JP7336965B2 - bath water heater - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bath water heater that performs an air purge operation for discharging air accumulated in a bath heat exchanger to a bathtub.

Conventionally, in this type of bath apparatus, as shown in Patent Document 1, a bathtub, an indirect heat exchanger (bath heat exchanger) that heats bathtub water, a hot water storage tank that heats the indirect heat exchanger, and a bathtub A bath outlet pipe and a bath return pipe that connect the indirect heat exchanger, a bath circulation pump provided in the bath return pipe, a temperature sensor that detects the temperature of the bathtub water flowing from the indirect heat exchanger to the bathtub, and a bath outlet pipe. A bypass pipe that communicates with the bath return pipe and bypasses the bathtub; and the indirect heat exchanger are circulated through a bath return pipe and a bath outgoing pipe to raise the bath water temperature (for example, Patent Document 1).

In addition, as in Patent Document 1, since the inside of the indirect heat exchanger (bath heat exchanger) is heated to the temperature of the upper part of the hot water storage tank, high-temperature hot water stays in the indirect heat exchanger. In order to prevent the hot water from being directly supplied to the bathtub, it is known that the opening degree of the flow path switching means is set to the intermediate position, and the bathtub water or the mixed water is mixed with the high temperature hot water to soften it little by little. had been

JP-A-2003-156251

By the way, in this conventional device, when air remains in the indirect heat exchanger (bath heat exchanger), the air is pushed out into the bathtub by driving the bath circulation pump during the reheating, and the air becomes squishy. At the beginning of the hot water filling operation when there is no one in the bathtub, hot water is supplied to the bathtub through the indirect heat exchanger, and the hot water is supplied to the bathtub in the indirect heat exchanger. There was a problem that it was necessary to perform an air purge operation to push out the air accumulated in the bathtub.

Further, when both the air purge operation and the prevention of hot water discharge are to be achieved, the flow path switching means is set to a state in which both the indirect heat exchanger (bath heat exchanger) side and the bypass side are communicated, and the hot water stays in the indirect heat exchanger. It is necessary to saturate the hot water with the hot water supply in the hot water filling operation while pushing out the hot water, but since the pressure loss is larger when the indirect heat exchanger is flowing than when the bypass pipe is flowing, it is difficult for the hot water to flow, and the air purge operation is performed. However, there was a problem that the

In order to solve the above problems, the present invention provides a hot water storage tank for storing hot water, a mixing valve for mixing high-temperature hot water in the hot water storage tank and water from a water supply pipe, and a bathtub for mixing water mixed by the mixing valve. a bath heat exchanger provided inside the hot water storage tank for exchanging heat with the upper part of the hot water storage tank to heat the bathtub water; and one end of the bathtub and the bath heat exchanger. a bath return pipe to which the hot water filling pipe is connected; a bath going pipe connecting the bathtub and the other end of the bath heat exchanger; A heat exchange bypass pipe that bypasses the bath heat exchanger by communicating without an exchanger, and a flow path on the side of the heat exchange bypass pipe and a flow path on the side of the bath heat exchanger are connected by the degree of opening of a valve. A switching valve that adjusts the flow of hot water, a return-side temperature sensor that detects a return-side temperature that is the temperature of hot water on the upstream side of the heat exchange bypass pipe, and a temperature of hot water on the downstream side of the heat exchange bypass pipe. and the switching valve are communicated with both the bath heat exchanger side and the heat exchange bypass pipe side, and the mixed water is supplied to the bath heat exchanger. In a hot water heater for a bath provided with a control device for controlling an air purge operation for pushing out accumulated air into the bathtub, the control device controls the switch when the going-side temperature is equal to or lower than the returning-side temperature during the air purge operation. The opening degree of the valve is driven to the bath heat exchanger side, and the switching valve is stopped when the going side temperature becomes higher than the returning side temperature.

A hot water storage tank for storing hot water, a mixing valve for mixing high-temperature hot water in the hot water storage tank and water from a water supply pipe, and a hot water filling pipe for supplying the mixed water mixed by the mixing valve to the bathtub. a bath heat exchanger provided inside the hot water storage tank for exchanging heat with the upper part of the hot water storage tank to heat the bath water, and connecting the bathtub and one end of the bath heat exchanger, and connecting the hot water filling pipe to the bath heat exchanger. a bath return pipe, a bath going pipe connecting the bathtub and the other end of the bath heat exchanger, and the bath going pipe and the bath return pipe communicating without passing through the bath heat exchanger. , a heat exchange bypass pipe that bypasses the bath heat exchanger, and a switching valve that adjusts the flow of hot water between the heat exchange bypass pipe side flow path and the bath heat exchanger side flow path according to the opening degree of the valve. and controlling an air purge operation in which the switching valve is communicated with both the bath heat exchanger side and the heat exchange bypass pipe side, and air accumulated in the bath heat exchanger is pushed out to the bathtub by supplying the mixed water. A bath hot water supply apparatus comprising a main body control device, wherein a flow rate detecting means for detecting a flow rate in the pipe is provided between the connection position of the heat exchange bypass pipe and the bath going pipe and the bath heat exchanger, When the value detected by the flow rate detection means is equal to or less than a predetermined flow rate during an air purge operation, the main body control device drives the valve opening of the switching valve to the bath heat exchanger side, and controls the flow rate detection means. The switching valve is stopped when the detected value becomes higher than a predetermined flow rate.

Further, the body control device stores a stop position when the switching valve is driven to change the valve opening degree during the air purge operation, and the body control device stores the stop position of the switching valve during the next air purge operation. The stop position is set to the initial position of the valve opening.

According to this invention, when the return-side temperature detected by the return-side temperature sensor and the send-side temperature detected by the send-side temperature sensor are lower than or equal to the return-side temperature detected by the return-side temperature sensor, the main body control device performs an air purge operation without hot water flow in the bath heat exchanger. is incomplete, open the valve opening of the switching valve to the bath heat exchanger side, and the temperature on the going side detected by the temperature sensor on the going side is higher than the temperature on the returning side detected by the temperature sensor on the returning side. By stopping the valve opening drive when the temperature rises, the air purge operation can actually be performed, and the switching valve can be set to a valve opening that does not open the bath heat exchanger side too much, To suppress the temperature of hot water flowing out to a bathtub while surely pushing out air accumulated in a bath heat exchanger.

1 is a schematic configuration diagram of a bath water heater according to an embodiment of the present invention; FIG. 4 is a flowchart for explaining an air purge operation of the first embodiment; 9 is a flowchart for explaining an air purge operation of the second embodiment;

Next, a bath water heater according to an embodiment of the present invention will be described with reference to FIG.
1 is a hot water storage tank unit having a hot water storage tank 2 for storing hot water, 3 is a heat pump unit as a heating means for heating the hot water in the hot water storage tank 2, 4 is a bathtub, and 5 is a remote control for remotely operating this bath apparatus. .

A heat pump circulation circuit 6 connects the hot water storage tank 2 and the heat pump unit 3 so as to circulate, and is composed of a heat pump forwarding pipe 7 connected to the lower portion of the hot water storage tank 2 and a heat pump return pipe 8 connected to the upper portion of the hot water storage tank 2. The hot water in the hot water storage tank 2 taken out from the heat pump supply pipe 7 is boiled by the heat pump unit 3 and returned to the hot water storage tank 2 through the heat pump return pipe 8 to store high temperature hot water. A plurality of stored hot water temperature sensors 9 serving as stored hot water temperature detection means are provided on the side surface of the hot water storage tank 2 in the vertical direction. It detects whether or not there is a remaining

10 is a hot water discharge pipe connected to the upper end of the hot water storage tank 2 for discharging hot water in the hot water storage tank 2; A mixing valve for mixing the water from the pipe 11 to a predetermined set temperature, 13 a hot water supply pipe for supplying hot water of the set temperature mixed by the mixing valve 12, It is a faucet provided in a kitchen, a washroom, or the like. A hot water supply temperature sensor 15 is provided downstream of the mixing valve 12, and a hot water supply flow rate sensor 16 counts the amount of hot water supplied. Reference numeral 17 denotes a pressure reducing valve for reducing the tap water pressure to a predetermined pressure, 18 denotes a water supply temperature sensor for detecting the temperature of the water supply, and 19 denotes an overpressure relief valve for releasing overpressure in the hot water storage tank.

The heat pump unit 3 includes a variable speed compressor 20 for compressing a refrigerant, a water-refrigerant heat exchanger 21 as a condenser, an electronic expansion valve 22 as pressure reducing means, and an air heat as a forced air-cooled evaporator. A heat pump circuit 24 configured with an exchanger 23, a heat pump circulation pump 25 that is provided in the heat pump feed pipe 7 and circulates the hot water in the hot water storage tank 2 to the water-refrigerant heat exchanger 21, and a heat pump that controls their driving A controller 26 is provided.

Numeral 27 denotes a bath heat exchanger consisting of a corrugated tube for heating the bath water in the bathtub 4, and is arranged in the upper part of the hot water storage tank 2. The bath heat exchanger 27 and the bathtub 4 are A bath circulation circuit 30 is formed by connecting a bath outlet pipe 28 for flowing water into the bathtub 4 and a bath return pipe 29 for flowing the bathtub water out of the bathtub 4, and the bathtub water in the bathtub 4 flows into the hot water storage tank 2. Reheating is performed by heating with hot water of high temperature.

A bath circulation pump 31 is provided in the bath circulation circuit 30 and circulates the bath water in the bathtub 4. A bath circulation pump 32 is provided in the bath supply pipe 28 and detects the temperature of the bath water flowing from the bath heat exchanger 27 to the bathtub 4. A going-side temperature sensor 33 as temperature detecting means is provided in the bath return pipe 29 and is a returning-side temperature sensor 33 as bath return temperature detecting means for detecting the temperature of bathtub water flowing from the bathtub 4 to the bath heat exchanger 27 .

34 is a heat exchange bypass pipe that connects the bath supply pipe 28 and the bath return pipe 29 downstream of the return temperature sensor 33 and upstream of the supply temperature sensor 32 and bypasses the bath heat exchanger 27; A switching valve 36 as flow path switching means provided at the connecting portion between the heat exchange bypass pipe 34 and the bath return pipe 29 has a microcomputer that receives input from the forward temperature sensor 32 and controls the driving of the switching valve 35. It is a flow path switching control unit.

37 is a hot water filling pipe branched from the middle of the hot water supply pipe 13 and connected to the bath return pipe 29 for pouring hot water into the bathtub 4; A hot water filling valve 39 is a bath flow rate sensor that counts the amount of hot water poured into the bathtub 4 .

The remote controller 5 is provided with a hot water supply temperature setting switch 40 for setting the hot water supply temperature setting and a bath temperature setting switch 41 as bath temperature setting means for setting the bath temperature setting. is filled with hot water by the amount set by the hot water filling amount setting switch (not shown) of the remote controller 5, and the bath temperature set by the bath temperature setting switch 41 or about 1 to 2 degrees higher than the bath setting temperature. A bath automatic switch 42 for keeping warm at a temperature for a predetermined time, and a reheating device that circulates the bath water in the bath tub 4 to the bath heat exchanger 27 and heats the bath water in the bath tub 4 to the reheating target temperature. A reheating switch 43 for executing operation is provided.

A microcomputer 44 is connected to the remote controller 5, the heat pump control unit 26, and the flow path switching control unit 36 by radio or wire, and communicates with each other, and receives inputs from each sensor in the hot water storage tank unit 1 and controls the driving of each actuator. It is a control device that controls hot water supply and bathing.

Next, the operation of the bath water heater of the present invention will be described.

<Boiling operation>
At the start time of the predetermined time period (midnight time period) when the power rate unit price is low, the main body control device 44 changes the hot water supply load to the heat pump unit 3 so as to start boiling the amount of hot water corresponding to the hot water supply load up to that time. Then, the heat pump unit 3 starts driving the compressor 20 , the electronic expansion valve 22 , the blower, and the heat pump circulation pump 25 , and takes out the water from the lower part of the hot water storage tank 2 . The hot water is boiled by the water-refrigerant heat exchanger 21 , heated to the target temperature, returned to the upper part of the hot water storage tank 2 , and the hot water of the set temperature boiled from the upper part of the hot water storage tank 2 is stored in a layered manner. 2 or reaches the end time of the predetermined time period, the heat pump unit 3 is instructed to stop boiling, and the heat pump unit 3 includes the compressor 20 , the expansion valve 22 , the blower, and the heat pump circulation pump. 25 is stopped to end the boiling operation.

<Hot water supply>
When the hot water tap 14 is opened, city water flows into the bottom of the hot water storage tank 2 from the water supply pipe 11 and high temperature hot water is discharged from the top of the hot water storage tank 2 through the hot water outlet pipe 10 . It is mixed with water from the water supply bypass pipe branched from and passes through the hot water supply pipe 13 . When the hot water supply flow rate sensor 16 detects the minimum operating water amount or more, the main body control device 44 feedback-controls the valve opening of the mixing valve 12 so that the temperature detected by the hot water supply temperature sensor 15 matches the hot water supply set temperature. , to supply hot water at the hot water supply set temperature. Then, when the hot water supply flow rate sensor 16 detects that the hot water supply flow rate sensor 16 is below the minimum operating water amount due to the closing of the hot water supply tap 14, etc., the main body control device 44 stops the feedback control of the valve opening degree of the mixing valve 12 so as to stop the hot water supply. there is

<Reheating operation>
When the main body control device 44 instructs the reheating operation, the main body control device 44 drives the bath circulation pump 31 to circulate the bath water through the bath circulation circuit 30 and the bath heat exchanger 27, and heat-exchange the bath water. Heat in vessel 27 . Then, when it is confirmed by the return-side temperature sensor 33 that the temperature of the bathtub water has risen to the bath set temperature, the driving of the bath circulation pump 31 is stopped.

<Hot water filling operation>
Next, referring to FIG. 1, the hot water filling operation will be described based on the flow chart shown in FIG.
When the automatic bath switch 42 of the remote control 5 connected to the main body control device 44 is operated and the hot water filling operation is instructed (Yes in S1), the hot water filling valve 38 is opened, and the flow path switching control unit 36 switches the switching valve. 35 is switched to the heat exchange bypass pipe 34 side (S2), and the main body control device 44 mixes so that the temperature detected by the hot water supply temperature sensor 15 becomes the hot water filling set temperature set by the bath temperature setting switch 41 of the remote controller 5. The valve opening degree of the valve 12 is feedback-controlled to start filling the bathtub 4 with hot water (S3).

Then, when a predetermined amount of hot water, which is an amount of water that makes the water level of the bathtub higher than at least the circulation port connecting the bathtub 4 and the bath circulation circuit 30, is filled (Yes in S4), the flow path switching control unit 36 switches the switching valve 35 so that both the heat exchange bypass pipe 34 side and the bath heat exchanger 27 side are communicated (S5), and starts an air purge operation to push out the air accumulated in the bath heat exchanger 27 (S6 ).

At this time, the water remaining in the bath heat exchanger 27 becomes hot, so the air contained in the water tends to accumulate above the bath heat exchanger 27. During operation, air is discharged into the bathtub, causing an unpleasant bubbling sound. Therefore, it is necessary to perform an air purge operation to discharge the air when supplying hot water (filling) to the bathtub, and the air remains in the bath heat exchanger 27. Since the water being heated is heated to a high temperature by the heat of the upper portion of the hot water storage tank 2, this high temperature is required during the reheating operation or when filling the bathtub with hot water so that the user does not feel uncomfortable due to sudden hot water discharge. It is necessary to mix the water with the mixed water of the hot water supply to make it blunt.

Therefore, during this air purge operation, the body control device 44 checks whether the temperature detected by the forward temperature sensor 32 is higher than the temperature detected by the return temperature sensor 33 (S7). If the temperature is equal to or lower than the temperature detected by the temperature sensor (S7 is No), the flow path switching control unit 36 drives the opening degree of the switching valve 35 toward the bath heat exchanger 27 (S8), and the main body control device 44 It is checked whether the temperature detected by the forward temperature sensor 32 is higher than the temperature detected by the return temperature sensor 33 (S7). This driving of the valve 35 is repeated until the temperature detected by the forward temperature sensor becomes higher than the temperature detected by the return temperature sensor.

Then, the body control device 44 determines that the value detected by the bath flow rate sensor 39 after the temperature detected by the forward temperature sensor becomes higher than the temperature detected by the return temperature sensor stays in the bath heat exchanger 27 at a predetermined value. If the specified air purge amount (10 L) required to push out the discharged air has been reached (Yes in S9), the flow path switching control unit 36 switches the switching valve to the heat exchange bypass pipe 34 side (S10), and performs an air purge operation. is completed (S11).

After that, when the total amount of hot water filling, which is the integrated value of hot water filling from the start of the hot water filling operation, reaches the preset hot water filling setting amount (S12), the main body control device 44 completes the hot water filling operation (S13). .

Thus, in the first embodiment, when the high-temperature hot water accumulated in the bath heat exchanger 27 is mixed with the mixed water mixed in the mixing valve 12 in the hot-water filling operation, the return-side temperature sensor 33 detects the return-side temperature sensor 33 . Since the outbound temperature detected by the outbound temperature sensor 32 is higher than the outbound temperature, the return temperature and the outbound temperature are compared to determine whether hot water flows normally through the bath heat exchanger 27. can be judged.

Therefore, when the incoming temperature detected by the incoming temperature sensor 32 is higher than the return temperature detected by the return temperature sensor 33, there is a flow of hot water in the bath heat exchanger 27, and the bath heat exchanger 27 The air remaining inside is also pushed out by the hot water supply during the hot water filling operation, and it can be determined that the air purge operation is being performed normally.

Further, when the return temperature detected by the return temperature sensor 33 and the temperature detected by the return temperature sensor 32 are equal to or lower than the temperature on the return side, the body control device 44 performs an air purge operation because there is no hot water flow in the bath heat exchanger 27. is incomplete, the flow path switching control unit 36 opens the valve opening of the switching valve 35 toward the bath heat exchanger 27 so that the return-side temperature detected by the return-side temperature sensor 33 is higher than the return-side temperature. By stopping the driving of the valve opening degree when the forward side temperature detected by the temperature sensor 32 becomes higher, the air purge operation can actually be performed, and the switching valve 35 is connected to the bath heat exchanger 27 side. can be set to a valve opening degree that does not open too much, and the temperature of hot water flowing out to the bathtub 4 can be suppressed while surely pushing out the air accumulated in the bath heat exchanger 27.例文帳に追加

Next, in the first embodiment, whether or not the air purge operation is normally performed is determined by comparing the temperature on the forward side and the temperature on the return side. and the bath heat exchanger 27 is provided with a flow rate detection means 45 for detecting the flow rate, and if the flow rate of the flow rate detection means 45 is equal to or less than a predetermined flow rate, it is determined that the air purge operation is not performed normally, A second embodiment will be described in which it is determined that the air purge operation is being performed normally when the flow rate is equal to or greater than a predetermined flow rate.

This second embodiment will be described in detail based on the flow chart of FIG.
When the automatic bath switch 42 of the remote controller 5 connected to the main body control device 44 is operated and the hot water filling operation is instructed (Yes in S14), the flow path switching control unit 36 switches the switching valve 35 to the heat exchange bypass pipe 34 side. Switching (S15), the body control device 44 starts filling the bathtub 4 with hot water so as to reach the set hot water filling temperature set by the bath temperature setting switch 41 of the remote controller 5 (S16).

Then, when a predetermined amount of hot water, which is an amount of water that makes the water level of the bathtub higher than at least the circulation port connecting the bathtub 4 and the bath circulation circuit 30, is filled (Yes in S17), the flow path switching control unit 36 switches the switching valve 35 so that both the heat exchange bypass pipe 34 side and the bath heat exchanger 27 side are communicated (S18), and starts an air purge operation to push out the air accumulated in the bath heat exchanger 27 (S19). ).

During this air purge operation, the main control unit 44 confirms whether the temperature detected by the forward temperature sensor 32 is higher than the temperature detected by the return temperature sensor 33 (S20), and the value detected by the flow rate detecting means 45 is equal to or less than the predetermined flow rate. (S20 is No), the flow path switching control unit 36 drives the valve opening degree of the switching valve 35 toward the bath heat exchanger 27 (S21), It is checked whether the detected value is higher than the predetermined flow rate (S20). This driving of the degree of eloquence of the switching valve 35 is repeated until the value detected by the flow rate detecting means 45 becomes higher than the predetermined flow rate .

Then, when the value detected by the flow rate detecting means 45 becomes higher than the predetermined flow rate (Yes in S20), the body control device 44 detects that the value detected by the bath flow rate sensor 39 is within the predetermined bath heat exchanger 27. If the specified air purge amount (10 L) required to push out the stagnant air is reached (Yes in S22), the flow path switching control unit 36 switches the switching valve to the heat exchange bypass pipe 34 side (S23), and the air purge is performed. The operation is completed (S24).

Thereafter, when the total amount of hot water filling, which is the total value of hot water filling from the start of the hot water filling operation, reaches the preset hot water filling setting (S25), the hot water filling operation is completed (S26).

In this way, the flow rate detection means 45 for detecting the flow rate is provided between the connection position of the heat exchange bypass pipe 34 and the bath supply pipe 28 and the bath heat exchanger 27, and the flow rate detection means 45 detects the bath heat exchange. Since it is possible to detect whether there is a flow of hot water in the bath 27, if the flow of hot water is less than a predetermined flow rate detected by the flow rate detecting means 45, there is no flow of hot water in the bath heat exchanger 27 and the air purge operation is incomplete. When it is determined that there is a hot water flow and the flow rate detecting means 45 indicates that the hot water flow is higher than the predetermined flow rate, it can be determined that there is hot water flowing in the bath heat exchanger 27 and the air purge operation is being performed normally. In addition, the flow path switching control unit 36 can drive the opening degree of the switching valve 35 so that the flow rate detected by the flow rate detection means 45 becomes higher than a predetermined flow rate, thereby performing the air purge operation normally.

Further, in the first embodiment and the second embodiment, the stop position of the valve opening degree of the switching valve 35 when the air purge operation is normally performed is stored in the main body control device 44, and when the next air purge operation is performed By performing the air purge operation using the stored stop position as the initial position of the switching valve 35, the air purge operation can be performed smoothly.

The present invention is not limited to the above embodiments, and can be modified within the scope of the invention. Although explained as an example, it may be an electric water heater that heats and stores hot water with an electric heater.

4 Bathtub 12 Mixing valve 13 Hot water supply pipe 27 Bath heat exchanger 28 Bath forward pipe 29 Bath return pipe 31 Bath circulation pump 32 Forward temperature sensor 33 Return temperature sensor 34 Heat exchange bypass pipe 35 Switching valve 36 Flow path switching controller 37 Hot water filling pipe 44 Main body control device 45 Flow rate detecting means

Claims (3)

a hot water tank for storing hot water;
a mixing valve for mixing high-temperature hot water in the hot water storage tank and water from the water supply pipe;
a hot water filling pipe for supplying the mixed water mixed by the mixing valve to the bathtub;
a bath heat exchanger provided inside the hot water storage tank for exchanging heat with the upper part of the hot water storage tank to heat the bath water;
a bath return pipe that connects the bathtub and one end of the bath heat exchanger and to which the hot water filling pipe is connected;
a bath pipe connecting the bathtub and the other end of the bath heat exchanger;
a heat exchange bypass pipe that connects the bath going pipe and the bath return pipe without passing through the bath heat exchanger and bypasses the bath heat exchanger;
a switching valve that adjusts the flow of hot water between the flow path on the heat exchange bypass pipe side and the flow path on the bath heat exchanger side according to the valve opening;
a return-side temperature sensor that detects a return-side temperature, which is the temperature of hot water upstream of the heat exchange bypass pipe;
a going-side temperature sensor that detects a going-side temperature, which is the temperature of hot water on the downstream side of the heat exchange bypass pipe;
The switching valve is communicated with both the bath heat exchanger side and the heat exchange bypass pipe side, and an air purge operation for pushing out air accumulated in the bath heat exchanger to the bathtub by supplying the mixed water is controlled. In a bath water heater equipped with a main body control device,
When the going-side temperature is equal to or lower than the return-side temperature during the air purge operation, the main body control device drives the valve opening degree of the switching valve toward the bath heat exchanger so that the going-side temperature rises to the return-side temperature. A hot water supply device for a bath, characterized in that the switching valve is stopped when the temperature becomes higher than the side temperature. a hot water tank for storing hot water;
a mixing valve for mixing high-temperature hot water in the hot water storage tank and water from the water supply pipe;
a hot water filling pipe for supplying the mixed water mixed by the mixing valve to the bathtub;
a bath heat exchanger provided inside the hot water storage tank for exchanging heat with the upper part of the hot water storage tank to heat the bath water;
a bath return pipe that connects the bathtub and one end of the bath heat exchanger and to which the hot water filling pipe is connected;
a bath pipe connecting the bathtub and the other end of the bath heat exchanger;
a heat exchange bypass pipe that connects the bath going pipe and the bath return pipe without passing through the bath heat exchanger and bypasses the bath heat exchanger;
a switching valve that adjusts the flow of hot water between the flow path on the heat exchange bypass pipe side and the flow path on the bath heat exchanger side according to the valve opening;
The switching valve is communicated with both the bath heat exchanger side and the heat exchange bypass pipe side, and an air purge operation for pushing out air accumulated in the bath heat exchanger to the bathtub by supplying the mixed water is controlled. In a bath water heater equipped with a main body control device,
A flow rate detection means for detecting a flow rate in the pipe is provided between the connection position between the heat exchange bypass pipe and the bath pipe and the bath heat exchanger,
When the value detected by the flow rate detection means is equal to or less than a predetermined flow rate during an air purge operation, the main body control device drives the valve opening of the switching valve to the bath heat exchanger side, and controls the flow rate detection means. A hot water supply apparatus for a bath, wherein the switching valve is stopped when the detected value becomes higher than a predetermined flow rate. The body control device stores a stop position when the switching valve is driven to change the valve opening degree during the air purge operation,
3. The bath hot-water supply apparatus according to claim 1, wherein the body control device sets the initial position of the valve opening of the switching valve to the stop position at the time of the next air purge operation.

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