Bath hot water supply device

Abstract

To provide a bath water heater capable of improving sterilizing and cleaning functions by ozone water in a cleaning operation of a reheating passage.SOLUTION: A bath hot water supply device (1) includes a hot water supply passage (22) for supplying hot water by heating tap water by a hot water supply heating means (14), a reheating passage (32) including a circulation pump (31) for heating hot water in a bathtub (4) by a reheating heating means (15) and returning the hot water, a hot water supply passage (25) branched from the hot water supply passage and supplying the hot water to the bathtub via the reheating passage, a hot water supply valve (26) for opening and closing the hot water supply passage, and a flow rate detection means (27) of the hot water supply passage. A control means (20) for controlling a washing operation for circulating washing water from a molten metal pouring passage to a reheating passage, a flow passage switching valve (28) of the molten metal pouring passage, a bypass passage (29) branched from the molten metal pouring passage and connected to the molten metal pouring passage on the downstream side thereof, and an ozone water generating device (30) in the bypass passage are provided.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a hot water supply device for a bath that supplies hot water heated by using the heat of combustion gas to a hot water supply destination including a bathtub. [Background technology]

[0002] Bath water heaters equipped with the function of using the heat of combustion gas to supply hot water and reheat the bathtub water have been widely used. The reheating function involves returning the bathtub water to the bath water heater, heating it, and then returning the heated water to the bathtub. Because the reheating passage for this reheating can become contaminated with dirt and bacteria from the human body, and because the bathtub water is at a temperature suitable for the growth of bacteria, it is preferable to clean the reheating passage after draining the bathtub to keep it clean.

[0003] Therefore, as in Patent Document 1, for example, a bath water heater is known that automatically circulates clean hot water as cleaning water through a reheating passage (circulation piping) after draining the bathtub, and then discharges the hot water containing bath dirt that has accumulated in this reheating passage. Because the reheating passage is replaced with clean hot water after draining the bathtub, you can take a bath in a clean state every time. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6805676 Summary of the Invention [Problem to be solved by the invention]

[0005] In Patent Document 1, the hot water in the reheating passage is replaced with clean hot water supplied from the hot water supply passage (hot water supply piping), thereby suppressing the growth of bacteria and other microorganisms in the reheating passage. At this time, a circulation pump installed in the reheating passage is driven to send clean hot water to the downstream side of the circulation pump, where water is difficult to circulate due to high water resistance. However, there is no mention of removing or sterilizing dirt adhering to the reheating passage. Meanwhile, there is known technology for sterilizing and cleaning the reheating passage using, for example, ozone water, which has a bactericidal effect, as cleaning water.

[0006] Ozone water is generated by electrolyzing hot water supplied to the hot water supply passage, for example, by an ozonated water generator installed midway through the hot water supply passage. To achieve a sufficient ozone concentration for sterilization, hot water is supplied to the hot water supply passage at a low flow rate, and ozonated water is circulated at a low flow rate. Therefore, ozonated water cannot be circulated downstream of the circulation pump, where there is a large resistance to flow.

[0007] Therefore, it is conceivable to drive a circulation pump to send ozonated water downstream of the circulation pump, but in this case, the ozonated water is supplied at a low flow rate, making it difficult to circulate upstream of the circulation pump. Therefore, there has been a need for a technology that can sufficiently sterilize and clean the reheating passage with ozonated water.

[0008] Therefore, an object of the present invention is to provide a hot water supply device for a bath that can improve the sterilization and cleaning function of the reheating passage using ozone water. [Means for solving the problem]

[0009] The bath water heater of the invention of claim 1 comprises a hot water supply heating means for heating tap water, a hot water supply passage for supplying hot water heated by the hot water supply heating means, a reheating heating means for heating hot water in a bathtub, a reheating passage equipped with a circulation pump for circulating the hot water in the bathtub between the reheating heating means, a hot water supply passage branching from the hot water supply passage and supplying hot water to the bathtub via the reheating passage, a hot water supply valve for opening and closing the hot water supply passage, a flow rate detection means provided in the hot water supply passage, and a control means for controlling a cleaning operation of the reheating passage by opening the hot water supply valve when the bathtub is drained and circulating tap water or high-temperature hot water heated by the hot water supply heating means from the hot water supply passage as cleaning water. The bath hot water supply device has a flow path switching valve installed in the hot water supply passage, a bypass passage branched from the hot water supply passage at the flow path switching valve and connected upstream of the circulation pump, and an ozone water generation device installed in the bypass passage, and the control means is configured to switch the flow path switching valve to the bypass passage side during the cleaning operation to perform ozone water cleaning in which ozone water generated by the ozone water generation device is circulated through the reheating passage, and to drive the circulation pump while circulating ozone water after a predetermined amount or predetermined time of ozone water has circulated since the start of the ozone water cleaning.

[0010] According to the above configuration, the circulation pump is driven after a predetermined amount of ozonated water has been circulated for a predetermined time. When ozonated water cleaning is started at a flow rate lower than that when tap water or high-temperature hot water is circulated to achieve an ozone concentration sufficient for sterilization, the ozonated water has difficulty circulating downstream of the circulation pump in the reheating passage, where the reheating heating means is located and water flow resistance is high. Therefore, the ozonated water flows upstream of the circulation pump toward the bathtub. Then, after a predetermined amount of ozonated water has been circulated upstream of the circulation pump for a predetermined time, the circulation pump is driven to send the ozonated water from the upstream side downstream of the circulation pump. Therefore, ozonated water can be circulated throughout the entire reheating passage, improving the sterilization and cleaning functions of the ozonated water during the reheating passage cleaning operation.

[0011] The bath water heater of the invention of claim 2 is characterized in that, in the invention of claim 1, the specified amount is an amount equivalent to the passage volume upstream of the circulation pump to the bathtub, and the specified time is the time required for the flow of ozone water to reach an amount equivalent to the passage volume. According to the above configuration, by supplying an amount of ozone water equivalent to the passage volume up to the bathtub upstream of the circulation pump and then driving the circulation pump, a sufficient amount of ozone water can be circulated downstream of the circulation pump, thereby improving the sterilization and cleaning functions of the ozone water.

[0012] The bath water heater of the invention of claim 3 is characterized in that, in the invention of claim 1 or 2, the control means is configured to switch the flow path switching valve to the hot water supply passage side after the ozone water cleaning, which has driven the circulation pump for a predetermined driving time, is completed, and then to circulate tap water or high-temperature hot water before terminating the cleaning operation. According to the above configuration, the ozone water remaining in the reheating passage can be washed away together with dirt, thereby enhancing the effectiveness of the cleaning operation. [Effects of the Invention]

[0013] According to the hot water supply device for bathtub of the present invention, the sterilization and cleaning function of the reheating passage by ozone water can be improved. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a configuration diagram of a hot water supply system in which a bath hot water supply device according to an embodiment of the present invention is installed. [Figure 2] 10 is a flowchart of a cleaning operation control according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, the mode for carrying out the present invention will be described based on examples. [Example]

[0016] First, the configuration of a bath hot water supply device 1 will be described with reference to FIG. Bath water heater 1 is a combustion-type water heater that uses combustion heat to heat clean water supplied through water supply pipe 2 (as indicated by arrow W), and supplies hot water adjusted to a predetermined temperature to the outside through hot water supply pipe 3 (as indicated by arrow HW). This bath water heater 1 performs a hot water supply operation that supplies hot water at a preset hot water supply temperature. Bath water heater 1 also performs a bath filling operation that fills a bathtub 4 installed in the bathroom with hot water at a preset bath temperature up to a preset water level, and a reheating operation that heats the hot water in bathtub 4 and returns it to bathtub 4 to bring the water to the preset bath temperature.

[0017] The bath water heater 1 includes a fuel gas supply unit 10, a blower fan 11 that supplies air for combustion, a hot water burner 12 and a reheating burner 13 that burn the fuel gas, a hot water heat exchanger 14 (hot water heating means) that uses the heat of the high-temperature combustion gas generated by combustion to heat the tap water, and a reheating heat exchanger 15 (reheating heating means) that heats the hot water in the bathtub 4. The hot water heat exchanger 14 includes a primary heat exchanger 14a that recovers the sensible heat of the combustion gas and a secondary heat exchanger 14b that recovers the latent heat of the combustion gas. Similarly, the reheating heat exchanger 15 includes a primary heat exchanger 15a and a secondary heat exchanger 15b.

[0018] A water supply temperature sensor 17 for detecting the temperature of the clean water and a water supply flow rate sensor 18 for detecting the flow rate of the clean water are disposed in a water supply passage 16 that supplies clean water from the water supply pipe 2 to the hot water heat exchanger 14. A distribution valve 19 capable of adjusting the distribution ratio is disposed in the water supply passage 16 upstream of the water supply flow rate sensor 18.

[0019] The bath water heater 1 has a control unit 20 (control means) to control various operations based on the temperature detected by the water supply temperature sensor 17 and the flow rate detected by the water supply flow rate sensor 18. The bath water heater 1 is also equipped with a neutralizer 21 containing a neutralizing agent to neutralize and discharge acidic condensed water (drainage) formed when latent heat is recovered in the hot water supply heat exchanger 14 and the reheating heat exchanger 15 and moisture in the combustion gas is condensed. The drainage flows into the neutralizer 21 through a drain passage 21a. The neutralizer 21 discharges the neutralized drainage from a discharge passage 21b to maintain a constant water level and maintain a water-sealed state.

[0020] When water supply flow rate sensor 18 detects a flow rate equal to or greater than a preset minimum operating flow rate, control unit 20 causes combustion in hot water burner 12 to heat the clean water supplied by hot water heat exchanger 14. The heated hot water is supplied to hot water supply passage 22 and mixed with clean water from a water supply bypass passage 23 that is branched off from water supply passage 16 by distribution valve 19 and connected to hot water supply passage 22, thereby adjusting the temperature. Hot water supply passage 22 is equipped with a hot water temperature sensor 22a that detects the temperature of the adjusted hot water, and a hot water supply flow rate adjustment valve 24 (flow rate adjustment valve) that adjusts the flow rate of hot water supplied from hot water supply passage 22. Hot water supply flow rate adjustment valve 24 is normally fully open, and the flow rate is adjusted as necessary.

[0021] A molten metal pouring passage 25 branches off from the molten metal supply passage 22 via a molten metal supply flow rate adjustment valve 24. The molten metal pouring passage 25 is equipped with a molten metal pouring valve 26 that opens and closes the molten metal pouring passage 25, and a molten metal pouring flow rate sensor 27 (flow rate detection means).

[0022] A flow path switching valve 28 is provided midway along the molten metal pouring passage 25. A molten metal pouring bypass passage 29 (bypass passage) branches off from the molten metal pouring passage 25 at this flow path switching valve 28, and this molten metal pouring bypass passage 29 is connected to the molten metal pouring passage 25 downstream of the flow path switching valve 28. The flow path switching valve 28 is switched to either the molten metal pouring passage 25 side or the molten metal pouring bypass passage 29 side so as to select the molten metal pouring passage 25 or the molten metal pouring bypass passage 29 as the flow path for the molten metal pouring. The molten metal pouring bypass passage 29 has an ozone water generator 30 that electrolyzes the molten metal pouring passage 29 and produces ozone water when the flow path switching valve 28 is switched to the molten metal pouring bypass passage 29 side.

[0023] A reheating passage 32 equipped with a circulation pump 31 is connected to the reheating heat exchanger 15 to circulate the hot water in the bathtub 4. The bathtub 4 and the reheating passage 32 are connected by a reheating piping 8 connected to the circulation adapter 4a of the bathtub 4. The reheating passage 32 is composed of a return passage 32a equipped with a circulation pump 31 that returns the hot water in the bathtub 4 to the bath hot water supply device 1 and sends it to the reheating heat exchanger 15, and a bathtub forward passage 32b that returns the hot water that has circulated through the reheating heat exchanger 15 to the bathtub 4. The hot water supply passage 25 is connected to the return passage 32a via the circulation pump 31. The hot water supply passage 25 may be connected to the return passage 32a, and the circulation pump 31 may be installed in the return passage 32a downstream of this connection (on the reheating heat exchanger 15 side), or the hot water supply bypass passage 29 may be connected to the return passage 32a upstream of the circulation pump 31.

[0024] A water level sensor 33, for example, a water pressure sensor, is disposed in the reheating passage 32 as a water level detection means for detecting the water level in the bathtub 4. A bath temperature sensor 34 for detecting the temperature of the water in the bathtub 4 and a water flow switch 35 as a water flow detection means for detecting the water flow in the reheating passage 32 are provided downstream of the circulation pump 31 in the return passage 32a. The water temperature in the bathtub 4 is detected when the circulation pump 31 is driven, the water in the bathtub 4 flows through the reheating passage 32, and the water flow is detected by the water flow switch 35.

[0025] When hot water is supplied from the bath water heater 1 to, for example, the bathroom faucet 5 or shower 6, hot water adjusted to the set hot water supply temperature is supplied via the hot water supply pipe 3. When filling the bathtub 4, hot water adjusted to the set bath temperature is poured into the bathtub 4 via the hot water pouring passage 25, the reheating passage 32, and the reheating pipe 8. At this time, the hot water from the hot water pouring passage 25 is split into the upstream and downstream sides of the circulation pump 31, and flows through the reheating passage 32 respectively to be supplied to the bathtub 4. The control unit 20 calculates the amount of hot water to be poured into the bathtub 4 based on the flow rate detected by the hot water pouring flow rate sensor 27 and the pouring time, and ends the bath filling operation when the calculated amount of hot water poured reaches the amount corresponding to the set water level.

[0026] In addition, when the bathtub 4 is being reheated, the control unit 20 drives the circulation pump 31 and, while the water flow switch 35 detects water flow, burns the reheating burner 13, causing the hot water in the bathtub 4 circulating through the reheating passage 32 to be heated by the reheating heat exchanger 15 and returned to the bathtub 4. The bath water heater 1 has an operation terminal for starting the reheating operation and for performing various setting operations such as the hot water temperature setting, bath temperature setting, and water level setting. This operation terminal, for example, a bathroom remote control 7 installed in the bathroom, is communicatively connected to the control unit 20. In addition to multiple operation buttons, the bathroom remote control 7 is equipped with a display unit 7a that displays setting information related to various operations, an audio output unit 7b, and a human presence sensor 7c that detects people in the bathroom, allowing it to detect the presence of people in the bathroom and their entry and exit.

[0027] When the water level of bathtub 4 detected by water level sensor 33 drops below the height of circulation adapter 4a and becomes undetectable, control unit 20 detects this as draining of bathtub 4. Then, for example, if the system is set to perform a pipe cleaning operation (hereinafter abbreviated as cleaning operation) in which cleaning water is circulated from hot water supply passage 25 to reheating passage 32 and discharged into bathtub 4 when draining of bathtub 4 is detected, control unit 20 executes the cleaning operation.

[0028] The cleaning operation is performed, for example, in the following order: pre-cleaning, ozone water cleaning, and rinse cleaning. Pre-cleaning involves circulating tap water or high-temperature hot water to wash away dirt, and high-temperature hot water can also be used for sterilization. To achieve an ozone concentration with sufficient sterilizing effect, ozone water cleaning involves adjusting the distribution valve 19 so that the flow rate on the water supply bypass passage 23 is maximized, throttling the flow rate with the hot water flow rate adjustment valve 24, and preventing combustion by the hot water burner 12, and then circulating ozone water generated by the ozone water generator 30 to perform sterilization. Rinse cleaning involves washing away stagnant ozone water with tap water or high-temperature hot water.

[0029] Next, the cleaning operation control by the control unit 20 will be described based on the flowchart of Fig. 2. In the figure, Si (i = 1, 2, . . . ) represents a step.

[0030] When drainage of bathtub 4 is detected and cleaning operation control is started, in S1, hot water supply valve 26 is opened to start pre-cleaning, and the process proceeds to S2. At this time, if high-temperature hot water is circulated as cleaning water, combustion begins in hot water burner 13, and if clean water is circulated as cleaning water, distribution valve 19 is adjusted so that the water supply bypass passage 23 side is fully open to prevent combustion in hot water burner 12. Cleaning water is divided into the upstream and downstream sides (reheating heat exchanger 15 side) of circulation pump 31 and flows through reheating passage 32 respectively before being discharged into bathtub 4.

[0031] Next, in S2, it is determined whether pre-washing has ended. Pre-washing ends when the flow of wash water since the start of pre-washing reaches a preset flow rate. The flow rate of wash water is calculated based on the flow rate detected by the hot water supply flow rate sensor 27 and the flow time. If the determination in S2 is No, the process returns to S2 and pre-washing continues. If the determination in S2 is Yes, the process proceeds to S3, where the flow path switching valve 28 is switched to the hot water supply bypass passage 29 side, and the process proceeds to S4. At this time, the hot water supply valve 26 is closed, and if high-temperature hot water was being circulated, the combustion of the hot water supply burner 12 is stopped and the distribution valve 19 is adjusted so that the water supply bypass passage 23 side is fully open, and the hot water supply flow rate adjustment valve 24 is adjusted to throttle the flow rate.

[0032] Next, in S4, the hot water supply valve 26 is opened to start ozonated water cleaning, and the process proceeds to S5. Specifically, power for electrolysis is supplied to the ozonated water generator 30 to generate ozonated water from the clean water flowing through the hot water supply bypass passage 29, and this ozonated water is circulated through the reheating passage 32. To increase the ozone concentration of the ozonated water generated by the ozonated water generator 30, the hot water supply flow rate adjustment valve 24 is adjusted to reduce the flow rate of the clean water supplied to the hot water supply passage 25. Therefore, it is more difficult for ozonated water to flow to the side of the reheating heat exchanger 15 where water flow resistance is high, i.e., the downstream side of the circulation pump 31, compared to the upstream side of the circulation pump 31, and most of the ozonated water flows into the upstream side of the circulation pump 31.

[0033] In S5, it is determined whether the flow of ozone water from the start of ozone water cleaning has reached a predetermined amount or a predetermined time. The flow rate of ozone water is calculated based on the flow rate detected by the hot water supply flow rate sensor 27 and the flow time. The predetermined amount is, for example, an amount equivalent to the passage volume up to the bathtub 4 upstream of the circulation pump 31. The predetermined time is the time required for the flow rate of ozone water in ozone water cleaning to reach a flow rate equivalent to this passage volume. The predetermined amount or the predetermined time is set, for example, when the bath hot water supply device 1 is installed.

[0034] If the determination in S5 is No, the process returns to S5 and the flow of ozone water continues. If the determination in S5 is Yes, the process proceeds to S6, where the circulation pump 31 starts to operate while the flow of ozone water continues, and the process proceeds to S7. As the circulation pump 31 operates, the ozone water that has flowed into the upstream side of the circulation pump 31 is sent to the downstream side of the circulation pump 31, flows through the reheating heat exchanger 15 and the bathtub supply passage 32b, and is discharged into the bathtub 4.

[0035] Next, in S7, it is determined whether the operation of the circulation pump 31 has reached a predetermined operation time. The predetermined operation time is, for example, the time required for an amount of ozone water equivalent to the passage volume from the upstream side of the circulation pump 31 to the bathtub 4 to be sent downstream of the circulation pump 31, and is set by the passage volume and the driving rotation speed of the circulation pump 31. The driving rotation speed of the circulation pump 31 is set so that the ozone water can be sufficiently circulated by the operation of the circulation pump 31, and is set, for example, to be equal to or lower than the driving rotation speed during reheating operation.

[0036] If the determination in S7 is No, the process returns to S7, continuing to drive the circulation pump 31. If the determination in S7 is Yes, the process proceeds to S8, where the drive of the circulation pump 31 is stopped, and the process proceeds to S9. At this time, the hot water supply valve 26 is closed, the hot water supply flow rate adjustment valve 24 is returned to full open, and the generation of ozone water in the ozone water generator 30 is stopped. Then, in S9, the flow path switching valve 28 is switched to the hot water supply passage 25 side, and the process proceeds to S10.

[0037] Next, in S10, the hot water supply valve 26 is opened to start rinsing, and the process proceeds to S11. If high-temperature hot water is used as the cleaning water, the combustion of the hot water supply burner 12 is started, and the distribution ratio of the distribution valve 19 is adjusted to provide the specified high-temperature hot water. Next, in S11, it is determined whether the rinsing has ended. The rinsing ends when the flow of cleaning water since the start of the rinsing has reached a preset flow rate. The flow rate of cleaning water is calculated based on the flow rate detected by the hot water supply flow rate sensor 27 and the flow time. If the determination in S11 is No, the process returns to S11, and the rinsing continues. If the determination in S11 is Yes, the process proceeds to S12, where the hot water supply valve 26 is closed, and the cleaning operation control ends. If high-temperature hot water is used as the cleaning water, the combustion of the hot water supply burner 12 is stopped.

[0038] The operation and effects of the above-described hot water supply device for bath 1 will be described. The bath water heater 1 drives the circulation pump 31 after circulating a predetermined amount of ozonated water for a predetermined time. When ozonated water cleaning is initiated at a lower flow rate than when tap water or high-temperature hot water is circulated to achieve an ozone concentration sufficient for sterilization, the ozonated water has difficulty flowing downstream of the circulation pump 31 in the reheating passage 32, where the reheating heat exchanger 15 is located and water resistance is high. Instead, the ozonated water flows upstream of the circulation pump 31 toward the bathtub 4. After circulating the ozonated water upstream of the circulation pump 31 for a predetermined amount or time, the circulation pump 31 is driven to send the upstream ozonated water downstream of the circulation pump 31. This allows ozonated water to flow throughout the entire reheating passage 32, improving the sterilization and cleaning functions of the ozonated water during cleaning operation of the reheating passage 32.

[0039] The predetermined amount is an amount equivalent to the passage volume up to bathtub 4 upstream of circulation pump 31, and the predetermined time is the time required for the flow rate of ozone water to reach an amount equivalent to the passage volume upstream of circulation pump 31 in reheating passage 32. Therefore, by supplying an amount of ozone water equivalent to the passage volume up to bathtub 4 upstream of circulation pump 31 and then driving circulation pump 31, a sufficient amount of ozone water can be circulated, thereby improving the sterilizing and cleaning functions of the ozone water.

[0040] After the ozone water cleaning operation, in which the circulation pump 31 is driven for a preset driving time, the control unit 20 switches the flow path switching valve 28 to the hot water supply passage 25 side, allowing tap water or high-temperature hot water to circulate, and then ends the cleaning operation. Therefore, the ozone water remaining in the reheating passage 32 can be washed away together with any adhering dirt, thereby improving the effectiveness of the cleaning operation.

[0041] In addition, a person skilled in the art can implement the present invention in a form in which various modifications are added to the above-described embodiment without departing from the spirit of the present invention, and the present invention includes such modifications. [Explanation of symbols]

[0042] 1: Bath water heater 2: Water supply piping 3: Hot water supply piping 4: Bathtub 5: Karan 6: Shower 7: Bathroom remote control 8: Reheating piping 10: Fuel gas supply unit 11: Blower fan 12: Hot water burner 13: Reheat burner 14: Hot water heat exchanger (hot water heating means) 15: Reheating heat exchanger (additional heating means) 16:Water supply passage 17: Water supply temperature sensor 18: Water supply flow sensor 19: Distribution valve 20: Control unit (control means) 21: Neutralizer 22: Hot water passage 23: Water supply bypass passage 24: Flow control valve 25: Pouring passage 26: Meltwater valve 27: Pouring flow rate sensor (flow rate detection means) 28: Flow path switching valve 29: Pouring bypass passage (bypass passage) 30: Ozone water generator 31: Circulation pump 32: Reburning passage 32a: Return passage 32b: Passage to the bathtub 33: Water level sensor 34: Bathtub temperature sensor 35: Water flow switch

Claims

1. a hot water supply passage for supplying hot water heated by the hot water supply heating means; a reheating heating means for heating hot water in a bathtub; a reheating passage equipped with a circulation pump for circulating the hot water in the bathtub between the reheating heating means; a hot water filling passage branching from the hot water supply passage and supplying hot water to the bathtub through the reheating passage; a hot water filling valve for opening and closing the hot water filling passage; a flow rate detection means provided in the hot water filling passage; and a control means for controlling a cleaning operation of the reheating passage by opening the hot water filling valve when the bathtub is drained, and circulating clean water or high-temperature hot water heated by the hot water supply heating means from the hot water filling passage as cleaning water. a flow path switching valve provided in the molten metal pouring passage; a bypass passage branched from the molten metal pouring passage at the flow path switching valve and connected to the upstream side of the circulation pump; and an ozone water generating device provided in the bypass passage, The control means is configured to perform ozone water cleaning in the cleaning operation by switching the flow path switching valve to the bypass passage side to circulate the ozone water generated by the ozone water generation device through the reheating passage, and to drive the circulation pump while circulating the ozone water after a predetermined amount or time of ozone water has circulated from the start of the ozone water cleaning.

2. The bath water heater described in claim 1, characterized in that the specified amount is an amount equivalent to the passage volume upstream of the circulation pump to the bathtub, and the specified time is the time required for the flow of ozone water to reach an amount equivalent to the passage volume.

3. The bath water heater device described in claim 1 or 2, characterized in that after the ozone water cleaning operation, which has driven the circulation pump for a predetermined driving time, is completed, the control means switches the flow path switching valve to the hot water supply passage side, allowing tap water or high-temperature hot water to circulate, and then terminates the cleaning operation.

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