JP5986455B2 - Hot water storage water heater - Google Patents

Description

  The present invention relates to a hot water storage type hot water heater that circulates hot water in a hot water storage tank to a primary side of a hot water supply external heat exchanger and heats flowing water flowing on a secondary side to supply hot water.

  Conventionally, in a hot water storage type water heater having an external heat exchanger of this type, as in Patent Document 1, a hot water storage tank for storing hot water, a heating means for heating the hot water in the hot water storage tank, and a primary side A hot water supply external heat exchanger that heats and supplies hot water flowing from the hot water in the hot water storage tank circulating through the hot water tank, and a primary side connecting the upper part of the hot water storage tank and the primary inlet of the hot water supply external heat exchanger A side return pipe, a primary return pipe connecting the primary outlet of the hot water supply external heat exchanger and the hot water storage tank, and a hot water in the hot water storage tank provided outside the hot water supply provided in the middle of the primary return pipe. A primary side pump that circulates to the primary side of the heat exchanger, a water supply pipe connected to the secondary side inlet of the hot water supply external heat exchanger, and a hot water supply pipe connected to the secondary side outlet of the hot water supply external heat exchanger There was something with.

JP 2012-107843 A

  However, in such a conventional type, when there is a risk of freezing in the hot water supply external heat exchange or the primary side circulation circuit of the hot water storage water heater installed outdoors in winter or the like, the hot water storage tank is driven by driving the primary side pump. The internal hot water flowed to prevent the heat exchanger outside the hot water supply and the primary circulation circuit from freezing. However, in such anti-freezing operation, the heat in the hot water storage tank was excessively increased every time the anti-freezing operation was performed. In addition to being consumed and inefficient, the amount of heat in the hot water storage tank may be insufficient during hot water supply, and hot water supply may become impossible.

Therefore, in order to solve the above-described problems, the present invention provides a hot water storage tank for storing hot water, heating means for heating the hot water in the hot water storage tank, and hot water in the hot water storage tank circulating in the primary side as a heat source as a secondary source. A hot water external heat exchanger that heats and supplies hot water to the hot water, a primary forward pipe that connects the upper part of the hot water storage tank and the primary inlet of the hot water external heat exchanger, and a primary side of the hot water external heat exchanger A primary side return pipe connecting an outlet and the hot water storage tank, a primary side pump provided in the middle of the primary side return pipe for circulating hot water in the hot water storage tank to a primary side of the hot water supply external heat exchanger, A hot water supply pipe connected to a secondary side inlet of the hot water supply external heat exchanger, a hot water supply pipe connected to a secondary side outlet of the hot water supply external heat exchanger, a lower part of the hot water storage tank, and an inlet of the heating means A heating forward pipe for connecting, an outlet of the heating means, A heating return pipe connecting the upper part of the hot water storage tank, a heating circulation pump provided in the middle of the heating forward pipe, and a downstream side of the primary pump of the primary return pipe branched from the heating return pipe A heating branch pipe to be connected; a heating switching valve that switches between returning hot water flowing through the heating return pipe to the upper part of the hot water storage tank or returning to the lower part of the hot water storage tank via the heating branch pipe and the primary return pipe; Freezing temperature detecting means for detecting whether or not the temperature has dropped to a temperature at which hot water may freeze, and detecting that the freezing temperature detecting means has dropped to a predetermined temperature at which there is a high risk of freezing, said heating circulation pump in a state of switching to the heating branch pipe side and driving the heating means, the heating return pipe, the switching valve, the heating branch pipes, said primary return pipe, the hot water storage tank, before And a control means for heating side antifreezing operation for circulating hot water in the order of the heating forward pipe, said primary pump proximate disposed below the hot water out of the heat exchanger, and wherein the heating branch pipes primary The connection point of the side return pipe was below and in the vicinity of the primary pump.

  In addition, a primary side temperature detecting means for detecting the temperature of the hot water on the primary side of the hot water supply external heat exchanger is provided, and the control means has the primary side temperature detecting means lowered to a predetermined primary side temperature at which the primary side temperature detecting means may be frozen. Is detected, the primary side freezing prevention operation for driving the primary side pump is performed.

  Further, a supplementary water pipe branched from the hot water supply pipe and connected to the primary return pipe via a pressure reducing valve is provided, and the pressure reducing valve is disposed in the vicinity of a connection point between the supplementary water pipe and the primary return pipe.

  According to the present invention, when the heating-side freeze prevention operation is performed, the primary return pipe can be prevented from freezing, and the connection point between the heating branch pipe and the primary return pipe is close to the primary pump and the hot water supply external heat exchanger. Therefore, the primary pump and the external hot water heat exchanger are heated by heat conduction from the circulating hot water, and the primary pump and the external hot water heat exchanger can be prevented from freezing at the same time. It will not be consumed transiently, and it will not cause a situation such as inability to supply hot water due to lack of heat in the hot water storage tank.

  In addition, when the temperature on the primary side of the hot water supply external heat exchanger drops to a temperature that is likely to freeze, the primary side pump is driven to perform the primary side antifreeze operation, but the heating branch pipe and the primary side return pipe are connected. Because the point is close to the primary pump and hot water external heat exchanger, the primary pump and hot water external heat exchanger are heated by the heat conduction from the circulating hot water and the temperature rises, preventing primary freezing prevention. The frequency of operation is reduced, the heat in the hot water storage tank is not transiently consumed, and no hot water supply failure due to insufficient heat in the hot water storage tank is prevented.

  In addition, since the temperature of the supplementary water pipe and the pressure reducing valve also rises due to the heating side freezing prevention operation or the primary side freezing prevention operation, the supplementary water pipe and the pressure reducing valve can be prevented from freezing.

Schematic configuration diagram of one embodiment of the present invention Flow chart for explaining the operation of the heating side freeze prevention operation Flow chart for explaining the operation of the primary side freezing prevention operation

Next, a hot water storage type water heater according to an embodiment of the present invention will be described with reference to the drawings.
1 is a tank unit having a hot water storage tank 2 for storing hot water, 3 is a hot water external heat exchanger composed of a plate heat exchanger for heating the hot water in the hot water tank 2 as a heat source, and 4 is a hot water tank 2. The primary side circulation circuit 4 circulates the hot water inside the hot water supply outside heat exchanger 3 to the primary side, and the primary side circulation circuit 4 connects the one side inlet 3 a of the hot water supply outside heat exchanger 3 and the upper part of the hot water storage tank 2. The primary side return pipe 5 is composed of a primary side return pipe 6 that connects the primary side outlet 3b of the hot water supply external heat exchanger 3 and the lower part of the hot water storage tank 2, and the upper part of the hot water storage tank 2 is in the middle of the primary side return pipe 6. A primary pump 7 is provided for circulating the hot water taken out from the primary side of the hot water supply external heat exchanger 3.

  8 is a water supply pipe connected to the secondary side inlet 3 c of the hot water supply external heat exchanger 3, and 9 is a hot water supply pipe connecting the secondary side outlet 3 d of the hot water supply external heat exchanger 3 and the hot water tap 10. Here, the water supply pipe 8 is directly connected from the city water to the hot water supply external heat exchanger 3 without going through the pressure reducing valve.

  Here, the hot water supply external heat exchanger 3 is arranged and fixed in the tank unit 1 in a posture in which a known plate type heat exchanger is set up, and a primary side inlet 3a and a secondary side outlet are provided at the lower part of one end plate. 3d is arranged, and a primary side outlet 3b and a secondary side inlet 3c are arranged on the same surface of the end plate.

  11 is a heat pump unit as a heating means for heating the hot water in the hot water storage tank 2, and 12 is a heating circulation circuit for circulating the hot water in the hot water storage tank 2 to the heat pump unit 11, which is connected to the inlet of the heat pump unit 11. And a heating return pipe 14 connecting the outlet side of the heat pump unit 11 and the upper part of the hot water storage tank 2. The hot water storage tank 13 is located in the middle of the heating forward pipe 13. 2 A heating circulation pump 16 for circulating hot water taken out from the lower part to the water side of the refrigerant water heat exchanger 15 of the heat pump unit 11 is provided.

  17 is a compressor that compresses refrigerant, 18 is an expansion valve that decompresses and expands the pressure of the refrigerant, 19 is an evaporator that evaporates liquid refrigerant, 20 is a blower that blows outside air as a heat source to the evaporator 19, and 21 is refrigerant water. An incoming water temperature sensor 22 detects the temperature of hot water from the hot water storage tank 2 that flows into the water side of the heat exchanger 15, and 22 is the temperature of hot water boiled up by the heat pump unit 11 that flows out from the water side of the refrigerant water heat exchanger 15. The boiling temperature sensor 23 detects the outside air temperature, and the outside air temperature sensor 23 detects the outside air temperature. The heat pump unit 11 compresses the refrigerant absorbed by the evaporator 19 by the compressor 17 and supplies water via the refrigerant water heat exchanger 15. It is intended to be heated.

  Reference numeral 24 denotes a heating branch pipe branched from the middle of the heating return pipe 14 and connected to the primary return pipe 6, and 25 is provided at a branch point between the heating return pipe 14 and the heating branch pipe 24. This is a heating switching valve that switches between returning to the upper part of the hot water storage tank 2 or returning to the lower part of the hot water storage tank 2 via the heating branch pipe 24 and the primary return pipe 6.

  26 is a supplementary water pipe branched from the hot water supply pipe 9 and connected between the primary side pump 7 of the primary side return pipe 6 and the connection point of the heating branch pipe 24, and 27 is provided in the middle of the supplementary water pipe 26 to control the supply water pressure. A pressure reducing valve 28 for reducing the pressure is an overpressure relief valve that is connected in the middle of the primary side outgoing pipe 5 and releases the overpressure in the hot water storage tank 2.

  Here, the primary pump 7 is disposed near the lower part of the hot water supply external heat exchanger 3, and the connection point between the heating branch pipe 24 and the primary return pipe 6 is disposed below and near the primary side circulation pump 7. The connection point between the water pipe 26 and the primary return pipe 6 is provided above the connection point between the heating branch pipe 24 and the primary return pipe 6 closer to the primary pump 7, and the pressure reducing valve 27 is connected to the auxiliary water pipe 26 and the primary return pipe 6. It is arranged in the vicinity of the connection point of the pipe 6.

  29 is a water supply temperature sensor that is provided in the middle of the water supply pipe 8 to detect the water supply temperature, 30 is a hot water supply temperature sensor that is provided in the middle of the hot water supply pipe 9 to detect the hot water supply temperature, and 31 is a water supply temperature sensor that is provided in the middle of the hot water supply pipe 9. The hot water supply flow sensor 32 detects the temperature of hot water as a heat source that is provided in the primary side forward pipe 5 and flows into the hot water external heat exchanger 3, and 33 is in the middle of the primary return pipe 6. A plurality of primary outlet temperature sensors 34 are provided on the upper and lower sides of the hot water storage tank 2 to detect the temperature of the hot water stored in the hot water tank.

  Here, the outside air temperature sensor 23 functions as a freezing temperature detecting means for detecting whether or not the temperature has dropped to a temperature at which hot water may be frozen, and the primary inlet temperature sensor 32 is the hot water on the primary side of the hot water supply external heat exchanger. It acts as a primary temperature detecting means for detecting temperature.

  Reference numeral 35 denotes a remote controller including an operation switch for setting a desired hot water supply set temperature and a display unit for displaying the hot water set temperature.

  Reference numeral 36 denotes an incoming water temperature sensor 21, a boiling temperature sensor 22, an outside air temperature sensor 23, a feed water temperature sensor 29, a hot water supply temperature sensor 30, a hot water supply flow rate sensor 31, a primary inlet temperature sensor 32, a primary outlet temperature sensor 33, and a hot water storage temperature sensor 34. The detection value is input, and the operation of the primary pump 7, the heat pump unit 11, the heating circulation pump 16, the compressor 17, the expansion valve 18, the blower 20, and the heating switching valve 25 is controlled and connected to the remote control 35 so as to be communicable. Control means. The control means 36 stores a program for controlling the operation of the water heater in advance, and has a calculation, comparison, storage function, and clock function.

<Boiling operation>
At the start time of a predetermined time zone (midnight time zone) at which the power unit price is cheap, the control means 36 drives the heat pump unit 11 and the heating circulation pump 16 so as to start boiling the hot water amount corresponding to the hot water supply load amount so far. The hot water taken out from the lower part of the hot water storage tank 2 is started and heated to the set temperature.

  At this time, the control means 36 keeps the heating switching valve 25 on the heating branch pipe 24 side while the boiling temperature detected by the boiling temperature sensor 22 is lower than a predetermined temperature lower than the boiling setting temperature, and the temperature is low. When hot water is prevented from flowing in from the upper part of the hot water storage tank 2 to lower the hot water storage temperature, and the boiling temperature reaches a predetermined temperature lower than the boiling temperature, the heating switching valve 25 is placed on the upper side of the hot water tank 2. The hot water that has been boiled so as to communicate with each other is returned to the upper part of the hot water storage tank 2, and hot water at the boiling set temperature is stored in a stacked manner from the upper part of the hot water storage tank 2.

  When the lowest hot water storage temperature sensor 34 detects a predetermined boiling end determination temperature, the control unit 36 stops driving the heat pump unit 11 and the heating circulation pump 16 and ends the boiling operation.

  At this time, the hot water stored in the hot water storage tank 2 expands as the temperature of the hot water in the hot water tank 2 rises, and when the pressure in the hot water storage tank 2 exceeds the set pressure of the overpressure relief valve 28, the overpressure relief valve 28 opens. When the expanded water is drained and the pressure in the hot water storage tank 2 falls below the set pressure of the overpressure relief valve 28, the overpressure relief valve 28 closes and the drainage stops, so that the hot water tank 2 is maintained at an appropriate pressure. Yes.

  Then, the hot water stored in the hot water storage tank 2 contracts due to the natural heat dissipation of the hot water in the hot water storage tank 2 over time and the temperature drop of the hot water in the hot water storage tank 2 due to the hot water supply described later, and the pressure in the hot water storage tank 2 is reduced. When the pressure becomes lower than the set pressure of 27, the city water flows into the hot water storage tank 2 from the supplementary water pipe 26 via the pressure reducing valve 27, and when the pressure in the hot water storage tank 2 becomes equal to or higher than the set pressure of the pressure reducing valve 27, The inflow of water stops and the hot water storage tank 2 is kept in a full water state at an appropriate pressure.

<Hot water supply operation>
Next, the hot water supply operation will be described. When the hot water tap 10 is opened, city water flows into the secondary side of the hot water supply external heat exchanger 3 from the water supply pipe 8 and passes through the secondary side of the hot water supply external heat exchanger 3. The discharged hot water flows out from the hot water supply pipe 9 toward the hot water tap 10. At this time, when the hot water supply flow sensor 31 detects a predetermined minimum working water amount or more, the control means 36 supplies the hot water temperature detected by the hot water temperature sensor 29, the hot water set temperature set by the remote controller 35, and the hot water flow sensor. The hot water required heat quantity is calculated from the hot water supply flow rate detected at 31, and the primary side pump 7 is started to drive at a rotational speed corresponding to the hot water storage temperature detected by the hot water storage temperature sensor 34 and the calculated hot water required heat quantity. .

  Then, the number of revolutions of the primary pump 7 is feedback-controlled so that the hot water temperature detected by the hot water temperature sensor 30 matches the hot water set temperature set by the remote controller 35 to perform hot water supply at the hot water set temperature.

  When the hot water supply flow rate detected by the hot water supply flow rate sensor 31 decreases to less than the minimum working water amount, for example, when the hot water tap 10 is closed, the control unit 36 stops the operation of the primary pump 7 and ends the hot water supply.

<Anti-freezing operation>
Next, in a state where neither boiling-up operation nor hot-water supply operation is performed in winter or the like, the hot water of the hot water storage type hot water heater may be frozen, and the anti-freezing operation at that time is based on the flowcharts of FIGS. I will explain.

  FIG. 2 is a flowchart for explaining the operation of the heating side freezing prevention operation for preventing the piping between the tank unit 1 and the heat pump unit 11 from freezing. The control means 36 is an outside air temperature sensor 23 as a freezing temperature detection means. Detects the first predetermined temperature (here, not less than −5 ° C. and less than 5 ° C.) at which the hot and cold water may freeze (Yes in step S1), the heating switching valve 25 is switched to the state in which the heating branch pipe 24 is in communication. (Step S2), the heating circulation pump 16 is turned ON / OFF in a predetermined cycle (Step S3).

  Here, the ON / OFF driving of the heating circulation pump 16 in a predetermined cycle means that the heating circulation pump 16 is only for a first predetermined time during a predetermined period (first predetermined time + second predetermined time). Is driven (ON), and the heating circulation pump 16 is stopped (OFF) only for the second predetermined time.

  By periodically driving the heating circulation pump 16 in this manner, the heating return pipe 14, the heating switching valve 25, the heating branch pipe 24, the primary side return pipe 6, the hot water storage tank 2, and the heating forward pipe 13 are arranged in this order. Since the hot water circulates, the primary side return pipe 6 is prevented from freezing without the heat in the hot water storage tank 2 being consumed by the circulation of the hot water by driving the heating circulation pump 16, and the heating branch pipe 24 and the primary side return pipe 6 are returned. Since the primary pump 7 is disposed above the connection point of the pipe 6 and the hot water supply external heat exchanger 3 is disposed in the vicinity thereof, the heat of the hot water circulating from the bottom of the hot water storage tank 2 is transferred from the connection point to the primary pump 7 side. The heat is transferred to the primary side pump 7 and further to the hot water supply external heat exchanger 3, and freezing of the primary side pump 7 and the hot water supply external heat exchanger 3 is also prevented.

  Next, when it is confirmed that the outside air temperature detected by the outside air temperature sensor 23 has not dropped below the second predetermined temperature (here, −5 ° C.) at which hot water is likely to freeze (Yes in step S4), the outside air again. When it is detected that the outside air temperature detected by the temperature sensor 23 has risen to a predetermined freezing prevention end temperature (here, 8 ° C.) at which the hot and cold water does not freeze (Yes in step S5), the heating circulation pump 16 is driven. It stops (step S6) and complete | finishes a heating side freezing prevention driving | operation.

  On the other hand, when the control unit 36 detects that the outside air temperature sensor 23 has decreased to a temperature equal to or lower than a second predetermined temperature (here, −5 ° C.) at which hot water is likely to freeze (Yes in step S7), heating switching is performed. The valve 25 is switched to a state where the heating branch pipe 24 is in communication (step S8), the heating circulation pump 16 is driven (step S9), and the compressor 17 is driven to bring the heat pump unit 11 into a boiling state (step S10). ).

  At this time, the hot water heated by the heat pump unit 11 flows in the order of the heating return pipe 14, the heating switching valve 25, the heating branch pipe 24, the primary return pipe 6, the hot water storage tank 2, and the heating forward pipe 13. The side return pipe 6 is prevented from freezing without consuming heat in the hot water storage tank 2 due to the circulation of hot water by driving the heating circulation pump 16, and above the connection point between the heating branch pipe 24 and the primary side return pipe 6. In addition, the hot water supply external heat exchanger 3 is disposed in the vicinity of the primary pump 7, so that the heat of the circulating hot water is transferred from the connection point to the primary pump 7 side by heat conduction, and the primary pump 7 Heat is transferred to the hot water supply external heat exchanger 3 to prevent the primary side pump 7 and the hot water supply external heat exchanger 3 from being frozen.

  Then, in the next step S11, it is determined whether or not the outside air temperature sensor 23 has risen to a fourth predetermined temperature (here, 0 ° C.) or higher where the risk of freezing is not so high, and the outside air temperature is lower than the fourth predetermined temperature. As it is, the heating circulation pump 16 and the compressor 17 are continuously driven, and the hot water boiled up by the heat pump unit 11 is continuously circulated to perform the freeze prevention operation.

  On the other hand, when the temperature rises to the fourth predetermined temperature (here, 0 ° C.) or higher at which the outside air temperature sensor 23 is not very likely to freeze in step S11, the compressor 17 is stopped (step S12). It progresses to said step S3, and it is made to change to the heating side freezing prevention operation which does not accompany the boiling operation in the heat pump unit 11. FIG.

  In this way, when the heating side freezing prevention operation is performed, the primary side return pipe 6 can be prevented from freezing. Further, the connection point between the heating branch pipe 24 and the primary side return pipe 6 is the primary side pump 7 and hot water supply outside heat exchange. The primary pump 7 and the hot water supply external heat exchanger 3 are heated by heat conduction from the circulating hot water because of the proximity to the water heater 3, and the freezing prevention of the primary pump 7 and the hot water supply external heat exchanger 3 is realized at the same time. In addition, the heat in the hot water storage tank 2 is not consumed transiently, and a situation in which hot water cannot be supplied due to insufficient heat in the hot water storage tank 2 is prevented.

  Next, FIG. 3 is a flowchart for explaining the operation of the primary side freezing prevention operation for preventing the primary side circulation circuit 4 in the tank unit 1 from freezing. The control means 36 is a primary inlet as a primary temperature detecting means. When the temperature sensor 32 detects that the temperature has dropped below the predetermined primary side temperature (3 ° C. in this case) at which hot water may freeze (step S21), the primary side pump 7 is driven (step S22).

  When the primary outlet temperature sensor 33 detects that the temperature has risen to a predetermined end temperature (here, 10 ° C.) that is free from freezing (step S23), the driving of the primary pump 7 is stopped (step S24). The primary side freezing prevention operation is terminated.

  In this way, when the primary circulation circuit 4 and the hot water supply external heat exchanger 3 in the tank unit 1 are lowered to a temperature that is likely to freeze, hot water is circulated from the upper part of the hot water storage tank 2 to prevent freezing. Like to do.

  Here, the primary-side freeze prevention operation is performed when the temperature in the tank unit 1 storing hot water is lowered to a temperature at which the hot water is likely to freeze, so the primary-side freeze prevention operation is started. In many cases, the heating-side freeze prevention operation involving the boiling operation by the heat pump unit 11 has already been started.

  Therefore, since the primary pump 7 and the hot water supply external heat exchanger 3 are heated by the heating-side freeze prevention operation, the frequency of the primary-side freeze prevention operation is drastically reduced, and the heat in the hot water storage tank is transiently consumed. In addition, there is no longer a situation in which hot water supply is not possible due to insufficient heat in the hot water storage tank.

  Here, the primary inlet temperature sensor 32 is used as the primary side temperature detection means, and the heating branch pipe 24 and the primary side return pipe 6 that are heat sources when the hot water supply heat exchanger 3 is heated by the heating side freezing prevention operation. The primary side temperature of the external hot water heat exchanger 3 at the position farthest from the connection point of the hot water is detected, so that the frequency of the primary side freezing prevention operation is reduced and the reliability of the freezing hot water heat exchanger 3 is improved. Are both compatible.

  Here, the connection point between the supplementary water pipe 26 and the primary return pipe 6 is provided above the connection point between the heating branch pipe 24 and the primary return pipe 6 and closer to the primary pump 7, and the pressure reducing valve 27 is provided in the supplementary water pipe 26. And the primary side return pipe 6 are arranged in the vicinity of the connection point, so that the temperature of the supplemental water pipe and the pressure reducing valve rises due to the heating side freezing prevention operation or the primary side freezing prevention operation. realizable.

  The present invention is not limited to the above-described embodiment, and can be modified without changing the gist of the invention. For example, the hot water supply external heat exchanger is preferably a plate heat exchanger, It is not limited to a type heat exchanger.

  Although the outside temperature sensor 23 has been described as an example of the freezing temperature detection means, the temperature sensor 23 is not limited to this. For example, a temperature sensor that detects the temperature of the casing that is in contact with the outside air of the incoming water temperature sensor 21, the tank unit 1, and the heat pump unit 11 ( (Not shown).

  Further, the primary inlet temperature sensor 32 has been described as an example of the primary side temperature detection means, but is not limited thereto, and may be, for example, the primary outlet temperature sensor 33, or the water supply temperature sensor 29, the hot water supply temperature sensor 30, or the hot water supply external heat exchange. A temperature sensor that can indirectly estimate the temperature on the primary side of the hot water supply heat exchanger 3, such as a temperature sensor (not shown) directly attached to the storage unit 3, may be used.

2 Hot water storage tank 3 External heat exchanger for hot water supply 5 Primary forward pipe 6 Primary return pipe 7 Primary pump 8 Water supply pipe 9 Hot water supply pipe 11 Heat pump unit (heating means)
13 Heating Outward Pipe 14 Heating Return Pipe 23 Outside Air Temperature Sensor (Freezing Temperature Detection Means)
24 Heating branch pipe 25 Heating switching valve 26 Water refilling pipe 27 Pressure reducing valve 32 Primary inlet temperature sensor (primary temperature detecting means)
36 Control means

Claims (3)

Hot water storage tank for storing hot water, heating means for heating the hot water in the hot water storage tank, and hot water outside heat exchange for supplying hot water by heating the running water on the secondary side using the hot water in the hot water tank circulating in the primary side as a heat source A primary side forward pipe connecting the upper part of the hot water storage tank and the primary inlet of the hot water supply external heat exchanger, and a primary return pipe connecting the primary outlet of the hot water supply external heat exchanger and the hot water storage tank A primary side pump provided in the middle of the primary side return pipe to circulate hot water in the hot water storage tank to a primary side of the hot water supply external heat exchanger, and connected to a secondary side inlet of the hot water supply external heat exchanger A hot water supply pipe connected to a secondary side outlet of the hot water supply external heat exchanger, a heating forward pipe connecting a lower part of the hot water storage tank and an inlet of the heating means, and an outlet of the heating means And a heating return pipe connecting the upper part of the hot water storage tank and A heating circulation pipe provided in the middle of the heating forward pipe, a heating branch pipe branched from the heating return pipe and connected to the downstream side of the primary pump of the primary return pipe, and circulating through the heating return pipe A heating switching valve that switches between returning hot water to the upper part of the hot water tank or returning to the lower part of the hot water tank via the heating branch pipe and the primary return pipe, and whether or not the temperature has dropped to a temperature at which hot water may freeze And when the freezing temperature detecting means detects that the freezing temperature detecting means has decreased to a predetermined temperature at which there is a high risk of freezing, the heating circulation pump is switched in the state where the heating switching valve is switched to the heating branch pipe side. said heating means is driven, the heating return pipe, the switching valve, the heating branch pipes, said primary return pipe, the hot water storage tank, antifreeze heating side for circulating hot water in the order of the heating forward pipe Control means for performing a prevention operation, the primary pump is disposed close to the lower side of the hot water supply external heat exchanger, and the connection point of the heating branch pipe and the primary return pipe is located below the primary pump And a hot water storage type hot water supply device characterized by being in the vicinity.   The primary side temperature detecting means for detecting the temperature of the hot water on the primary side of the hot water supply external heat exchanger is provided, and the control means detects that the primary side temperature detecting means has decreased to a predetermined primary temperature at which freezing may occur. Then, the hot water storage type hot water supply apparatus according to claim 1, wherein a primary side freezing prevention operation for driving the primary side pump is performed.   A supplementary water pipe branched from the hot water supply pipe and connected to the primary return pipe via a pressure reducing valve is provided, and the pressure reducing valve is disposed in the vicinity of a connection point between the supplementary water pipe and the primary return pipe. The hot water storage type hot water supply apparatus according to claim 1 or 2.

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