JP2005156156A - Multifunctional water heater - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multifunctional water heater capable of utilizing hot-water heat stored as hot water in a hot-water tank effectively for a heat releasing means, and reduced in a heat loss. <P>SOLUTION: The hot water heated by a heating means such as a heat pump is stored from an upper part of the hot-water tank 16, the hot water in the upper part of the hot-water tank 16 is circulated by a load side circulation passage, a heating medium in a heat releasing side circulation passage is heated by the hot water in the load side circulation passage via a heat exchanger 30, and heat is released by the heat releasing means 21 connected to the heat releasing side circulation passage. An opening and closing valve 50 in the load side circulation passage is closed when heat releasing operation is stopped, so as to prevent heat dissipation by natural circulation. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a heat pump water heater having multiple functions such as bathing or heating.

Conventionally, as this type of hot water supply apparatus, for example, there has been a hot water supply apparatus having a bath reheating function as shown in FIG. 14, 1 is a hot water storage tank, 2 is a boiling heater, 3 is a rapid boiling heater, 4 and 5 are temperature detection means, 6 is an electromagnetic on-off valve, 7 is a hot water supply pipe, 8 is a bathtub, and 9 is a circulation. The pump 10 is a heat exchanging means for exchanging heat between the hot water in the upper part of the hot water tank 1 and the water in the bathtub 8 (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 11-83156

  However, in the conventional configuration, in the case of bath reheating as the heat radiating means, the temperature of the hot water in the upper part of the hot water storage tank 1 is lowered during the bath reheating operation, so that the temperature of the hot water flowing into the heat radiating means becomes unstable, which is convenient. Is also bad. For example, the temperature difference between the hot water temperature at the upper part of the hot water storage tank 1 and the bath replenishment circulating water decreases as the number of times of bath replenishment increases, and the heat radiation amount decreases. Moreover, the warm water temperature which is heated and returns to the bathtub 8 also becomes low. Furthermore, the utilization temperature of the hot water in the upper part of the hot water tank 1 is limited and cannot be used effectively.

  The present invention solves the above-mentioned conventional problems, and operates hot water in hot water storage tanks with high efficiency, prevents a decrease in hot water temperature, allows a stable hot water temperature to flow to the heat radiating means, and adds rationality. The hot water supply is possible.

  In order to solve the above-mentioned conventional problems, the multi-function water heater of the present invention includes a hot water storage tank that stores hot water heated by heating means from above, and a load-side circulation that circulates hot water at the top of the hot water storage tank. A heat radiation side circulation path in which a fluid is heated with hot water of the load side circulation path through a heat exchanger, and a heat radiation means connected to the heat radiation side circulation path, and the load side circulation path Is provided with natural circulation prevention means to prevent natural circulation of hot water.

  As a result, the heat stored by using inexpensive late-night power can be utilized according to the purpose of the heat dissipating means, and heat loss is also suppressed.

  According to the present invention, the hot water in the hot water tank can be stored with high efficiency, the temperature of the hot water can be prevented from being lowered, a stable fluid can be flowed to the heat radiating means, and the convenience of the heat radiating means can be enhanced. It is.

  An embodiment of the present invention includes a hot water storage tank that stores hot water heated by a heating means from above, a load-side circulation path that circulates hot water in the upper part of the hot water storage tank, and the load via a heat exchanger. A natural circulation prevention system comprising a heat radiation side circulation path in which fluid is heated by hot water in the side circulation path and a heat radiation means connected to the heat radiation side circulation path, and preventing natural circulation of hot water in the load side circulation path Means.

  Therefore, heat radiation by the heat radiation means is ensured, and heat loss when the heat radiation operation is stopped is suppressed as much as possible.

  The natural circulation preventing means is, for example, an open / close valve that opens and closes the load side circulation path, and is closed in conjunction with the stop of heat radiation.

  The heating means is a heat pump, and carbon dioxide is used as the refrigerant, so that high efficiency and high environmental efficiency can be realized.

  Hereinafter, reference examples and examples of the present invention will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected about the same structure and the same operation | movement as a prior art example, and the thing of a prior art example is used for description.

(Reference Example 1)
In FIG. 1, reference numeral 11 denotes a heating means, which is a heat pump heat source that constitutes a heat pump cycle including a compressor 12, a radiator 13, a decompression device 14, and an atmospheric heat exchanger 15 that absorbs atmospheric heat. Then, carbon dioxide whose refrigerant pressure on the high pressure side is equal to or higher than the critical pressure is used as the refrigerant. Reference numeral 16 denotes a hot water storage tank, which supplies water from the lower part through the water supply pipe 16a and discharges the hot water from the upper hot water discharge pipe 16b to the terminal. Reference numeral 17 denotes a circulation pump, and 18 denotes a hot water supply heat exchanger, which has a heat exchange relationship with the radiator 13 and exchanges heat between the refrigerant flowing through the radiator 13 and the water flowing through the hot water heat exchanger 18 in a counterflow. is there.

  And the hot water supply circuit which connects the circulation pump 17, the hot water supply heat exchanger 18, and the upper part of the hot water storage tank 16 in order from the lower part of the hot water storage tank 16 is comprised. Reference numeral 19 denotes a temperature detecting means, which is provided at the outlet of the hot water supply heat exchanger 18 for detecting the temperature of the hot water heated by the heat pump heat source 15. A hot water control means 20 controls the circulation flow rate of the hot water supply circuit by controlling the rotation speed of the circulation pump 17 so that the outlet hot water of the hot water heat exchanger 18 reaches a predetermined temperature. Reference numeral 21 denotes, for example, a floor heater serving as a heat radiating unit, and the hot water in the upper part of the hot water tank 16 circulates and heats. Reference numeral 22 denotes hot water temperature detecting means for detecting the temperature of hot water flowing to the heat radiating means 21.

  Reference numeral 23 denotes a bypass circuit, which is a connection circuit that joins the hot water flowing out from the heat radiating means 21 to the hot water circuit that bypasses the hot water storage tank 16 and flows into the heat radiating means 21. A temperature adjusting valve 24 mixes the high temperature water flowing from the hot water tank 16 and the medium temperature water flowing out from the heat radiating means. Reference numeral 25 denotes a control means that controls the temperature adjustment valve 24 so that the temperature detection signal of the hot water temperature detection means 22 becomes a set temperature. Reference numeral 26 denotes a heat radiating pump for flowing hot water to the heat radiating means.

  The operation and action of the multi-function water heater configured as described above will be described below. In FIG. 1, a case where a hot water supply operation is performed using atmospheric heat with a heat pump heat source will be described. A high-temperature and high-pressure refrigerant having a pressure equal to or higher than the critical pressure discharged from the compressor 12 flows into the radiator 13 and exchanges heat with water sent from the lower part of the hot water storage tank 16 via the hot water supply heat exchanger 18.

  Then, the high-temperature refrigerant flowing into the radiator 13 and the water flowing out from the hot water supply heat exchanger 18 are exchanged to exchange heat, and the hot water flowing into the radiator 13 causes the outlet hot water of the hot water supply heat exchanger 18 to have a predetermined temperature. Thus, the rotational speed of the circulation pump 17 is controlled. And the hot water of predetermined temperature flows in from the hot water storage tank 16 upper part, and is stored.

  On the other hand, the high-temperature refrigerant that has flowed into the radiator 13 lowers the temperature by the heat radiation action, flows out of the radiator 13, flows into the decompression device 14, is decompressed, and flows into the atmospheric heat exchanger 15. Then, it absorbs atmospheric heat, evaporates, and returns to the compressor 12. Hot water is stored from the upper part of the hot water tank 16 to the lower part of the hot water tank 16 while repeating this cycle.

  Next, a case where hot water stored in a hot water tank is used for hot water supply will be described. When used for hot water supply, when the terminal curan is released, the hot water is discharged from the upper hot water discharge pipe 16b while being supplied from the lower part of the hot water storage tank 16 by the supply water pressure. And the hot water in the hot water storage tank 16 moves to the upper part whenever it is poured out.

  Next, the operation | movement which utilizes the high temperature water stored by the hot water storage tank with a thermal radiation means is demonstrated. When the heat dissipating means is started, the heat dissipating pump 26 causes the hot water in the upper part of the hot water tank 16 to flow to the heat dissipating means 21 side. Then, the medium / low temperature water flowing out from the heat radiation means 21 mixes with the high temperature hot water flowing out from the hot water storage tank 16 side through the bypass circuit 23. At that time, the temperature adjustment valve 24 adjusts the flow rate of the bypass circuit 23 and the flow rate of the hot water on the hot water storage tank 16 side so as to control the temperature of the hot water flowing to the heat radiation means 21 to be a predetermined temperature. And the warm water which became predetermined temperature flows into the thermal radiation means 21, and heats it. On the other hand, the medium / low temperature water that flows out of the heat radiation means 21 and does not flow into the bypass circuit 23 returns to the hot water storage tank 16.

  Therefore, comfortable heating can be obtained to keep the temperature of the hot water flowing through the floor heater constant. Of course, it is easy to change the setting of the temperature of the hot water flowing to the heat radiating means 21 to a desired predetermined temperature and to flow the hot water at the set temperature to the heat radiating means 21.

  When the heat radiation load is large, the temperature of the hot water flowing out from the heat radiating means 21 is low. Therefore, when mixing to a predetermined hot water temperature, the mixing flow rate ratio of the hot water in the hot water tank 16 is increased. On the contrary, when the heat radiation load is reduced, the temperature of the hot water flowing out from the heat radiation means is relatively high. Therefore, when mixing to a predetermined hot water temperature, the mixing flow rate of the hot water in the hot water tank 16 is small. Become. Therefore, the hot water in the hot water tank 16 can be used according to the heat radiation load.

  Then, as shown in FIG. 1, by providing a heat radiation pump 26 between the mixing by the temperature control valve 24 and the inlet of the heat radiation means 21, this can be realized by one circulation pump.

  Further, as shown in FIG. 2, the same effect can be obtained by providing a flow rate adjusting valve 27 in the bypass circuit 23 in place of the temperature adjusting valve to adjust the bypass flow rate, mixing to a predetermined temperature, and sending it to the heat radiating means.

  In addition, as shown in FIG. 3, without using a bypass circuit in the circulation circuit, a temperature adjustment heat exchanger 28 is provided for exchanging heat between the hot water from the hot water tank 16 and the medium / low temperature water flowing from the heat radiating means 21, The temperature of hot water flowing out from the hot water storage tank 16 is adjusted with the medium and low temperature water flowing from the heat radiating means 21, and the temperature of the hot water flowing to the heat radiating means 21 is set to a predetermined temperature. In this case, the temperature of the outlet of the hot water supply heat exchanger 18 heated by the heat pump, that is, the temperature of the hot water stored in the hot water storage tank 16 and the fluctuation of the heat radiation load can be naturally designed.

  In addition, as shown in FIG. 4, when the flow control means 29 for changing the circulation flow rate of the hot water flowing into the heat radiating means 21 is provided and the load is very large, for example, when high capacity heating is desired at the start of heating Then, while maintaining the temperature of the hot water circulating to the heat radiating means 21 at a predetermined temperature, the number of rotations of the heat radiating pump 26 serving as the flow rate controlling means is increased to increase the circulation flow rate of the circulation circuit and increase the heat radiation amount. When the load is small, the number of heat radiation is reduced by reducing the number of revolutions of the heat radiation pump 26 to reduce the circulation flow rate of the circulation circuit. Therefore, the desired ability is realized while maintaining the hot water temperature at a predetermined temperature.

  Moreover, since a heat pump heat source is used as the heating means, high capacity or low power consumption is realized.

  Furthermore, by using carbon dioxide as the refrigerant sealed in the heat pump heat source, hot water (approximately 90 ° C.) is stored in the hot water storage tank. Therefore, the amount of heat stored in the hot water storage tank increases, and the amount of heat released from the heat radiating means and the operation time increase. It also contributes to global environmental conservation. Furthermore, the boiling temperature range from high temperature hot water to medium hot water is increased, and the convenience of the heat radiating means is improved.

  Further, in the present embodiment, the heat radiating means 21 has been described with floor heating, but naturally, those having a heat radiating function such as a dryer and a hot air heater are included.

(Reference Example 2)
In FIG. 5, reference numeral 30 denotes a heat exchanger that exchanges heat with hot water in the hot water tank 16 circulating from the upper part of the hot water tank 16 to the middle or lower part of the hot water tank 16 and circulating water circulating in the heat radiation means 21. A hot water storage pump 31 circulates the hot water in the upper part of the hot water tank 16 to the heat exchanger 30 and returns it to the middle or lower part of the hot water tank 16.

  The operation and action of the above configuration will be described. High temperature water flowing out from the upper part of the hot water storage tank is passed through the heat exchanger 30 to heat the medium and low temperature water in the circulation circuit flowing out from the heat radiation means 21. At that time, the temperature adjustment valve 24 adjusts the temperature so that the temperature detection signal of the hot water temperature detection means 22 becomes a predetermined temperature, and the hot water of the predetermined temperature is circulated to the heat dissipation means 21 to radiate heat. On the other hand, the hot water tank water whose temperature has been lowered by the heat exchanger 30 is returned to the middle part or the lower part of the hot water tank.

  Moreover, the same effect is acquired even if it carries out by natural circulation using the hot water density difference at the time of radiating heat with the heat exchanger 30, without using the hot water storage water pump 31. And the power consumption of the hot water storage pump 31 can be reduced.

  Moreover, as shown in FIG. 6, when using for the bath heating of the bathtub 32 as a thermal radiation means, by providing the heat exchanger 30, the hot water of the hot water tank 16 and the water of the bathtub 32 can be isolate | separated and used for another circuit. And since warm water made into favorite temperature can be poured into a bathtub, mild bath heating and bath retreat can be performed. Further, by controlling the temperature adjusting valve 24 and controlling the flow rate of the bypass circuit 23, bath renewal is realized with high temperature and high capacity.

(Reference Example 3)
In FIG. 7, reference numeral 33 denotes a temperature detection unit that detects the temperature of hot water flowing into the heat dissipation unit 21. Reference numeral 34 denotes a hot water storage flow rate control means, which controls the hot water pump 31 so that the temperature detection signal of the temperature detection means 33 becomes a predetermined temperature signal.

  The operation and action of the above configuration will be described. High temperature water flowing out from the upper part of the hot water tank 16 is passed through the heat exchanger 30 to heat the medium and low temperature water in the circulation circuit flowing out from the heat radiating means 21. Then, the flow rate of the hot water is controlled so that the temperature of the hot water flowing into the heat radiating means 21 becomes a predetermined temperature. For example, when the temperature of the hot water flowing into the heat radiating means 21 is lower than a predetermined temperature, the flow rate of the hot water is increased. Conversely, when the temperature of the hot water flowing into the heat radiating means 21 is higher than the predetermined temperature, Reduce water flow. Accordingly, the hot water is used at an optimum flow rate corresponding to the load of the heat radiating means or the hot water temperature, so that the hot water and the amount of hot water are used effectively.

(Reference Example 4)
In FIG. 8, 35 is a temperature detection means, and detects the temperature at which the hot water in the hot water tank flows out of the heat exchanger 30. Reference numeral 36 denotes circulating water temperature detecting means for detecting the temperature of hot water flowing out from the heat radiating means 21 and flowing into the heat exchanger 30. Reference numeral 37 denotes hot water control means, which controls the hot water pump 31 so that the detection signal of the temperature detection means 35 becomes a signal of a predetermined temperature. Here, the predetermined temperature is a temperature obtained by adding a preset temperature difference based on the hot water temperature based on the temperature detection signal of the stored hot water temperature detecting means 36.

  The operation and action of the above configuration will be described. High temperature water flowing out from the upper part of the hot water tank 16 is passed through the heat exchanger 30 and heated so that the medium and low temperature water in the circulation circuit flowing into the heat exchanger 30 reaches a predetermined temperature. At that time, the flow rate of the stored hot water is controlled so that the temperature of the stored hot water flowing out from the heat exchanger 30 becomes a predetermined temperature (higher by the set temperature) than the low temperature water temperature of the circulation circuit flowing into the heat exchanger 30. Therefore, the temperature difference between the hot water temperature and the water temperature circulating through the heat radiating means can be made the minimum and the optimum temperature difference, so that the hot water can be effectively used.

(Reference Example 5)
In FIG. 9, reference numeral 38 denotes a switching means, which switches between a circuit A39 for returning the hot water flowing out from the upper part of the hot water tank to the intermediate part of the hot water tank and a circuit B40 for returning the hot water flowing out from the upper part of the hot water tank to the lower part of the hot water tank. 41 is a remaining hot water temperature detecting means for detecting the remaining hot water temperature in the hot water storage tank in the vicinity of the position returning to the intermediate part of the hot water storage tank 16.

  Reference numeral 42 denotes a control means which commands the switching means 38 based on the temperature signal from the remaining hot water temperature detection means 41. And since the hot water tank capacity is usually set so that the remaining hot water capacity is a little with respect to the total amount of hot water used for hot water supply, bathing, heating, etc. It is the position where low-temperature water supplied from the lower part of the hot water tank is stored during chasing or heating in the evening.

  The operation and action of the above configuration will be described. First, a case where the amount of hot water in the hot water tank 16 is large will be described. For example, the amount of hot water in the hot water tank 16 boiled at midnight is close to full in the morning.

  And in the morning, when using as the heat dissipation means 21 for heating, etc., the hot water in the hot water storage tank 16 flows into the heat dissipation means for heating. Then, the medium-temperature water flowing out from the heat radiating means 21 is returned to the lower part of the hot water tank 16 by the circuit 40. Therefore, since the hot water in the hot water tank is maintained, a stable hot water temperature can be supplied to the heat radiating means. And the hot water in a hot water tank is effectively used as a heating heat source for a long time.

  Next, a case where the amount of hot water in the hot water tank is small will be described. For example, when the hot water in the hot water tank 16 is used for heating or bathing when the hot water amount in the hot water tank is small due to hot water supply in the morning and noon hours, or when the hot water in the hot water tank is small, When there is low-temperature water in the vicinity of the intermediate portion 16, the medium-temperature water flowing out from the heat radiation means 21 is returned to the intermediate portion of the hot water tank 16 by the circuit 39.

  And the low temperature water which is in contact with the high temperature hot water in the hot water tank 16 is heated by the medium temperature water flowing from the intermediate portion. Therefore, the intermediate hot water is stored in the lower part of the high temperature hot water, and can be reused for the hot water supply or the heat radiating means used for the intermediate hot water.

  Therefore, since the low-temperature water below the hot water storage tank is boiled by the heat pump with the heat pump, the efficiency during the hot water storage operation is improved. In particular, a heat pump using carbon dioxide as a refrigerant can prevent a significant decrease in efficiency and heating capacity. Therefore, it is used properly according to the amount of hot water in the hot water tank and the hot water temperature.

  In addition, as shown in FIG. 10, the same effect can be obtained when the hot water in the hot water storage tank 16 and the circulating water circulating through the heat dissipating means 21 are heat-exchanged via the heat exchanger 30.

(Reference Example 6)
In FIG. 11, reference numeral 43 denotes an intermediate temperature hot water pipe, which is connected to the hot water tank intermediate connection port 44 and the hot water pipe 16b in the vicinity of the position returned to the intermediate portion of the hot water tank 16. Reference numeral 45 denotes a hot water adjustment valve, which controls hot water discharged from the intermediate temperature hot water discharge pipe 43 and hot water discharged from the upper part of the hot water tank 16. Reference numeral 46 denotes temperature detection means for detecting the hot water storage temperature in the vicinity of the hot water tank connection port.

  47 is a control means for controlling the hot water adjustment valve 45 based on the detection signal of the temperature detection means 46. For example, when the hot water temperature of the intermediate temperature hot water discharge pipe 43 is satisfied, the hot water is discharged from the intermediate temperature hot water discharge pipe 43.

  And when the hot water temperature of the intermediate temperature hot water discharge pipe 43 does not satisfy the hot water supply temperature, the hot water is discharged from the upper part of the hot water storage tank 16, or the hot water of the intermediate temperature hot water discharge pipe 43 and the hot water of the hot water storage tank 16 are mixed and discharged. .

  The operation and action of the above configuration will be described. The hot water in the hot water tank 16 flows out from the upper part, and the hot water in the medium temperature water used as a heat source for the heat radiating means is returned to the intermediate part of the hot water tank 16. And while continuing the operation | movement by the thermal radiation means 21, the hot water of middle temperature water is stored in the intermediate part of the hot water storage tank 16. FIG.

  When the hot water temperature is satisfied with the hot water temperature in the intermediate portion of the hot water tank 16, the hot water is discharged from the intermediate temperature hot water discharge pipe 43. Further, when the hot water temperature in the intermediate temperature hot water discharge pipe 43 does not satisfy the hot water supply temperature, the hot water is discharged from the upper part of the hot water storage tank 16 or the hot water in the intermediate temperature hot water discharge pipe 43 and the hot water in the upper part of the hot water storage tank 16 are mixed and discharged. .

  Therefore, the medium temperature water used as the heat source of the heat radiating means is again discharged from the intermediate temperature hot water discharge pipe in the middle of the hot water storage tank and used for hot water supply. To use.

(Reference Example 7)
In FIG. 12, reference numeral 48 denotes a reheating temperature detecting means for detecting the remaining hot water temperature in the upper hot water storage tank from the position returned to the intermediate portion of the hot water storage tank. 49 is an operation control means, and starts the heat pump operation when the temperature detection signal of the follow-up temperature detection means 48 falls to a predetermined temperature signal.

  The operation and action of the above configuration will be described. When the hot water is reduced while the hot water in the hot water tank is being discharged or the heat radiating means such as heating is running, and the detection signal of the reheating temperature detecting means 48 is lowered to a predetermined temperature, the heat pump operation is started and the hot water tank is started from the upper part. Store hot water. Therefore, since the amount of hot water at the upper part of the hot water tank increases, hot water can be stably supplied to the heat dissipating means.

(Example 1)
FIG. 13 shows Embodiment 1 of the present invention, 50 is an on-off valve, and is provided in a circuit through which hot water in hot water tank 16 flows. Reference numeral 51 denotes on-off valve control means for closing the on-off valve 50 based on the operation stop signal 52 of the heat dissipating means 21.

  The operation and action of the above configuration will be described. The operation stop signal 52 of the heat dissipating means 21 such as the heat dissipating pump 26 is detected and the on-off valve 50 is closed.

  Therefore, in the hot water circuit of the hot water storage tank 16, the heat exchanger 30, and the hot water storage tank 16, even when the hot water in the circuit radiates heat and the temperature is lowered, due to the difference in density between the hot water in the hot water storage tank 16 and the low temperature water in the circuit. There is no natural circulation descending in the circuit from the upper part of the hot water tank 16. Therefore, the amount of hot water at the top of the hot water tank can be used effectively.

  As described above, the multi-function water heater according to the present invention operates the hot water in the hot water storage tank with high efficiency, prevents a decrease in the hot water temperature, allows a stable fluid to flow to the heat radiating means, and further radiates the heat. It is very useful as a general household composite device.

The block diagram of the multifunctional water heater of the reference Example 1 of this invention Configuration diagram of another multi-function water heater in Reference Example 1 of the present invention Configuration diagram of another multi-function water heater in Reference Example 1 of the present invention Configuration diagram of another multi-function water heater in Reference Example 1 of the present invention The block diagram of the multifunctional water heater of the reference Example 2 of this invention Configuration diagram of another multi-function water heater in Reference Example 2 of the present invention The block diagram of the multifunctional water heater of the reference Example 3 of this invention The block diagram of the multifunctional water heater of the reference Example 4 of this invention The block diagram of the multifunctional water heater which shows the reference Example 5 of this invention The block diagram of the other multifunctional water heater which shows the reference Example 5 of this invention The block diagram of the multifunctional water heater which shows the reference Example 6 of this invention The block diagram of the multifunctional water heater which shows the reference Example 7 of this invention The block diagram of the multi-function water heater which shows Example 1 of this invention Configuration diagram of a conventional multifunction hot water supply device

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Heating means 12 Compressor 16 Hot water storage tank 21 Heat radiation means 30 Heat exchanger 50 On-off valve 51 On-off valve control means

Claims (4)

A hot water storage tank that stores hot water heated by the heating means from above, a load-side circulation path that circulates hot water at the top of the hot-water storage tank, and a fluid in the hot water of the load-side circulation path via a heat exchanger A multi-function water heater comprising a heat radiation side circulation path to be heated and a heat radiation means connected to the heat radiation side circulation path, and a natural circulation prevention means for preventing natural circulation of hot water in the load side circulation path . The multi-function hot water heater according to claim 1, wherein the natural circulation prevention means is an on-off valve that opens and closes the load-side circulation path, and is closed in conjunction with the stop of heat radiation operation. The multifunction hot water supply device according to claim 1 or 2, wherein the heating means is a heat pump provided with a compressor. The multi-function water heater according to any one of claims 1 to 3, wherein the refrigerant sealed in the heat pump is carbon dioxide.

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