, the switching means is switched to the upper side of the hot water storage tank. When the heating means and the heating circulation pump are operated in a state where the hot water storage temperature sensor is located below the intermediate return pipe detects a temperature equal to or higher than a second predetermined temperature lower than the first predetermined temperature, the switching is performed. The means is switched to the intermediate return pipe side, and an intermediate boiling operation for returning hot water heated by the heating means to the intermediate portion of the hot water storage tank is performed.

  A hot water storage tank for storing hot water; a water supply pipe connected to the bottom of the hot water storage tank; a hot water pipe connected to the top of the hot water storage tank; A circulation circuit; heating means provided in the middle of the heating circulation circuit for heating hot water; a heating circulation pump provided in the middle of the heating circulation circuit for flowing hot water in the hot water storage tank to the heating circulation circuit; and in the hot water storage tank An indirect heat exchanger that is provided at the top and heats an external fluid by the heat of hot water in the hot water storage tank, and is branched from the downstream side of the heating means of the heating circulation circuit and below the upper end of the indirect heat exchanger. An intermediate return pipe connected to the intermediate portion of the hot water storage tank, and the hot water heated by the heating means is returned to the upper part of the hot water storage tank via the heating circulation circuit or the intermediate return pipe Switching means for switching whether to return to the intermediate portion of the hot water storage tank, and a hot water storage temperature sensor for detecting the temperature of the hot water in the hot water storage tank that is provided in a plurality of vertical directions on the side surface of the hot water storage tank, the intermediate return The hot water storage temperature sensor located above the pipe and in the vicinity of the indirect heat exchanger detects the first predetermined temperature or less, and the hot water storage temperature sensor located below the intermediate return pipe is lower than the first predetermined temperature. When the second predetermined temperature or lower is detected, the heating means and the heating circulation pump are operated in a state where the switching means is switched to the upper side of the hot water storage tank, and then the lower position is lower than the intermediate return pipe. When the hot water storage temperature sensor detects the second predetermined temperature or higher, the hot water heated by the heating means by switching the switching means to the intermediate return pipe side is stored in the hot water storage tank. An intermediate boiling operation is performed to return to the section, the hot water storage temperature sensor located above the intermediate return pipe and in the vicinity of the indirect heat exchanger detects the first predetermined temperature or less, and below the intermediate return pipe. When the hot water storage temperature sensor located above detects the second predetermined temperature or higher, the heating means and the heating circulation pump are operated in the state where the switching means is switched to the intermediate return pipe side, and heating is performed by the heating means. An intermediate boiling operation for returning the hot water to the intermediate portion of the hot water storage tank was performed.

  In addition, when the hot water storage temperature sensor located above the intermediate return pipe and above the lower end of the indirect heat exchanger detects a temperature equal to or higher than a third predetermined temperature higher than the first predetermined temperature, the intermediate boiling operation is stopped. did.

  The heating means includes a compressor for compressing the refrigerant, a refrigerant water heat exchanger for exchanging heat between the refrigerant and water, a decompression means for reducing the refrigerant pressure, and an evaporator for evaporating the liquid refrigerant. A heat pump heating means was used.

  As described above, according to the present invention, the hot water heated by the intermediate boiling operation can be returned above the temperature boundary layer of the hot water in the hot water storage tank, so that the hot water storage efficiency is not destroyed without destroying the temperature boundary layer. The hot water temperature in the vicinity of the indirect heat exchanger can be quickly raised.

Next, an embodiment of the present invention will be described with reference to the drawings.
1 is a stainless steel hot water storage tank for storing hot water, 2 is a water supply pipe for supplying city water to the bottom of the hot water storage tank 1, 3 is a hot water discharge pipe for discharging hot water from the top of the hot water storage tank 1, 4 is a water supply bypass branched from the water supply pipe 2 A hot water mixing valve that mixes hot water from the hot water discharge pipe 3 and water from the hot water supply bypass pipe 4 so as to reach a hot water supply set temperature, 6 is a hot water supply pipe through which hot water mixed by the hot water mixing valve 5 flows, 7 is a hot-water tap for supplying hot water from the hot-water supply pipe 6, 8 is a hot-water supply temperature sensor for detecting the hot-water supply temperature provided in the middle of the hot-water supply pipe 6, and 9 is a hot-water supply flow rate sensor for detecting the amount of hot water provided in the middle of the hot-water supply pipe 6. A pressure reducing valve 10 is provided in the water supply pipe 2 to reduce the supply pressure of city water to a constant pressure, and 11 is an overpressure relief valve for releasing the overpressure in the hot water storage tank 1.

  Reference numeral 12 denotes a bathtub, reference numeral 13 denotes an indirect heat exchanger provided in the upper part of the hot water storage tank 1 for heating the bathtub water with the heat of the hot water in the hot water storage tank 1, and reference numeral 14 denotes a bathtub water that connects the bathtub 12 and the indirect heat exchanger 13. 15 is connected to the flow circulation circuit 14. The flow circulation circuit 15 is connected to the flow circulation circuit 14. The flow circulation circuit 15 is connected to the flow circulation circuit 14. Is a hot water on / off valve provided in the middle of the hot water filling pipe 16 to open and close the hot water filling pipe 16, and 18 is a flow temperature for detecting the temperature of bath water flowing from the bathtub 12 to the indirect heat exchanger 13 provided in the middle of the flow circulation circuit 14. It is a sensor. Here, the indirect heat exchanger 13 has a configuration in which a stainless steel tube is spirally wound.

  19 is a heat pump type heating means as a heating means, a compressor 20 that compresses the refrigerant, a refrigerant water heat exchanger 21 that exchanges heat between the refrigerant and water, a decompressor 22 that reduces the pressure of the refrigerant, and a liquid refrigerant An evaporator 23 that evaporates the refrigerant, and the refrigerant that has absorbed heat by the evaporator 23 is compressed by the compressor 20 to heat the water through the refrigerant water heat exchanger 21.

  A heating circulation circuit 24 connects the lower part of the hot water storage tank 1, the water side of the refrigerant water heat exchanger 21 and the upper part of the hot water storage tank 1 so that hot water can circulate, and 25 a heating circulation pump provided in the middle of the heating circulation circuit 24. , 26 is an intermediate return pipe that is branched downstream of the refrigerant water heat exchanger 21 in the heating circuit 24 and connects the intermediate part of the hot water storage tank 1, and 27 is for heating hot water heated by the refrigerant water heat exchanger 21. Switching means comprising a three-way valve that switches between returning to the upper part of the hot water tank 1 via the circulation circuit 24 or returning to the intermediate part of the hot water tank 1 via the intermediate return pipe 26. Here, the intermediate return pipe 26 is connected to the side surface of the hot water storage tank 1 below the upper end of the indirect heat exchanger 13 of the hot water storage tank 1, and is preferably connected to the vicinity of the lower end of the indirect heat exchanger 13.

  28 is a water temperature sensor that detects the temperature of water flowing into the refrigerant water heat exchanger 21, 29 is a boiling temperature sensor that detects the temperature of hot water heated by the refrigerant water heat exchanger 21, and 30 is a hot water storage tank 1. A plurality of hot water storage temperature sensors provided in the vertical direction of the side surface are used to detect the temperature of hot water in the hot water storage tank 1, and are referred to as 30a, 30b, 30c, 30d, 30e, and 30f from the top. Of these hot water storage temperature sensors 30a to 30f, 30b is provided at a position near the middle of the indirect heat exchanger 13 and above the intermediate return pipe 26 to detect the hot water storage temperature, and 30c is the indirect heat exchanger 13. It is provided at a position for detecting the hot water storage temperature below the lower end and below the intermediate return pipe 26.

  31 is a remote control for setting and operating various types of information related to the hot water supply device (hot water supply set temperature, flow set temperature, remaining hot water amount, operating state of the hot water supply device, etc.), and hot water set temperature and flow set temperature. Temperature setting switch 33, a hot water filling switch 34 for instructing the bathtub 12 to fill with a certain amount of water, and a reheating switch 35 for instructing reheating of the bath water.

  Reference numeral 36 denotes a hot water supply temperature sensor 8, a hot water supply flow rate sensor 9, a flow temperature sensor 18, an incoming water temperature sensor 28, a boiling temperature sensor 29, and hot water storage temperature sensors 30 a to 30 f. 17 is a control means that controls the operation of the compressor 20, the decompressor 22, the heating circulation pump 25, and the switching means 27 and is communicably connected to the remote controller 31. The control means 36 stores a program for controlling the operation of the hot water supply device in advance, and has a calculation, comparison, storage function, and clock function.

Next, a normal boiling operation will be described.
When the control means 36 recognizes that it is the midnight time zone, the control means 36 calculates the amount of heat necessary for the next day based on the actual hot water supply up to that day, and the remaining amount in the hot water storage tank 1 detected by the hot water temperature sensors 30a to 30f. Peak shift calculation of the heating start time so that the required amount of heat rises the next day before the end time of the midnight time period from the heat amount, the rated heating capacity of the heat pump type heating means 19 and the feed water temperature detected by the hot water storage temperature sensor 30f at the bottom Calculated by

  When the current time reaches the heating start time, the control means 36 drives and controls the compressor 20, the decompressor 22 and the heating circulation pump 25, and the switching means 27 is connected to the refrigerant water heat exchanger 21 at the upper side of the hot water storage tank 1. The hot water heated to the target boiling temperature is stacked from the upper part of the hot water storage tank 1 through the heating circulation circuit 24, and the normal boiling operation is performed to store the hot water. Normal boiling operation is terminated.

  Next, the hot water supply operation will be described. When the hot water tap 7 is opened, city water flows into the bottom of the hot water storage tank 1 from the water supply pipe 2 and hot water is discharged from the top of the hot water storage tank 1 through the hot water discharge pipe 3. Then, the control means 36 adjusts the opening of the hot water mixing valve 5 so that the hot water temperature detected by the hot water temperature sensor 8 becomes the hot water set temperature set by the temperature setting switch 33 of the remote controller 31, and sets hot water from the hot water tap 7. Hot water at a temperature is supplied and the hot-water tap 7 is closed to end the hot water supply operation.

  At this time, the water flowing into the bottom of the hot water storage tank 1 is sufficiently decelerated in the hot water storage tank 1 having a sufficiently large cross-sectional area compared to the cross-sectional area of the water supply pipe 2, and is downward without disturbing the hot water layer. Forms a layer of water from A temperature boundary layer L is formed in which the hot water at the upper part of the hot water storage tank 1 and the low temperature water at the lower part of the hot water storage tank 1 are in contact. As the amount of hot water supply increases, the hot water layer at the upper part of the hot water tank 1 decreases, the water layer at the lower part of the hot water tank 1 increases, and the temperature boundary layer L rises. The temperature boundary layer L does not mix due to the difference in specific gravity based on the respective temperatures if there is a predetermined temperature difference. The thickness of the temperature boundary layer L increases due to heat conduction over time, and the temperature gradient gradually increases. Will become loose.

  Next, the hot water filling operation will be described. When the hot water filling switch 34 of the remote control 31 is operated, the control means 36 opens the hot water on / off valve 17 and the hot water supply temperature detected by the hot water supply temperature sensor 8 is the temperature setting of the remote control 31. When the opening of the hot water mixing valve 5 is adjusted so that the flow setting temperature set by the switch 33 is adjusted, hot water of an appropriate temperature is filled, and when the hot water flow rate sensor 9 accumulates the desired hot water flow rate, the hot water opening / closing valve 17 is filled. To close the hot water filling operation.

  And the heat retention operation | movement which keeps the temperature of bathtub water at a flow setting temperature for the predetermined fixed time after completion | finish of hot-water filling operation | movement is performed. The heat retaining operation will be described. The control means 36 drives the flow circulation pump 15 at predetermined intervals, circulates the bathtub water through the flow circulation circuit 14, and detects the temperature of the bath water with the flow temperature sensor 18. When the temperature of the bath water is lower than the flow setting temperature, the flow circulation pump is continuously driven, and the bath water is heated by absorbing the heat of the hot water in the hot water storage tank 1 from the indirect heat exchanger 13. When the temperature detected by the flow temperature sensor 18 detects the flow set temperature, the operation of the flow circulation pump 15 is terminated, and the same operation is repeated when the interval time elapses again. Then, when the predetermined time is finished, the heat retaining operation is finished.

  Further, a description will be given of a chasing operation when the chasing switch 35 of the remote controller 31 is operated. The control means 36 is configured to chas the bath water temperature to the preset flow temperature + a constant temperature (for example, 2 ° C.). The circulation pump 15 is driven, the bathtub water is circulated to the indirect heat exchanger 13, and the bathtub water is heated by absorbing the heat of the hot water in the hot water storage tank 1 from the indirect heat exchanger 13. When the temperature detected by the flow temperature sensor 18 detects the flow set temperature + the constant temperature, the flow circulation pump 15 is driven to end the chasing operation.

  In these heat retaining operations and chasing operations, the temperature of the hot water from the upper end of the indirect heat exchanger 13 in the hot water tank 1 to the position of the temperature boundary layer L in order to absorb the heat of the hot water in the hot water tank 1 to the bath water. Decreases. When the hot water temperature in the vicinity of the indirect heat exchanger 13 is lowered in this way, the heating capacity or heating efficiency of the bath water is lowered. Therefore, the control means 36 will be described below in order to maintain the bath water heating capacity. Perform intermediate boiling operation.

  FIG. 2 is a flow chart for explaining the intermediate boiling operation. The control means 36 uses the hot water storage temperature sensor 30b located above the intermediate return pipe 26 and in the vicinity of the indirect heat exchanger 13 so that the heating capacity or heating efficiency of the bath water is constant. When it is detected that the temperature has decreased to a first predetermined temperature (for example, 60 ° C.) that has decreased (step S1), the hot water storage temperature sensor 30c positioned below the intermediate pipe return pipe 26 has a second predetermined temperature (lower than the first predetermined temperature). For example, it is determined whether the temperature is lower than 45 ° C. (step S2).

  When the hot water storage temperature sensor 30c located below the intermediate return pipe 26 detects a temperature lower than the second predetermined temperature, the switching means 27 is connected to the outflow side of the refrigerant water heat exchanger 21 and the hot water storage tank 1 of the heating circuit 24. Switching to a state in which the upper side is in communication (step S3), driving and controlling the compressor 20 and the decompressor 22 to operate the heat pump type heating means 19 to drive the heating circulation pump 25 (step S4), An intermediate boiling operation is performed so that the boiling temperature detected by the boiling temperature sensor 29 becomes a predetermined temperature. At this time, the boiling temperature is preferably about 80 ° C., which is a certain level higher than the hot water temperature in the vicinity of the indirect heat exchanger 13 detected by the hot water temperature sensor 30b. Then, the hot water returned from the upper part of the hot water storage tank 1 into the hot water storage tank 1 increases the hot water layer, and pushes down the temperature boundary layer L of the hot water as it is.

  When the temperature boundary layer L is moved to a lower position and the hot water storage temperature sensor 30c located below the intermediate return pipe 26 detects the second predetermined temperature or higher (step S5), the switching means 27 is changed to the refrigerant water heat exchanger 21. The hot water returned to the intermediate part in the hot water storage tank 1 from the intermediate return pipe 26 is converted into a hot water near the indirect heat exchanger 13. The hot water above the temperature boundary layer L is increased so that the temperature boundary layer L of the hot water is pushed down as it is, and the low temperature water at the bottom of the hot water storage tank 1 is supplied to the heat pump heating means 19. Is done.

  And the control means 36 is the 3rd predetermined temperature (for example, 70) in which the hot water storage temperature sensor 30a or 30b located above the intermediate return pipe 26 and above the lower end of the indirect heat exchanger 13 has the heating capacity or heating efficiency of bath water. When the above is detected (step S7), the compressor 20 and the decompressor 22 are stopped to stop the heat pump type heating means 19, and the heating circulation pump 25 is also stopped to stop the intermediate boiling operation. (Step S8).

  As described above, when the temperature boundary layer L exists at the connection position of the intermediate return pipe 26 or above it, the hot water boiled by the intermediate boiling operation is once supplied from the upper part of the hot water storage tank 1, Since the high temperature hot water is supplied from the intermediate return pipe 26 after the boundary layer L is pushed down below the connection position of the intermediate return pipe 26, the hot water boiled up by the intermediate boiling operation is reliably transferred to the temperature boundary. The hot water near the indirect heat exchanger 13 can be quickly heated without disturbing the temperature boundary layer L, and the subsequent hot water storage efficiency can be deteriorated. Absent.

  On the other hand, when the hot water storage temperature sensor 30c located below the intermediate return pipe 26 detects a temperature higher than the second predetermined temperature in step S2, the hot water temperature boundary layer L exists below the intermediate return pipe 26. Therefore, the switching means 27 is switched to a state where the outflow side of the refrigerant water heat exchanger 21 and the intermediate return pipe 26 communicate with each other (step S9), and the compressor 20 and the decompressor 22 are driven and controlled. Then, the heat pump type heating means 19 is operated to drive the heating circulation pump 25 (step S10), and an intermediate boiling operation is performed so that the boiling temperature detected by the boiling temperature sensor 29 becomes a predetermined temperature. At this time, the boiling temperature is preferably about 80 ° C., which is a certain level higher than the hot water temperature in the vicinity of the indirect heat exchanger 13 detected by the hot water temperature sensor 30b.

  Then, the hot water returned from the intermediate portion of the hot water storage tank 1 into the hot water storage tank 1 contributes to the temperature rise of the hot water in the vicinity of the indirect heat exchanger 13, and the temperature boundary layer L pushes down the temperature boundary layer L of the hot water. In addition, the hot water at the top is increased, and the cold water at the bottom of the hot water storage tank 1 is supplied to the heat pump heating means 19.

  And the control means 36 is the 3rd predetermined temperature (for example, 70) in which the hot water storage temperature sensor 30a or 30b located above the intermediate return pipe 26 and above the lower end of the indirect heat exchanger 13 has the heating capacity or heating efficiency of bath water. When the above is detected (step S7), the compressor 20 and the decompressor 22 are stopped to stop the heat pump type heating means 19, and the heating circulation pump 25 is also stopped to stop the intermediate boiling operation. (Step S8).

  Thus, when the temperature boundary layer L exists below the connection position of the intermediate return pipe 26, the hot water boiled in the intermediate boiling operation can be caused to flow into the intermediate portion of the hot water storage tank 1 from the beginning. The hot water in the vicinity of the indirect heat exchanger 13 is quickly raised without disturbing the temperature boundary layer L, and the subsequent hot water storage efficiency is not deteriorated.

  The control means 36 performs an intermediate boiling operation when the reheating switch 35 is operated or when the hot water storage temperature sensor 30c detects a predetermined temperature or less during a certain period of time during which the bath water is kept warm. In other cases, the intermediate boiling operation is not performed even when the hot water storage temperature sensor 30c detects a predetermined temperature or less. If there is no need to heat the bath water, the intermediate boiling operation can be performed wastefully. In addition, the hot water in the hot water storage tank 1 is prevented from being boiled in a larger amount than the necessary amount of heat.

  In addition, this invention is not limited to this one Embodiment, It does not prevent changing in the range which does not change a summary. For example, the external fluid flowing to the indirect heat exchanger 13 may be a circulating fluid for heating instead of bath water. The heating means 19 may be a heater type heating means instead of a heat pump type. Further, the switching means 27 is not limited to a three-way valve, and for example, an open / close valve may be provided on the hot water storage tank 1 upper side of the heating circuit 24 and the intermediate return pipe 26, and only one of them may be opened.

1 is a system diagram of an embodiment of the present invention. The flowchart figure explaining the action | operation of the same embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Hot water storage tank 2 Water supply pipe 3 Hot water discharge pipe 13 Indirect heat exchanger 19 Heating means 24 Heating circulation circuit 25 Heating circulation pump 26 Intermediate return pipe 27 Switching means 30a-f Hot water storage temperature sensor

Claims (4)

  A hot water storage tank for storing hot water, a water supply pipe connected to the bottom of the hot water storage tank, a hot water pipe connected to the top of the hot water storage tank, and a heating circulation circuit for returning hot water taken out from the lower part of the hot water storage tank to the upper part of the hot water storage tank Heating means provided in the middle of the heating circulation circuit for heating hot water, a heating circulation pump provided in the middle of the heating circulation circuit for flowing hot water in the hot water storage tank to the heating circulation circuit, and an upper part in the hot water storage tank An indirect heat exchanger that is provided and heats an external fluid with the heat of hot water in the hot water storage tank, and the hot water storage that is branched from the downstream side of the heating means of the heating circulation circuit and that is below the upper end of the indirect heat exchanger. An intermediate return pipe connected to the tank intermediate part and hot water heated by the heating means are returned to the upper part of the hot water storage tank via the heating circulation circuit or via the intermediate return pipe. Switching means for switching whether to return to the intermediate portion of the hot water storage tank, and a hot water storage temperature sensor that is provided in plural in the vertical direction on the side surface of the hot water storage tank and detects the temperature of the hot water in the hot water storage tank, from the intermediate return pipe When the hot water storage temperature sensor located above and in the vicinity of the indirect heat exchanger detects a temperature equal to or lower than a first predetermined temperature, the heating means and the heating circulation pump are switched in a state where the switching means is switched to the upper side of the hot water storage tank. After that, when the hot water storage temperature sensor located below the intermediate return pipe detects a second predetermined temperature or more lower than the first predetermined temperature, the switching means is switched to the intermediate return pipe side to A hot water storage type hot water supply apparatus characterized by performing an intermediate boiling operation for returning hot water heated by a heating means to an intermediate portion of the hot water storage tank.   A hot water storage tank for storing hot water, a water supply pipe connected to the bottom of the hot water storage tank, a hot water pipe connected to the top of the hot water storage tank, and a heating circulation circuit for returning hot water taken out from the lower part of the hot water storage tank to the upper part of the hot water storage tank Heating means provided in the middle of the heating circulation circuit for heating hot water, a heating circulation pump provided in the middle of the heating circulation circuit for flowing hot water in the hot water storage tank to the heating circulation circuit, and an upper part in the hot water storage tank An indirect heat exchanger that is provided and heats an external fluid with the heat of hot water in the hot water storage tank, and the hot water storage that is branched from the downstream side of the heating means of the heating circulation circuit and that is below the upper end of the indirect heat exchanger. An intermediate return pipe connected to the tank intermediate part and hot water heated by the heating means are returned to the upper part of the hot water storage tank via the heating circulation circuit or via the intermediate return pipe. Switching means for switching whether to return to the intermediate portion of the hot water storage tank, and a hot water storage temperature sensor that is provided in plural in the vertical direction on the side surface of the hot water storage tank and detects the temperature of the hot water in the hot water storage tank, from the intermediate return pipe The hot water storage temperature sensor located above and in the vicinity of the indirect heat exchanger detects the first predetermined temperature or lower, and the hot water storage temperature sensor located below the intermediate return pipe is lower than the first predetermined temperature. When a temperature equal to or lower than a predetermined temperature is detected, the heating means and the heating circulation pump are operated in a state where the switching means is switched to the upper side of the hot water storage tank, and then the hot water storage temperature located below the intermediate return pipe When the sensor detects the second predetermined temperature or more, the switching means is switched to the intermediate return pipe side, and the hot water heated by the heating means is sent to the hot water storage tank intermediate portion. An intermediate boiling operation is performed, and the hot water storage temperature sensor located above the intermediate return pipe and near the indirect heat exchanger detects the first predetermined temperature or lower and is located below the intermediate return pipe. When the hot water storage temperature sensor detects the second predetermined temperature or more, the hot water heated by the heating means by operating the heating means and the heating circulation pump in a state where the switching means is switched to the intermediate return pipe side. The hot water storage type hot water supply apparatus is characterized in that an intermediate boiling operation for returning the hot water to the hot water storage tank intermediate part is performed.   When the hot water storage temperature sensor located above the intermediate return pipe and above the lower end of the indirect heat exchanger detects a temperature equal to or higher than a third predetermined temperature higher than the first predetermined temperature, the intermediate boiling operation is stopped. The hot water storage type hot water supply apparatus according to claim 1 or 2.   The heating means includes a compressor that compresses the refrigerant, a refrigerant water heat exchanger that exchanges heat between the refrigerant and water, a decompression means that depressurizes the refrigerant pressure, and an evaporator that evaporates the liquid refrigerant. The hot water storage type hot water supply apparatus according to any one of claims 1 to 3, wherein the hot water storage apparatus is a heating means.

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