Hot water supply apparatus

Abstract

To more accurately detect abnormality of a mixing valve of a hot water supply device with a simpler configuration.SOLUTION: The hot water supply device 1 includes a bypass passage 14 connected to a water inlet pipe and a hot water outlet pipe and configured as a water passage different from a heat exchanger, a mixing valve 32 having a valve body 32B for opening and closing the bypass passage 14 and a drive source for driving the valve body 32B, a detection unit for detecting that the valve body 32B is in a fully open position, and a control unit 22A for controlling the mixing valve 32 and the gas burner. The valve body 32B can be changed from a fully closed position where the bypass passage 14 is closed to a fully open position where the opening degree is maximized. In a case where a predetermined operation start condition is satisfied, the control unit 22A performs closing control of moving the valve body 32B by a predetermined amount in a closing direction and then performs opening control of moving the valve body 32B in an opening direction, and determines that the mixing valve 32 is abnormal in a case where an elapsed time from a predetermined timing after the operation start condition is satisfied until the fully open position is detected by the detection unit is less than a reference time.SELECTED DRAWING: Figure 5

Description

[Technical Field]

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

[0002] The hot water supply device disclosed in Patent Document 1 is composed of a hot water supply circuit and a bath circuit. The hot water supply circuit includes a water inlet pipe through which water flows from a water inlet, a hot water outlet pipe through which hot water is delivered to a hot water outlet, and a heat exchanger consisting of a primary heat exchanger and a secondary heat exchanger that exchanges combustion heat from a gas burner, and functions as a path for heating tap water and delivering hot water. Furthermore, the hot water supply device is provided with a bypass path that bypasses the water inlet pipe and hot water outlet pipe, and is configured as a water flow path separate from the heat exchanger. The bypass path is provided with a bypass valve that can be switched between a closed state in which water flow through the bypass path is blocked and an open state in which the valve is opened to a greater degree than the closed state.

[0003] In this water heater, the control unit closes 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. When the water flow sensor detects water flow in the blocked state due to the start of water flow in the water inlet pipe, the control unit performs a predetermined normal combustion control to put the gas burner into a combustion state, and after stopping the gas burner combustion and completing the normal combustion control, leaves the bypass passage open. When the water flow sensor detects water flow in the blocked state due to the start of water flow in the water inlet pipe, the control unit performs an opening control to open the bypass passage, and performs an unfreezing combustion control to burn the gas burner and continue the combustion state of the gas burner until a predetermined termination condition is met. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 6320226 Summary of the Invention [Problem to be solved by the invention]

[0005] In a water heater equipped with a mixing valve (bypass valve) that changes the amount of water flowing through the bypass passage, the mixing valve may become inoperable due to freezing. If the mixing valve freezes when it is in the fully open position and is determined to be in a normal state due to some malfunction, the mixing valve cannot be controlled, and heating will continue even with a small amount of water flowing through the heat exchanger.

[0006] One object of the present disclosure is to provide a technology that can more accurately detect an abnormality in a mixing valve of a water heater with a simpler configuration. [Means for solving the problem]

[0007] 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 pipe 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 pipe and a drive source that drives the valve element, wherein the drive source drives the valve element to change the valve element from a fully closed position that closes the bypass pipe to a fully open position that has the largest opening degree; a detection unit that detects that the valve element is in the fully open position; a control unit for controlling the mixing valve and the gas burner; Equipped with When a predetermined operation start condition is satisfied, the control unit executes opening and closing control by attempting closing control to move the valve element a predetermined amount in a closing direction, and then executing opening control to move the valve element in an opening direction, and determines that the mixing valve is abnormal if the elapsed time from a predetermined timing after the operation start condition is satisfied until the detection of the fully open position by the detection unit is less than a reference time, The reference time is shorter than the time required from the timing until the fully open position is detected by the detection unit when the opening / closing control is performed in a state where the mixing valve is normal. [Effects of the Invention]

[0008] According to the technology disclosed herein, an abnormality in a mixing valve of a water heater can be detected more accurately with a simpler configuration. [Brief explanation of the drawings]

[0009] [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 illustrating control when the operation start condition is met in the water heater of FIGS. [Figure 5] FIG. 5 is a flowchart showing the abnormality detection process of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0010] Each of the following [1] to [5] is an example of a water heater included in the present disclosure. [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 pipe 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 pipe and a drive source that drives the valve element, wherein the drive source drives the valve element to change the valve element from a fully closed position that closes the bypass pipe to a fully open position that has the largest opening degree; a detection unit that detects that the valve element is in the fully open position; a control unit for controlling the mixing valve and the gas burner; Equipped with When a predetermined operation start condition is satisfied, the control unit executes opening and closing control by attempting closing control to move the valve element a predetermined amount in a closing direction, and then executing opening control to move the valve element in an opening direction, and determines that the mixing valve is abnormal if the elapsed time from a predetermined timing after the operation start condition is satisfied until the detection of the fully open position by the detection unit is less than a reference time, The reference time is shorter than the time required from the timing until the fully open position is detected by the detection unit when the opening / closing control is performed in a state where the mixing valve is normal. Water heater.

[0011] In the water heating apparatus of [1], if the area around the mixing valve is frozen when the operation start condition is met, even if a closing control attempt is made to move the valve disc a predetermined amount in the closing direction, the valve disc may not move the predetermined amount and may remain near the fully open position or may only move slightly from the fully open position. However, this water heating apparatus performs an opening / closing control to move the valve disc in the opening direction after attempting a closing control, and can determine an abnormality based on this opening / closing control. Specifically, the water heating apparatus determines that the mixing valve is abnormal if the elapsed time from a predetermined timing after the operation start condition is met until the detection unit detects the fully open position is less than a reference time. In the water heating apparatus of [1], if the area around the mixing valve is frozen when the operation start condition is met and the closing control attempt is made to move the valve disc a predetermined amount and may remain near the fully open position or may only move slightly from the fully open position, the time until the detection unit detects the fully open position is likely to be shorter than normal when an opening control is subsequently performed. In such a case, the time elapsed from the timing mentioned above until the fully open position is detected by the detector is likely to be less than the reference time. The reference time is shorter than the time required for the detector to detect the fully open position from the timing mentioned above when the opening and closing control is performed while the mixing valve is normal. Therefore, if the elapsed time falls short of the reference time, it is highly likely that the predetermined amount of movement was not achieved during the closing control, and that an abnormality has occurred in the mixing valve. In this way, the water heating device can more accurately detect an abnormality in the mixing valve with a simpler configuration by using the "method of determining that the mixing valve is abnormal if the elapsed time is less than the reference time."

[0012] [2] The detection unit is a switch that outputs a detection signal when the valve element is at the fully open position, and outputs a non-detection signal when the valve element moves from the fully open position in the closing direction by a certain amount that is smaller than the predetermined amount, When the predetermined operation start condition is satisfied, the control unit attempts the closing control by issuing a movement instruction to the drive source to move the valve element in the closing direction by the predetermined amount, and then performs the opening control by moving the valve element in the opening direction until the switch outputs the detection signal.The control unit determines that the elapsed time is the period from the start of the opening control to the time when the switch outputs the detection signal, and determines that the mixing valve is abnormal if the elapsed time is less than the reference time. The water heater according to [1].

[0013] In the water heater of [2], the detection unit is configured with "a switch that outputs a detection signal when the valve is in the fully open position and outputs a non-detection signal when the valve is moved a certain amount less than a predetermined amount from the fully open position in the closing direction," making it easier to configure the detection unit. In this way, the water heater can more accurately detect abnormalities in the mixing valve while realizing a configuration that makes it easier to further simplify the detection unit.

[0014] [3] When the predetermined operation start condition is established, the control unit permits combustion of the gas burner on condition that the elapsed time is equal to or longer than the reference time. The water heater according to [1] or [2].

[0015] The water heater of [3] allows the gas burner to burn on the condition that the elapsed time is equal to or greater than the reference time, so the gas burner can be burned after confirming that there is a high possibility that the valve body is not moving poorly due to freezing.

[0016] [4] An operation unit for turning on and off the operation; a setting unit that sets the water heating apparatus to an operable state when the operation-on operation is performed on the operation unit, and sets the water heating apparatus to an operation-stop state when the operation-off operation is performed on the operation unit; Equipped with When the operation-off operation is performed on the operation unit, the control unit maintains the valve disc in the fully open position, and when the predetermined operation start condition is met for the first time after switching from the operation-stop state to the operable state, attempts the closing control to give the drive source the movement instruction to move the valve disc by the predetermined amount in the closing direction, and then performs the opening control to move the valve disc by the predetermined amount in the opening direction, determines that the mixing valve is abnormal if the elapsed time is less than the reference time, determines that the mixing valve is abnormal if the elapsed time is equal to or greater than a time limit that is greater than the reference time, and permits combustion of the gas burner on the condition that the elapsed time is equal to or greater than the reference time and less than the time limit. The water heater according to [2].

[0017] The water heater described in [4] can be configured to maintain the valve disc in the fully open position while the system is in the shutdown state, while simplifying the detection unit configuration. This allows for easier draining of the bypass passage when the system is in the shutdown state. In such a configuration, if the mixing valve is frozen or otherwise damaged when the system is switched from the shutdown state to the operational state and the start-up conditions are met for the first time, the valve disc may remain near the fully open position even when the system is closed. In such a scenario, a method of determining an abnormality in the mixing valve when the switch does not output a non-detection signal during a closing control attempt can detect an abnormality in the case where the detection unit continues to detect the fully open position during a closing control attempt, since it confirms that the non-detection signal is not output. However, a method of determining an abnormality in the mixing valve when the switch does not output a non-detection signal during a closing control attempt cannot detect an abnormality in the case where the detection unit malfunctions and outputs a non-detection signal during a closing control attempt, or where the valve disc moves only a small amount instead of the required amount during a closing control attempt, causing the detection unit to output a non-detection signal. However, as in the above water heater, the above problem can be solved by combining the method of "determining that the mixing valve is abnormal if the elapsed time is less than the reference time" and the method of "determining that the mixing valve is abnormal if the elapsed time is equal to or greater than a time limit that is greater than the reference time." The water heater allows combustion of the gas burner on the condition that the elapsed time is equal to or greater than the reference time and less than the time limit, so the gas burner can be burned after confirming that no abnormalities have occurred in the closing or opening directions of the valve body.

[0018] [5] The driving source is a motor, When the rotational position of the drive shaft of the motor when the valve element is in the fully open position is defined as a reference rotational position, the opening degree of the valve element decreases according to the number of rotations of the drive shaft of the motor in a predetermined direction from the reference rotational position, When the predetermined operation start condition is satisfied, the control unit attempts the closing control to instruct the motor to rotate the drive shaft by a specified number of rotations in the predetermined direction, and after the closing control, performs the opening control to instruct the motor to rotate the drive shaft by the specified number of rotations in a direction opposite to the predetermined direction. The water heater according to any one of [1] to [4].

[0019] The water heater of [5] uses a motor as a drive source, and can more accurately detect abnormalities in the mixing valve of the water heater with a simpler configuration. This water heater performs a closing control that attempts to rotate the drive shaft a specified number of rotations in a specified direction, and an opening control that attempts to rotate it a specified number of rotations in the opposite direction, and can determine an abnormality based on whether the elapsed time from the above timing until the fully open position is detected is less than a reference time. This allows for more accurate detection of abnormalities in the mixing valve with simpler control.

[0020] First Embodiment The following description relates to the first embodiment. (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.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] The heat transfer tube 8a of the secondary heat exchanger 58 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 58 to the heat transfer tube 7a of the primary heat exchanger 57. The heat transfer tube 7a of the primary heat exchanger 57 is connected to this piping 20, and the hot water outlet pipe 10 is connected to the outlet of the primary heat exchanger 57 so that the hot water heated by the primary heat exchanger 57 is discharged. A thermistor 26 that detects the temperature of the water in the hot water outlet pipe 10 is installed in the hot water outlet pipe 10. Of these, the hot water supply side water passage consisting of the water inlet pipe 12, heat transfer tube 8a, piping 20, heat transfer tube 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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 .

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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).

[0036] 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.

[0037] 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.

[0038] 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.

[0039] (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, and the water flow 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."

[0040] 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."

[0041] (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.

[0042] 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 element 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 element 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 in the fully open position (when the valve element 32B has moved 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] (Control at the start of hot water supply) Fig. 4 is a flowchart illustrating the flow of control executed when the operation start condition is satisfied. Fig. 5 is a flowchart illustrating the flow of the abnormality detection process of Fig. 4.

[0047] The control in Fig. 4 is executed by control unit 22A when the operation is switched from a stopped state (operation off state) to an operable 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 the operable state (operation on state) and starts the control in Fig. 4. As described above, when water heating apparatus 1 is set to the 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, controller 22A determines in step S11 whether or not water inflow has been detected. Specifically, controller 22A determines in step S11 whether or not the water flow rate detected by water flow sensor 34 exceeds a predetermined value. If the water flow rate does not exceed the predetermined value, controller 22A repeats the determination in step S11. If controller 22A determines in step S11 that the water flow rate detected by water flow sensor 34 exceeds the predetermined value, controller 22A performs an abnormality detection process in step S12. For example, when hot water starts to be discharged from hot water outlet 18 and water flows through water inlet pipe 12 and hot water outlet pipe 10, the water flow rate detected by water flow sensor 34 exceeds the predetermined value, and a "Yes" determination is made in step S11. Note that the "hot water discharge state" described above refers to a state in which hot water is discharged outside water heater 1. Specifically, this refers to a state in which hot water is discharged from hot water outlet 18 or bathtub 60 while water is flowing through water inlet pipe 12 and hot water supply-side gas burner 4 is burning. The "water discharge stopped state" is a state in which the flow of water through the water inlet pipe 12 is stopped and the combustion of the gas burner 4 is stopped.

[0049] In this embodiment, the "predetermined operation start condition is met" when the control of Figure 4 is started (i.e., when the operation is switched from a stopped state (operation off state) to an operable state (operation on state)) and water inflow is detected in step S11 (i.e., when the water flow rate detected by the water volume sensor 34 exceeds a predetermined value).

[0050] The control unit 22A performs the abnormality detection process in step S12 according to the flow shown in Fig. 5. When performing the abnormality detection process, the control unit 22A first checks the fully open position in step S21. For example, the control unit 22A checks whether the detection unit has detected that the valve element 32B is in the fully open position, specifically, whether the switch 35 is outputting a detection signal. In this embodiment, the control unit 22A does not perform any special process even if it determines in step S21 that the switch 35 is not outputting a detection signal.

[0051] After step S21, the control unit 22A proceeds to step S22 to perform closing control, moving the valve element 32B a predetermined amount in the closing direction. Specifically, in step S22, the control unit 22A attempts closing control by instructing the motor 32A to rotate the drive shaft 32C a predetermined number of rotations in a predetermined direction. In this case, the control unit 22A outputs a first pulse signal having a predetermined number of pulses corresponding to the predetermined number of rotations to the motor 32A at a first period. When the first pulse signal is output in this manner, if the mixing valve 32 is normal, the drive shaft 32C rotates the predetermined number of rotations in the predetermined direction, and the valve element 32B reduces its opening by an amount corresponding to the predetermined number of rotations upon starting the process of step S22. In this embodiment, when the mixing valve 32 is normal, the predetermined amount is the "amount of movement of the valve element 32B when the opening is reduced by the predetermined number of rotations" (i.e., the amount of movement of the valve element 32B when the drive shaft 32C rotates the predetermined number of rotations in the predetermined direction). When closing control is performed in this manner, if valve element 32B operates normally, valve element 32B will stop at a position where it has moved a predetermined amount in the closing direction from the fully open position. However, if freezing or other conditions occur near valve element 32B and valve element 32B is stuck to the extent that it cannot be moved even when motor 32A applies driving force to valve element 32B via drive shaft 32C, valve element 32B may not reach the position where it has moved the predetermined amount at the end of closing control, and valve element 32B may remain near the fully open position.

[0052] The predetermined time T0 required to reach the predetermined rotation speed during the closing control (the time required when the first pulse signal is output a predetermined number of pulses in the first period) is shorter than the maximum time Ta required to move the valve element 32B from the "fully open position" to the "fully closed position." Specifically, the maximum time Ta is the time required when the first pulse signal is output a maximum number of pulses in the first period. The maximum number of pulses is the number of pulses required to move the valve element 32B from the "fully open position" to the "fully closed position." When the valve element 32B is in the "fully open position," if a first pulse signal with the maximum number of pulses is applied to the motor 32A, the valve element 32B moves to the "fully closed position." The predetermined time T0 is, for example, 2 seconds. The maximum time Ta is, for example, 3 seconds. The predetermined number of pulses is a value smaller than the maximum number of pulses. The predetermined time T0 or the predetermined number of pulses is stored in advance in the memory 22B or the like. When performing the close control, the control unit 22A may end the close control when the number of first pulse signals output in the first cycle after the start of the close control reaches a specified number of pulses, or may end the close control when the time that has elapsed since the start of the close control (the start time of outputting the first pulse signal) reaches a specified time T0. In either case, the close control ends when the number of output pulses of the first pulse signal output in the first cycle after the start of the close control reaches a specified number of pulses.

[0053] After executing the above-described closing control in step S22, the control unit 22A proceeds to step S23 and starts opening control. The opening control is a control for moving the valve element 32B in the opening direction from the position where the above-described closing control ended. When the control unit 22A starts the opening control in step S23, the control unit 22A outputs a second pulse signal to the motor 32A at a second period. The second period is, for example, the same period as the above-described first period. In other words, if the mixing valve 32 is normal, the rotational speed of the drive shaft 32C during closing control is the same as the rotational speed of the drive shaft 32C during opening control.

[0054] After starting the opening control in step S23, control unit 22A determines in step S24 whether or not the elapsed time T2 since the start of the opening control has reached or exceeded the time limit Tm. Specifically, the time T2 since the start of the opening control is the time since the start of the output of the second pulse signal in the second cycle. The time limit Tm is a time longer than the predetermined time T0, and may be set to a value greater than or equal to the maximum time Ta, for example.

[0055] If the control unit 22A determines in step S24 that the elapsed time T2 is not equal to or greater than the time limit Tm, the control unit 22A proceeds to step S25 to determine whether the switch 35 has turned on, i.e., whether the switch 35 has output a detection signal. If the control unit 22A determines in step S25 that the switch 35 has not output a detection signal, the control unit 22A returns to step S24 and performs the determination in step S24. In other words, if the elapsed time T2 is not equal to or greater than the time limit Tm and the switch 35 is not in the on state, the control unit 22A repeats the determinations in steps S24 and S25.

[0056] If the control unit 22A determines in step S24 that the elapsed time T2 is equal to or greater than the time limit Tm, i.e., if the switch 35 does not output a detection signal even after the time limit Tm has elapsed since the start of the opening control, the control unit 22A proceeds to step S27 and notifies the mixing valve 32 of an abnormality. In this embodiment, the timing of the start of the opening control in step S23 corresponds to an example of the "predetermined timing after the operation start condition is satisfied." When notifying the abnormality in step S27, the control unit 22A may, for example, display an error message, error code, or error message indicating the abnormality on a display unit of the remote controller 80 or the like, or may provide an audio notification of the abnormality (such as an error message or a buzzer sound) using an audio output unit, or may transmit error information indicating the abnormality to an external device using a communication unit. Note that the example in FIG. 5 is merely an example. If the determination in step S24 is Yes, the control unit 22A may only restrict the ignition operation without notifying the abnormality in step S27.

[0057] If the control unit 22A determines in step S25 that the switch 35 has entered the ON state, that is, if the switch 35 outputs a detection signal before the elapsed time T2 becomes equal to or greater than the time limit Tm, the process proceeds to step S26. In step S26, the control unit 22A determines whether the elapsed time T2 at the time when step S25 becomes Yes, that is, at the time when the control unit 22A confirms that the switch 35 has output a detection signal, is equal to or greater than a reference time Tb. It is desirable to set Tb to a value at least equal to or less than T0, and for example, it can be set to a time shorter than T0 by a certain time A2.

[0058] If control unit 22A determines in step S26 that the elapsed time T2 is not equal to or greater than reference time Tb, control unit 22A proceeds to step S27, and issues a notification of an abnormality in mixing valve 32, as described above in step S27. In this way, control unit 22A determines that mixing valve 32 is abnormal if elapsed time T2 from the start of the opening control in step S23 to the detection of the fully open position by the detection unit is less than reference time Tb. Note that the example in Fig. 5 is merely one example, and if the result in step S26 is No, it is also possible to only restrict the ignition operation without issuing a notification of an abnormality in step S27.

[0059] If the control unit 22A determines in step S26 that the elapsed time T2 at the time when step S25 becomes Yes (i.e., the time when the switch 35 outputs the detection signal) is equal to or longer than the reference time Tb, it determines Yes in step S26 and terminates the abnormality detection process of Fig. 5. If the control unit 22A determines Yes in step S26, it proceeds to step S13 (Fig. 4) and performs ignition and combustion control of the gas burner 4. The ignition and combustion control of the gas burner 4 is performed by opening the gas main solenoid valve 42, the hot water gas proportional control valve 44, the hot water switching solenoid valve 46, etc. to start the supply of gas to the gas burner 4, and by generating a spark discharge by an ignition device (not shown) to ignite the gas burner 4 and cause the gas burner 4 to burn. In this way, when the control unit 22A determines in steps S24 to S26 that the elapsed time T2 from the start of the opening control is equal to or greater than the reference time Tb and less than the time limit Tm, it determines that the condition is normal without issuing an abnormality alert in step S27, and operates to ignite and burn the gas burner 4 in step S13.

[0060] After step S13, the control unit 22A advances the process to step S14 and controls the opening degree of the mixing valve 32. In step S14, the control unit 22A controls the amount of water passing through the bypass path 14 by controlling the opening degree of the mixing valve 32 in accordance with the set temperature, the inlet water temperature, the amount of hot water discharged, etc. When the water amount sensor 34 detects that the water flow has stopped, the control unit 22A stops the combustion of the gas burner 4.

[0061] The following description relates to an example of the effect of this configuration. In the above-described water heating apparatus 1, if the vicinity of mixing valve 32 is frozen when the operation start condition is met, even if a closing control is attempted to move valve element 32B a predetermined amount in the closing direction, the valve element 32B may not move the predetermined amount and may remain near the fully open position, or may move only slightly from the fully open position. However, the above-described water heating apparatus 1 executes opening / closing control to move valve element 32B in the opening direction after attempting a closing control, and can determine an abnormality based on this opening / closing control. Specifically, the water heating apparatus 1 determines that mixing valve 32 is abnormal if the elapsed time from a predetermined timing after the operation start condition is met until the fully open position is detected by the detection unit is less than a reference time. If the vicinity of the mixing valve 32 is frozen when the operation start condition is met and the valve element 32B is maintained near the fully open position or moves slightly from the fully open position during the closing control, the time elapsed from the start of the opening control until the fully open position is detected by the detection unit is likely to be shorter than normal. In such a case, the time elapsed from the start of the opening control until the fully open position is detected by the detection unit is likely to be shorter than the reference time. The reference time is shorter than the time required for the detection unit to detect the fully open position when the opening and closing control is performed under normal conditions. Therefore, if the elapsed time is shorter than the reference time, it is likely that the predetermined amount of movement was not achieved during the closing control, and an abnormality is likely occurring in the mixing valve. In this way, the water heating apparatus 1 can more accurately detect abnormalities in the mixing valve 32 with a simpler configuration by using the "method of determining that the mixing valve is abnormal if the elapsed time is shorter than the reference time."

[0062] In water heating apparatus 1, the detection unit is configured by a switch that outputs a detection signal when valve element 32B is in the fully open position and outputs a non-detection signal when valve element 32B moves a certain distance less than a predetermined distance from the fully open position in the closing direction, making it easier to configure the detection unit. In this way, water heating apparatus 1 can more accurately detect abnormalities in mixing valve 32 while achieving a configuration that makes it easier to further simplify the detection unit.

[0063] The water heater 1 allows the gas burner to burn on the condition that the elapsed time is equal to or greater than the reference time, and therefore the gas burner can be burned after confirming that there is a high possibility that the valve body 32B is not malfunctioning due to freezing.

[0064] By using switch 35 as a detector, water heater 1 can be simplified and configured to maintain valve element 32B in the fully open position when the device is off (stopped). This facilitates draining water from bypass path 14 during the stopped state. In a water heater configured in this manner, if mixing valve 32 is frozen or otherwise damaged when the start-up condition is first met after switching from the stopped state to the operable state, there is a concern that valve element 32B may remain near the fully open position even when control is performed to close the valve element. In situations where this situation occurs, a method of determining that the mixing valve is abnormal if switch 35 does not output a non-detection signal when attempting a closing control can be used. This allows for the detection of an abnormality in which the detector continues to detect the fully open position when attempting a closing control, since it confirms that the non-detection signal is not output. However, if the abnormality is "such as a malfunction of the detector that causes the output of a non-detection signal when a closing control is attempted" or "such as a slight movement of the valve element 32B that does not move the predetermined distance and causes the detector to output a detection signal when a closing control is attempted," the abnormality cannot be detected by the method of "determining that the mixing valve is abnormal when the switch 35 does not output a non-detection signal when a closing control is attempted." For example, if the switch 35 is equipped with a Hall IC, and the Hall IC outputs a detection signal when the valve element 32B is in the fully open position and outputs a non-detection signal when the valve element 32B moves away from the fully open position, there may be a situation in which the Hall IC does not output an ON signal (detection signal) (outputs a non-detection signal) even when the valve element 32B is in the fully open position due to low temperatures. In such a situation, the abnormality cannot be detected by the method of "determining that the mixing valve is abnormal when the switch 35 does not output a non-detection signal when a closing control is attempted." However, as in the water heater 1, the above problem can be solved by combining the method of "determining that the mixing valve 32 is abnormal if the elapsed time is less than the reference time" and the method of "determining that the mixing valve 32 is abnormal if the elapsed time is equal to or greater than a time limit that is greater than the reference time."The water heater 1 allows the gas burner to burn on the condition that the elapsed time is equal to or greater than the reference time and less than the time limit, so the gas burner can be burned after confirming that no abnormalities described above have occurred in the closing or opening directions of the valve body 32B.

[0065] Water heater 1 uses motor 32A as a drive source, and can more accurately detect an abnormality in mixing valve 32 of water heater 1 with a simpler configuration. Water heater 1 performs close control, which attempts to rotate the drive shaft a specified number of rotations in a predetermined direction, and open control, which attempts to rotate the drive shaft a specified number of rotations in the opposite direction, and can determine an abnormality based on whether the elapsed time from the start of open control to detection of the fully open position is less than a reference time. This makes it possible to more accurately determine an abnormality in mixing valve 32 with simpler control.

[0066] <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.

[0067] In the above-described embodiment, "when a predetermined operation start condition is met" is when the control of Fig. 4 is started and water inflow is detected in step S11, but this is not limited to this example. For example, "when a predetermined operation start condition is met" may be when the operation is switched from a stopped state to an operable state and a predetermined operation start operation (such as an operation to instruct automatic filling) is performed on the remote controller, or may be other cases.

[0068] In the above-described embodiment, the timing of starting the open control in step S23 corresponds to an example of "predetermined timing after the operation start condition is satisfied," but is not limited to this example. For example, the timing of starting the close control in step S22 may be "predetermined timing after the operation start condition is satisfied." In this case, the reference time needs to be shorter than the time Tx required for the close control and the open control when the mixing valve is normal, and can be, for example, a certain amount of time shorter than the time Tx.

[0069] 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]

[0070] 1: Hot water supply equipment 4: Gas burner 5: Housing 6: Hot water side heat exchanger (heat exchanger) 7: Primary heat exchanger (heat exchanger) 7a: Heat transfer tube 8: Secondary heat exchanger (heat exchanger) 8a: Heat transfer tube 10: Outlet pipe 12: Water inlet pipe 14: Bypass route (bypass pipe) 16:Water inlet 18: Hot water outlet 22: Controller 22A: Control unit 22E: Setting section 32: Mixing valve 32A: Motor (drive source) 32B: Valve body 32C: Drive shaft 35: Switch (detection part)

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 pipe 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 pipe and a drive source that drives the valve element, wherein the drive source drives the valve element to change the valve element from a fully closed position that closes the bypass pipe to a fully open position that has the largest opening degree; a detection unit that detects that the valve element is in the fully open position; a control unit for controlling the mixing valve and the gas burner; Equipped with When a predetermined operation start condition is satisfied, the control unit executes opening and closing control by attempting closing control to move the valve element a predetermined amount in a closing direction, and then executing opening control to move the valve element in an opening direction, and determines that the mixing valve is abnormal if the elapsed time from a predetermined timing after the operation start condition is satisfied until the detection of the fully open position by the detection unit is less than a reference time. The reference time is a time shorter than the time required for the detection unit to detect the fully open position from the timing when the opening / closing control is performed in a state where the mixing valve is normal. Water heater.

2. the detection unit is a switch that outputs a detection signal when the valve element reaches the fully open position, and outputs a non-detection signal when the valve element moves from the fully open position in a closing direction by a certain amount that is smaller than the predetermined amount, When the predetermined operation start condition is satisfied, the control unit attempts the closing control by issuing a movement instruction to the drive source to move the valve element in the closing direction by the predetermined amount, and then performs the opening control by moving the valve element in the opening direction until the switch outputs the detection signal.The control unit determines that the elapsed time is the period from the start of the opening control to the time when the switch outputs the detection signal, and determines that the mixing valve is abnormal if the elapsed time is less than the reference time. The water heater according to claim 1 .

3. When the predetermined operation start condition is established, the control unit permits combustion of the gas burner on the condition that the elapsed time in the opening control after the closing control is attempted is equal to or longer than the reference time. The water heater according to claim 1 or 2.

4. an operation unit for performing an operation-on operation and an operation-off operation; a setting unit that sets the water heating apparatus to an operable state when the operation-on operation is performed on the operation unit, and sets the water heating apparatus to an operation-stop state when the operation-off operation is performed on the operation unit; Equipped with When the operation-off operation is performed on the operation unit, the control unit maintains the valve disc in the fully open position, and when the predetermined operation start condition is met for the first time after switching from the operation-stop state to the operable state, attempts the closing control to give the drive source the movement instruction to move the valve disc by the predetermined amount in the closing direction, and then performs the opening control to move the valve disc by the predetermined amount in the opening direction, determines that the mixing valve is abnormal if the elapsed time is less than the reference time, determines that the mixing valve is abnormal if the elapsed time is equal to or greater than a time limit that is greater than the reference time, and permits combustion of the gas burner on the condition that the elapsed time is equal to or greater than the reference time and less than the time limit. The water heater according to claim 2 .

5. the drive source is a motor, When the rotational position of the drive shaft of the motor when the valve element is in the fully open position is defined as a reference rotational position, the opening degree of the valve element decreases according to the number of rotations of the drive shaft of the motor in a predetermined direction from the reference rotational position, When the predetermined operation start condition is satisfied, the control unit attempts the closing control to instruct the motor to rotate the drive shaft by a specified number of rotations in the predetermined direction, and after the closing control, performs the opening control to instruct the motor to rotate the drive shaft by the specified number of rotations in a direction opposite to the predetermined direction. The water heater according to claim 1 or 2.

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