JP2007187325A - Instantaneous hot water supply system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a system that can stabilize water temperature at instantaneous hot water supply. <P>SOLUTION: The instantaneous hot water supply system comprises a hot water supply circuit 20, a heat source part 11 for hot water supply disposed in the hot water supply circuit 20 to heat water flowing in the hot water supply circuit, a circulation circuit 40, and a pump 41 and an auxiliary heat source part 12 disposed in the circulation circuit 40. A bypass line 31 is connected in the hot water supply circuit 20 downstream of the heat source part 11 for hot water supply, and a liquid/liquid heat exchanger 32 is connected to the circulation circuit 40 and bypass line 31 to transfer the heat of a heating medium flowing in the circulation circuit 40 to water flowing in the bypass line 31. A mixing valve 33 is disposed at an upstream connection point P1 between the hot water supply circuit 20 and the bypass line 31. During initial hot water supply, the mixing valve 33 is controlled according to temperatures detected by temperature sensors 34, 36, etc. to bring an output water temperature at a set temperature. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a hot water supply apparatus in which hot water is immediately discharged when a hot water supply operation is started by opening a hot water tap or the like.

  In the case of a hot water supply device with a heat source installed outdoors, the heat source is cold at the beginning of the hot water supply operation, and the pipe from the heat source machine to the hot water tap is long and low temperature water is stored in this pipe Therefore, it takes time from the start of the hot water supply operation until the hot water comes out. This waiting time is inconvenient and the water that flows during the waiting time is also wasted.

Therefore, a device has been developed in which a hot water storage tank located in the vicinity of the hot water tap is provided in the pipe line from the heat source unit, and the water in the hot water storage tank is heated by an electric heater so that hot water is immediately discharged from the hot water. Yes.
However, the above apparatus has a drawback of requiring a large installation space for a hot water storage tank. If the hot water storage tank is made small, there is a disadvantage that the temperature of the hot water is not stable, for example, cold water comes out after the hot water is used up.

In the apparatus disclosed in Patent Document 1, a liquid / liquid heat exchanger is provided in the middle of the heating circulation circuit, a hot water supply circuit is passed through the liquid / liquid heat exchanger, and water passing through the hot water supply circuit is supplied to the liquid / liquid heat exchanger in the initial stage of hot water supply. It is heated by a liquid heat exchanger so that it can be immediately discharged.
JP 2004-21901 A

  The instant hot water supply device of Patent Document 1 does not require a large hot water storage tank, but only heats the water in the hot water supply circuit with a liquid / liquid heat exchanger and does not control the temperature. It was.

  The present invention has been made to solve the above problems, and in an instant hot water supply apparatus, (a) a hot water supply circuit, and (b) a hot water supply heat source section that is provided in the hot water supply circuit and heats water flowing through the hot water supply circuit, (C) a circulation circuit; (d) a pump provided in the circulation circuit; (e) an auxiliary heat source unit provided in the circulation circuit and heating water flowing through the circulation circuit by driving the pump; F) a bypass path connected to the downstream side of the hot water supply heat source section in the hot water supply circuit; and (g) water flowing through the bypass path, connected to the circulation circuit and the bypass path. The liquid / liquid heat exchanger that communicates with the hot water supply circuit and the upstream connection point between the hot water supply circuit and the bypass passage to control the distribution of the amount of water to both, so that the hot water supply circuit and the bypass passage join at the downstream connection point. Control the temperature of hot water Mixing means; (i) an upstream temperature sensor provided between the heat source for hot water supply and the upstream connection point in the hot water supply circuit; and a downstream temperature provided downstream of the downstream connection point. At least one of the temperature sensors and (co) at the initial stage of the hot water supply operation, drive the pump and supply heat by the auxiliary heat source unit to circulate a high-temperature heat medium in the circulation circuit, Control means for controlling the mixing means based on the temperature detected by the temperature sensor to bring the tapping temperature close to the set temperature or to set the set temperature.

  According to this configuration, in the initial stage of hot water supply, the hot water temperature can be brought close to or set to the set temperature by mixing control, and immediate hot water supply can be performed at a stable temperature. Moreover, a large hot water storage tank is not required.

  Preferably, a flow sensor provided in the hot water supply circuit is further provided, and the control means performs feedforward control of the mixing means based on the detected water amount of the flow sensor, the detected temperature of the upstream temperature sensor, and the set temperature. Thereby, temperature control in the initial stage of hot water supply can be performed quickly.

  Preferably, the control means performs feedback control of the mixing means based on a deviation between a temperature detected by the downstream temperature sensor and a set temperature. Thereby, hot water supply initial temperature control can be performed correctly.

Preferably, a plurality of branch pipes are connected in parallel to the common pipe provided with the auxiliary heat source unit and the pump, and the circulation circuit is configured by one of the branch pipes and the common pipe, and the one branch The pipe is provided with an on-off valve, and the control means opens the on-off valve together with the driving of the pump and the heat supply by the auxiliary heat source, thereby circulating the high-temperature heat medium and closing the heat supply. To stop the circulation of the high-temperature heat medium.
According to this, when it can be used together with other uses such as heating and a liquid / liquid heat exchanger is not required, the flow rate to the branch pipe for other uses is increased by closing the on-off valve. Can be made.

Preferably, the hot water supply circuit is provided with a water amount control valve upstream from the upstream connection point of the bypass passage, and the control means can maintain a hot water temperature even if the mixing means maximizes the distribution ratio to the bypass passage side. If it does not reach or reach the set temperature, the flow rate is controlled by controlling the water amount control valve.
According to this, even if the amount of heat supplied to the heat / heat exchanger is insufficient in the initial stage of hot water supply, the hot water temperature can be brought close to or set to the set temperature by controlling the flow rate.

Preferably, the control means stops the circulation of the high-temperature heat medium in the circulation circuit when the tapping temperature reaches a set temperature and the distribution ratio to the bypass path in the mixing means is minimized.
According to this, the heat loss accompanying the unnecessary circulation of a high-temperature heat medium can be avoided.

Preferably, it further includes an immediate hot water supply mode command switch, and the control means executes an immediate hot water supply mode by turning on the switch, and in this immediate hot water supply mode, in principle, maintains the circulating state of the high-temperature heat medium in the circulation circuit, When the outlet temperature reaches the set temperature during the hot water supply operation and the distribution ratio to the bypass passage by the mixing means is minimized, the circulation of the heat medium is stopped even in the immediate hot water supply mode. The circulation stop state of the high-temperature heat medium in the circulation circuit is continued for a predetermined time of 1.
According to this, attention is paid to the fact that the water in the hot water supply heat exchanging section and the hot water supply pipe is warm even after the hot water supply operation, and heat loss can be avoided by circulation of the unnecessary high-temperature heat medium.

  Preferably, when a second predetermined time longer than the first predetermined time has elapsed from the ON operation of the switch, the immediate hot water supply mode is terminated and the circulation of the high-temperature heat medium in the circulation circuit is stopped. According to this, heat loss can be avoided by unnecessary circulation of the high-temperature heat medium.

  According to the present invention, hot water can be supplied without delay from the start of hot water supply, and the tapping temperature can be stabilized.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1, the immediate hot water supply apparatus includes a heat source unit 10 arranged outdoors, a hot water supply circuit 20, a unit 30 for immediate hot water arranged indoors (hereinafter referred to as an instant hot water unit), And a circulation circuit 40 for immediate hot water supply.

  The heat source machine 10 includes a hot water supply heat source unit 11 and a heating heat source unit 12 (auxiliary heat source unit) housed in a housing 10a. These heat source parts 11 and 12 have combustion parts 11a and 12a, respectively, and heat exchange parts 11b and 12b that receive the combustion heat of the combustion parts 11a and 12a.

  The hot water supply circuit 20 includes a water supply pipe 21 whose downstream end is connected to the heat exchange unit 11b, and a hot water supply pipe 22 whose upstream end is connected to the heat exchange unit 11b. The water supply pipe 21 is provided with a water supply temperature sensor 23, and the hot water supply pipe 22 (or the water supply pipe 21) is provided with a flow sensor 24.

  The hot water supply pipe 22 passes through the housing 30a of the immediate hot water unit 30, and is branched into a plurality of branch pipes through a header when it exits the housing 30a. Only one of the branch pipes is shown in the figure. A hot water tap 25 (a hot water outlet) is attached to the downstream end of each branch pipe. Generally, the hot water supply pipe 22 connecting the outdoor heat source unit 10 and the immediate hot water unit 30 is long.

  The instant hot water unit 30 has a bypass pipe 31 (bypass path) connected to the hot water supply pipe 22 in the housing 30a. A connection point on the upstream side of the bypass pipe 31 is indicated by a symbol P1, and a connection point on the downstream side is indicated by a symbol P2.

  The hot water unit 30 further includes a liquid / liquid heat exchanger 32 provided in the bypass pipe 31, a mixing valve 33 (mixing means) provided in the connection point P1, and a hot water supply pipe upstream of the connection point P1. 22 has an upstream temperature sensor 34 and a water amount control valve 35, and a downstream temperature sensor 36 provided in the hot water supply pipe 22 on the downstream side of the connection point P2.

  The circulation circuit 40 is connected to the heat exchange unit 12b of the heating heat source unit 12 and circulates a heat medium such as hot water by a pump 41. More specifically, the housing 10a of the heat source unit 10 is provided with an outlet side header 42 and an inlet side header 43, and a common pipe line is connected between the headers 42 and 43 in the housing 10a. A heat source unit 12 and a pump 41 are provided. On the other hand, a plurality of branch pipes are connected between the headers 42 and 43 outside the housing 10a. A circulation circuit 40 for instantaneous hot water supply is constituted by the one branch pipe shown and the common pipe. Other branch passages are equipped with floor heaters and other heaters for heating.

  The circulation circuit 40 is connected to the liquid / liquid heat exchanger 32 of the immediate hot water unit 30. The liquid / liquid heat exchanger 32 has, for example, a double pipe structure. In this embodiment, the circulation circuit 40 is connected to the inner pipe, and the above-described bypass pipe 31 is connected to the outer pipe.

  In the circulation circuit 40, a thermal valve 45 (open / close valve) is provided in a pipe 44 (outward pipe) between the header 42 and the liquid / liquid heat exchanger 32, and the header 43 and the liquid / liquid heat exchanger 32 are provided. A temperature sensor 47 is provided in a pipe 46 (return pipe) between the two. These thermal valve 45 and temperature sensor 47 are also disposed in the housing 30a.

A control unit 50 (control means) is disposed in the housing 10a of the heat source device 10. This control unit 50 is based on the command information from the controller 55 and the detection information from the flow sensor 24 and the temperature sensors 23, 34, 36, 47, the combustion control of the combustion sections 11a, 12a, the pump 41, the mixing valve 33, the amount of water. Control of the control valve 35 and the thermal valve 45 is performed.
The controller 55 includes an immediate hot water switch 55a for instructing an immediate hot water supply mode, a temperature setting unit 55b for setting a hot water supply temperature, and the like.

  The operation of the immediate hot water supply apparatus having the above configuration will be described. When the tap tap 25 is opened without turning on the immediate hot water switch 55a, the control unit 50 performs a normal hot water supply operation. Briefly, the flow sensor 24 detects the amount of water equal to or greater than the threshold value in the hot water supply circuit 20, and in response to this, the control unit 50 starts combustion in the combustion section 11a of the hot water supply heat source section 11. And the amount of combustion heat in the combustion part 11a is controlled so that the tapping temperature becomes the temperature set by the temperature setting part 55b of the controller 55. As is well known, this combustion heat amount control is performed based on the amount of water detected by the flow sensor 24 and the temperature detected by the temperature sensors 23 and 34. When the tapping temperature does not reach the set temperature with the maximum combustion heat amount in the combustion unit 11a, the water amount control valve 35 is controlled to reduce the water amount.

  When the immediate hot water switch 55a is turned on, the control unit 50 executes the immediate hot water mode (immediate hot water supply mode). This will be described with reference to the time chart of FIG. When the immediate hot water switch 55a is turned on (time t0), in response to this, the microcomputer of the control unit 50 enters the immediate hot water mode. The instant hot water mode ends when a predetermined time (second predetermined time), for example, 30 minutes elapses (t10).

  When the instant hot water mode is entered, the thermal valve 45 is opened and the pump 41 is driven to start combustion in the combustion section 12a. Thereby, the hot water as a heat medium circulates through the circulation circuit 40. In addition, when heating is performed with a heater of another branch pipe (not shown), the drive of the pump 41 and the combustion of the combustion unit 12a are already performed, so the opening operation of the thermal valve 45 is performed. Only high-temperature hot water is circulated in the circulation circuit 40.

  When the circulation of hot water in the circulation circuit 40 is started, the temperature of the hot water passing through the liquid / liquid heat exchanger 32 eventually reaches a predetermined temperature, for example, 80 ° C. When the predetermined temperature is detected by the temperature sensor 47 (time point t1), the control unit 50 outputs a display instruction for immediate hot water preparation completion to the controller 55. In response to this display command, the controller 55 informs the user that the hot water preparation is complete. The controller 55 notifies the user that the hot water preparation is completed by lighting or display display until the quick hot water mode ends (time t10) after the hot water preparation is completed.

  In principle, the circulation of the high-temperature hot water in the circulation circuit 40 is continued until the quick hot water mode ends. After 30 minutes, the circulation of the hot water in the circulation circuit 40 is stopped, so that waste of heat energy can be eliminated. Note that the circulation stop of high-temperature hot water only closes the thermal valve 45 when heating is continued with any of the heaters, and when heating is not performed with the heater, The closing operation, the pump 41 is stopped, and the combustion in the combustion section 12a is stopped.

  When the tap tap 25 is opened in the immediate hot water mode (time t2), the hot water supply operation similar to that described above is performed. In the initial stage of hot water supply, low temperature water is accumulated in the long hot water supply pipe 22, the heat exchanging portion 11b is cooled, there is an ignition delay in the combustion portion 11a, and the like, and the upstream temperature sensor 34 is passed. The water temperature is much lower than the set temperature.

  In the hot water mode, therefore, the mixing valve 33 is controlled to control the distribution ratio of the amount of water passing through the hot water supply pipe 22 and the amount of water passing through the bypass pipe 31. The water distributed at the mixing valve 33, that is, the connection point P <b> 1 joins at the connection point P <b> 2 and travels toward the hot water tap 25. Since the water passing through the bypass pipe 31 is supplied with heat from the hot water flowing through the circulation circuit 40 by the liquid / liquid heat exchanger 32, the hot water can be immediately supplied from the hot water tap 25.

  The distribution control of the mixing valve 33 will be described in detail. The mixing valve 33 is normally in a state in which the bypass pipe 31 side is fully closed. When the flow sensor 24 detects an amount of water that is greater than or equal to the threshold value, the control unit 50 uses a map or the like based on the detected temperature of the upstream temperature sensor 34, the set temperature, and the detected flow rate of the flow sensor 24, so that the tapping temperature is Calculate the feedforward component to become Further, the feedback component is calculated based on the deviation between the temperature detected by the downstream temperature sensor 36 and the set temperature, and the feedforward component and the feedback component are added to determine the distribution ratio at the mixing valve 33. Thereby, the hot water temperature can be brought close to or set to the set temperature.

  In the control of the mixing valve 33, the lower the detected temperature of the upstream temperature sensor 34, the greater the detected flow rate of the flow sensor 24, the lower the detected temperature of the downstream temperature sensor 36, and the greater the deviation thereof, the greater the bypass. The distribution ratio of water toward the pipe 31 is increased. Since the temperature of the water or hot water coming out of the heat exchanger 11b is lowest at the start of hot water supply, the distribution ratio to the bypass pipe 31 by the mixing valve 33 is highest at the start of hot water supply. In FIG. 2, the higher the distribution ratio is, the higher the distribution ratio is, but it does not accurately represent the actual distribution ratio.

  When the hot water tap 25 is closed (time point t3), the combustion in the combustion section 11a on the hot water supply side is stopped, and the mixing valve 33 is returned to the position where the bypass pipe 31 side is fully closed.

  When the time from opening the tap tap 25 to closing (time from t2 to t3) is short (for example, less than 1 minute), the heat exchanging portion 1a is not sufficiently warmed by the combustion heat, and the hot water supply pipe 22 Since the temperature of the water in the inside has not risen sufficiently, the temperature detected by the upstream temperature sensor 34 does not reach the set temperature, and heat supply by the liquid / liquid heat exchanger 32 is required. The amount of distribution to the pipe 31 side will not be almost zero (the distribution ratio is minimal). In such a case, in order to ensure immediate hot water supply in the next hot water supply, the hot water circulation in the circulation circuit 40 is continued and heat exchange in the liquid / liquid heat exchanger 32 during the next hot water supply operation is ensured.

  Next, control when the hot water supply time is long will be described. When the elapsed time from opening the hot water tap 25 (time point t4) becomes long and, for example, about 1 minute elapses, the temperature of the hot water passing through the upstream temperature sensor 34 reaches the set temperature. At this time, the mixing valve 33 is in a position where the bypass pipe 31 side is fully closed (the distribution amount is almost zero and the distribution ratio is minimum).

  The control unit 50 stops the circulation of the hot water in the circulation circuit 40 in response to the detected temperature of the upstream temperature sensor 34 reaching the set temperature or the mixing valve 33 fully closing the bypass side. (Time t5).

  Thereafter, when the hot water tap 25 is closed (time point t6), the combustion in the hot water supply side combustion section 11a is stopped as in the previous time.

  As described above, the hot water supply operation continues for a long time, and when the hot water supply operation is terminated after the hot water supply is stopped in the circulation circuit 40, the hot water circulation stop state in the circulation circuit 40 is maintained thereafter. This stop state is maintained for a predetermined time (first predetermined time), for example, 5 minutes from the end of the hot water supply operation (time point t6). This is because relatively hot water remains in the hot water supply pipe 22 and the heat exchanging portion 11b on the hot water supply side is sufficiently warmed, so that the high temperature state can be maintained without cooling for about 5 minutes even after the hot water supply operation is completed. This is because hot water can be supplied immediately without performing heat exchange in the liquid / liquid heat exchanger 32.

  Therefore, when the hot water tap 25 is opened again within 5 minutes from the end of the hot water supply operation (time point t7), only the hot water supply side combustion unit 11 is combusted, and the circulation of the high temperature hot water in the circulation circuit 40 is stopped. The mixing valve 33 also maintains the bypass side fully closed state.

  When the hot water supply operation is short and stops within one minute (time point t8), the hot water circulation stop time of the circulation circuit 40 from the time point t6 is not changed. When the hot water supply operation from time t7 becomes longer and the situation is similar to that at time t5, the hot water circulation stop time is changed to 5 minutes from the end of the current hot water supply operation.

  The circulation of the high-temperature hot water in the circulation circuit 40 is resumed after 5 minutes from the time t6. This is because the hot water in the hot water supply pipe 22 is cooled and the heat exchanging portion 11b on the hot water supply side is also cooled, so that heat exchange in the liquid / liquid heat exchanger 32 is required at the initial stage of the subsequent hot water supply operation.

  The control unit 50 controls the water amount control valve 35 as necessary in the quick water mode. That is, when the hot water temperature reaches the set temperature only by the distribution control (mixing control) of the mixing valve 33, the water amount control valve 35 is maintained in the fully open state. When the temperature of the feed water is low and the temperature detected by the upstream temperature sensor 34 is low, or the amount of water detected by the flow sensor 24 is large, the bypass pipe 31 side is fully opened by the mixing valve 33 (bypass pipe 31 side distribution). If the hot water temperature does not reach the set temperature even when the ratio is maximized and the distribution amount to the hot water supply circuit 21 side is almost zero), the liquid / liquid heat exchanger is reduced by reducing the water volume by reducing the water volume control valve 35. The hot water temperature passing through 32 is increased, and the hot water temperature is set to the set temperature.

  Further, in the present embodiment, the heater may be used at the same time. In that case, since the hot water is also supplied to the branch pipe portion in which the heater is provided, the high temperature in the circulation circuit 40 for the instant hot water. The circulating amount of hot water is reduced, and the amount of heat that can be supplied in the liquid / liquid heat exchanger 32 is reduced. Even in such a case, the control unit 50 controls the opening of the water amount control valve 35 so as to set the tapping temperature to the set temperature.

  The present invention is not limited to the above-described embodiment, and various aspects can be made. For example, when a predetermined time, for example, 1 minute has elapsed since the start of hot water supply, the bypass side of the mixing valve 33 may be fully closed, and the circulation of the hot water in the circulation circuit 40 may be stopped. In this embodiment, when the mixing 33 is not fully closed on the bypass side after 1 minute has elapsed, the water amount is then reduced by the water amount control valve 35 to maintain the hot water temperature at the set temperature. In this embodiment, the circulation of the hot water after the hot water supply operation may be stopped on condition that the hot water supply operation time exceeds 1 minute.

It is a schematic block diagram of the immediate hot water supply apparatus which makes one Embodiment of this invention. It is a time chart which shows the immediate hot water supply control by the same apparatus.

Explanation of symbols

11 Heat source section for hot water supply 12 Heat source section for heating (auxiliary heat source section)
20 Hot water supply circuit 31 Bypass pipe (bypass)
32 Liquid / liquid heat exchanger 33 Mixing valve (mixing means)
34 upstream temperature sensor 35 water quantity control valve 36 downstream temperature sensor 40 circulation circuit 41 pump 45 thermal valve (open / close valve)
50 Control unit (control means)
55a Instant hot water switch (immediate hot water supply mode command switch)

Claims (8)

(A) Hot water supply circuit,
(A) a hot water supply heat source section that is provided in the hot water supply circuit and heats water flowing through the hot water supply circuit;
(C) a circulation circuit;
(D) a pump provided in the circulation circuit;
(E) an auxiliary heat source unit that is provided in the circulation circuit and heats water flowing through the circulation circuit by driving the pump;
(F) In the hot water supply circuit, a bypass path connected to the downstream side of the heat source part for hot water supply,
(G) a liquid / liquid heat exchanger that is connected to the circulation circuit and the bypass path, and transfers the heat of the heat medium flowing through the circulation circuit to the water flowing through the bypass path;
(G) Mixing means for controlling the temperature of hot water joining at the hot water supply circuit and the downstream connection point of the bypass path by controlling the distribution of the amount of water to the hot water supply circuit and the upstream path of the bypass path. ,
(K) In the hot water supply circuit, at least one of an upstream temperature sensor provided between the hot water source and the upstream connection point, and a downstream temperature sensor provided downstream of the downstream connection point. One of the temperature sensors,
(E) In the initial stage of the hot water supply operation, the pump is driven and the heat is supplied by the auxiliary heat source unit to circulate a high-temperature heat medium in the circulation circuit, and the mixing means is based on the temperature detected by the temperature sensor. By controlling the tapping temperature close to the set temperature or the set temperature,
An instant hot water supply device characterized by comprising:   And a flow sensor provided in the hot water supply circuit, wherein the control means performs feedforward control of the mixing means based on a detected water amount of the flow sensor, a detected temperature of the upstream temperature sensor, and a set temperature. The immediate hot water supply apparatus according to claim 1.   The immediate hot water supply apparatus according to claim 1 or 2, wherein the control means performs feedback control of the mixing means based on a deviation between a temperature detected by the downstream temperature sensor and a set temperature.   A plurality of branch pipes are connected in parallel to the common pipe provided with the auxiliary heat source section and the pump, and the circulation circuit is constituted by one of the branch pipes and the common pipe. The on-off valve is provided, and the control means opens the on-off valve together with the driving of the pump and the heat supply by the auxiliary heat source unit to circulate the high temperature heat medium, and closes the heat supply to The immediate hot water supply apparatus according to any one of claims 1 to 3, wherein circulation of the heating medium is stopped.   The hot water supply circuit is provided with a water amount control valve upstream from the upstream connection point of the bypass passage, and the control means uses the mixing means to maximize the distribution ratio to the bypass passage side so that the hot water temperature remains at the set temperature. The immediate hot water supply apparatus according to any one of claims 1 to 4, wherein the water flow control valve is controlled to limit the flow rate when it does not approach or reaches.   The said control means stops the circulation of the high-temperature heat medium of the said circulation circuit, when the tapping temperature reaches the set temperature and the distribution ratio to the bypass path in the mixing means is minimized. 5. The immediate hot water supply apparatus according to any one of 5 above.   Furthermore, an immediate hot water supply mode command switch is provided, and the control means executes an immediate hot water supply mode by turning on the switch, and in this immediate hot water supply mode, in principle, maintains the circulating state of the high-temperature heat medium in the circulation circuit, When the temperature of the hot water reaches the set temperature and the distribution ratio to the bypass passage by the mixing means is minimized, the circulation of the heat medium is stopped even in the immediate hot water supply mode. The hot water supply apparatus according to any one of claims 1 to 5, wherein the circulation stop state of the high-temperature heat medium in the circulation circuit is continued for a period of time.   8. The hot water supply mode is terminated when the second predetermined time longer than the first predetermined time has elapsed from the ON operation of the switch, and the circulation of the high-temperature heat medium in the circulation circuit is stopped. Instant water heater.

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