hot water supply equipment

Abstract

A technology is provided that can prevent a heat exchanger from remaining in an overheated state for an extended period of time while minimizing a decrease in user convenience in a water heater equipped with a heat exchanger. [Solution] In a water heater (1), a control unit (22A) places a gas burner (4) in a combustion state on the condition that a water flow detection unit detects water flow. The control unit (22A) performs combustion adjustment control to switch between a combustion state and a combustion stop state, such that the gas burner (4) is placed in a combustion stop state when a temperature T detected by a thermistor (27) (temperature detection unit) while the gas burner (4) is in the combustion state becomes equal to or higher than a first temperature T1, and the gas burner (4) is placed in a combustion state again when the temperature detected by the thermistor (27) (temperature detection unit) while in the combustion stop state falls to or lower than a second temperature T2 that is lower than the first temperature T1. The control unit (22A) restricts the notification unit from issuing an abnormality notification during combustion adjustment control until a predetermined notification condition is met.

Description

[Technical Field]

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

[0002] The water heater disclosed in Patent Document 1 includes a heat transfer pipe between a water inlet pipe and a hot water outlet pipe, a heat exchanger that transfers heat generated by a gas burner to water passing through the heat transfer pipe and exchanges it with the heat, a bypass passage between the water inlet pipe and the hot water outlet pipe that serves as a water passage separate from the heat exchanger, and a water flow sensor that detects water flow through the water inlet pipe. This water heater is equipped with a bypass valve in the bypass passage, and the bypass flow rate of the bypass passage is adjusted by the bypass valve to dispense hot water at an appropriate temperature. This water heater is configured to close the bypass passage when the water flow sensor changes from a non-detecting state, in which it does not detect water flow in the water inlet pipe, to a detecting state, in which it detects water flow in the water inlet pipe, and starts water flow.

[0003] In the water heating device of Patent Document 1, when the water flow sensor enters a detection state while the bypass path is blocked due to the start of water flow through the water inlet pipe, it is considered that water flow is ensured through the water flow path of the heat exchanger, and in such cases, normal combustion control is performed to put the gas burner into a combustion state without performing any special defreezing operation, thereby quickly performing normal water heating operation.

[0004] On the other hand, if the bypass passage is blocked due to the start of water flow in the water inlet pipe and the water flow sensor goes into a non-detecting state, this water heater performs opening control to open the bypass passage, and also performs defreezing combustion control to burn the gas burner and continue the gas burner combustion state until a predetermined termination condition is met. In other words, if there is a high possibility that a blockage has occurred in the water flow path of the heat exchanger, this water heater ensures water flow in the bypass passage while heating the area around the heat exchanger by burning the gas burner, so that if the blockage is caused by freezing, it can defrost the ice. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 6320226 Summary of the Invention [Problem to be solved by the invention]

[0006] In this type of water heater, if a blockage occurs in the water flow path of the heat exchanger, more water will flow through the bypass path to the hot water outlet pipe, and the proportion of water flowing to the heat exchanger will decrease, making it easy for the hot water passing through the heat exchanger to become overheated.

[0007] One possible method for detecting such an abnormality is to use a sensor to detect the temperature of the hot water flowing out of the heat exchanger and determine that an abnormality exists if the temperature remains above a certain level for a certain period of time. However, when the hot water flowing through the heat exchanger is at a high temperature near the boiling point, the conditions around the sensor are likely to become unstable due to factors such as the generation of bubbles, causing the temperature detected by the sensor to temporarily drop. When this occurs, a temperature below the certain level is detected while counting the time during which the high temperature continues to be above the certain level. This resets the count before determining that an abnormality exists, and then restarts the process of counting the time during which the high temperature remains above the certain level. This repeated process results in the heat exchanger continuing to maintain a high temperature without determining that an abnormality exists. This can easily lead to problems such as heat exchanger failure due to prolonged overheating.

[0008] One of the objects of the present disclosure is to provide a technology in a water heater equipped with a heat exchanger that can prevent the heat exchanger from remaining overheated for an excessive period of time while minimizing a decrease in convenience for users. [Means for solving the problem]

[0009] The hot water heater according to the present disclosure includes: a gas burner for burning gas; a water inlet pipe configured as a path through which water flows from the water inlet; A hot water outlet pipe configured as a path for sending hot water to a hot water outlet; a heat exchanger including a heat transfer tube configured as a water passage between the water inlet pipe and the hot water outlet pipe, and performing heat exchange so as to transfer heat generated by combustion in the gas burner to water passing through the heat transfer tube; a bypass path connected to the water inlet pipe and the hot water outlet pipe and configured as a water passage different from the heat exchanger; a mixing valve including a valve element that opens and closes the bypass passage and a drive source that drives the valve element, the drive source driving the valve element to adjust the opening degree of a predetermined position in the bypass passage; a temperature detector that is provided in the hot water outlet pipe closer to the heat exchanger than the connection portion with the bypass passage and detects the temperature of the hot water flowing through the hot water outlet pipe; a water flow detection unit that detects the flow of water in a water flow path between the water inlet and the hot water outlet; a notification unit that notifies of an abnormality; a control unit that controls the mixing valve, the gas burner, and the notification unit; Equipped with the control unit performs combustion adjustment control to switch between the combustion state and the combustion stop state so as to place the gas burner in a combustion state on the condition that water flow is detected by the water flow detection unit, place the gas burner in a combustion stop state when an abnormality occurs in which the temperature detected by the temperature detection unit becomes equal to or higher than a first temperature while the gas burner is in the combustion state, and place the gas burner in the combustion state again when the temperature detected by the temperature detection unit becomes equal to or lower than a second temperature that is lower than the first temperature while the gas burner is in the combustion stop state; The control unit restricts the notification unit from notifying an abnormality during the combustion adjustment control until a predetermined notification condition is met. [Effects of the Invention]

[0010] According to the technology disclosed herein, in a water heater equipped with a heat exchanger, it is possible to prevent the heat exchanger from remaining in an overheated state for an excessive period of time while minimizing a decrease in convenience for the user. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a front view illustrating the appearance of a water heater according to a first embodiment. [Figure 2] FIG. 2 is a schematic circuit diagram conceptually illustrating the internal configuration of the water heater of FIG. [Figure 3] FIG. 3 is a block diagram illustrating a schematic example of the electrical configuration of the controller, remote controller, and the like that constitute the water heater of FIGS. [Figure 4] FIG. 4 is a flowchart showing a process including combustion adjustment control of the water heater. [Figure 5] FIG. 5 is a flowchart showing the abnormality recording process of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0012] Each of the following [1] to [4] is an example of a water heater included in the present disclosure.

[0013] [1] A gas burner for burning gas; a water inlet pipe configured as a path through which water flows from the water inlet; A hot water outlet pipe configured as a path for sending hot water to a hot water outlet; a heat exchanger including a heat transfer tube configured as a water passage between the water inlet pipe and the hot water outlet pipe, and performing heat exchange so as to transfer heat generated by combustion in the gas burner to water passing through the heat transfer tube; a bypass path connected to the water inlet pipe and the hot water outlet pipe and configured as a water passage different from the heat exchanger; a mixing valve including a valve element that opens and closes the bypass passage and a drive source that drives the valve element, the drive source driving the valve element to adjust the opening degree of a predetermined position in the bypass passage; a temperature detector that is provided in the hot water outlet pipe closer to the heat exchanger than the connection portion with the bypass passage and detects the temperature of the hot water flowing through the hot water outlet pipe; a water flow detection unit that detects the flow of water in a water flow path between the water inlet and the hot water outlet; a notification unit that notifies of an abnormality; a control unit that controls the mixing valve, the gas burner, and the notification unit; Equipped with the control unit performs combustion adjustment control to switch between the combustion state and the combustion stop state so as to place the gas burner in a combustion state on the condition that water flow is detected by the water flow detection unit, place the gas burner in a combustion stop state when an abnormality occurs in which the temperature detected by the temperature detection unit becomes equal to or higher than a first temperature while the gas burner is in the combustion state, and place the gas burner in the combustion state again when the temperature detected by the temperature detection unit becomes equal to or lower than a second temperature that is lower than the first temperature while the gas burner is in the combustion stop state; The control unit restricts the notification unit from notifying an abnormality during the combustion adjustment control until a predetermined notification condition is met. Water heater.

[0014] If the gas burner continues to burn while the heat exchanger is slightly clogged and the mixing valve is open to some extent, more water will flow through the bypass, making it more difficult for water to flow through the heat exchanger, which can lead to excessive heating of the water in the heat exchanger. Therefore, in the water heater described in [1] above, the temperature detector detects the temperature of hot water at a position closer to the heat exchanger than the hot water outlet pipe connection, and the controller switches the gas burner to a combustion-stopped state if an abnormality occurs, such that the temperature detected by the temperature detector exceeds a first temperature while the gas burner is in a combustion-stopped state. The controller then performs combustion adjustment control to switch the gas burner between a combustion state and a combustion-stopped state, so that the gas burner is again in a combustion state when the temperature detected by the temperature detector during the combustion-stopped state drops below a second temperature, which is lower than the first temperature. In this way, the water heater described in [1] above turns the gas burner off in response to the detection of a hot water temperature equal to or higher than the first temperature. Even if the detected hot water temperature temporarily drops below the first temperature due to the generation of bubbles or the like, the gas burner maintains the combustion-stopped state without returning to the combustion state until the detected hot water temperature drops below the second temperature. This prevents the heat exchanger from overheating for too long. Furthermore, in this water heater, the control unit restricts the notification unit from notifying an abnormality during combustion adjustment control until a predetermined notification condition is met. In other words, this water heater does not notify an abnormality even if a hot water temperature equal to or higher than the first temperature is detected until the predetermined notification condition is met during combustion adjustment control. Therefore, the water heater notifies an abnormality even when hot water is available for dispensing until the predetermined notification condition is met, which helps prevent users from feeling confused or uncomfortable. Furthermore, if the cause of the "blockage" or overheating is freezing, there is a possibility that the freezing will be resolved during combustion adjustment control, and if the freezing is resolved and the "blockage" disappears before the specified notification conditions are met, it is easy to transition to normal control without significantly impairing user convenience.

[0015] [2] Further, a memory unit is provided, The control unit counts the number of times that the temperature detected by the temperature detection unit reaches the first temperature during the combustion adjustment control, and when the number of times that the temperature reaches the first temperature reaches a predetermined number during the combustion adjustment control, the control unit stores abnormality information in the storage unit while restricting the notification unit from notifying an abnormality. The water heater according to [1].

[0016] In the water heating apparatus described in [2] above, even if an abnormality occurs in which the temperature detected by the temperature detection unit exceeds the first temperature and combustion adjustment control is performed, the abnormality is not notified until a predetermined notification condition is met. Therefore, this water heating apparatus may continue to be used without recognizing that the detected temperature has exceeded the first temperature. However, if the temperature detected by the temperature detection unit repeatedly exceeds the first temperature, it may place a strain on equipment such as the heat exchanger, potentially leading to equipment failure. Therefore, in the water heating apparatus described in [2] above, the control unit stores abnormality information when the detected temperature reaches the first temperature a predetermined number of times. Therefore, this water heating apparatus allows the user to check after the fact whether the abnormality information has been stored, i.e., whether the temperature has reached the predetermined number of times. This makes it easier for a repairer to identify the cause of a malfunction, for example, if a malfunction occurs.

[0017] [3] The control unit causes the notification unit to notify an abnormality when the temperature detected by the temperature detection unit during the combustion stop state becomes equal to or higher than a third temperature higher than the first temperature. The water heater according to [1] or [2].

[0018] In the water heater of the above [3], if the detected temperature continues to rise even after switching to the combustion stopped state when the detected temperature reaches the first temperature, there is a possibility that dry heating is occurring in the heat exchanger. Therefore, the water heater of the above [3] can prompt a person who receives the notification from the notification unit (for example, a user) to take action to address the abnormality by having the notification unit notify the person who receives the notification from the notification unit when the detected temperature reaches the third temperature.

[0019] [4] The control unit sets the water heater to a predetermined use-prohibited state when the temperature detected by the temperature detection unit in the combustion-stopped state becomes equal to or higher than a third temperature that is higher than the first temperature. The water heater according to any one of [1] to [3].

[0020] In the water heater of [4] above, if the detected temperature continues to rise even after switching to the combustion stop state when the detected temperature reaches the first temperature, there is a possibility that the heat exchanger is running dry. Therefore, the water heater of [4] above can prevent normal use by setting the water heater to a predetermined prohibited state when the detected temperature reaches the third temperature.

[0021] First Embodiment The following description relates to the first embodiment. 1. Configuration and basic operation of the water heater (Basic configuration) The water heater 1 shown in Figures 1 and 2 is a device that at least performs the operation of supplying water heated by heat exchangers 6, 56 to a bathtub 60, and is configured as a bath and hot water system that has the function of supplying hot water to the bathtub 60 and the function of circulating and heating the water in the bathtub 60. The water heater 1 has an appearance as shown in Figure 1. The water heater 1 has a configuration as shown in Figure 2, and mainly includes a hot water supply side circuit 2 and a bath side circuit 3. As shown in Figures 1 and 2, the water heater 1 has a housing 5, the hot water supply side circuit 2 including the heat exchanger 6, and the bath side circuit 3 having a pipe (drop pipe 70) branching off from the hot water supply side circuit 2. As shown in Figures 1 and 2, the water heater 1 has the hot water supply side circuit 2 and the bath side circuit 3 housed within the housing 5.

[0022] As shown in Figure 2, the hot water supply side circuit 2 includes a hot water supply side water passage, a gas burner 4, a heat exchanger 6, etc. The hot water supply side circuit 2 functions as a circuit that heats tap water supplied from an external source and dispenses hot water. The bath side circuit 3 includes a bath side water passage, a gas burner 54, a heat exchanger 56, a circulation pump 62, thermistors 64 and 65, etc. The bath side circuit 3 is used for circulating and heating water when filling the bathtub, reheating the bath, etc.

[0023] In the hot water supply side circuit 2, a pipe consisting of a water inlet pipe 12, a heat transfer pipe 8a, a pipe 20, a heat transfer pipe 7a, and a hot water outlet pipe 10 functions as the hot water supply side water passage. The water inlet pipe 12 is a flow path (pipe) into which water flows from a water inlet 16. The hot water outlet pipe 10 is a flow path (pipe) that sends hot water to a hot water outlet 18. The gas burner 4 functions as a hot water supply side burner, burning combustion gas to generate combustion exhaust. The heat exchanger 6 functions as a hot water supply side heat exchanger 6. The heat exchanger 6 transfers heat generated by the gas burner 4 to water passing through the hot water supply side water passage (a pipe consisting of the water inlet pipe 12, a heat transfer pipe 8a, a pipe 20, a heat transfer pipe 7a, and a hot water outlet pipe 10) to boil water. The heat exchanger 6 is located midway along the hot water supply side water passage and transfers heat generated by combustion in the gas burner 4 to the water passing through the hot water supply side water passage. Heat exchanger 6 includes a primary heat exchanger 57 and a secondary heat exchanger 58. Primary heat exchanger 57 is disposed in hot water supply combustion chamber 90 on the upstream side of the combustion exhaust path of gas burner 4. Secondary heat exchanger 58 is disposed in hot water supply combustion chamber 90 on the downstream side of the combustion exhaust path.

[0024] In the hot water supply side circuit 2, a water inlet pipe 12 is connected to the inlet of secondary heat exchanger 58 so as to supply tap water. Water inlet pipe 12 is provided with a thermistor 25 that detects the temperature of the water passing through water inlet pipe 12 (specifically, the water temperature at a position in the water supply pipe upstream of heat exchanger 6 and downstream of water inlet 16), and a water volume sensor 34 that serves as a water volume detector that detects the amount of water flowing through water inlet pipe 12 (i.e., the amount of water flowing through the water supply pipe). Thermistor 25 functions to detect the temperature of water introduced from outside. When hot water supply to bathtub 60 is stopped (hot water supply solenoid valve 72 is closed), and the stopper (e.g., a faucet) at hot water outlet 18 is closed and the release of hot water from hot water outlet 18 is stopped, no water flows through water inlet pipe 12, causing the flow of water to stop, and water volume sensor 34 detects the water flow stop state. When a stopper (such as a faucet) provided at the hot water outlet 18 is opened and hot water begins to be discharged from the hot water outlet 18, water flows through the water inlet pipe 12 and the hot water outlet pipe 10, and the water flow is detected by the water volume sensor 34.

[0025] The heat transfer tube 8a of the secondary heat exchanger 8 is connected downstream of the water inlet pipe 12, and further downstream is connected piping 20 that connects the heat transfer tube 8a of the secondary heat exchanger 8 to the heat transfer tube 7a of the primary heat exchanger 7. The heat transfer tube 7a of the primary heat exchanger 57 is connected to the piping 20, and the hot water outlet pipe 10 is connected to the outlet of the primary heat exchanger 7 so as to discharge the hot water heated by the primary heat exchanger 7. A thermistor 27 that detects the temperature of the hot water near the outlet of the primary heat exchanger 7 is provided in the hot water outlet pipe 10 near the primary heat exchanger 7. The thermistor 27 is an example of a temperature detection unit. The thermistor 27 is provided on the hot water outlet pipe 10 closer to the heat exchanger (specifically, on the primary heat exchanger 7 side) than the connection part 10A with the bypass passage 14, and functions to detect the temperature of the hot water flowing through the hot water outlet pipe 10. Furthermore, the hot water outlet pipe 10 is provided with a thermistor 26 that detects the temperature of the water in the hot water outlet pipe 10 downstream of the connection part 10A. Of these, the hot water supply side water passage consisting of the water inlet pipe 12, heat transfer pipe 8a, piping 20, heat transfer pipe 7a, and hot water outlet pipe 10 functions as a water passage provided in the hot water supply side circuit 2. On the other hand, the bath side water passage consisting of the drop pipe 70 and piping 66 functions as a second water pipe provided in the bath side circuit 3.

[0026] The heat exchanger 6 transfers heat generated by the gas burner 4 to water passing through a portion of the hot water supply side water pipe. The heat exchanger 6 includes a primary heat exchanger 7 and a secondary heat exchanger 8. The heat exchanger 6 functions to recover sensible heat from the combustion exhaust gas using the primary heat exchanger 7 and then recover latent heat using the secondary heat exchanger 8. The primary heat exchanger 7 includes a heat transfer tube 7a that serves as a water passage within the primary heat exchanger 7, and transfers combustion heat contained in the combustion exhaust gas generated by the gas burner 4 to the water passing through the heat transfer tube 7a, thereby transferring the thermal energy of the sensible heat to the passing water. The secondary heat exchanger 8 includes a heat transfer tube 8a that serves as a water passage within the secondary heat exchanger 8, and transfers combustion heat from the combustion exhaust gas generated by the gas burner 4 after passing through the primary heat exchanger 7 to the water passing through the heat transfer tube 8a, thereby transferring the thermal energy of the latent heat to the passing water.

[0027] A bypass passage 14, configured as a water passage bypassing the heat exchanger 6, is provided between the water inlet pipe 12 and the hot water outlet pipe 10. The bypass passage 14 is configured, for example, as a bypass pipe and is a flow path for water. The bypass passage 14 is provided with a mixing valve 32 that can be switched between a closed state, in which water flow through the bypass passage 14 is blocked, and an open state, in which the opening is increased from the closed state. A water flow control valve 33 is provided in the water inlet pipe 12 upstream of the branch point where the bypass passage 14 connects. The water flow control valve 33 has a motor whose drive shaft rotation angle is controlled by instructions from the controller 22, and is configured to continuously change the opening of the water inlet pipe 12 between a closed state and a fully open state. The water flow control valve 33 functions to adjust the amount of water flowing through the water pipe.

[0028] The gas pipe 40 that supplies gas to the gas burners 4 is provided with, from the upstream side, a gas main solenoid valve 42, a hot water gas proportional control valve 44, and hot water switching solenoid valves 46, 46, ... for each branch pipe to each gas burner 4. In addition, a fan 48 that supplies combustion air to each gas burner 4 and gas burner 54 is provided below the hot water combustion chamber 90. A switching solenoid valve 53 is provided in a branch pipe from the gas pipe that is connected to gas burner 54. The hot water gas proportional control valve 44 and hot water switching solenoid valve 46 function to adjust the amount of gas to the gas burner 4.

[0029] In the bath-side circuit 3, the piping 66 includes a piping 67 for guiding water from the bathtub 60 side to the heat exchanger 56 side, a piping 68 for guiding water from the heat exchanger 56 side to the bathtub 60 side, and an intermediate piping 69 connected to the piping 67 and 68 and passing through the heat exchanger 56. The piping 66 has one end and the other end connected to the bathtub 60, and serves as a path through which water leaving the bathtub 60 passes and returns to the bathtub 60. The piping 66 circulates water drawn from the bathtub 60, for example, during reheating or heating operation. The piping 67 guides the water drawn from the bathtub 60 to the heat exchanger 56, and the water that passes through the heat exchanger 56 is then guided back to the bathtub 60 via the piping 68. The gas burner 54 functions as a bath-side burner, combusting combustion gas to generate combustion exhaust. The heat exchanger 56 transfers heat generated by the gas burner 54 to water passing through a portion of the bath-side water pipe (specifically, water passing through the piping 66). The heat exchanger 56 includes a primary heat exchanger 57 and a secondary heat exchanger 58 and functions to transfer heat generated by the gas burner 54 to water passing through a pipe 66 .

[0030] Piping 67 is arranged between bathtub 60 and secondary heat exchanger 58, and is provided with a circulation pump 62 and a thermistor 64 (bath thermistor) that detects the temperature of the water passing through piping 67. The thermistor 64 functions to detect the temperature of the water discharged from bathtub 60 (i.e., the water temperature inside bathtub 60). Circulation pump 62 is a device that moves the water in piping 66, and functions to draw water from the bathtub 60 side and discharge the drawn water toward heat exchanger 56 side.

[0031] Piping 68 is arranged between primary heat exchanger 57 and bathtub 60. A drop pipe 70 branching off from hot water outlet pipe 10 is connected to piping 68, and hot water supplied from drop pipe 70 flows into piping 68. Drop pipe 70 is provided with a hot water supply solenoid valve 72 and a drop water volume sensor 74. By opening the hot water supply solenoid valve 72 provided on drop pipe 70, hot water heated in hot water supply side circuit 2 can be supplied to bathtub 60. Drop water volume sensor 74 has the function of detecting the amount of water supplied to bathtub 60 via drop pipe 70.

[0032] The drop pipe 70 is a path for passing hot water from the hot water supply side water passage of the hot water supply side circuit 2 to the piping 66 (circulation path) of the bath side circuit 3. The drop pipe 70 branches off from the hot water outlet pipe 10 and communicates with the piping 67, and functions to guide water heated in the heat exchanger 6 through the hot water supply side water passage to the bathtub 60.

[0033] As shown in Fig. 2, water heating apparatus 1 is provided with controller 22. As shown in Fig. 3, controller 22 includes control unit 22A configured as a known microcomputer or the like, memory 22B configured as a known semiconductor memory or the like, communication unit 22C configured as an interface for communicating with the outside, timer 22D capable of measuring time, and setting unit 22E that switches between a stopped state and an operable state. Note that the example in Fig. 2 conceptually illustrates controller 22, and a different configuration from that shown in Fig. 2 may be used as long as it has equivalent functions to control unit 22A, memory 22B, communication unit 22C, timer 22D, and setting unit 22E.

[0034] The controller 22 is configured to be able to acquire signals from various sensors provided in the hot water supply side circuit 2 and the bath side circuit 3, and can control various actuators provided in the hot water supply side circuit 2 and the bath side circuit 3. The controller 22 controls the operation of the gas burners 4, 54, the mixing valve 32, etc. The controller 22 is electrically connected to receive power from the power receiving unit 23. The power receiving unit 23 enables power to be supplied to the hot water supply device 1, and is a power supply voltage generating unit having, for example, an outlet plug, a power line, a power circuit, etc. When an external power source is connected to the power receiving unit 23 and power can be supplied from the outside, power supply begins so that the power supply voltage is applied to the control unit 22A.

[0035] The control unit 22A is electrically connected to the mixing valve 32, the water flow rate adjustment valve 33, the water volume sensor 34, and other components external to the controller 22. The control unit 22A outputs a control signal (pulse signal) to the motor 32A of the mixing valve 32 to change the opening of the mixing valve 32 and adjust the amount of water flowing through the bypass passage 14. When the amount of water flow detected by the water volume sensor 34 exceeds a predetermined value, the control unit 22A opens the gas main solenoid valve 42, the hot water gas proportional control valve 44, the hot water switching solenoid valve 46, and other components to start supplying gas to the gas burner 4, and also ignites the gas burner 4 by causing a spark discharge using an ignition device (not shown), thereby continuing combustion of the gas burner 4. The setting unit 22E is provided in the controller 22 and switches between an operation-stopped state (operation-off state) and an operation-enabled state (operation-on state) in response to an operation on the remote controller 80.

[0036] As shown in Fig. 3, the multiple remote controllers 80 are arranged in a configuration that allows communication with the controller 22. In the example of Figs. 2 and 3, the multiple remote controllers 80 include a first remote controller 81 provided in the bathroom and a second remote controller 82 provided in a location other than the bathroom (for example, the kitchen).

[0037] 3, the first remote controller 81 includes a control unit 81A configured as a known microcomputer or the like, a display unit 81B configured as a liquid crystal display device or the like, an operation unit 81C provided with a plurality of known switches such as push buttons, an audio output unit 81D configured as a speaker or the like that outputs audio, and a communication unit 81E that communicates with the controller 22 and the second remote controller 82. The operation unit 81C is made up of a plurality of operation units including an operation switch.

[0038] In this configuration, when the operation switch is pressed, the controller 22 switches between an operable state (operation on state) and an operation stopped state (operation off state) for hot water supply operation. Specifically, when the operation switch is pressed (when the operation on operation is performed) while the controller 22 is set to the operation off state (operation stopped state), the controller 22 switches to the operation on state (operable state), and when the operation switch is pressed (when the operation off operation is performed) while the controller 22 is set to the operation off state (operation stopped state). The operation stopped state (operation off state) is a "state in which power is supplied to the power receiving unit 23" and a "state in which the controller 22 does not control the ignition of the gas burner 4 and does not supply hot water even when the hot water outlet 18 is opened and water is flowing." The operable state (operation on state) is a state in which power is supplied to power receiving unit 23 and in which, when hot water outlet 18 is opened and water is allowed to flow, controller 22 ignites gas burner 4 to supply hot water. The other operating units are used for input operations to instruct filling bathtub 60 with hot water (input operations to instruct automatic filling and input operations to instruct energy-saving filling), input operations to schedule filling, input operations to switch the on / off states of the additional functions described above, etc.

[0039] The second remote controller 82 is similar and includes a control unit 82A configured as a known microcomputer or the like, a display unit 82B configured as a liquid crystal display device or the like, an operation unit 82C provided with a plurality of known switches such as push buttons, an audio output unit 82D configured as a speaker or the like for outputting audio, and a communication unit 82E for transmitting signals generated by the second remote controller 82 to the controller 22. The second remote controller 82 has the same configuration as the first remote controller 81 or a simplified configuration, and can be set in the same way as the first remote controller 81. The on / off states of both remote controllers 80 are linked. Settings made on one remote controller 80 are reflected in the other remote controller 80.

[0040] (Basic operation) In water heater 1, when the supply of hot water to the bathtub is stopped (hot water solenoid valve 72 is closed), the stopper (such as a faucet) at hot water outlet 18 is closed and the release of hot water from hot water outlet 18 is stopped, no water flows through water inlet pipe 12, the flow of water stops, and water volume sensor 34 detects the water flow stop state. In this state, when the stopper (such as a faucet) at hot water outlet 18 is opened and the release of hot water from hot water outlet 18 begins, or when hot water solenoid valve 72 is opened and the release of hot water into drop pipe 70 begins, water flows through water inlet pipe 12 and hot water outlet pipe 10, and water volume sensor 34 detects the water flow. When the water flow rate detected by water volume sensor 34 exceeds a predetermined value, control unit 22A opens gas main solenoid valve 42, hot water gas proportional control valve 44, hot water switching solenoid valve 46, etc., to start supplying gas to gas burner 4, and also ignites gas burner 4 by generating a spark discharge using an ignition device (not shown), thereby continuing combustion of gas burner 4. If combustion of gas burner 4 continues while a stopper (such as a faucet) provided at hot water outlet 18 is open or while hot water solenoid valve 72 is open, water flows through water inlet pipe 12, heat exchanger 6, and hot water outlet pipe 10, and is heated as it passes through heat exchanger 6, causing hot water to be released from hot water outlet 18 and the bathtub. In this way, the state in which hot water is released outside the hot water heater while gas burner 4 continues to burn when the operation is on (operable state) is the "hot water discharge state."

[0041] On the other hand, in this "hot water dispensing state," if the stopper (such as a faucet) at the hot water outlet 18 and the hot water solenoid valve 72 are both closed and the discharge of hot water from the hot water outlet 18 and into the drop pipe 70 is stopped, water flow stops in the water inlet pipe 12, and the amount of water flow detected by the water flow sensor 34 falls below a predetermined value (water flow stopped state). When the amount of water flow detected by the water flow sensor 34 falls below a predetermined value (water flow stopped state), the control unit 22A closes at least one of the gas main solenoid valve 42, the hot water gas proportional control valve 44, and the hot water switching solenoid valve 46 to cut off the supply of gas to the gas burner 4 and stop combustion of the gas burner 4. In this way, the state in which combustion of the gas burner 4 stops and the supply of hot water to the outside of the hot water heater is stopped in the operation-on state (operable state), which is the "hot water dispensing stopped state."

[0042] 2. Details of bypass valves, etc. The mixing valve 32 functions as a bypass valve and is configured to switch the bypass passage 14 between a water-passing state (a state in which water is allowed to flow into the bypass passage 14 through the mixing valve 32) and a blocked state (a state in which water is blocked from flowing into the bypass passage 14 through the mixing valve 32), and is further configured to adjust the amount of water passing through the bypass passage 14. The mixing valve 32 has a valve element 32B that opens and closes the bypass passage 14 and a motor 32A, which is an example of a drive source that drives the valve element 32B. The motor 32A (drive source) drives the valve element 32B, so that the valve element 32B can be changed from a fully closed position that closes the bypass passage 14 to a fully open position, at which the valve element 32B is at its largest opening. The greater the opening of the valve element 32B in the mixing valve 32, the greater the amount of water passing through the mixing valve 32, and the smaller the opening of the valve element 32B, the smaller the amount of water passing through the mixing valve 32.

[0043] A switch 35 capable of detecting a fully open state is provided near the mixing valve 32. The switch 35 corresponds to an example of a detection unit and functions to detect when the valve disc 32B is in the fully open position. The switch 35 may be, for example, a limit switch with a built-in Hall IC, or other switches. The switch 35 outputs a detection signal (e.g., an ON signal) when the mixing valve 32 is in the fully open state (when the valve disc 32B is in the fully open position), and outputs a non-detection signal (e.g., an OFF signal) different from the detection signal when the mixing valve 32 is not in the fully open position (when the valve disc 32B has moved a predetermined amount in the closing direction from the fully open position). "When the mixing valve 32 is in the fully open state" may be when water is permitted to flow through the mixing valve 32, or when the opening of the mixing valve 32 is equal to or greater than a predetermined minimum opening. In a typical example, switch 35 is configured as a switch that outputs a detection signal (e.g., an ON signal) when valve element 32B is in the fully open position and outputs a non-detection signal (e.g., an OFF signal) when valve element 32B moves a certain amount in the closing direction from the fully open position. In a typical example, when mixing valve 32 is fully open, approximately 60% of the water entering through water inlet 16 flows into bypass path 14, and approximately 40% flows into heat exchanger 6. When mixing valve 32 is fully closed (valve element 32B is in the fully closed position), approximately 100% of the water entering through water inlet 16 flows into heat exchanger 6, and approximately 0% flows into bypass path 14 (i.e., water flow through mixing valve 32 is blocked). In mixing valve 32 configured in this manner, the position of valve element 32B can be adjusted to any position (any opening degree) between the fully open position and the fully closed position. In the example of FIG. 3, the switch 35 is a part of the mixing valve 32, but the switch 35 does not have to be a part of the mixing valve 32 as long as it is configured to be able to detect that the valve element 32B is in the fully open position.

[0044] The control unit 22A is electrically connected to the controller 22 so as to be able to control the mixing valve 32, the water flow rate adjustment valve 33, and the like, which are provided outside the controller 22. For example, the control unit 22A outputs a control signal (pulse signal) to the water flow rate adjustment valve 33, thereby changing the opening degree of the water flow rate adjustment valve 33 and adjusting the amount of water flowing from the water inlet 16 to the hot water outlet 18.

[0045] The control unit 22A is configured to be able to check the signal output by the switch 35. For example, when the switch 35 outputs a detection signal (e.g., an ON signal), the detection signal itself or a first signal corresponding to the detection signal is input to the control unit 22A. When the switch 35 outputs a non-detection signal (e.g., an OFF signal), the non-detection signal itself or a second signal corresponding to the non-detection signal is input to the control unit 22A.

[0046] The motor 32A is configured as, for example, a stepping motor. The motor 32A has a drive shaft 32C that is interlocked with the valve element 32B. The rotational position of the drive shaft 32C when the valve element 32B is in the fully open position is the reference rotational position. As the drive shaft 32C rotates in a predetermined direction from the reference rotational position, the opening degree of the valve element 32B decreases. When the drive shaft 32C rotates Nmax in the predetermined direction from the reference rotational position, the valve element 32B reaches the fully closed position. When the drive shaft 32C rotates Nmax in the opposite direction from the rotational position (maximum rotation position) of the drive shaft 32C when the valve element 32B is in the fully closed position, the valve element 32B reaches the fully open position, and the drive shaft 32C reaches the reference rotational position. The control unit 22A can output to the motor 32A a first pulse signal that rotates the drive shaft 32C in a predetermined direction and a second pulse signal that rotates the drive shaft 32C in the opposite direction to the predetermined direction. The first pulse signal is a pulse signal with a first period. The second pulse signal is a pulse signal with a second period. It is desirable that the first period and the second period have the same value. When the control unit 22A outputs one pulse (one step) of the first pulse signal to the motor 32A, the drive shaft 32C of the motor 32A rotates a predetermined angle in a predetermined direction (closing direction). When the control unit 22A outputs one pulse (one step) of the second pulse signal to the motor 32A, the drive shaft 32C of the motor 32A rotates a predetermined angle in a direction opposite to the predetermined direction (opening direction). If the rotational position of the drive shaft 32C of the motor 32A when the valve element 32B is in the fully open position is defined as a reference rotational position, the opening degree of the valve element 32B decreases according to the number of rotations of the drive shaft 32C of the motor 32A in the predetermined direction from the reference rotational position. When the valve element 32B is in the fully open position (when the drive shaft 32C is in the reference rotation position), if a first pulse signal with a predetermined maximum number of pulses (maximum number of steps) is output to the motor 32A, the drive shaft 32C will be displaced to the maximum rotation position, and the valve element 32B will be in the fully closed position. When the valve element 32B is in the fully closed position (when the drive shaft 32C is in the maximum rotation position), if a second pulse signal with the maximum number of pulses (maximum number of steps) is output to the motor 32A, the drive shaft 32C will be displaced to the reference rotation position, and the valve element 32B will be in the fully open position.

[0047] 3. Control when operation is on The control in Fig. 4 is executed by control unit 22A when switching from an operation-stopped state (operation-off state) to an operation-enabled state (operation-on state). When the operation switch is pressed (when the operation-on operation is performed) while water heating apparatus 1 is set to the operation-off state (operation-stopped state), control unit 22A switches the setting of water heating apparatus 1 to an operation-enabled state (operation-on state) and starts the control in Fig. 4. Note that when water heating apparatus 1 is set to the operation-stopped state (operation-off state), control unit 22A maintains valve element 32B in the fully open position.

[0048] After starting the control of Fig. 4, the control unit 22A determines in step S11 whether or not water inflow has been detected. Specifically, in step S11, the control unit 22A determines whether or not the water flow rate detected by the water volume sensor 34 exceeds a predetermined value, and repeats the determination in step S11 while the water flow rate does not exceed the predetermined value. If the control unit 22A determines in step S11 that the water flow rate detected by the water volume sensor 34 exceeds the predetermined value, the control unit 22A determines in step S12 whether or not the mixing valve 32 is normal. For example, after the control of Fig. 4 is started, if the release of hot water from the hot water outlet 18 begins and water flows through the water inlet pipe 12 and the hot water outlet pipe 10, the water flow rate detected by the water volume sensor 34 exceeds the predetermined value, and the control unit 22A determines "Yes" in step S11.

[0049] In this specification, the above-mentioned "hot water discharge state" refers to a state in which hot water is discharged outside of water heater 1, and more specifically, a state in which water is flowing through water inlet pipe 12, hot water supply-side gas burner 4 is burning, and hot water is discharged from hot water outlet 18 or bathtub 60. The above-mentioned "hot water discharge stop state" refers to a state in which water flow through water inlet pipe 12 is stopped and combustion of gas burner 4 is stopped.

[0050] When determining whether the mixing valve 32 is normal in step S12, the control unit 22A performs, for example, full-open control, outputting a pulse signal to the motor 32A to move the mixing valve 32 until it reaches a fully open state, and then performs closing control, outputting a pulse signal to the motor 32A to move the valve element 32B a certain amount in the closing direction until the switch 35 outputs a non-detection signal. When full-open control and closing control are performed in this manner, if the mixing valve 32 is normal, the switch 35 outputs a detection signal (e.g., an ON signal) when the full-open control is performed, and outputs a non-detection signal (e.g., an OFF signal) when the closing control is performed. Therefore, if the switch 35 outputs a detection signal when the full-open control is performed in step S12 and then outputs a non-detection signal when the closing control is performed immediately thereafter, the control unit 22A determines that the mixing valve 32 is normal in step S12, and proceeds to step S13. If the switch 35 does not output a detection signal when the full-open control is performed in step S12, or if the switch 35 does not output a non-detection signal when the closing operation control is performed after the full-open control, the control unit 22A determines that the mixing valve 32 is not normal in step S12 and performs a predetermined abnormality response process in step S25. When performing the abnormality response process in step S25, the control unit 22A may, for example, notify the user that an abnormality has occurred (for example, that the mixing valve 32 is abnormal) or may prohibit the subsequent combustion operation of the gas burner 4. When notifying the user that an abnormality has occurred in step S25, for example, the control unit 22A may display an indication that an abnormality has occurred on the display units 81B, 82B, etc., or may issue an audio notification of the abnormality using a buzzer, speaker, etc.

[0051] If the control unit 22A determines in step S12 that the mixing valve 32 is normal, the control unit 22A ignites the gas burner 4 in step S13. When igniting the gas burner 4 in step S13, the control unit 22A controls the gas main solenoid valve 42, the hot water gas proportional control valve 44, the hot water switching solenoid valve 46, etc., to open to supply gas to the gas burner 4, and controls an ignition device (not shown) to generate a spark discharge to ignite the gas burner 4. After the gas burner 4 is ignited in step S13, the gas burner 4 continues to burn until the gas burner 4 is extinguished. In this embodiment, the water flow sensor 34 and the control unit 22A correspond to an example of a water flow detection unit, and "the control unit 22A determining that the amount of water flow detected by the water flow sensor 34 has exceeded a predetermined value" corresponds to an example of detecting water flow. Then, as described above, the control unit 22A places the gas burner 4 in a combustion state when the water flow detection unit detects water flow.

[0052] After igniting gas burner 4 in step S13, control unit 22A proceeds to step S14 and controls the aperture of mixing valve 32. Specifically, after completing step S13, control unit 22A repeats the process of controlling the aperture of mixing valve 32 until temperature T detected by thermistor 27 becomes equal to or higher than first temperature T1. The control of the aperture of mixing valve 32 is a control that sets the outlet hot water temperature detected by thermistor 26 to a set temperature (a target temperature set by a remote controller or the like), and various known control methods can be used. Specifically, for example, when repeating the process of controlling the aperture of mixing valve 32 in steps S14 and S15, control unit 22A controls the amount of water flowing through bypass path 14 by controlling the aperture of mixing valve 32 based on the set temperature, the inlet water temperature detected by thermistor 25, the water flow rate detected by water flow sensor 34, and the outlet hot water temperature detected by thermistor 26.

[0053] After step S14, in step S15, control unit 22A determines whether an abnormality has occurred in which the temperature T detected by thermistor 27 (inner body outlet thermistor) is equal to or greater than first temperature T1 (97°C), and if temperature T is lower than first temperature T1 (No in step S15), control unit 22A returns to step S14 and repeats the processes of steps S14 and S15 until an abnormality has occurred in which the temperature T detected by thermistor 27 is equal to or greater than first temperature T1. If control unit S22A determines in step S15 that an abnormality has occurred in which the temperature T detected by thermistor 27 (inner body outlet thermistor) is equal to or greater than first temperature T1 (97°C) (Yes in step S15), control unit S22A proceeds to step S16.

[0054] When the control unit 22A advances the processing to step S16, it initializes the abnormality count C in step S16, and then in step S17 performs control to extinguish the gas burner 4, stopping the combustion of the gas burner 4. By stopping the combustion of the gas burner 4 in step S17, the supply of hot and cold water passing through the heat exchanger 6 is permitted while suppressing any further temperature rise in the heat exchanger 6. The value of the abnormality count C is a value indicating the number of times that the temperature T detected by the thermistor 27 has become equal to or higher than the first temperature T1.

[0055] After step S17, control unit 22A performs an abnormality recording process in step S18. Control unit 22A performs the abnormality recording process in step S18, for example, as shown in FIG. 5. In the example of FIG. 5, after starting the abnormality recording process, control unit 22A adds 1 to the value of abnormality count C at the current time (at the start of step S31) in step S31, and updates the value of abnormality count C after the increment to become the new value of abnormality count C. For example, if abnormality count C was 0 at the start of step S31, 1 is added in step S31, and the new value of abnormality count C is updated to 1.

[0056] After step S31, in step S32, the control unit 22A determines whether the value of the abnormality count C at the current time (at the start of step S32) is a predetermined "predetermined number of times." In this embodiment, this "predetermined number of times" is stored in a storage unit (for example, memory 22B) in advance. In the following, an example in which the "predetermined number of times" is 3 will be described, but the predetermined number may be a natural number other than 3. If the control unit 22A determines in step S32 that the value of the abnormality count C at the current time (at the start of step S32) is not the "predetermined number of times" (No in step S32), the control unit 22A ends the abnormality recording process of FIG. 5 and proceeds to step S19 of FIG. 4. For example, if the abnormality count C is 1 or 2 at the time of step S32, the determination in step S32 will be No.

[0057] If control unit 22A determines in step S32 that the value of abnormality count C at the current time (start time of step S32) is the "predetermined number of times" (if Yes in step S32), control proceeds to step S33, where it stores (records) predetermined abnormality information (error information) in a storage unit (e.g., memory 22B). The abnormality information (error information) may be a predetermined error code, or may be information indicating that the number of times the temperature detected by thermistor 27 has reached or exceeded first temperature T1 has reached a predetermined number of times. The abnormality information stored (recorded) in a storage unit (e.g., memory 22B) is readable. For example, when a predetermined operation is performed on an operation unit of water heating apparatus 1, the abnormality information may be displayed on a display unit of water heating apparatus 1, or may be displayed on an external device provided outside water heating apparatus 1. Alternatively, when predetermined request information is input to water heating apparatus 1 from an external device provided outside water heating apparatus 1 so as to be able to communicate with water heating apparatus 1, control unit 22A may transmit the abnormality information to the external device. In this way, the abnormality information can be used when water heater 1 is maintained or repaired.

[0058] In the water heating device 1 of this embodiment, even if abnormality information is stored (recorded) in step S33, the notification unit will not issue a notification (for example, a notification to the user about an abnormality) until the notification condition (in this embodiment, the condition that results in Yes in step S20) is met, and the user can dispense hot water as usual without being aware that such an abnormality has occurred.

[0059] After steps S17 and S18, in step S19, control unit 22A determines whether temperature T detected by thermistor 27 is equal to or lower than second temperature T2 (80°C). If control unit 22A determines in step S19 that temperature T detected by thermistor 27 is higher than second temperature T2 (No in step S19), control unit 22A proceeds to step S20, where it determines whether temperature T detected by thermistor 27 is equal to or higher than third temperature T3 (140°C). If control unit 22A determines in step S20 that temperature T detected by thermistor 27 is lower than third temperature T3 (140°C), it returns the process to step S19, where it determines whether temperature T detected by thermistor 27 is equal to or lower than second temperature T2 (80°C). If control unit 22A determines in step S20 that temperature T detected by thermistor 27 is equal to or higher than third temperature T3 (140°C), control unit 22A proceeds to step S21. If control unit 22A determines in step S20 that temperature T detected by thermistor 27 is equal to or higher than third temperature T3, it can be said that the temperature continues to rise despite the fact that the temperature should have decreased due to combustion being stopped. In such a case (Yes in step S20), control unit 22A performs a predetermined abnormal stop operation in step S21 and notifies the user of the abnormality.

[0060] When notifying the user of an abnormality in step S21, control unit 22A may, for example, notify the user of the abnormality by displaying on a display unit (e.g., display units 81B, 82B, etc.) of water heating apparatus 1 that an abnormality has occurred or that use is prohibited (e.g., displaying an error code or an error message), or may notify the user of the abnormality by causing an audio output unit (e.g., audio output units 81D, 82D, etc.) to emit an abnormal sound. In this embodiment, control unit 22A, the display unit (e.g., display units 81B, 82B, etc.), and the audio output unit (e.g., audio output units 81D, 82D, etc.) correspond to examples of notification units, and function to notify the user of an abnormality to the outside of water heating apparatus 1.

[0061] When performing an abnormal shutdown operation in step S21, control unit 22A places water heating apparatus 1 in a predetermined use-prohibited state. The predetermined use-prohibited state may be "a state in which it is prohibited to perform an operation to instruct hot water supply (e.g., an operation to instruct automatic filling) using operation units 81C, 82C of remote controller 80," "a state in which it is prohibited to perform an operation to set hot water supply (e.g., an operation to set a set temperature, an amount of hot water supplied, etc.) using operation units 81C, 82C of remote controller 80," or "a state in which gas burner 4 is not allowed to burn even if the amount of water flow detected by water volume sensor 34 exceeds a predetermined value." When control unit 22A places water heating apparatus 1 in a "state in which it is prohibited to perform an operation to instruct hot water supply (e.g., an operation to set a set temperature, an amount of hot water supplied, etc.)" in step S21, it is desirable to maintain this state until a predetermined release operation is performed.

[0062] If control unit 22A determines in step S19 that temperature T detected by thermistor 27 is equal to or lower than second temperature T2 (Yes in step S19), control proceeds to step S22, where it ignites gas burner 4. If temperature T detected by thermistor 27 is equal to or lower than second temperature T2 (Yes in step S19), the temperature has dropped sufficiently, and there is a concern that a further drop in temperature may cause discomfort to the user. Therefore, in step S22, gas burner 4 is ignited so that heat exchanger 6 can be heated.

[0063] After igniting gas burner 4 in step S22, control unit 22A proceeds to step S23 and controls the aperture of mixing valve 32. Specifically, after completing step S22, control unit 22A repeats the process of controlling the aperture of mixing valve 32 until temperature T detected by thermistor 27 becomes equal to or higher than first temperature T1. The control of the aperture of mixing valve 32 is a control that sets the outlet hot water temperature detected by thermistor 26 to a set temperature (a target temperature set by a remote controller or the like), and various known control methods can be employed. Specifically, for example, when repeating the process of controlling the aperture of mixing valve 32 in steps S23 and S24, control unit 22A controls the amount of water passing through bypass path 14 by controlling the aperture of mixing valve 32 based on the set temperature, the inlet water temperature detected by thermistor 25, the water flow rate detected by water flow sensor 34, and the outlet hot water temperature detected by thermistor 26.

[0064] After step S23, control unit 22A determines in step S24 whether temperature T detected by thermistor 27 is equal to or higher than first temperature T1 (97°C), and if temperature T is lower than first temperature T1 (No in step S24), returns the process to step S23 and repeats the processes of steps S23 and S24 until temperature T detected by thermistor 27 becomes equal to or higher than first temperature T1. If control unit S22A determines in step S24 that temperature T detected by thermistor 27 is equal to or higher than first temperature T1 (97°C) (Yes in step S24), returns the process to step S17 and extinguishes gas burner 4 in step S17 to stop combustion of gas burner 4.

[0065] In this embodiment, the processes of steps S14, S15, S16, S17, S18, S19, S20, S22, S23, and S24 after igniting the gas burner 4 in step S13 are an example of combustion adjustment control. By performing combustion adjustment control in this manner, the control unit 22A switches between the combustion state and the combustion stop state so that the gas burner 4 is placed in the combustion stop state when the temperature T detected by the thermistor 27 (temperature detection unit) when the gas burner 4 is in the combustion state becomes equal to or higher than a first temperature T1, and the gas burner 4 is placed in the combustion state again when the temperature detected by the thermistor 27 (temperature detection unit) when in the combustion stop state falls to or lower than a second temperature T2 that is lower than the first temperature T1.

[0066] 4 omits the normal extinguishing operation of the gas burner 4, but for example, after water inflow is detected in step S11, if the amount of water flow detected by the water flow sensor 34 falls below a predetermined value before the processing of step S21 or step S25 is performed (if a water flow stop state is detected), the control unit 22A performs a termination operation to turn the gas burner 4 into an extinguished state and set the mixing valve 32 to the fully open position. When the control unit 22A performs such a termination operation, the process may return to step S11. Note that if the operation is switched to the operation-off state while the control of FIG. 4 is being performed, the control of FIG. 4 is terminated, and if the operation is switched to the operation-on state again, the control of FIG. 4 is resumed.

[0067] 4.Example of effects If the combustion of the gas burner 4 continues while the heat exchanger 6 is slightly clogged and the mixing valve 32 is open to some extent, more water will flow through the bypass path 14, making it more difficult for water to flow through the heat exchanger 6. This makes it easier for the water in the heat exchanger 6 to be overheated. Therefore, in the water heater 1, the thermistor 27 (temperature detection unit) detects the temperature of hot water at a position on the hot water outlet pipe 10 closer to the heat exchanger 6 than the connection unit 10A. The control unit 22A switches the gas burner 4 to a combustion-stopped state when the temperature detected by the thermistor 27 (temperature detection unit) is equal to or higher than a first temperature T1 while the gas burner 4 is in the combustion-stopped state. The control unit 22A performs combustion adjustment control to switch between the combustion state and the combustion-stopped state, so that the gas burner 4 is again switched to the combustion state when the temperature detected by the thermistor 27 (temperature detection unit) during the combustion-stopped state drops to or below a second temperature T2, which is lower than the first temperature T1. In this way, after the water heater 1 switches the gas burner 4 to a combustion-stopped state in response to the detection of a hot water temperature equal to or higher than the first temperature T1, the gas burner 4 maintains the combustion-stopped state without returning to the combustion state until the detected hot water temperature falls to or below the lower second temperature T2, even if the detected hot water temperature temporarily drops below the first temperature T1 due to the generation of bubbles or the like. This prevents the heat exchanger 6 from remaining overheated for too long. Furthermore, in the water heater 1, the control unit 22A restricts the notification unit from notifying an abnormality during combustion adjustment control until a predetermined notification condition is met. In other words, the water heater 1 does not notify an abnormality even if a hot water temperature equal to or higher than the first temperature T1 is detected during combustion adjustment control until the predetermined notification condition is met. This helps prevent the user from being confused or uncomfortable by the notification of an abnormality when hot water is available for dispensing. Furthermore, if the cause of the "blockage" or overheating is freezing, there is a possibility that the freezing will be resolved during combustion adjustment control, and if the freezing is resolved and the "blockage" disappears before the specified notification conditions are met, it is easy to transition to normal control without significantly impairing user convenience.

[0068] The first temperature T1 is preferably set to a temperature lower than the boiling temperature (e.g., 100°C), and more preferably to a temperature close to the boiling temperature. Setting the first temperature T1 lower than the boiling temperature is advantageous in terms of protecting the heat exchanger and the like from excessively high temperatures. Furthermore, setting the first temperature T1 to a temperature close to the boiling temperature is advantageous in terms of making it easier to supply hot water at the temperature desired by the user.

[0069] The second temperature T2 is preferably set higher than the target temperature set by a remote controller or the like. Setting it in this manner makes it easier to resume combustion before the temperature of the hot water being dispensed becomes too low and the user feels uncomfortable. For example, in water heater 1, the set temperature set by remote controller 80 is set as the target temperature, and controller 22 controls water heater 1 so as to dispense hot water at this target temperature, and second temperature T2 is set higher than the target temperature set by remote controller 80. More preferably, when the temperature range that can be set by remote controller 80 is a predetermined range, second temperature T2 is set higher than the upper limit temperature of the predetermined range.

[0070] In water heating apparatus 1, even if the temperature detected by thermistor 27 (temperature detection unit) exceeds first temperature T1 (e.g., 97°C) and combustion adjustment control is performed, an abnormality is not reported until a predetermined reporting condition is met. Therefore, water heating apparatus 1 may continue to be used without recognizing that the temperature detected by thermistor 27 (temperature detection unit) has exceeded first temperature T1. However, if the temperature detected by thermistor 27 (temperature detection unit) repeatedly exceeds first temperature T1, it may place a strain on devices such as heat exchanger 6, potentially resulting in equipment failure. Therefore, in water heating apparatus 1, when the temperature detected by thermistor 27 (temperature detection unit) reaches first temperature T1 a predetermined number of times (e.g., three times), control unit 22A stores abnormality information. Therefore, water heating apparatus 1 can subsequently check whether abnormality information has been stored, i.e., whether the temperature has reached the predetermined number of times. This makes it easier for a repairer to identify the cause of a malfunction, for example, if a malfunction occurs.

[0071] In water heating apparatus 1, if the temperature detected by thermistor 27 (temperature detection unit) continues to rise even after switching to a combustion-stopped state in response to the temperature detected by thermistor 27 (temperature detection unit) reaching first temperature T1, there is a possibility that dry-heating is occurring in heat exchanger 6. Therefore, water heating apparatus 1 can prompt a person who receives the notification from the notification unit (e.g., a user) to take action against the abnormality by causing the notification unit to notify the abnormality when the temperature detected by thermistor 27 (temperature detection unit) reaches third temperature T3 (e.g., 140°C). Note that third temperature T3 is preferably set to a temperature higher than the boiling temperature (e.g., 100°C).

[0072] Furthermore, when the temperature detected by thermistor 27 (temperature detection unit) reaches third temperature T3, water heating device 1 puts water heating device 1 into a predetermined prohibited state, thereby preventing normal use of water heating device 1.

[0073] <Other embodiments> The present disclosure is not limited to the embodiments described above and in the drawings. For example, any combination of features of the above-described or following embodiments is possible within a range that does not contradict. Furthermore, any feature of the above-described or following embodiments may be omitted unless explicitly stated as essential. Furthermore, the above-described embodiment may be modified as follows.

[0074] In the embodiment described above, water heating apparatus 1 initializes abnormality count C to 0 in step S34, and then stores abnormality information in step S33 each time abnormality count C reaches 3, but this is not limiting. For example, water heating apparatus 1 may not perform initialization in step S34, and may store the latest abnormality count C at the time of step S33 in addition to the abnormality information in step S33.

[0075] In the water heating device 1 of the above-described embodiment, the judgment process of step S12 is performed each time a Yes judgment is made in step S11 in FIG. 4, but the judgment process of step S12 may be performed only when a Yes judgment is made in step S11 for the first time after switching from the operation-off state to the operation-on state.

[0076] It should be noted that the embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is not limited to the embodiments disclosed herein, but is intended to include all modifications within the scope indicated by the claims or the scope equivalent to the claims. [Explanation of symbols]

[0077] 1...Hot water supply equipment 4...Gas burner 6...Heat exchanger 7a...heat transfer tube 10...Hot water outlet pipe 12...Water inlet pipe 14...Bypass road 16…Water inlet 18…Hot water outlet 20...Piping 22...Controller 22A...Control unit (water flow detection unit, notification unit) 22B...Memory (storage section) 27...Thermistor (temperature detection part) 32...Mixing valve 32A...Motor (drive source) 32B...Valve body 34...Water volume sensor (water flow detection part) 81B, 82B...Display unit (notification unit) 81D, 82D...Audio output unit (alert unit)

Claims

1. a gas burner for burning gas; a water inlet pipe configured as a path through which water flows from the water inlet; A hot water outlet pipe configured as a path for sending hot water to a hot water outlet; a heat exchanger including a heat transfer tube configured as a water passage between the water inlet pipe and the hot water outlet pipe, and performing heat exchange so as to transfer heat generated by combustion in the gas burner to water passing through the heat transfer tube; a bypass path connected to the water inlet pipe and the hot water outlet pipe and configured as a water passage different from the heat exchanger; a mixing valve including a valve element that opens and closes the bypass passage and a drive source that drives the valve element, the drive source driving the valve element to adjust the opening degree of a predetermined position in the bypass passage; a temperature detector that is provided in the hot water outlet pipe closer to the heat exchanger than the connection portion with the bypass passage and detects the temperature of the hot water flowing through the hot water outlet pipe; a water flow detection unit that detects the flow of water in a water flow path between the water inlet and the hot water outlet; a notification unit that notifies of an abnormality; a control unit that controls the mixing valve, the gas burner, and the notification unit; Equipped with the control unit performs combustion adjustment control to switch between the combustion state and the combustion stop state, so as to place the gas burner in a combustion state on the condition that water flow is detected by the water flow detection unit, place the gas burner in a combustion stop state when an abnormality occurs in which the temperature detected by the temperature detection unit becomes equal to or higher than a first temperature while the gas burner is in the combustion state, and place the gas burner in the combustion state again when the temperature detected by the temperature detection unit becomes equal to or lower than a second temperature that is lower than the first temperature while the gas burner is in the combustion stop state; The control unit restricts the notification unit from notifying an abnormality during the combustion adjustment control until a predetermined notification condition is met. Water heater.

2. Further, a storage unit is provided, The control unit counts the number of times that the temperature detected by the temperature detection unit reaches the first temperature during the combustion adjustment control, and when the number of times that the temperature reaches the first temperature reaches a predetermined number during the combustion adjustment control, the control unit stores abnormality information in the storage unit while restricting the notification unit from notifying an abnormality. The water heater according to claim 1 .

3. The control unit causes the notification unit to notify of an abnormality when the temperature detected by the temperature detection unit in the combustion stopped state becomes equal to or higher than a third temperature that is higher than the first temperature. The hot water supply device according to claim 1 or 2.

4. The control unit sets the water heater to a predetermined use-prohibited state when the temperature detected by the temperature detection unit in the combustion-stopped state becomes equal to or higher than a third temperature that is higher than the first temperature. The hot water supply device according to claim 1 or 2.

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