Water heater

Abstract

To provide a water heater which can accurately determine if a circulation abnormality occurs in a bath circulation circuit.SOLUTION: A water heater according to the disclosure includes: a bath circulation circuit including a circulation passage for taking out hot water in a bathtub to the outside of the bathtub and returning the hot water into the bathtub; a bath circulation pump which circulates hot water in the bath circulation circuit; pressure sensors which are provided at several positions of the bath circulation circuit and detect pressure in the bath circulation circuit at installation positions; and a control unit which acquires detection values of the pressure sensors and controls the bath circulation pump. The control unit acquires a difference between the detection values of the pressure sensors when the bath circulation pump is driven at a predetermined rotation number to circulate the hot water in the bath circulation circuit in predetermined reference conditions as a reference value and determines that a circulation abnormality occurs in the bath circulation pump when a value of a difference between detection values of the pressure sensors when the bath circulation pump is driven at the predetermined rotation number to circulate the hot water in the bath circulation circuit after acquisition of the reference value is different from the reference value by a specified or larger value.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present disclosure relates to a water heater.

Background Art

[0002] In a conventional water heater disclosed in Patent Document 1 below, when circulating the hot water in the bathtub, a device has been proposed that uses a plurality of pressure sensors to calculate the flow rate from the pressure difference between them to detect the presence or absence of circulation (see Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, when clogging occurs between the pressure sensors in the device proposed in Patent Document 1, since the pressure difference increases, it is determined that there is a flow rate, and there is a problem that it is determined that circulation is possible even though circulation is not possible.

[0005] The present disclosure has been made to solve the above-described problems. An object of the present disclosure is to provide a water heater that can accurately determine an abnormal circulation in a bathtub circulation circuit.

Means for Solving the Problems

[0006] The water heater according to the present disclosure includes a bath circulation circuit having a circulation flow path for taking out the hot water in the bathtub to the outside of the bathtub and then returning it to the inside of the bathtub, a bath circulation pump for circulating the hot water in the bath circulation circuit, a plurality of pressure sensors installed at a plurality of locations in the bath circulation circuit for detecting the pressure in the bath circulation circuit at the installation location, and a control unit for acquiring the detection value of the pressure sensor and controlling the bath circulation pump. The control unit obtains, as a reference value, the difference between the detection values of the plurality of pressure sensors when the bath circulation pump is driven at a predetermined rotation speed to circulate the hot water in the bath circulation circuit in a predetermined reference state. After obtaining the reference value, when the difference between the detection values of the plurality of pressure sensors when the bath circulation pump is driven at a predetermined rotation speed to circulate the hot water in the bath circulation circuit is greater than or equal to a predetermined value compared to the reference value, it is determined that a circulation abnormality has occurred in the bath circulation circuit.

Effect of the Invention

[0007] According to the present disclosure, it is possible to provide a water heater capable of accurately determining a circulation abnormality in a bath circulation circuit.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Modes for Carrying Out the Invention

[0009] Hereinafter, embodiments will be described with reference to the drawings. In each figure, common or corresponding elements are denoted by the same reference numerals to simplify or omit the description. In the following description, descriptions such as "water", "hot water", "warm water", and "hot and cold water" generally mean liquid water, and may include anything from cold water to boiling water. Also, the configurations shown in the embodiments below are examples of the technical idea according to the present disclosure, and it is possible to combine them with other known technologies, or to combine a plurality of technical ideas described in the present disclosure. Further, within the scope not departing from the gist of the present disclosure, it is also possible to omit or change a part of the configuration.

[0010] Embodiment 1. FIG. 1 is a diagram showing a water heater according to Embodiment 1. In the present embodiment, the case where the water heater of the present disclosure is applied to a storage-type water heater will be described as an example. However, the water heater of the present disclosure is also applicable to a non-storage-type water heater. As shown in FIG. 1, the storage-type water heater 35 of the present embodiment includes a tank unit 33, an HP unit 7 that uses a heat pump cycle, and a remote controller 44 for operating commands or changing set values. The HP unit 7 and the tank unit 33 are connected via an HP forward pipe 14, an HP return pipe 15, and electrical wiring (not shown). A control unit 36 is built into the tank unit 33. The operations of various valves, pumps, etc. provided in the tank unit 33 and the HP unit 7 are controlled by the control unit 36 that is electrically connected to them. The control unit 36 and the remote controller 44 are connected so as to be able to communicate with each other. Although not shown, the remote controller 44 is equipped with a display unit for displaying information such as the state of the storage-type water heater 35, an operation unit such as a switch operated by the user, a speaker, a microphone, etc. The display unit of the remote controller 44 functions as a notification means for notifying the user of information.

[0011] The HP unit 7 functions as heating means for heating the low-temperature water led from the hot water storage tank 8 provided in the tank unit 33. The HP unit 7 annularly connects a compressor 1, a water-cooled refrigerant heat exchanger 3, an expansion valve 4, and an air heat exchanger 6 with a refrigerant pipe 5 to constitute a heat pump cycle. The water-cooled refrigerant heat exchanger 3 is for performing heat exchange between the refrigerant flowing through the refrigerant pipe 5 and the low-temperature water led from the tank unit 33.

[0012] The following various components, pipes, etc. are built in the tank unit 33. The hot water storage tank 8 is for storing hot water and cold water. A third water supply pipe 9c is connected to a water inlet 8a provided at the lower part of the hot water storage tank 8. The water supplied from a water source such as a water supply is regulated to a predetermined pressure by a pressure reducing valve 31 and then flows into the hot water storage tank 8 through the third water supply pipe 9c. A hot water supply pipe 21 for supplying the hot water stored in the hot water storage tank 8 to the outside of the storage-type water heater 35 and an upper hot water supply pipe 13b are connected to a hot water introduction outlet 8d provided at the upper part of the hot water storage tank 8. Note that the high-temperature hot water heated by using the HP unit 7 flows into the hot water storage tank 8 from the hot water introduction outlet 8d, and the low-temperature water from the third water supply pipe 9c flows into the hot water storage tank 8 from the water inlet 8a, so that the hot water and cold water are stored such that a temperature difference is generated between the upper and lower parts. In addition, a plurality of hot water storage temperature sensors 41, 42, 43 are attached to the surface of the hot water storage tank 8 at different heights. By detecting the temperature distribution of the hot water and cold water in the hot water storage tank 8 with these hot water storage temperature sensors 41, 42, 43, the remaining amount of hot water in the hot water storage tank 8 is grasped, and the start, stop, etc. of the boiling operation of the hot water and cold water in the hot water storage tank 8 by the HP unit 7 are controlled.

[0013] Inside the tank unit 33, a heat source pump 12 and a bathtub heat exchanger 20 are incorporated. The heat source pump 12 is a pump for circulating hot and cold water through various pipes, which will be described later, inside the tank unit 33, and is provided on the HP forward pipe 14. The bathtub heat exchanger 20 is a heat exchanger for heating the bathtub water, which is the water to be heated on the secondary side, by using the high-temperature hot water supplied from the hot water storage tank 8 or the HP unit 7. In the present embodiment, as the configuration on the secondary side of the bathtub heat exchanger 20, a bathtub forward pipe 27a and a bathtub return pipe 28 that form a bathtub circulation circuit for circulating the hot and cold water in the bathtub 30 will be exemplified and described. The bathtub heat exchanger 20 is installed midway between the bathtub forward pipe 27a and the bathtub return pipe 28. Also, midway between the bathtub forward pipe 27a and the bathtub return pipe 28, a bathtub circulation pump 29 for circulating the bathtub water, a bathtub return temperature sensor 38 for detecting the temperature of the bathtub water that has exited the bathtub 30, and a bathtub forward temperature sensor 37 for detecting the temperature of the hot water after heat exchange that has exited the bathtub heat exchanger 20 are installed.

[0014] The hot and cold water three-way valve 11a is a flow path switching means having ports a and b through which hot and cold water flows in, and port c through which hot and cold water flows out. The medium-temperature three-way valve 11b is a flow path switching means having ports a and b through which hot and cold water flows in, and port c through which hot and cold water flows out. The medium-temperature four-way valve 18a is a flow path switching means having ports b and c through which hot and cold water flows in, and ports a and d through which hot and cold water flows out, and is configured to be able to switch the flow path among four paths, a-b, a-c, b-d, and c-d. Further, the tank unit 33 has a water outlet pipe 10, a hot water introduction pipe 20a, a first bypass pipe 16, a hot water outlet pipe 20b, and a second bypass pipe 17. The water outlet pipe 10 connects the water outlet 8b provided at the lower part of the hot water storage tank 8 and port a of the hot and cold water three-way valve 11a. The HP forward pipe 14 connects port c of the hot and cold water three-way valve 11a and the inlet side of the HP unit 7. The HP return pipe 15 connects the outlet side of the HP unit 7 and port c of the medium-temperature four-way valve 18a. The lower hot water supply pipe 13a connects port d of the medium-temperature four-way valve 18a and port a of the medium-temperature four-way valve 18b. The first bypass pipe 16 connects port a of the medium-temperature four-way valve 18a and the hot water inlet 8c provided between the central part and the lower part of the hot water storage tank 8. The hot water introduction pipe 20a connects port c of the medium-temperature four-way valve 18b and the primary side inlet of the bath heat exchanger 20. The hot water outlet pipe 20b connects the primary side outlet of the bath heat exchanger 20 and port b of the hot and cold water three-way valve 11a. The second bypass pipe 17 branches from between the heat source pump 12 and the inlet side of the HP unit 7 in the HP forward pipe 14 and is connected to port b of the medium-temperature four-way valve 18a.

[0015] The upper hot water supply pipe 13b connects port d of the medium-temperature four-way valve 18a and the hot water introduction outlet 8d at the upper part of the hot water storage tank 8. The first medium-temperature pipe 19a connects port b of the medium-temperature four-way valve 18b and the medium-temperature water inlet 8e provided at the middle part of the hot water storage tank 8.

[0016] The water inlet three-way valve 11a is used by switching the flow path of the hot and cold water in the tank unit 33 between two flow path configurations: one in which the water outlet pipe 10 communicates with the HP forward pipe 14, and the other in which the hot water outlet pipe 20b communicates with the HP forward pipe 14. The second medium-temperature pipe 19b is connected between the medium-temperature water outlet 8f provided in the middle part of the hot water storage tank 8 and the b port of the medium-temperature three-way valve 11b. The medium-temperature three-way valve 11b is used by switching the flow path of the hot and cold water in the tank unit 33 between two flow path configurations: one in which the second water supply pipe 9b communicates with the fourth water supply pipe 9d, and the other in which the second medium-temperature pipe 19b communicates with the fourth water supply pipe 9d. The four-way valve 18a for medium temperature uses four flow path configurations, namely, a configuration in which the HP return pipe 15 communicates with the lower hot water supply pipe 13a, a configuration in which the HP return pipe 15 communicates with the first bypass pipe 16, a configuration in which the first bypass pipe 16 communicates with the second bypass pipe 17, and a configuration in which the lower hot water supply pipe 13a communicates with the second bypass pipe 17, to switch and use the flow path of the hot and cold water in the tank unit 33.

[0017] The water inlet three-way valve 11a allows the a port and the c port to communicate, the four-way valve 18a for medium temperature allows the c port and the d port to communicate, and the four-way valve 18b for medium temperature allows the a port and the d port to communicate, thereby forming a flow path for flowing the hot and cold water at the lower part of the hot water storage tank 8 to the upper hot water supply pipe 13b. An intermediate hot water storage temperature sensor 42 is installed in the middle part of the hot water storage tank 8, and a lower hot water storage temperature sensor 43 is installed at the lower part thereof, and the temperature of the hot and cold water can be measured respectively.

[0018] Furthermore, the tank unit 33 includes a first water supply pipe 9a, a second water supply pipe 9b, a mixing valve 22 for hot water supply, a mixing valve 23 for bath use, a first hot water supply pipe 24, and a second hot water supply pipe 25. One end of the first water supply pipe 9a is connected to a water source such as a water supply, and the other end of the first water supply pipe 9a is connected to the second water supply pipe 9b and the third water supply pipe 9c via a pressure reducing valve 31. The fourth water supply pipe 9d branches off from the middle and is connected to the mixing valve 22 for hot water supply and the mixing valve 23 for bath use respectively. Also, the hot water supply pipe 21 branches off from the middle and is connected to the mixing valve 22 for hot water supply and the mixing valve 23 for bath use respectively. In the middle of the second hot water supply pipe 25, a solenoid valve 26 for bath use for opening and closing the second hot water supply pipe 25 and a flow sensor 45 for bath use for detecting the flow rate of the hot water passing through the second hot water supply pipe 25 are provided.

[0019] The hot water mixing valve 22 for hot water supply and the hot water mixing valve 23 for bath adjust the flow rate ratio between the high-temperature hot water supplied from the hot water supply pipe 21 and the low-temperature water supplied from the fourth water supply pipe 9d to generate hot water at the set temperature set by the user with the remote control 44, and cause the hot water to flow into the first hot water supply pipe 24 and the second hot water supply pipe 25 respectively. The hot water whose temperature is adjusted by the hot water mixing valve 22 for hot water supply is supplied from the first hot water supply pipe 24 via the hot water faucet 34 to a faucet (not shown) such as a shower or a calan used by the user. On the other hand, the hot water adjusted to the set temperature by the hot water mixing valve 23 for bath is supplied from the second hot water supply pipe 25 to the bathtub 30 through the electromagnetic valve 26 for bath, the flow sensor 45 for bath, the bath forward pipe 27a, and the bath return pipe 28.

[0020] In addition, a first pressure sensor 39a is provided in the bath forward pipe 27a, and a second pressure sensor 39b is provided in the bath return pipe 28. At this time, each pressure sensor is installed so as to sandwich the heat exchanger 20 for bath. This is because a pressure difference is likely to occur when the bath circulation circuit is circulated by sandwiching a component such as the heat exchanger 20 for bath that is likely to cause a pressure loss.

[0021] In addition, the first pressure sensor 39a and the second pressure sensor 39b are both arranged so as to be located downstream of the bath circulation pump 29. In this way, it is desirable to install both the first pressure sensor 39a and the second pressure sensor 39b either upstream or downstream of the bath circulation pump 29. This is because when installed across the bath circulation pump 29, it is difficult to obtain an accurate pressure difference ΔP because the pressure fluctuates due to the drive of the bath circulation pump 29.

[0022] In this embodiment, an example in which two pressure sensors, i.e., a first pressure sensor 39a and a second pressure sensor 39b, are provided will be described. However, three or more pressure sensors may be provided in the bathtub circulation circuit. In that case, it is desirable to install at least one pressure sensor on each of the upstream side and the downstream side of the bathtub heat exchanger 20. Further, it is desirable that all the pressure sensors are installed on the upstream side of the bathtub circulation pump 29 or all the pressure sensors are installed on the downstream side of the bathtub circulation pump 29.

[0023] The remote controller 44 is equipped with automatic bathtub operation. When the automatic bathtub operation is set, hot water supply is performed so that the temperature and amount of hot water in the bathtub become the temperature and amount set by the remote controller 44. Thereafter, heat retention and additional hot water supply of the bath water are performed as necessary so as to maintain the set temperature and water level. Regarding the hot water supply, when supplying the amount of hot water set by the remote controller 44, a flow for driving the bathtub circulation pump 29 to confirm the presence or absence of hot water in the bathtub 30 is performed. At this time, the bathtub circulation pump 29 is driven at a predetermined rotational speed (for example, 6000 rpm) to acquire the numerical values of the first pressure sensor 39a and the second pressure sensor 39b, thereby obtaining the pressure difference in the state where there is bath water in the bathtub 30 when the bathtub circulation pump 29 is driven at a predetermined rotational speed in the reference state. Using this numerical value as a reference value, the pressure difference when the bathtub circulation pump 29 is driven at a predetermined rotational speed is confirmed when determining the presence or absence of water in the bathtub circulation circuit or when determining a pipe blockage, etc., and the presence or absence of circulation in the bathtub circulation circuit is determined. By acquiring in advance reference values at a plurality of different predetermined rotational speeds of the bathtub circulation pump 29, it is possible to determine the presence or absence of abnormality in the circulation state under operating conditions where the rotational speed of the bathtub circulation pump 29 is different.

[0024] FIG. 2 is a configuration diagram illustrating the flow of hot water when the bathtub circulation operation is performed in the hot water storage type water heater 35 of Embodiment 1. The thick line in the figure indicates the circuit through which the hot water flows, and the arrow in the figure indicates the flow of the hot water. FIG. 3 is a flowchart of the control for determining the circulation abnormality in the bathtub circulation circuit in Embodiment 1. The determination of the presence or absence of circulation in the bathtub circulation circuit will be described with reference to the flowchart.

[0025] As step S1, the bath circulation pump 29 is driven at a predetermined rotational speed to detect the presence or absence of circulation within the bath circulation circuit. As step S2, numerical values P1 and P2 of the first pressure sensor 39a and the second pressure sensor 39b at that time are acquired, and the pressure difference ΔP between P1 and P2 is calculated. As step S3, a waiting time of one minute is provided thereafter for draining the remaining water in the bath piping and the like. As step S4, if ΔP is less than the first predetermined value ΔP1 (for example, 5 kPa), it is determined that there is no bath water, or there is a blockage in the piping on the secondary side of the first pressure sensor 39a of the bath circulation circuit, or on the primary side of the second pressure sensor 39b. Thereafter, as step S5, the bath circulation pump 29 is stopped, and as step S6, it is displayed on the remote controller 44 that there is no bath water or there is a blockage in the bath piping, that is, a circulation abnormality has occurred in the bath circulation circuit. At this time, it may be notified that there may be a blockage in the piping on the secondary side of the first pressure sensor 39a of the bath circulation circuit, or on the primary side of the second pressure sensor 39b. In this way, by specifying the location of the circulation abnormality based on the numerical value of the pressure difference acquired by the control unit 36 and notifying it by the notification means, the convenience is improved.

[0026] When ΔP is greater than or equal to the first predetermined value ΔP1 in step S4, as step S7, when ΔP is greater than or equal to the second predetermined value ΔP2 (for example, 15 kPa), it is determined that there is a blockage between the first pressure sensor 39a and the second pressure sensor 39b. The second predetermined value ΔP2 is a value calculated by the following formula. ΔP2 = reference value + predetermined value When ΔP is greater than or equal to the second predetermined value ΔP2 in step S7, it corresponds to the case where ΔP has a difference of a predetermined value or more compared to the reference value.

[0027] After step S7, as step S8, the bath circulation pump 29 is stopped, and as step S9, it is displayed on the remote controller 44 that clogging has occurred inside the product, that is, a circulation abnormality has occurred in the bath circulation circuit. At this time, it may be notified that clogging has occurred between the first pressure sensor 39a and the second pressure sensor 39b. In this way, the location of the circulation abnormality is specified by the numerical value of the pressure difference acquired by the control unit 36 and notified by the notification means, thereby improving convenience.

[0028] When ΔP is less than the second predetermined value ΔP2 in step S7, as step S10, the elapsed time (for example, 5 minutes) since the bath circulation pump 29 was driven is confirmed. When the predetermined elapsed time has not passed, steps S4 and S7 are repeated to check whether there is no circulation abnormality during bath circulation. When the bath circulation pump 29 has been driven for a predetermined time, as step S11, the bath circulation pump 29 is stopped to complete the determination of the presence or absence of circulation in the bath circulation circuit.

[0029] In addition, when a function of generating microbubbles by a bubble injection means (not shown) in the bath supply pipe 27a and the bath return pipe 28 to clean the inside of the pipes when draining the hot and cold water in the bathtub 30 is implemented, since there is a possibility of erroneously detecting the pressure by the bubbles in the pipes, the determination of the presence or absence of circulation in the bath circulation circuit is prohibited, and the determination of the pressure difference of the pressure sensor is not performed.

[0030] Before obtaining the reference value at a predetermined rotation speed (for example, 6000 rpm) when performing a test run immediately after installing the product, it is compared whether the difference in the detected values by the pressure sensors is different from the initial value (for example, 10 kPa) stored in advance by a predetermined value or more. For example, in this way, if there are problems such as clogging or crushing in the bathtub circulation pipes in an existing house and only the water heater is newly replaced, when the water heater is installed and circulated for the first time, the circulation abnormality cannot be determined without the initial value. However, the circulation abnormality can be determined by the comparison determination with this initial value, thereby improving convenience.

[0031] In addition, if the water heater obtains inappropriate reference values due to construction defects in the piping on the housing side, incorrect piping or connection of components, etc., even if such construction defects are corrected, if the reference values are inappropriate, the water heater may make an incorrect circulation abnormality determination. For this countermeasure, after correcting construction defects or the like, the reset means may be operated to reset the reference values once and then obtain the reference values again. This makes it possible to avoid false detection due to the acquisition of incorrect initial values due to construction defects or the like.

[0032] Hereinafter, various aspects of the present disclosure will be summarized as appendices.

[0033] (Appendix 1) A bath circulation circuit including a circulation flow path for taking out the hot water in the bathtub to the outside of the bathtub and then returning it to the inside of the bathtub, A bath circulation pump for circulating the hot water in the bath circulation circuit, Pressure sensors installed at a plurality of locations in the bath circulation circuit for detecting the pressure in the bath circulation circuit at the installation locations, A control unit that acquires the detection values of the pressure sensors and controls the bath circulation pump, Comprising, The control unit acquires, as a reference value, the difference between the detection values of the plurality of pressure sensors when driving the bath circulation pump at a predetermined rotation speed and circulating the hot water in the bath circulation circuit in a predetermined reference state, After acquiring the reference value, when the difference in the detection values of the plurality of pressure sensors when driving the bath circulation pump at the predetermined rotation speed and circulating the hot water in the bath circulation circuit is greater than or equal to a predetermined value compared to the reference value, a water heater that determines that a circulation abnormality has occurred in the bath circulation circuit. (Appendix 2) A hot water storage tank for storing hot water, A bath heat exchanger provided in the bath circulation circuit for exchanging heat between the hot water in the hot water storage tank and the bath water, Further comprising, The water heater according to Appendix 1, wherein the installation positions of the pressure sensors are installed such that at least one is provided on each of the upstream side and the downstream side of the bath heat exchanger. (Appendix 3) The water heater according to Appendix 1 or Appendix 2, wherein all of the pressure sensors are installed upstream of the bathtub circulation pump or all of the pressure sensors are installed downstream of the bathtub circulation pump. (Appendix 4) The water heater according to any one of Appendices 1 to 3, wherein when the pressure difference between the two pressure sensors is less than a first predetermined value while the bathtub circulation pump is driven at the predetermined rotational speed, the control unit determines that there is an abnormality in the circulation of the bathtub circulation circuit. (Appendix 5) The water heater according to any one of Appendices 1 to 4, wherein when the pressure difference between the two pressure sensors is equal to or greater than a second predetermined value while the bathtub circulation pump is driven at the predetermined rotational speed, the control unit determines that there is an abnormality in the circulation of the bathtub circulation circuit. (Appendix 6) The water heater according to any one of Appendices 1 to 5, further comprising notification means for stopping the bathtub circulation pump and notifying the user when the control unit determines that there is an abnormality in the circulation of the bathtub circulation circuit. (Appendix 7) The water heater according to Appendix 6, wherein when notifying the user by the notification means, the control unit specifies the location where there is an abnormality in the circulation based on the numerical value of the pressure difference acquired, and notifies the user by the notification means. (Appendix 8) The bathtub circulation circuit further comprises bubble injection means for injecting bubbles into the bathtub circulation circuit, The water heater according to any one of Appendices 1 to 7, wherein when the control unit injects bubbles into the hot water during circulation in the bathtub circulation circuit by the bubble injection means while circulating the hot water in the bathtub circulation circuit by the bathtub circulation pump, the control unit does not perform the determination of the pressure difference of the pressure sensor. (Appendix 9) The water heater according to any one of Appendices 1 to 8, wherein before obtaining the reference value, when the difference between the detected values of the pressure sensors when the bathtub circulation pump is driven at the predetermined rotational speed and the hot water is circulated in the bathtub circulation circuit is different from the initial value stored in advance by a predetermined value or more, the control unit determines that there is an abnormality in the circulation of the bathtub circulation circuit. (Appendix 10) The water heater according to any one of Appendices 1 to 9, comprising reset means for clearing the reference value acquired by the control unit. (Appendix 11) having a plurality of types of the predetermined rotation speeds, the control unit acquires the reference value corresponding to each of the predetermined rotation speeds, and after the acquisition of the reference value, when driving the bath circulation pump at the predetermined rotation speed to circulate the hot water in the bath circulation circuit, if the difference value of the detection values of the plurality of pressure sensors has a difference of a predetermined value or more from each of the reference values, it is determined that a circulation abnormality has occurred in the bath circulation circuit. The water heater according to any one of Appendices 1 to 10.

Explanation of Signs

[0034] 1 Compressor, 3 Water-cooled refrigerant heat exchanger, 4 Expansion valve, 5 Refrigerant pipe, 6 Air heat exchanger, 7 HP unit, 8 Hot water storage tank, 8a Water inlet, 8b Water outlet, 8c Warm water inlet, 8d Warm water inlet / outlet, 8e Medium warm water inlet, 9a First water supply pipe, 9b Second water supply pipe, 9c Third water supply pipe, 9d Fourth water supply pipe, 10 Water outlet pipe, 11a Water inlet three-way valve, 11b Medium warm water three-way valve, 12 Heat source pump, 13a Lower hot water supply pipe, 13b Upper hot water supply pipe, 14 HP forward pipe, 15 HP return pipe, 16 First bypass pipe, 17 Second bypass pipe, 18a Medium warm water four-way valve, 18b Medium warm water four-way valve, 19a First medium warm water pipe, 19b Second medium warm water pipe, 20 Bath heat exchanger, 20a Warm water inlet pipe, 20b Warm water outlet pipe, 21 Hot water supply pipe, 22 Hot water supply mixing valve, 23 Bath mixing valve, 24 First hot water supply pipe, 25 Second hot water supply pipe, 26 Bath solenoid valve, 27a Bath forward pipe, 28 Bath return pipe, 29 Bath circulation pump, 30 Bathtub, 31 Pressure reducing valve, 33 Tank unit, 34 Hot water supply faucet, 35 Storage type water heater, 36 Control unit, 37 Bath forward temperature sensor, 38 Bath return temperature sensor, 39a First pressure sensor, 39b Second pressure sensor, 41 Hot water storage temperature sensor, 42 Intermediate hot water storage temperature sensor, 43 Lower hot water storage temperature sensor, 44 Remote control, 45 Bath flow sensor

Claims

1. A bath circulation circuit having a circulation flow path for taking out the hot water in the bathtub to the outside of the bathtub and then returning it to the inside of the bathtub, a bath circulation pump for circulating the hot water in the bath circulation circuit, pressure sensors installed at a plurality of locations in the bath circulation circuit for detecting the pressure in the bath circulation circuit at the installation location, a control unit that acquires the detection value of the pressure sensor and controls the bath circulation pump, and comprising, in a predetermined reference state, the control unit drives the bath circulation pump at a predetermined rotation speed and circulates the hot water in the bath circulation circuit, and acquires the difference between the detection values of the plurality of pressure sensors as a reference value, After obtaining the reference value, when the difference in the detection values of the plurality of pressure sensors when the bath circulation pump is driven at the predetermined rotation speed and the hot water is circulated in the bath circulation circuit is different from the reference value by a predetermined value or more, a water heater that determines that a circulation abnormality has occurred in the bath circulation circuit.

2. a hot water storage tank for storing hot water, a bath heat exchanger provided in the bath circulation circuit for exchanging heat between the hot water in the hot water storage tank and the bath water, further comprising, The water heater according to claim 1, wherein the pressure sensors are installed at least one each on the upstream side and the downstream side of the bath heat exchanger.

3. The water heater according to claim 1 or claim 2, wherein all the pressure sensors are installed on the upstream side of the bath circulation pump, or all the pressure sensors are installed on the downstream side of the bath circulation pump.

4. The water heater according to claim 1 or claim 2, wherein when the pressure difference between two of the pressure sensors is less than a first predetermined value while the bath circulation pump is being driven at the predetermined rotation speed, the control unit determines that there is a circulation abnormality in the bath circulation circuit.

5. The water heater according to claim 1 or claim 2, wherein when the pressure difference between two of the pressure sensors is equal to or greater than a second predetermined value while the bath circulation pump is being driven at the predetermined rotation speed, the control unit determines that there is a circulation abnormality in the bath circulation circuit.

6. The water heater according to claim 1 or claim 2, further comprising notification means for stopping the bath circulation pump and notifying the user when the control unit determines that there is a circulation abnormality in the bath circulation circuit.

7. The water heater according to claim 6, wherein when notifying the user by the notification means, the location where there is a circulation abnormality is specified based on the numerical value of the pressure difference acquired by the control unit, and the notification is made by the notification means.

8. The hot water circulation circuit further comprises a bubble injection means for injecting bubbles into the bath circulation circuit. When the control unit injects bubbles into the hot water during circulation in the bath circulation circuit by the bubble injection means while the hot water is being circulated in the bath circulation circuit by the bath circulation pump, the control unit does not perform the determination of the pressure difference of the pressure sensor. The water heater according to claim 1 or claim 2.

9. Before the control unit acquires the reference value, when the difference value of the detection values of the pressure sensor when the bath circulation pump is driven at the predetermined rotation speed and the hot water is circulated in the bath circulation circuit is different from the initial value stored in advance by a predetermined value or more, it is determined that a circulation abnormality has occurred in the bath circulation circuit. The water heater according to claim 1 or claim 2.

10. The water heater according to claim 1 or claim 2, further comprising a reset means for clearing the reference value acquired by the control unit.

11. There are a plurality of types of the predetermined rotation speeds. The control unit acquires the reference value corresponding to each of the predetermined rotation speeds, and after the acquisition of the reference value, when the difference value of the detection values of the plurality of pressure sensors when the bath circulation pump is driven at the predetermined rotation speed and the hot water is circulated in the bath circulation circuit is different from each of the reference values by a predetermined value or more, it is determined that a circulation abnormality has occurred in the bath circulation circuit. The water heater according to claim 1 or claim 2.

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