JP2019095160A - Water heater - Google Patents

Abstract

To effectively suppress high temperature tapping even when a hot water supply circuit is used after single use of a bath circuit in a one-can and two-channel type water heater.SOLUTION: When termination of reheating in a bath circuit is confirmed in S1, a controller executes circulation of hot water in the bath circuit by operating a pump in S2. Thus heat of a hot water supply heat pipe heated in single use of the bath circuit is transferred to a bath heat transfer pipe, and hot water temperature in the hot water supply heat transfer pipe is lowered. When it is confirmed that a detection temperature of the hot water supply heat transfer pipe obtained from a water pipe thermistor becomes 60°C or less by determination in S3, and an outlet temperature obtained from a hot water supply heat exchanger thermistor becomes 60°C or less by determination in S4, the controller stops an operation of the pump in S5, and the control is terminated.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a so-called one-can-bichannel water heater in which a hot water supply heat exchanger on the hot water supply circuit side and a bath heat exchanger on the bath circuit side are provided side by side in one combustion chamber provided with a burner.

A water heater connects a water supply pipe and a hot water discharge pipe to a hot water supply heat exchanger that is heated by a burner, and opens the external hot water supply tap to which the hot water discharge pipe is connected. Water supplied from the water supply pipe via a water pipe The system is equipped with a hot water supply circuit that exchanges heat with the combustion exhaust of the burner and discharges hot water. In addition to this, a bath circuit connecting an external bathtub to the bath heat exchanger through a pipe is formed, and the bath heat exchanger heats and repels while circulating hot and cold water by a pump provided in the pipe Things are also known.
In such a water heater, a hot water supply heat exchanger and a bath heat exchanger are respectively installed in different combustion chambers and heated by different burners (two-can two-channel type) as disclosed in Patent Document 1 In addition, a hot water supply heat exchanger and a bath heat exchanger are provided side by side in one combustion chamber, and a single-can two-channel type configuration in which two heat exchangers are heated by a common burner is also often used. .

JP, 2017-155956, A

  However, in a single-can, dual-channel type water heater having a hot water supply circuit and a bath circuit, when the bath circuit is used alone and the bathtub is driven away, the same burner can also heat the hot water supply heat exchanger. Become. For this reason, the hot water temperature may reach a high temperature of 100 ° C. or more in the heat transfer pipe of the hot water supply heat exchanger in which the hot and cold water is stagnant. When the hot water supply plug is opened in this state and the hot water supply circuit is used, There is a risk that hot water will be discharged from the hot water discharge pipe. In the hot water supply circuit, a bypass pipe is provided to connect the water supply pipe and the hot water discharge pipe to bypass the hot water supply heat exchanger, and at the time of hot water discharge, control is performed to suppress the hot water temperature by mixing water from the bypass pipe. However, if a component such as a distribution valve that controls the amount of water to the bypass pipe fails, high temperature hot water can not be avoided.

  Therefore, according to the present invention, even in the case of using a hot water supply circuit after single use of a bath circuit in a one-can two-channel type in which one water flow path is a hot water supply circuit and the other water flow path is a bath circuit, It is an object of the present invention to provide a water heater capable of effectively suppressing high temperature hot water discharge.

In order to achieve the above object, the invention according to claim 1 is a combustion chamber in which a burner is disposed at the lower part,
A hot water supply circuit including a hot water supply heat exchanger disposed above the combustion chamber and heated by the burner, and a water supply pipe and a hot water discharge pipe connected to the hot water supply heat exchanger;
A bath heat exchanger which is connected with a hot water supply heat exchanger at the top of the combustion chamber and heated by the burner, a pipe connected to the bath heat exchanger and connected to an external bath, and a pump provided on the pipe A bath circuit comprising
Hot water temperature detection means for detecting the temperature of hot water in the hot water supply heat exchanger,
A water heater comprising a controller for controlling the combustion of a burner and the operation of a pump, comprising:
The controller operates the pump after combustion of the burner by single use of the bath circuit is performed, and the hot water is circulated in the bath circuit until the temperature detected by the hot water temperature detection means becomes lower than a predetermined temperature. I assume.
The invention according to claim 2 connects the outlet pipe and the pipe in the configuration according to claim 1, and supplies the hot water from the outlet pipe to the bathtub through the pipe, and the flow path of the outlet pipe. The controller is characterized in that when the pump is operated, the controller opens the flow passage of the drop-in pipe by the opening and closing means and drops hot and cold water in the hot water supply heat exchanger into the bath.
The invention according to claim 3 is characterized in that, in the configuration according to claim 1 or 2, a fan capable of supplying combustion air into the combustion chamber is provided, and the controller rotates the fan together with the operation of the pump.

According to the first aspect of the present invention, the controller operates the pump after combustion of the burner by single use of the bath circuit is performed, and the temperature detected by the hot water temperature detection means becomes equal to or lower than the predetermined temperature Since hot water is circulated in the bath circuit, heat transfer from the hot water supply heat exchanger to hot water circulating in the bath heat exchanger can be performed to lower the temperature of the hot water in the hot water supply heat exchanger. Therefore, even in the case where the hot water supply circuit is used after single use of the bath circuit in the one-can two-water channel type, it is possible to effectively suppress high-temperature tapping. In particular, when a bypass pipe is provided to connect the water supply pipe and the hot water discharge pipe to bypass the hot water supply heat exchanger, the operation of the pump is such that the distribution valve provided on the bypass pipe breaks down and sufficient water is output from the bypass pipe. Even when mixing can not be performed, it is performed regardless of the relationship, so high temperature hot water can be prevented with high reliability.
According to the second aspect of the invention, in addition to the effect of the first aspect, the controller opens the flow passage of the drop-in pipe by the opening / closing means when the pump is operated, By dropping hot and cold water into the bath, the hot water in the hot water supply heat exchanger can be replaced with water, and the hot water temperature in the hot water supply heat exchanger can be reduced quickly.
According to the third aspect of the invention, in addition to the effect of the first or second aspect, the controller rotates the fan together with the operation of the pump so that the inside of the hot water supply heat exchanger can be released by the heat dissipation function using combustion air. The hot water temperature can be effectively reduced.

It is a schematic circuit diagram of a water heater. It is a flowchart of high temperature tapping prevention control. It is a flowchart of the example of a change of high temperature tapping prevention control. It is a flowchart of the example of a change of high temperature tapping prevention control. It is explanatory drawing which shows the example of arrangement | positioning of each heat exchanger tube of a hot-water-supply heat exchanger and a bath heat exchanger.

Hereinafter, embodiments of the present invention will be described based on the drawings.
FIG. 1 is a schematic circuit diagram showing an example of a water heater. This water heater 1 supplies combustion air to each burner unit 3 and three burner units 3, 3... Provided with a plurality of burners 4, 4. A combustion fan 5 is provided, and a hot water supply heat exchanger 6 and a bath heat exchanger 7 through which the combustion exhausts of the burners 4, 4... Pass at an upper portion in the combustion chamber 2. 8 is a spark plug, 9 is a flame rod, and an exhaust hood 10 for exhausting the combustion exhaust gas passing through both heat exchangers 6, 7 is provided at the upper part of the combustion chamber 2. A sheet-like overheat protection device 11 printed with a fuse circuit for detecting leakage of combustion exhaust gas from the chamber 2 is wound.

  A gas pipe 12 to which a gas pipe from the outside is connected is connected to a gas inlet of a device accommodating the combustion chamber 2 and the like. Are connected to each other, and each branch pipe 13 is provided with a gas solenoid valve 14 for opening and closing a gas flow path. In addition, a source gas solenoid valve 15 and a gas proportional valve 16 are provided on the upstream side of the gas pipe 12 before branching.

The hot water supply heat exchanger 6 includes a hot water supply heat transfer pipe 18 penetrating the plurality of fins 17, 17 ··· arranged at a predetermined interval in a serpentine manner, and the inlet of the hot water supply heat transfer pipe 18 is a water inlet of an appliance. The water supply pipe 19 connected to is connected, and the outlet pipe 20 connected to the hot water outlet of the appliance is connected to the outlet of the hot water supply heat transfer pipe 18. A water pipe thermistor 21 for detecting the temperature of the hot water supply heat transfer pipe 18 is provided at a bent portion of the hot water supply heat transfer pipe 18 exposed to the outside of the hot water supply heat exchanger 6. Further, a bypass pipe 22 bypassing the hot water supply heat exchanger 6 is connected between the water supply pipe 19 and the hot water discharge pipe 20, and a connection portion between the water supply pipe 19 and the bypass pipe 22 is driven by a stepping motor. A distribution valve 23 for variably controlling the flow rate of the bypass pipe 22 is provided.
There is.

Further, on the upstream side of the connection portion of the water supply pipe 19 with the bypass pipe 22, a water inlet thermistor 24 for detecting the temperature of the incoming water and a hot water supply sensor 25 for detecting the amount of water flowing through the water supply pipe 19 are provided.
Then, at the outlet of the hot water supply heat exchanger 6 in the hot water discharge pipe 20, a hot water supply heat exchanger thermistor 26 for detecting the outlet temperature is provided, and the hot water discharge temperature is detected downstream of the connection portion with the bypass pipe 22 A hot water supply hot water discharge thermistor 27 and a water amount control valve 28 which is driven by a stepping motor to variably control the flow rate of the hot water discharge pipe 20 are provided.
Therefore, the hot water supply heat exchanger 6 heated by the burner unit 3 and the hot water supply circuit 19 including the water supply pipe 19 and the hot water discharge pipe 20 connected to the hot water supply heat exchanger 6 and the bypass pipe 22 are formed here.

On the other hand, the bath heat exchanger 7 includes a bath heat transfer pipe 30 penetrating the fins 17 17 in a meandering manner, and the bath adapter 32 of the external bath 31 at the inlet of the bath heat transfer pipe 30 via external piping. The bath return pipe 33 connected is connected to the outlet of the bath heat transfer pipe 30, and the bath return pipe 34 connected to the bath adapter 32 via an external pipe is connected. A pump 35 is provided in the bath return pipe 33, and a bath return thermistor 36 for detecting a bath return temperature is provided on the upstream side thereof, and a hot water in the bath return pipe 33 is provided on the downstream side of the pump 35. A bath water flow switch 37 which is turned ON / OFF by the flow, and a water level sensor 38 which detects the water level in the bathtub 31 by water pressure are provided. Further, a bath-tripping thermistor 34 is provided in the bath-passing pipe 34 for detecting the bath-passing temperature.
Therefore, a bath circuit B including a bath heat exchanger 7 to be heated by the burner unit 3 and a bath return pipe 33 and a bath forward pipe 34 connected between the bath heat exchanger 7 and the bath 31 are provided here. Is formed.
As described above, the water heater 1 is heated by the common burner units 3, 3 ··· with the hot water supply heat exchanger 6 and the bath heat exchanger 7 which are different in water passage in one combustion chamber 2 side by side It is one can and two channels type.

Then, between the hot water supply circuit A and the bath circuit B, a drop pipe 41 is connected between the pump 35 and the bath return thermistor 36 in the bath return pipe 33 on the downstream side of the water quantity control valve 28 in the hot water pipe 20 There is. A bath water amount sensor 42 for detecting the amount of water flowing through the dropping pipe 41 is provided on the upstream side of the dropping pipe 41, and a dropping water solenoid valve 43 for opening and closing the dropping pipe 41 is provided on the downstream side. Furthermore, two check valves 44, 44 are provided on the downstream side of the dropping water solenoid valve 43, respectively, and between the check valves 44, 44, the hot and cold water flowing back from the bath return pipe 33 is A discharge valve 45 is connected.
Reference numeral 50 denotes a controller, which includes a drive circuit for each motor, a detection circuit for each thermistor and sensor, etc. in addition to a microcomputer and memory, receives detection signals from each thermistor and sensor, and operates each valve etc. Water filling control to the bathtub 31 is performed. 51 is a hot water supply remote control, 52 is a bath remote control.

In the water heater 1 configured as described above, first, normal hot water supply is performed as follows.
The hot water supply tap of the external piping connected to the hot water outlet is opened and water flows in the device, and when the water flow is detected by the hot water supply amount sensor 25, the controller 50 rotates the combustion fan 5 for a predetermined time to burn The combustion exhaust stored in the chamber 2 is discharged (prepurge). Thereafter, the source gas solenoid valve 15 of the gas pipe 12 and each gas solenoid valve 14 are opened, the gas proportional valve 16 is opened at a predetermined opening degree, gas is supplied to each burner unit 3, and the igniter is operated. The burner 4, 4,... Is ignited by the spark plug 8.
Thereby, in the hot water supply heat exchanger 6, the water flowing through the hot water supply heat transfer pipe 18 is heat-exchanged with the combustion exhaust of the burner 4, and the heated hot water is discharged from the hot water supply tap through the hot water discharge pipe 20 and the external piping.

The controller 50 monitors the outlet temperature by the hot water supply heat exchanger thermistor 26 of the hot water discharge pipe 20, and drives the stepping motor of the distribution valve 23, and the outlet temperature prevents the generation and overheating of the drain in the hot water supply heat exchanger 6. The flow rate (bypass rate) to the bypass pipe 22 is controlled so as to be maintained within the possible temperature range.
The controller 50 monitors the hot water temperature by the hot water discharge thermistor 27 and controls the opening and closing control of each gas solenoid valve 14 so that the hot water temperature becomes the set temperature set by the hot water supply remote control 51 or the bath remote control 52. While adjusting the opening degree of the valve 16, the air amount is continuously changed by controlling the rotational speed of the combustion fan 5.
When the hot water supply plug is closed, the controller 50 that has confirmed the stop of the signal from the hot water supply amount sensor 25 closes the original gas solenoid valve 15 and the gas solenoid valve 14 to extinguish the burner 4 and rotates the combustion fan 5 for a predetermined time (post purge).

On the other hand, when the automatic switch of the hot water supply remote control 51 or the bath remote control 52 is pressed, the controller 50 opens the drop water electromagnetic valve 43 of the drop pipe 41 to cause the hot water supply heat exchanger 6 to flow water to burn the burner 4. The hot water from the hot water discharge pipe 20 is supplied to the bathtub 31 through the drop-in pipe 41, the bath return pipe 33, and the bath return pipe 34. When the amount of water detected by the bath water amount sensor 42 provided in the dropping pipe 41 reaches the set amount of water, the dropping water solenoid valve 43 is closed to complete the dropping.
Next, the pump 35 is operated to circulate hot water between the bath heat exchanger 7 and the bath 31. Therefore, the bath circulating water circulating between the bath heat exchanger 7 and the bath 31 is subjected to heat exchange with the combustion exhaust of the burner 4 when flowing through the bath heat transfer pipe 30, and is driven to the set temperature. When the set temperature is reached, the combustion of the burner 4 is stopped and the pump 35 is stopped. Further, by operating the reheating switch of the bath remote control 52, reheating can be performed at any timing.

  Then, after the bath circuit B is used alone and the reheating is performed, the controller 50 operates the pump 35 so that the hot water in the hot water heat transfer pipe 18 of the hot water heat exchanger 6 which has been heated by the burner 4. The temperature is lowered to prevent the hot water from being discharged even if the hot water supply circuit A is used thereafter. Hereinafter, the high temperature tapping prevention control will be described based on the flowchart of FIG.

  First, when it is confirmed in S1 that reheating of the bath circuit B is completed, the controller 50 operates the pump 35 in S2 to execute circulation of hot and cold water in the bath circuit B. By this circulation, the heat of the hot water supply heat transfer pipe 18 heated by the burner 4 at the time of single use of the bath circuit B is transmitted to the bath heat transfer pipe 30 through the fins 17, 17. It will move to the hot and cold water. Therefore, the hot water temperature of the hot and cold water accumulated in the hot water supply heat transfer pipe 18 is lowered.

Next, in the determination of S3, it is determined whether the detected temperature of the hot water supply heat transfer pipe 18 obtained from the water pipe thermistor 21 is 60 ° C. or less. Here, if the temperature is 60 ° C. or less, it is determined in the subsequent S4 whether or not the outlet temperature obtained from the hot water supply heat exchanger thermistor 26 is 60 ° C. or less. Here, if either the detected temperature at S3 or the outlet temperature at S4 still exceeds 60 ° C., the operation of the pump 35 is continued, but it is confirmed that both temperatures are below 60 ° C. Then, the controller 50 stops the operation of the pump 35 at S5 and ends the present control.
Since the hot water temperature in the hot water supply heat transfer pipe 18 is lowered by this high temperature hot water prevention control, even if the hot water supply plug is opened thereafter and the hot water supply circuit A is used, high temperature hot water of 100 ° C. or more from the hot water discharge pipe 20 There is no risk of being

  As described above, according to the water heater 1 of the above embodiment, the controller 50 operates the pump 35 after the burner 4 is burned by using the bath circuit B alone, and the temperature detected by the water tube thermistor 21 By circulating the hot water in the bath circuit B until the temperature becomes lower than a predetermined temperature (60 ° C. in this case), heat is transferred from the hot water supply heat transfer pipe 18 to the hot water circulating in the bath heat transfer pipe 30 and the hot water in the hot water heat transfer pipe 18 Temperature can be reduced. Therefore, even in the case where the hot water supply circuit A is used after single use of the bath circuit B in the one-can two-water channel type, it is possible to effectively suppress the high temperature tapping. In particular, the operation of the pump 35 is performed regardless of the case where the distributing valve 23 or the like is broken and sufficient water can not be mixed from the bypass pipe 22. Therefore, high temperature hot water can be prevented with high reliability.

  In the above embodiment, the water tube thermistor and the hot water supply heat exchanger thermistor are used as the hot water temperature detection means, and the pump is turned off when both detected temperatures are 60 ° C. or less. The pump may be turned off by monitoring only the temperature detected by the water tube thermistor without using the detected temperature. The predetermined temperature at which the pump is turned off is not limited to 60 ° C., and can be appropriately increased or decreased.

Further, as shown in FIG. 3, in the routine of FIG. 2, after confirmation of the end of reheating in S11, the pump 35 is operated and the combustion fan 5 is also rotated to send air into the combustion chamber 2 in S12. You may do so.
In this case, since the air sent into the combustion chamber 2 passes through the hot water supply heat exchanger 6 and contacts the hot water supply heat transfer pipe 18 and the fins 17 around it, heat radiation in the hot water supply heat exchanger 5 can be promoted. it can.
Then, when it is confirmed that the detected temperature of the hot water supply heat transfer pipe 18 and the outlet temperature from the hot water supply heat exchanger 6 have become 60 ° C. or lower in the judgment of S13 and S14, the controller 50 operates the pump 35 in S15. At the same time as stopping, the rotation of the combustion fan 5 is stopped and this control is ended.

Thus, according to the modification of FIG. 3, since the combustion fan 5 is rotated with the operation of the pump 35, the hot water heat transfer pipe 18 is released by the heat radiation action utilizing combustion air in addition to the hot water temperature lowering action by the pump 35. The water temperature inside can be effectively reduced.
In the modification of FIG. 3, the ON / OFF of the combustion fan 5 does not have to be the same timing as the ON / OFF of the pump 35, and the ON / OFF of the combustion fan 5 is delayed from the ON / OFF of the pump 35 Timing may be shifted.
Also in this modification, the pump and the combustion fan may be turned off by monitoring only the temperature detected by the water tube thermistor without using the temperature detected by the hot water supply heat exchanger thermistor. The temperature at which the pump is turned off can also be increased or decreased not limited to 60 ° C.

  Furthermore, in the modified example shown in FIG. 4, in the routine of FIG. 3, after confirming the end of reheating in S21 and turning on the pump 35 and the combustion fan 5 in S22, the detected temperature of the water tube thermistor 21 is S23. If the temperature exceeds 60 ° C., the controller 50 drops the water at S24. In this water dropping, the dropping water solenoid valve 43 is opened and the hot and cold water in the hot water supply circuit A is dropped from the dropping pipe 41 into the bath 31 through the bath return pipe 33 and the bath passing pipe 34. It does not burn and it is performed until the water volume detected by the bath water volume sensor 42 reaches a predetermined water volume. By this water dropping, the hot and cold water in the hot water supply heat transfer pipe 18 is replaced with the water newly supplied from the water supply pipe 19.

After execution of water dropping, the detected temperature of the water tube thermistor 21 is confirmed again in S23, and if the detected temperature still exceeds 60 ° C., the process of dropping water again is repeated in S24. If the detected temperature is 60 ° C. or less, it is determined in S25 whether the outlet temperature from the hot water supply heat exchanger thermistor 26 is 60 ° C. or less.
Then, when the outlet temperature exceeds 60 ° C. in S25, the same water dropping as in S24 is performed in S26, and the operation is repeated until the outlet temperature becomes 60 ° C. or less. When the outlet temperature becomes 60 ° C. or lower, the pump 35 and the combustion fan 5 are turned off in S27, and the present control is ended.

  Thus, according to the modification of FIG. 4, the controller 50 opens the flow passage of the drop-in pipe 41 by the drop-in water solenoid valve 43 when the pump 35 is operated, so that the inside of the hot water supply heat exchanger 6 is Since hot and cold water is dropped into the bath 31, in addition to the hot water temperature lowering action by the pump 35 and the combustion fan 5, the high temperature hot water in the hot water supply heat transfer pipe 18 is replaced with water to rapidly reduce the hot water temperature in the hot water supply heat transfer pipe 18 It can be done.

Also in this modification, only the temperature detected by the water tube thermistor may be monitored without using the temperature detected by the hot water supply heat exchanger thermistor, and the water may be dropped or the pump and the combustion fan may be turned off. The temperature at which the pump is turned off can also be increased or decreased not limited to 60 ° C.
Also, in this modification, the water dropping is performed at the timing when it is confirmed that the detection temperature of the water pipe thermistor and the hot water supply heat exchanger thermistor exceeds the predetermined temperature, but the detection temperature decreases after the predetermined time elapses. If you do not see it, you may drop the water. Furthermore, water dropping may be performed simultaneously with the turning on of the pump without setting such conditions.
And it is also possible to add water dropping to ON / OFF control of a pump like FIG. 2 without using a combustion fan.

In addition, common to the above-described embodiment and the modifications, the configuration of the water heater itself is also a single-can-bichannel type, each heat exchanger is provided with a secondary heat exchanger for latent heat recovery, etc. No problem.
On the other hand, in the side-by-side configuration of the hot water supply heat exchanger and the bath heat exchanger in the one-can two-channel type, the heat transfer pipes of both heat exchangers are separately disposed laterally and vertically or vertically in one combustion chamber. In addition to the form, the heat transfer tubes of both heat exchangers may be in a mixed form in which the heat transfer tubes are alternately arranged left and right, front and back, or up and down.
In FIG. 5, the example of arrangement of the heat exchanger tube in the water heater 1 of the said form is shown. Here, the straight pipe portions 18a, 18a, ··· of the hot water supply heat transfer pipe 18 disposed in a serpentine manner in the combustion chamber 2 are arranged in the upper and lower parts separately, and the hot water heat transfer pipe 18 and fins connected from the lower to the upper 17 form the hot water supply heat exchanger 6, and the straight pipe portions 30a, 30a, ··· of the bath heat transfer pipe 30 similarly disposed in a serpentine manner in the combustion chamber 2, the straight pipe portions 18a, 18a in the upper and lower stages. The bath heat exchanger 7 is formed by the bath heat transfer pipe 30 and the fins 17 connected in the middle stage, and the hot water supply heat transfer pipe 18 and the bath heat transfer pipe 30 are alternately arranged in the vertical direction. ing.

  1 · · · water heater, 2 · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · combustion fan (fan), 6 · · hot water heat exchanger, 7 · · bath heat exchanger, · Gas pipe, 17 · · Fin, 18 · Hot water supply heat pipe, 19 · · Water supply pipe, 20 · · Hot water discharge pipe, 21 · · Water pipe thermistor (hot water temperature detection means), 22 · · Bypass pipe, · · · Distribution Valve, 24 · · · incoming water thermistor, 25 · · hot water supply amount sensor, 26 · · hot water heat exchanger thermistor (hot water temperature detection means), 27 · · hot water discharge thermistor, 28 · · water amount control valve, 30 · · bath heat transfer tube , · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · , 43 · · Drop water solenoid valve (opening and closing means), 50 · · Roller, 51 ... hot water remote control, 52 ... bath remote controller, A .. hot water supply circuit, B ... bath circuit.

Claims (3)

A combustion chamber in which a burner is disposed at the bottom,
A hot water supply circuit including a hot water supply heat exchanger disposed above the combustion chamber and heated by the burner, and a water supply pipe and a hot water discharge pipe connected to the hot water supply heat exchanger;
Provided in the upper portion of the combustion chamber is a bath heat exchanger which is juxtaposed to the hot water supply heat exchanger and heated by the burner, a pipe connected to the bath heat exchanger and connected to an external bath, and the pipe A pump circuit comprising:
Hot water temperature detecting means for detecting the temperature of hot water in the hot water supply heat exchanger;
A water heater comprising a controller for controlling the combustion of the burner and the operation of the pump, the water heater comprising:
After the controller burns the burner by using the bath circuit alone, the controller operates the pump until the temperature detected by the hot water temperature detection means falls below a predetermined temperature. Water heater characterized by circulating. The feed pipe and the pipe are connected to each other, and the feed pipe is capable of supplying hot water from the feed pipe to the bath through the pipe, and an opening / closing means for opening and closing the flow path of the feed pipe.
The controller is characterized in that the hot water in the hot water supply heat exchanger is dropped into the bath by opening the flow passage of the drop-in pipe by the opening and closing means when the pump is operated. Water heater described. A fan capable of supplying combustion air into the combustion chamber;
The water heater according to claim 1 or 2, wherein the controller rotates the fan with the operation of the pump.

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