JP7307333B2 - water heater - Google Patents

Description

The present invention relates to a water heater.

Patent Document 1 (Japanese Unexamined Patent Application Publication No. 2009-156470) describes a bath hot water supply system. The bath hot water supply system described in Patent Document 1 includes a hot water supply pipe for supplying hot water, a circulation pipe for circulating bathtub water, and a hot water filling pipe connecting the hot water supply pipe and the circulation pipe. have. A silver (Ag) ion generator is arranged in the hot water filling pipe.

In the bath hot water supply system described in Patent Document 1, the circulation pipeline is washed when the bathtub water is drained. When cleaning the circulation pipeline, hot water is supplied to the circulation pipeline through the hot water supply pipeline and the hot water filling pipeline, and the silver ion generator is operated. Therefore, according to the bath hot water supply system described in Patent Document 1, the circulation pipe can be washed with hot water containing silver ions generated from the silver ion generator.

JP 2009-156470 A

However, in the bath hot water supply system described in Patent Document 1, due to the arrangement of the silver ion generator, when the bathtub water is circulated through the circulation conduit (reheating operation is performed), the silver ion generator generates silver ions. Bathwater cannot be sterilized by silver ions. Moreover, even if additives such as silver ions are added to the bath water flowing through the circulation pipe, various harmful effects may occur unless the additives are removed before the bath water returns to the bath. (If the bath water contains silver ions, the silver ions may be oxidized and attached to the bath, causing the bath to darken.)

The present invention has been made in view of the problems of the prior art as described above. More specifically, according to the present invention, it is possible to wash a circulation pipe with hot water to which an additive has been added, and to circulate the bathtub water without leaving the additive in the bathtub. To provide a hot water device capable of sterilizing bacteria.

A hot water device according to an aspect of the present invention includes a hot water supply pipeline for supplying hot water, a circulation pipeline for circulating bathtub water, a hot water supply pipeline connecting the hot water supply pipeline and the circulation pipeline, and hot water. a filter for removing the additive; and a pump for circulating the bathtub water through the circulation line. The pouring pipeline includes a first pipeline connected to the hot water supply pipeline, a second pipeline and a third pipeline connecting the circulation pipeline and the first pipeline, and a first valve section. have. At the first position, which is the connection position between the second pipe and the circulation pipe, the bathtub water is circulated through the circulation pipe with the pump more than at the second position, which is the connection position between the third pipe and the circulation pipe. on the upstream side of The circulation line includes a second valve positioned between the first position and the second position. The first valve portion has a first state in which water can flow between the first pipeline and the second pipeline, a second state in which water can flow between the first pipeline and the third pipeline, and A third state in which water can flow between the second pipeline and the third pipeline can be switched. The second valve is configured to be switchable between a fourth state in which water can pass between the first position and the second position and a fifth state in which water cannot pass between the first position and the second position. ing. The additive generator is closer to the first location than the filter on the path from the first location to the second location through the second and third conduits.

In the above water heater, the additive generator may be arranged in the second pipeline. In the above water heater, the filter may be arranged in the third pipeline.

In the above water heater, the additive generator may be arranged at the first position. A filter may be arranged in the third conduit.

In the above water heater, the third pipeline may include a check valve that disables water flow from the second position and allows water flow to the second position. The check valve may be closer to the second position on the path than the filter.

In the above water heater, the hot water supplied from the hot water supply pipe may contain chlorine. The filter may be configured to further remove chlorine.

In the above water heater, the additive generator may generate ozone as the additive. In the above water heater, the filter may be an activated carbon filter.

The water heater described above may further include a control unit. The control unit switches the first valve unit to the first state and switches the second valve to the fourth state when the circulation pipe is washed with hot water supplied from the hot water supply pipe, so that the bath water is supplied to the circulation pipe. The first valve portion may be switched to the third state and the second valve may be switched to the fifth state when circulating to.

In the above water heater, the control unit switches the first valve unit to the second state and switches the second valve to the fourth state when hot water supplied from the hot water supply pipe is poured into the bathtub. may be configured to

In the above water heater, the control unit switches the first valve unit and the second valve to the first state and the fourth state, respectively, when pouring hot water supplied from the hot water supply pipe into the bathtub, and adds The operation of the object generator may be stopped.

In the above water heater, the additive generator and the filter may be arranged in the second pipeline.

According to the hot water apparatus according to one aspect of the present invention, it is possible to wash the circulation pipe with hot water to which the additive has been added, and at the time of circulating the bathtub water, the additive can be used without leaving the additive in the bathtub. Bathtub water can be sterilized.

1 is a schematic diagram of a water heater according to an embodiment; FIG. 1 is a functional block diagram of a water heater according to an embodiment; FIG. It is a mimetic diagram of a water heater concerning the 1st modification of an embodiment. It is a schematic diagram of the water heater which concerns on the 2nd modification of embodiment. It is a schematic diagram of the water heater which concerns on the 3rd modification of embodiment.

Details of embodiments will be described with reference to the drawings. In the drawings below, the same or corresponding parts are denoted by the same reference numerals, and redundant description will not be repeated.

(Configuration of hot water device according to embodiment)
The configuration of the water heater according to the embodiment will be described below.

As shown in FIG. 1, the water heater according to the embodiment has a hot water supply pipeline 1, a circulation pipeline 2, a hot water supply pipeline 3, an additive generator 4, and a filter 5. . The water heater according to the embodiment further has a pump 7 and a water level sensor 8 . Although not shown in FIG. 1, the water heater according to the embodiment further includes a control section 9a and an operation section 9b (see FIG. 2).

The hot water supply pipeline 1 is a pipeline for supplying hot water. Hot water supply pipe 1 is connected at one end to a water supply. Hot water supply pipe line 1 is connected to a callan or the like at the other end. Hot water supplied from the water supply contains chlorine. The hot water supply pipeline 1 has a heat exchanger 11 . The heat exchanger 11 exchanges heat between hot water flowing through the heat exchanger 11 and combustion gas generated from the burner 11a. Burner 11a is, for example, a Bunsen burner.

The circulation conduit 2 is a conduit for circulating hot water (hereinafter referred to as “bathtub water”) stored in the bathtub 10 . The circulation line 2 is connected to a circulation adapter 6 at one end and the other end. More specifically, one end of circulation pipeline 2 is connected to the suction port of circulation adapter 6 , and the other end of circulation pipeline 2 is connected to the discharge port of circulation adapter 6 .

The circulation line 2 has a return line 21 , a forward line 22 , a heat exchanger 23 and a second valve 24 . The return line 21 is connected at one end to the suction port of the circulation adapter 6 and at the other end to the heat exchanger 23 . One end of the forward pipeline 22 is connected to the heat exchanger 23 , and the other end is connected to the discharge port of the circulation adapter 6 . The heat exchanger 23 exchanges heat between hot water flowing through the heat exchanger 23 and combustion gas generated from the burner 23a. The burner 23a is, for example, a Bunsen burner.

The second valve 24 is arranged in the circulation line 2 (return line 21) between a first position P1 and a second position P2, which will be described later. The second valve 24 is in a water-permeable state (fourth state) between the first position P1 and the second position P2, and a water-impermeable state (a fourth state) between the first position P1 and the second position P2. 5th state) can be switched. The second valve 24 is, for example, a ball valve type two-way valve, and the water flow state of the two-way valve can be switched by a stepping motor or the like.

The hot water supply pipe 3 connects the hot water supply pipe 1 and the circulation pipe 2 . The pouring pipeline 3 has a first valve portion 31, a first pipeline 32, a second pipeline 33, a third pipeline 34, a check valve 35, and a pouring valve 36. there is The first valve portion 31 is configured by a first valve 31a.

The first pipeline 32 is connected to the hot water supply pipeline 1 . The second pipeline 33 connects the first pipeline 32 and the circulation pipeline 2 . More specifically, the second pipeline 33 connects the first pipeline 32 and the return pipeline 21 . The third pipeline 34 connects the first pipeline 32 and the circulation pipeline 2 . More specifically, the third pipeline 34 connects the first pipeline 32 and the return pipeline 21 . The first valve 31a is arranged at a position where the first pipeline 32 and the second pipeline 33 and the third pipeline 34 are connected. From another point of view, the second pipeline 33 and the third pipeline 34 are connected to the first pipeline 32 by the first valve 31a.

A position where the second pipeline 33 and the circulation pipeline 2 (return pipeline 21) are connected is referred to as a "first position P1". A position where the third pipeline 34 and the circulation pipeline 2 (return pipeline 21) are connected is referred to as a "second position P2". The first position P1 is upstream of the second position P2 when the bath water is circulated through the circulation line 2 by the pump 7 .

The first valve portion 31 (more specifically, the first valve 31a) is in a state (first state) in which water can flow between the first pipeline 32 and the second pipeline 33, and A state (second state) in which water can flow between 32 and third pipeline 34 and a state (third state) in which water can flow between second pipeline 33 and third pipeline 34 are defined. configured to be switchable. The first valve 31a is, for example, a ball valve type three-way valve, and the water flow state of the three-way valve can be switched by a stepping motor or the like.

A check valve 35 is arranged in the third pipeline 34 . The check valve 35 does not allow water to flow from the second position P2, but allows water to flow to the second position P2. The check valve 35 is closer to the second position P2 than the filter 5 is.

A pouring valve 36 is arranged in the first pipeline 32 . By opening and closing the pouring valve 36, the first pipe line 32 is allowed to pass water. The pouring valve 36 is composed of, for example, an electromagnetic valve.

The additive generator 4 is a device that generates an additive for sterilizing hot water. The additive generated from the additive generator 4 is ozone (O ₃ ). The additive generator 4 is arranged in the second pipeline 33 . The additive generator 4 applies a voltage between a pair of electrodes inserted into the second pipe 33 to generate ozone in the hot water flowing through the second pipe 33 . Note that the additive generator 4 is not limited to a device that generates ozone. The additive generator 4 may generate silver ions as additives, for example.

A filter 5 is arranged in the third conduit 34 . That is, the additive generator 4 is closer to the first position P1 than the filter 5 on the route from the first position P1 to the second position P2 through the second pipe 33 and the third pipe 34. are placed. Filter 5 is configured to be able to remove the additive generated from additive generator 4 . The filter 5 may be configured to remove chlorine contained in hot water. Filter 5 is, for example, an activated carbon filter.

Circulation adapter 6 is attached to bathtub 10 . The circulation adapter 6 has an inlet through which bathtub water stored in the bathtub 10 is sucked, and an outlet through which the bathtub water circulated through the circulation conduit 2 is discharged into the bathtub 10 .

A pump 7 is arranged in the circulation line 2 . More specifically, the pump 7 is arranged in the return line 21 at a position closer to the suction port of the circulation adapter 6 than the first position P1. By driving the pump 7 , bathtub water is sucked from the suction port of the circulation adapter 6 into the return pipe 21 .

A water level sensor 8 is arranged in the circulation pipeline 2 . More specifically, the water level sensor 8 is arranged in the return line 21 . A water level sensor 8 detects the water level of bathtub water stored in the bathtub 10 . Water level sensor 8 detects the water level of bathtub water stored in bathtub 10 by detecting the pressure of hot water in circulation conduit 2 (return conduit 21).

The control unit 9a is composed of, for example, a microcontroller. As shown in FIG. 2, the controller 9a is connected to the second valve 24, the first valve 31a (the first valve portion 31), the hot water supply valve 36, the pump 7 and the water level sensor 8. As shown in FIG. The controller 9a is also connected to the burner 11a and the burner 23a.

The operation unit 9b is configured so that an instruction regarding the operation of the water heater can be input. This operation includes a hot water filling operation and a reheating operation. The operation unit 9b is connected to the control unit 9a, and signals corresponding to instructions input to the operation unit 9b are input to the control unit 9a.

<Modification>
Configurations of water heaters according to the first, second, and third modifications of the embodiment will be described below. Here, differences from the configuration of the water heater according to the embodiment will be mainly described, and redundant description will not be repeated.

As shown in FIG. 3 , in the water heater according to the first modified example of the embodiment, the additive generator 4 and the filter 5 are arranged in the second pipeline 33 . The additive generator 4 is closer to the first position P1 than the filter 5 is. As shown in FIG. 4, in the water heater according to the second modification of the embodiment, the additive generator 4 is arranged at the first position P1, and the filter 5 is arranged at the third pipe line 34. ing.

That is, the additive generator 4 is arranged closer to the first position P1 than the filter 5 on the route from the first position P1 to the second position P2 through the second pipe 33 and the third pipe 34. However, the arrangement of the additive generator 4 and the filter 5 is not limited.

As shown in FIG. 5, in the water heater according to the third modification of the embodiment, the first valve portion 31 is composed of a third valve 31b, a fourth valve 31c, and a fifth valve 31d. A third valve 31 b is arranged in the first pipeline 32 , a fourth valve 31 c is arranged in the second pipeline 33 , and a fifth valve 31 d is arranged in the third pipeline 34 . The third valve 31b, the fourth valve 31c and the fifth valve 31d are, for example, ball valve type two-way valves. In the water heater according to the third modified example of the embodiment, the first valve portion 31 opens the third valve 31b and the fourth valve 31c, and closes the fifth valve 31d to open the first state. Then, the third valve 31b and the fifth valve 31d are opened, and the fourth valve 31c is closed to enter the second state, and the fourth valve 31c and the fifth valve 31d are opened. At the same time, the third state is entered by closing the third valve 31b.

(Operation of water heater according to embodiment)
The operation of the water heater according to the embodiment will be described below.

<Hot water filling operation>
By inputting a hot water filling operation instruction to the operation part 9b, the control part 9a starts the hot water filling operation. Since the controller 9a controls the burner 11a to operate when the hot water filling operation is performed, the hot water supplied from one end of the hot water supply pipe 1 flows through the heat exchanger 11. The temperature is raised by exchanging heat with the combustion gas generated from the burner 11a.

During the filling operation, the control unit 9a controls the pouring valve 36 to be open. Further, while the hot water filling operation is being performed, the control unit 9a controls the first valve 31a to the second state and controls the second valve 24 to the fourth state. Therefore, the hot water supplied from the hot water supply pipeline 1 is supplied to the circulation pipeline 2 from the second position P2 via the first valve 31a, the first pipeline 32, the third pipeline 34 and the check valve 35. be. Chlorine contained in the hot water supplied from the hot water supply pipe 1 is removed by the filter 5 when flowing through the third pipe 34 .

The hot water from which chlorine has been removed and which is supplied to the circulation pipeline 2 passes through the circulation pipeline 2 (the return pipeline 21, the heat exchanger 23, and the forward pipeline 22) from the suction port and the discharge port of the circulation adapter 6. , is supplied to the bathtub 10 . The hot water filling operation is performed as described above.

In addition, when the hot water filling operation is performed, the control unit 9a controls the first valve 31a and the second valve 24 to the first state and the fourth state, respectively, and stops the additive generator 4. may be in control. As a result, hot water from which chlorine has not been removed can be supplied to the bathtub 10 .

<Reheating operation>
When a reheating operation instruction is input to the operation unit 9b, the control unit 9a starts the reheating operation. While the reheating operation is being performed, the controller 9a controls the pouring valve 36 to be closed. Further, when the reheating operation is being performed, the control unit 9a controls the first valve 31a to the third state and controls the second valve 24 to the fifth state. Therefore, the bathtub water sucked from the suction port of the circulation adapter 6 into the return pipe 21 by the controller 9a operating the pump 7 flows through the second pipe 33, the first valve 31a and the third pipe 34. from the first position P1 to the second position P2.

While the reheating operation is being performed, the control unit 9a controls the additive generator 4 to operate. Therefore, when the bathtub water flows through the second conduit 33, the bathtub water is sterilized by adding the additive to the bathtub water. Further, the added additive is removed by the filter 5 when the bath water flows through the third conduit 34 .

The bathtub water that has reached the second position P2 flows through the rest of the return line 21, the heat exchanger 23, and the forward line 22, and returns to the bathtub 10. When the reheating operation is being performed, the control unit 9a controls the burner 23a to operate. The temperature is raised by exchanging heat between them.

Since the reheating operation is performed as described above, the bathtub water circulated through the circulation line 2 and returned to the bathtub 10 is sterilized and the additives are removed. Note that the water heater according to the embodiment can also circulate bathtub water through the circulation conduit 2 (circulation operation) without using the reheating operation. The circulation operation is the same as the reheating operation except that the control unit 9a controls the burner 23a to stop.

<Washing operation>
When the water level sensor 8 detects that the water level of the bathtub water stored in the bathtub 10 after being drained from the bathtub 10 has fallen below a predetermined threshold value, the controller 9a cleans the circulation conduit 2. Start working.

While the circulation line 2 is being washed, the controller 9a controls the pouring valve 36 to be open. Further, when the circulation pipeline 2 is being washed, the control unit 9a controls the first valve 31a and the second valve 24 to the first state and the fourth state, respectively. Therefore, the hot water supplied from the hot water supply pipeline 1 is supplied to the circulation pipeline 2 via the first pipeline 32 , the first valve 31 a and the second pipeline 33 . Further, the control unit 9a controls the additive generator 4 to operate while the circulation line 2 is being washed. Therefore, when the hot water flows through the second pipeline 33, the additive is added to the hot water.

The hot water supplied to the circulation pipeline 2 is supplied to the bathtub 10 through the circulation pipeline 2 (the return pipeline 21, the heat exchanger 23, and the forward pipeline 22) from the suction port and the discharge port of the circulation adapter 6. be done. Since the control unit 9a controls the burner 11a to stop while the circulation pipe 2 is being washed, the hot water supplied from the hot water supply pipe 1 is not heated. .

Since the cleaning operation of the circulation pipeline 2 is performed as described above, the circulation pipeline 2 can be washed with hot water containing additives and chlorine.

<Modification>
The operation of the water heater according to the first modification and the second modification of the embodiment will be described below. Here, differences from the operation of the water heater according to the embodiment will be mainly described, and redundant description will not be repeated.

In the water heater according to the first modified example of the embodiment, the controller 9a controls the first valve 31a and the second valve 24 to the first state and the fourth state, respectively, while the hot water filling operation is being performed. Therefore, hot water is supplied to the circulation line 2 through the first line 32, the first valve 31a and the second line 33. Further, in the water heater according to the first modified example of the embodiment, the controller 9a controls the additive generator 4 to stop when the hot water filling operation is performed. Therefore, hot water from which chlorine has been removed is supplied to the bathtub 10 also in the hot water filling operation of the water heater according to the first modification of the embodiment.

The reheating operation of the water heater according to the first modification of the embodiment is the same as the reheating operation of the water heater according to the embodiment, except that the additive is removed when the bathtub water flows through the second pipe line 33. is similar to

In the cleaning operation of the water heater according to the first modification of the embodiment, chlorine is removed by the filter 5 when the hot water flows through the second pipe 33, so that the hot water flowing through the circulation pipe 2 contains chlorine. not present. Except for this point, the cleaning operation of the water heater according to the first modification of the embodiment is the same as the cleaning operation of the water heater according to the embodiment.

The hot water filling operation, reheating operation, and cleaning operation in the water heater according to the second modification of the embodiment are the same as the hot water filling operation, reheating operation, and cleaning operation in the water heater according to the embodiment, respectively.

The hot water filling operation, reheating operation, and cleaning operation in the water heater according to the third modification of the embodiment are the same as the hot water filling operation, reheating operation, and cleaning operation in the water heater according to the embodiment, respectively.

(Effect of the water heater according to the embodiment)
Below, the effect of the water heater according to the embodiment will be described.

In the reheating operation of the water heater according to the embodiment, when the bathtub water passes through the second conduit 33, the additive generated from the additive generator 4 can sterilize the bathtub water. , the additive can be removed from the bath water by the filter 5 when the bath water passes through the third conduit 34 .

In the cleaning operation of the water heater according to the embodiment, when hot water passes through the second pipe line 33, the additive generated by the additive generator 4 is added to the hot water. It is possible to wash the circulation pipe 2 with warm water, that is, hot water with high sterilizing power. As a result, when the additive is ozone, the bath water does not retain an ozone odor, and when the additive is silver ions, the bathtub 10 is less likely to darken.

Thus, according to the hot water apparatus according to the embodiment, it is possible to wash the circulation pipe 2 with hot water to which the additive has been added, and to allow the additive to remain in the bathtub 10 when the bathtub water is circulated. It is possible to sterilize the bath water with additives without any additives.

In the hot water supply operation of the water heater according to the embodiment, chlorine is removed from the hot water by the filter 5 when the hot water passes through the third pipeline 34, so that the hot water from which the chlorine has been removed is supplied to the bathtub 10. is possible. In addition, in the hot water supply operation of the water heater according to the embodiment, normal hot water can be supplied to the bathtub 10 by flowing hot water through the second pipe line 33 and not operating the additive generator 4 at that time. can. Thus, according to the water heater according to the embodiment, it is possible to select whether or not to remove chlorine from the hot water when performing the hot water supply operation.

When the additive generated by the additive generator 4 is ozone and the filter 5 is an activated carbon filter, the additive is well adsorbed on the filter 5, so the additive can be efficiently removed by the filter 5. .

The effect of the water heater according to the first modification of the embodiment is the same as the effect of the water heater according to the embodiment except that the hot water for washing the circulation pipe 2 does not contain chlorine in the washing operation. be. Also, the effect of the water heater according to the second modification of the embodiment is the same as the effect of the water heater according to the embodiment. Furthermore, the effect of the water heater according to the third modification of the embodiment is the same as the effect of the water heater according to the embodiment.

Although the embodiment of the present invention has been described as above, it is also possible to modify the above-described embodiment in various ways. Also, the scope of the present invention is not limited to the embodiments described above. The scope of the present invention is indicated by the scope of claims, and is intended to include all changes within the meaning and scope of equivalence to the scope of claims.

The above embodiments are particularly advantageously applied to water heaters that perform cleaning, reheating, and hot water supply operations.

1 Hot water supply pipe 2 Circulation pipe 3 Pouring pipe 4 Additive generator 5 Filter 6 Circulation adapter 7 Pump 8 Water level sensor 9a Control unit 9b Operation unit 10 Bathtub 11 Heat exchange vessel, 11a burner, 21 pipeline, 22 forward pipeline, 23 heat exchanger, 23a burner, 24 second valve, 31 first valve section, 31a first valve, 31b third valve, 31c fourth valve, 31d third 5 valves, 32 first line, 33 second line, 34 third line, 35 check valve, 36 pour valve, P1 first position, P2 second position.

Claims (12)

a hot water supply pipe for supplying hot water;
a circulation conduit for circulating bathtub water;
a pouring pipeline connecting the hot water supply pipeline and the circulation pipeline;
an additive generator that generates an additive that sterilizes hot water;
a filter that removes the additive;
a pump for circulating the bathtub water in the circulation conduit;
The pouring pipeline includes a first pipeline connected to the hot water supply pipeline, a second pipeline and a third pipeline connecting the circulation pipeline and the first pipeline, and a 1 valve part,
At the first position, which is the connection position between the second conduit and the circulation conduit, the bathtub water is pumped more by the pump than at the second position, which is the connection position between the third conduit and the circulation conduit. Located on the upstream side when circulating in the circulation pipeline,
the circulation line has a second valve positioned between the first position and the second position;
The first valve part is in a first state in which water can flow between the first pipeline and the second pipeline, and in which water can flow between the first pipeline and the third pipeline. It is configured to be switchable between a second state and a third state in which water can flow between the second pipeline and the third pipeline,
The second valve has a fourth state in which water can pass between the first position and the second position, and a fifth state in which water cannot pass between the first position and the second position. is configured to be able to switch between
The additive generator is closer to the first position than the filter on a path from the first position to the second position through the second pipeline and the third pipeline, hot water system. The water heater according to claim 1, wherein said additive generator is arranged in said second pipeline. The water heater according to claim 1 or 2, wherein said additive generator is arranged at said first position. The water heater according to any one of claims 1 to 3, wherein said filter is arranged in said third pipeline. The third pipeline includes a check valve that disables water flow from the second position and allows water flow to the second position,
The water heater according to any one of claims 1 to 4, wherein the check valve is closer to the second position than the filter on the path. hot water supplied from the hot water supply pipeline contains chlorine,
A water heater according to any one of claims 1 to 5, wherein the filter is configured to further remove the chlorine. The water heater according to any one of claims 1 to 6, wherein the additive generator generates ozone as the additive. The water heater according to any one of claims 1 to 7, wherein the filter is an activated carbon filter. further comprising a control unit,
The control unit switches the first valve unit to the first state and switches the second valve to the fourth state when the circulation pipe is washed with hot water supplied from the hot water supply pipe. , wherein the first valve portion is switched to the third state and the second valve is switched to the fifth state when the bath water is circulated in the circulation conduit. The water heater according to item 1. The control unit switches the first valve unit to the second state and switches the second valve to the fourth state when pouring hot water supplied from the hot water supply pipe into the bathtub. 10. The water heater of claim 9, wherein the water heater is configured to: The control unit switches the first valve unit and the second valve to the first state and the fourth state, respectively, when pouring hot water supplied from the hot water supply pipe into the bathtub, The water heater according to claim 9, wherein the operation of the additive generator is stopped. The water heater according to claim 1, wherein said additive generator and said filter are arranged in said second pipeline.

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