JP2023145169A - water heater - Google Patents

Abstract

To provide a water heater capable of being expected to extend a service life of a UV irradiation device.SOLUTION: A water heater according to the present disclosure comprises: a circulation device that circulates hot water in a pipe; a micro bubble generation device that can generate micro bubbles when hot water passes therethrough; a UV irradiation device that is arranged on a downstream side with respect to the micro bubble generation device in a hot water circulation direction and irradiates the hot water with UV; and a control unit that starts driving the UV irradiation device at the same time as or after the micro bubble generation device starts generating micro bubbles in conjunction with the drive of the circulation device.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to a water heater.

The hot water supply device disclosed in Patent Document 1 below has a water channel, an ultraviolet light source, an ultraviolet irradiation means for irradiating water passing through the waterway with ultraviolet rays, a heating means for heating the water, and a control unit that adjusts the irradiation intensity of the ultraviolet irradiation means. The apparatus includes a deterioration detection means for detecting deterioration, and a control means for operating the heating means in a heat sterilization mode when deterioration in irradiation intensity is detected. The temperature of the water heated by the heating means in the heat sterilization mode is higher than when no deterioration in irradiation intensity is detected.

International Publication No. 2018/073866

Conventionally, in water heaters that use UV (ultraviolet light) to sterilize hot water passing through pipes, in order to improve sterilization performance, it has been necessary to increase the irradiation intensity of the UV irradiation device or shorten the wavelength. In order to ensure a high irradiation intensity, the issue is that the use of a high-output UV irradiation device increases the size and cost of the cooling structure or equipment. Further, when an LED capable of outputting short wavelength light is used as a UV irradiation device, problems arise such as shortened life due to increased input current, or increased size and cost of the cooling device.

The present disclosure has been made to solve the above-mentioned problems, and aims to provide a water heater that can be expected to extend the life of a UV irradiation device.

The hot water supply device according to the present disclosure includes a circulation device that circulates hot water in piping, a fine bubble generation device that can generate fine bubbles when the hot water passes through, and a fine bubble generation device that is arranged in a direction in which hot water circulates. The UV irradiation device, which is placed on the downstream side and irradiates UV onto hot water, is linked to the drive of the circulation device, and at the same time as the micro-bubble generator starts generating micro-bubbles, or starts micro-bubble generation. A control section that later starts driving the UV irradiation device is provided.

According to the present disclosure, it is possible to provide a water heater that can be expected to extend the life of a UV irradiation device.

1 is a diagram showing a water heater according to a first embodiment; FIG. FIG. 2 is a longitudinal cross-sectional view showing an example of the structure of a microbubble generator. It is a perspective view showing an example of the structure of a UV irradiation device. 4 is a longitudinal cross-sectional view of the UV irradiation device shown in FIG. 3. FIG. 5 is a timing chart showing an example of drive timing of a UV irradiation device in the water heater according to the first embodiment. FIG. 3 is a diagram showing a water heater according to a second embodiment. FIG. 7 is a diagram showing a water heater according to a third embodiment. FIG. 3 is a diagram showing a water heater according to a fourth embodiment.

Embodiments will be described below with reference to the drawings. Common or corresponding elements in each figure are denoted by the same reference numerals, and description thereof will be simplified or omitted. In the following description, descriptions such as "water", "hot water", "warm water", "hot water", etc. basically mean liquid water, and can include anything from cold water to hot water. Further, the configurations shown in the embodiments described below are examples of technical ideas according to the present disclosure, and can be combined with another known technology, or can be combined with multiple technologies described in the present disclosure. It is also possible to combine ideas. Further, it is also possible to omit or change a part of the configuration without departing from the gist of the present disclosure.

Embodiment 1.
FIG. 1 is a diagram showing a water heater 1A according to the first embodiment. The hot water supply device 1A of the first embodiment has a function of supplying hot water to the bathtub 10. In the following description, the hot water stored in the bathtub 10 may be referred to as "bath water." Furthermore, in the present disclosure, "sterilization" corresponds to at least one of reducing the number of microorganisms such as bacteria and suppressing the growth of microorganisms.

As shown in FIG. 1, the water heater 1A includes a heat source unit 2 that heats water and a tank unit 3 having a hot water storage tank 5. The hot water supply device 1A of this embodiment corresponds to a hot water storage type hot water supply device that stores hot water in a hot water storage tank 5. In this embodiment, such a hot water storage type hot water supply device will be described as an example, but the present disclosure is also applicable to hot water supply devices other than the hot water storage type hot water supply device (for example, an instantaneous hot water supply device).

The heat source unit 2 may be of any type, such as a heat pump type, a type equipped with an electric heating device, a type equipped with a combustion type heating device, or a type using solar heat. The heat source unit 2 may be placed outdoors.

In this embodiment, a hot water storage tank 5, a control unit 6, a circulation pump 11, a reheating heat exchanger 12, a microbubble generator 21, and a UV irradiation device are installed inside the casing of the tank unit 3. 22 are provided. The tank unit 3 may be placed outdoors or indoors.

The hot water storage tank 5 stores hot water heated by the heat source unit 2. Due to the difference in the density of water depending on the temperature, temperature stratification can be formed in the hot water storage tank 5, with the upper side having a higher temperature and the lower side having a lower temperature. A water supply pipe 7 is connected to the lower part of the hot water storage tank 5. Water supplied from a water source, such as a water supply, flows into the hot water storage tank 5 through a water supply pipe 7.

The first passage 8 connects the lower part of the hot water storage tank 5 and the water inlet of the heat source unit 2. The second passage 9 connects the hot water outlet of the heat source unit 2 and the upper part of the hot water storage tank 5. During boiling operation, which is an operation in which water in the hot water storage tank 5 is heated by the heat source unit 2, the following occurs. Water in the lower part of the hot water storage tank 5 is sent to the heat source unit 2 through the first passage 8. The hot water heated by the heat source unit 2 passes through the second passage 9 and flows into the upper part of the hot water storage tank 5.

The reheating heat exchanger 12 can heat the bath water circulating from the bathtub 10. The reheating heat exchanger 12 may heat the bath water by exchanging heat between the hot water stored in the hot water storage tank 5 and the bath water. Alternatively, the reheating heat exchanger 12 may heat the bath water by exchanging heat between the hot water generated by the heat source unit 2 and the bath water.

The reheating heat exchanger 12 is connected to the bathtub 10 through a reheating circuit. The reheating circuit includes a reheating forwarding pipe 13 and a reheating return pipe 14. The hot water discharge section 15 connects the reheating outgoing piping 13 and the reheating return piping 14 to the bathtub 10, respectively. The hot water discharge part 15 is attached to the side surface of the bathtub 10, for example. The hot water discharge part 15 includes a suction port that sucks the bath water in the bathtub 10 into the reheating piping 13 and a discharge port that discharges the bath water flowing through the reheating return piping 14 into the bathtub 10.

The reheating piping 13 connects the suction port of the hot water discharge part 15 and the bath water inlet of the reheating heat exchanger 12. The reheating return pipe 14 connects the bath water outlet of the reheating heat exchanger 12 and the discharge port of the hot water discharge section 15 .

The circulation pump 11 is a pump for circulating bath water between the bathtub 10 and the reheating heat exchanger 12. That is, the circulation pump 11 corresponds to a circulation device that circulates bath water in the piping of the reheating circuit. In the illustrated example, a circulation pump 11 is provided in the reheating piping 13.

The hot water filling pipe 16 is a pipe for supplying hot water stored in the hot water storage tank 5 to the bathtub 10. The hot water filling pipe 16 connects the hot water storage tank 5 and a branch part 17 provided in the middle of the reheating pipe 13. When filling with hot water, hot water stored in the hot water storage tank 5 is supplied into the bathtub 10 through a hot water filling pipe 16, a reheating forwarding pipe 13, and a reheating return pipe 14. The hot water filling pipe 16 is provided with a flow rate adjustment valve (not shown) that adjusts the amount of hot water supplied from the hot water storage tank 5 to the bathtub 10 .

A drain plug 18 is provided at the bottom of the bathtub 10. When draining the inside of the bathtub 10, when the drain plug 18 is opened, the bath water in the bathtub 10 is discharged from the drain plug 18 to the outside of the bathtub 10.

The control unit 6 corresponds to a control means that controls the operation of the water heater 1A. The control unit 6 may include, for example, at least one memory and at least one processor. Further, the control unit 6 may include a storage circuit, an arithmetic processing unit, and an input/output circuit. The control unit 6 may have a timer function for managing date and time. Note that the configuration is not limited to the configuration in which the operation is controlled by a single control unit 6 as shown in the figure, but a configuration in which the operation is controlled by a plurality of control devices working together may be adopted.

A sensor system for detecting the operating state of the water heater 1A is connected to the input side of the control unit 6. This sensor system includes a plurality of sensors that detect the temperature of water flowing through the pipes of each part, the water pressure, the amount of dirt inside the pipes, and the like. Further, the output side of the control unit 6 is connected to a flow rate adjustment valve of the hot water filling pipe 16, a circulation pump 11, a flow rate adjustment valve and an on-off valve of the micro bubble generator 21, a UV irradiation device 22, and the like. Further, the control unit 6 can adjust the water level in the bathtub 10 by supplying hot water in the hot water storage tank 5 to the bathtub 10 via the hot water filling pipe 16 and the reheating circuit.

Bidirectional communication is possible between the control unit 6 and the remote controller 4 through wired or wireless communication. The remote control 4 is an example of a user interface. The control unit 6 and the remote controller 4 may be able to communicate via a network. In this embodiment, the remote control 4 may be installed in the bathroom.

The remote control 4 includes a display section 4a and an operation section 4b. The display section 4a may be, for example, a liquid crystal display or an organic EL display. The display unit 4a can display, for example, information regarding the status of the water heater 1A, information regarding the settings of the water heater 1A, and the like. The display section 4a corresponds to a notification means for notifying the user of information. The operation unit 4b may include buttons, dials, keys, etc. for user operation. The display section 4a may be a touch screen that also functions as an operation section. The remote control 4 may further include a speaker, a microphone, and the like. The remote control 4 in this embodiment may include a notification means other than the display section 4a, such as a voice guidance device.

A plurality of remote controllers 44 may be able to communicate with the control unit 6. Instead of or in addition to the remote control 44, other user interfaces may be used, such as a mobile device such as a smartphone, or a smart speaker.

In this embodiment, the microbubble generator 21 and the UV irradiation device 22 are placed in the middle of the reheating return pipe 14 . The micro-bubble generator 21 can generate micro-bubbles when bath water passes through it. According to the microbubble generator 21, air can be microbubbled and mixed into the hot water returned to the bathtub 10 from the reheating circuit.

The UV irradiation device 22 is arranged downstream of the microbubble generator 21 in the bath water circulation direction. The UV irradiation device 22 irradiates the passing bath water with UV.

When the circulation pump 11 operates, bath water is circulated as follows. Bath water in the bathtub 10 is sucked into the reheating piping 13 from the suction port of the hot water discharge part 15. The bath water passes through the circulation pump 11 and the reheating heat exchanger 12, passes through the reheating return pipe 14, and is discharged into the bathtub 10 from the outlet of the hot water discharge section 15. When the bath water passes through the reheating return pipe 14, it passes through the micro bubble generator 21 and the UV irradiation device 22. The bath water discharged into the bathtub 10 from the discharge port of the hot water discharge part 15 is sucked into the reheating piping 13 from the suction port of the hot water discharge part 15, and circulates through the reheating circuit again.

FIG. 2 is a longitudinal cross-sectional view showing an example of the structure of the microbubble generator 21. As shown in FIG. The microbubble generator 21 shown in FIG. 2 includes a housing 23, a fixed blade 24, a gas introduction part 25, and the like. The housing 23 is formed into a cylindrical shape. A housing 23 is connected in the middle of the reheating circuit. Bath water flows inside the housing 23 in the direction of arrow A in FIG. A reduced diameter portion 26 that is smaller in diameter than both sides in the axial direction is formed in the middle of the housing 23 in the axial direction. The fixed blades 24 generate a swirling flow SF in the hot water flowing inside the housing 23. The fixed blade 24 is made of, for example, a spirally curved plate. A plurality of fixed blades 24 are provided on the inner circumferential surface of the housing 23 upstream of the reduced diameter portion 26 .

The gas introduction section 25 introduces gas into the reduced diameter section 26 of the housing 23 from the outside, and is configured with a pipe or the like through which the gas passes. The gas introduced by the gas introduction section 25 may be, for example, air or carbon dioxide. The piping constituting the gas introduction section 25 is provided with a flow rate adjustment valve (not shown) that adjusts the flow rate of gas and an on-off valve (not shown) that opens and closes the piping.

When hot water is flowing inside the housing 23, when the control unit 6 opens the on-off valve of the gas introduction part 25, the gas flowing from the gas introduction part 25 mixes with the swirling flow SF, so that fine particles are mixed into the hot water. Bubbles B are generated. When the control section 6 closes the on-off valve of the gas introduction section 25, the inflow of gas from the gas introduction section 25 is stopped, and therefore the generation of the fine bubbles B is stopped.

Although FIG. 2 illustrates a Venturi-type micro-bubble generator 21 in which the inner diameter of the housing 23 is once reduced from upstream to downstream and then expanded, the present disclosure describes other methods of micro-bubble generation. Device 21 may also be used.

The micro bubble generator 21 may generate ultra fine bubbles with a diameter of less than 1 μm as the micro bubbles B, may generate micro bubbles with a diameter of 1 μm to 100 μm, or may generate ultra fine bubbles and micro bubbles. Both may occur. The smaller the diameter of the microbubbles B, the more effective the bather will be in promoting blood circulation and raising body temperature, and in removing dirt from the skin surface without washing with detergent. On the other hand, the larger the diameter of the microbubbles B, the better the effect of diffusing UV light. In view of such matters, the microbubble generator 21 may have a mechanism for changing the average diameter of the microbubble B to be generated. For example, the micro-bubble generator 21 may change the average diameter of the micro-bubbles B to be generated by adjusting the flow rate of the gas using a flow rate adjustment valve of the gas introduction section 25. The control unit 6 makes the average diameter of the fine bubbles B generated by the fine bubble generating device 21 relatively small when a person is bathing in the bathtub 10, and stops generating fine bubbles after the person has finished bathing in the bathtub 10. The average diameter of the microbubbles B generated by the device 21 may be relatively large.

FIG. 3 is a perspective view showing an example of the structure of the UV irradiation device 22. As shown in FIG. FIG. 4 is a longitudinal cross-sectional view of the UV irradiation device 22 shown in FIG. The UV irradiation device 22 shown in these figures includes a UV-LED module 27, a flow path section 28, an inlet section 30, and an outlet section 31.

The UV-LED module 27 outputs ultraviolet light, that is, light containing wavelengths in the UV region. The flow path portion 28 forms a flow path through which bath water flows while being irradiated with UV light. The irradiation section 29 transmits the UV emitted from the UV-LED module 27 to the channel section 28 . Further, the irradiation section 29 protects the UV-LED module 27 from bath water flowing through the flow path section 28. The inflow section 30 allows bath water to flow into the channel section 28 from the side with respect to the UV irradiation direction from the irradiation section 29 . The discharge section 31 discharges the bath water that has been sterilized by receiving UV light in the channel section 28 to the outside of the channel section 28 .

The UV-LED module 27 includes an ultraviolet LED using a light emitting diode as an ultraviolet light source. The ultraviolet LED of the UV-LED module 27 may have a center wavelength between 220 nm and 300 nm. Ultraviolet light having a wavelength of 220 nm to 300 nm not only acts on nucleic acids, which are the protoplasm of bacteria, and deprives them of their ability to proliferate, but also has the effect of destroying the protoplasm and killing the bacteria. Therefore, by irradiating ultraviolet rays with such wavelengths, the sterilization effect is further improved. The ultraviolet LED of the UV-LED module 27 is turned on by direct current supplied from the power supply section. The UV-LED module 27 has a heat radiation section 32 on the opposite side from the flow path section 28. By dissipating heat by the heat dissipation section 32, it is possible to suppress the temperature rise of the ultraviolet LED due to energization.

As described above, the fine bubble generator 21 is incorporated into the piping path that forms the reheating circuit, and is installed downstream of the reheating heat exchanger 12. When the circulation pump 11 is operated, the bath water stored in the bathtub 10 passes through the microbubble generator 21 and contains microbubbles B made of air, and then flows into the bathtub 10 again. Supplied.

The UV irradiation device 22 is incorporated into a piping path that forms a reheating circuit, and is installed downstream of the microbubble generator 21 . When the circulation pump 11 is operated, the bath water stored in the bathtub 10 passes through the UV irradiation device 22, receives UV light emitted from the ultraviolet source of the UV-LED module 27, and removes the water contained in the bath water. Bacteria that may be present are sterilized. The sterilized bath water is supplied into the bathtub 10. The bath water in the bathtub 10 is repeatedly passed through the UV irradiation device 22. This makes it possible to sterilize the entire bath water in the bathtub 10.

In this embodiment, the fine bubble generator 21 is placed on the upstream side with respect to the bath water circulation direction, and the UV irradiation device 22 is placed on the downstream side with respect to the bath water circulation direction, so that fine bubbles are generated on the upstream side. The layout is such that the microbubbles B mixed in the bath water in the device 21 can be supplied to the UV irradiation device 22 on the downstream side. Thereby, the microbubbles B that have flowed into the UV irradiation device 22 can diffuse UV light inside the UV irradiation device 22. As a result, UV light can be evenly irradiated evenly, even if the bacteria are not biased due to the flow velocity distribution inside the UV irradiation device 22. Therefore, the sterilization performance when passing through the UV irradiation device 22 can be improved without increasing the output of UV light.

Moreover, in this embodiment, the fine bubble generator 21 is arranged downstream of the reheating heat exchanger 12 in the bath water circulation direction. Therefore, the fine bubbles B can be allowed to flow into the UV irradiation device 22 without expanding or coalescing. Therefore, the sterilization efficiency when the bath water passes through the UV irradiation device 22 can be further improved. On the other hand, assuming that the fine bubble generator 21 is placed upstream of the reheating heat exchanger 12, the fine bubbles B flowing into the reheating heat exchanger 12 are heated and expanded. The bubbles coalesce and the bubble diameter becomes coarse. For this reason, it may be difficult to improve the sterilization efficiency.

The control unit 6 may control the fine bubble generator 21 and the UV irradiation device 22 to be driven when the reheating heat exchanger 12 is not heating the bath water. This makes it possible to more reliably prevent the fine bubbles B from heating, expanding, and forming bubbles, which is more advantageous in preventing the bubble diameter from becoming coarser, making it possible to further improve sterilization efficiency. becomes.

FIG. 5 is a timing chart showing an example of drive timing of the UV irradiation device 22 in the water heater 1A according to the first embodiment. The hot water supply device 1A of this embodiment includes a bathing detection means for detecting that a person has taken a bath in the bathtub 10. The bathing detection means may use a water level sensor that detects the water level in the bathtub 10. In this case, the control unit 6 can detect that a person has taken a bath in the bathtub 10 by detecting changes in the water level in the bathtub 10 using a water level sensor. In the present disclosure, the act of a person taking a bath in the bathtub 10 coming out of the bathtub 10 is referred to as "leaving the bath." The control unit 6 can detect leaving the bath, for example, by detecting fluctuations in the water level in the bathtub 10 using a water level sensor.

In the example shown in FIG. 5, when the bathing detection means detects bathing, the control unit 6 starts the generation of microbubbles by the microbubble generator 21 in conjunction with the driving of the circulation pump 11, which is a circulation device. After that, the control unit 6 starts driving the UV irradiation device 22. According to this embodiment, high sterilization performance can be achieved with a relatively short UV output time, so it is expected that the life of the UV irradiation device 22 will be extended. Note that the control unit 6 may start driving the UV irradiation device 22 at the same time that the micro-bubble generator 21 starts generating micro-bubbles in conjunction with the driving of the circulation device. Further, the control unit 6 may control the UV irradiation device 22 to output an intermittent pulse as the UV irradiation pattern. This makes it possible to further extend the life of the UV irradiation device 22.

Further, in this embodiment, the control unit 6 starts driving the UV irradiation device 22 after the bathing detection means detects bathing. Bacteria or dirt in the bath water infiltrates into the piping especially when a person takes a bath in the bathtub 10 and the bath water is circulated through the reheating circuit due to reheating or the like. According to this embodiment, bacteria or dirt that has entered the pipe in this way can be efficiently sterilized by the UV irradiation device 22. On the other hand, if the bathing detection means does not detect bathing, the control unit 6 does not start driving the UV irradiation device 22. Therefore, the present embodiment is more advantageous in achieving high sterilization performance with a short UV output time, and can be expected to further extend the life of the UV irradiation device 22.

In the example shown in FIG. 5, when a predetermined post-bathing UV irradiation time has elapsed after the bathing detection means detects leaving the bath, the control unit 6 stops driving the circulation pump 11 and causes the fine bubble generator 21 to The generation of fine bubbles is stopped, and the driving of the UV irradiation device 22 is stopped. The time from when the bathing detection means detects taking a bath to when it detects leaving the bath is referred to as "bathing time." It can be said that the longer the bathing time, the more bacteria or dirt contained in the bathing water tends to increase. Therefore, the control unit 6 may control the UV irradiation time after bathing to be longer when the bathing time is relatively long than when the bathing time is relatively short. This makes it possible to more reliably sterilize and clean the bath water in the bathtub 10 before the next person takes a bath.

Embodiment 2.
Next, a second embodiment will be described with reference to FIG. 6, focusing on differences from the first embodiment described above, and common explanations will be simplified or omitted. Further, elements common to or corresponding to those described above are given the same reference numerals.

FIG. 6 is a diagram showing a water heater 1B according to the second embodiment. As shown in FIG. 6, in the hot water supply apparatus 1B of the present embodiment, a fine bubble generator 21 and a UV irradiation device 22 are arranged downstream of the hot water discharge section 15 in the bath water circulation direction. In the illustrated example, a fine bubble generator 21 and a UV irradiation device 22 are arranged in the middle of the reheating piping 13 between the suction port of the hot water discharge part 15 and the circulation pump 11. A microbubble generator 21 and a UV irradiation device 22 are arranged outside the tank unit 3. A microbubble generator 21 and a UV irradiation device 22 may be placed near the bathtub 10. Instead of the illustrated example, the micro bubble generator 21 and the UV irradiation device 22 may be arranged within the tank unit 3.

In this embodiment, immediately after bath water contaminated with bacteria or dirt during bathing is circulated by reheating or the like, and enters the reheating piping 13 from the bathtub 10 through the hot water discharge part 15. , and are sterilized and cleaned by the UV irradiation device 22. Therefore, it is possible to more reliably prevent bacteria or dirt from adhering to the inside of the pipe. Moreover, when the bath water is discharged into the bathtub 10 again after being circulated through the reheating circuit, it is discharged into the bathtub 10 as clean bath water. Therefore, the user can take a bath in clean bath water.

Embodiment 3.
Next, a third embodiment will be described with reference to FIG. 7, focusing on the differences from the first embodiment described above, and common explanations will be simplified or omitted. Further, elements common to or corresponding to those described above are given the same reference numerals.

FIG. 7 is a diagram showing a water heater 1C according to the third embodiment. As shown in FIG. 7, in the hot water supply device 1C of the present embodiment, the fine bubble generator 21 is arranged upstream with respect to the hot water discharge section 15 in the bath water circulation direction, and the fine bubble generator 21 is disposed on the downstream side with respect to the hot water discharge section 15. A UV irradiation device 22 is arranged at. In the illustrated example, a fine bubble generator 21 is arranged in the reheating return piping 14 between the reheating heat exchanger 12 and the discharge port of the hot water discharge section 15, and the fine bubble generator 21 is arranged between the reheating heat exchanger 12 and the discharge port of the hot water discharge section 15 and the circulation pump 11. A UV irradiation device 22 is arranged in the reheating piping 13 between. A microbubble generator 21 and a UV irradiation device 22 are arranged outside the tank unit 3. A microbubble generator 21 and a UV irradiation device 22 may be placed near the bathtub 10. Instead of the illustrated example, at least one of the microbubble generator 21 and the UV irradiation device 22 may be disposed within the tank unit 3.

In this embodiment, the fine bubbles B generated by the fine bubble generator 21 are discharged into the bathtub 10 while maintaining the fine size after generation. This makes it possible to more effectively ensure the effects of hot bathing on the human body. In addition, when the bath water returns from the bathtub 10 to the piping of the reheating circuit, the UV irradiation device 22 is applied immediately after the bath water containing bacteria or dirt enters the piping while leaving the microbubbles B in the bath water. Sterilized and cleaned. Therefore, it is possible to more reliably prevent bacteria or dirt from adhering to the inside of the pipe. Moreover, when the bath water is discharged into the bathtub 10 again after being circulated through the reheating circuit, it is discharged into the bathtub 10 as clean bath water. Therefore, the user can take a bath in clean bath water.

Embodiment 4.
Next, with reference to FIG. 8, Embodiment 4 will be described, focusing on differences from Embodiment 1 described above, and common explanations will be simplified or omitted. Further, elements common to or corresponding to those described above are given the same reference numerals.

FIG. 8 is a diagram showing a water heater 1D according to the fourth embodiment. As shown in FIG. 8, in the water heater 1D of the present embodiment, the control unit 6 controls the circulation pump while the drain valve 18 is being opened and the bath water in the bathtub 10 is being discharged from the drain valve 18. 11 and the UV irradiation device 22, the microbubble generator 21 generates microbubbles B, and the UV irradiation device 22 irradiates the bath water containing the microbubbles B with UV.

According to this embodiment, when the bath water in the bathtub 10 is drained, the bath water containing the microbubbles B circulates through the piping of the reheating circuit, so that the piping can be cleaned. Furthermore, when the bath water mixed with the microbubbles B passes through the UV irradiation device 22, the dirt captured by the microbubbles B is irradiated with UV, thereby decomposing or making the dirt microscopic. Therefore, when bath water flows from the piping of the reheating circuit to the drain plug 18 of the bathtub 10, it is possible to more reliably prevent dirt from adhering to the inner wall of the piping.

For example, the control unit 6 may detect draining of the bath water in the bathtub 10 by detecting a decrease in the water level in the bathtub 10 using a water level sensor, and may perform the above control. Furthermore, if the drain plug 18 is an automatic drain plug that can be opened and closed automatically, the above control may be performed when the control unit 6 detects that the drain plug 18 is opened.

Note that among the features of the plurality of embodiments described above, two or more features that can be combined may be combined and implemented.

1A water heater, 1B water heater, 1C water heater, 1D water heater, 2 heat source unit, 3 tank unit, 4 remote control, 4a display section, 4b operation section, 5 hot water tank, 6 control section, 7 water supply pipe, 8 first passage, 9 second passage, 10 bathtub, 11 circulation pump, 12 reheating heat exchanger, 13 reheating outgoing piping, 14 reheating return piping, 15 hot water discharge section, 16 hot water filling piping, 17 branch section, 18 drainage Plug, 21 Microbubble generator, 22 UV irradiation device, 23 Housing, 24 Fixed blade, 25 Gas introduction part, 26 Diameter reduction part, 27 UV-LED module, 28 Channel part, 29 Irradiation part, 30 Inflow part, 31 discharge section, 32 heat dissipation section, 44 remote control

Claims (7)

A circulation device that circulates hot water in the pipes,
a fine bubble generator capable of generating fine bubbles when the hot water passes through;
a UV irradiation device that is disposed downstream of the microbubble generator in the hot water circulation direction and that irradiates the hot water with UV;
A control unit that starts driving the UV irradiation device at the same time as or after the microbubble generation device starts generating microbubbles in conjunction with the driving of the circulation device;
A water heater equipped with. A reheating heat exchanger capable of heating the hot water is provided,
The hot water supply device according to claim 1, wherein the fine bubble generator is arranged downstream of the reheating heat exchanger in the circulation direction. A reheating heat exchanger capable of heating the hot water is provided,
The water heater according to claim 1, wherein the control section drives the fine bubble generator and the UV irradiation device when the reheating heat exchanger is not heating the hot water. The hot water is circulated via a hot water discharge part that discharges the hot water into the bathtub,
The hot water supply device according to any one of claims 1 to 3, wherein the micro bubble generator and the UV irradiation device are arranged downstream of the hot water discharge section in the circulation direction. The hot water is circulated via a hot water discharge part that discharges the hot water into the bathtub,
Claims 1 to 3, wherein in the circulation direction, the micro-bubble generator is disposed upstream of the hot water discharge section, and the UV irradiation device is disposed downstream of the hot water discharge section. The water heater according to any one of the above. Equipped with a bathing detection means for detecting that a person has taken a bath in the bathtub,
The water heater according to any one of claims 1 to 3, wherein the control section starts driving the UV irradiation device after the bathing is detected. The hot water can be circulated through a bathtub,
While draining the inside of the bathtub, the control unit causes the microbubble generator to generate microbubbles, and the UV irradiation device irradiates UV to the hot water containing the microbubbles. The water heater according to claim 3.

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