JP7695527B2 - Hot water supply equipment - Google Patents

Description

The present invention relates to a hot water supply system, and more specifically to a hot water supply device that supplies hot water by mixing high-temperature water and low-temperature water.

Hot water supply systems that control the hot water outlet temperature using a mixing valve for high-temperature and low-temperature water are known. For example, Japanese Patent Publication No. 4264081 (Patent Document 1) describes a storage-type hot water supply device configured such that high-temperature water from an outlet pipe and low-temperature water from a water supply pipe are mixed by a hot water supply mixing valve and output to a hot water supply pipe.

In Patent Document 1, a check valve is provided in the water supply pipe to allow hot water to flow only in the direction toward the hot water mixing valve. Furthermore, as a function for determining failure of the check valve, it is described that a blockage failure of the check valve is detected using the flow rate detection value of the hot water supply pipe when the hot water mixing valve is controlled to be fully open with low-temperature water.

Patent No. 4264081

Generally, the check function of a check valve is achieved by the operation of a mechanical structure in response to the application of water supply pressure, rather than by electronic control using a controller. For this reason, it is difficult to simply detect an open failure in which the check function is lost by directly monitoring the operating status of the check valve.

On the other hand, Patent Document 1 does not disclose or suggest how to detect an open failure of a check valve installed in a water supply pipe.

The present invention was made to solve these problems, and its purpose is to realize a function for detecting an open failure of a check valve arranged in the pipe that leads low-temperature water to a mixing valve in a hot water supply device equipped with a mixing valve for high-temperature water and low-temperature water.

According to one aspect of the present invention, a hot water supply device is provided. The hot water supply device includes a high-temperature water pipe for supplying high-temperature water, a low-temperature water pipe for supplying low-temperature water from a water supply end, a hot water outlet pipe connected to a hot water outlet end, a mixing valve, a control device, a check valve, and a temperature detector. The mixing valve has a first port connected to the high-temperature water pipe, a second port connected to the low-temperature water pipe, and a third port connected to the hot water outlet pipe. The control device controls the mixing ratio of hot water flowing from the first port to the third port and hot water flowing from the second port to the third port depending on the opening degree of the mixing valve. The check valve is connected to the low-temperature water pipe and has a check function that prevents flow from the second port toward the water supply end. The temperature detector is disposed in the low-temperature water path between the water supply end and the check valve. The control device includes a fault diagnosis unit. The fault diagnosis unit detects an open fault in which the check valve has lost its check function when the temperature detected by the temperature detector rises above a reference temperature set according to the temperature of the low-temperature water introduced into the water supply end.

According to the present invention, in a hot water supply device equipped with a mixing valve for high-temperature water and low-temperature water, an open failure of a check valve arranged in a pipe leading to the mixing valve for low-temperature water can be detected by using the temperature detection value upstream of the check valve.

1 is a block diagram illustrating a configuration of a water heating device according to an embodiment of the present invention. 2 is a conceptual diagram for explaining a connection relationship between the water heating apparatus shown in FIG. 1 and other external devices. FIG. 2 is a table illustrating the operation of the water heater shown in FIG. 1 . 5 is a flowchart illustrating a control process for re-discharge standby control in the hot water supply apparatus according to the present embodiment. 4 is a first flowchart illustrating a failure diagnosis process for a check valve in the hot water supply apparatus according to the present embodiment. 10 is a second flowchart illustrating the failure diagnosis process for the check valve in the water heating apparatus according to the present embodiment. 10 is a third flowchart illustrating the failure diagnosis process for the check valve in the water heating apparatus according to the present embodiment. 5 is a flowchart illustrating a first example of control when an open failure of a check valve is detected in the hot water supply device according to the present embodiment. 10 is a flowchart illustrating a second example of control when an open failure of the check valve is detected in the water heating apparatus according to the present embodiment.

Below, an embodiment of the present invention will be described in detail with reference to the drawings. Note that in the following, the same or corresponding parts in the drawings will be given the same reference numerals, and in principle, their description will not be repeated.

(Example of the configuration of a hot water supply device)
FIG. 1 is a block diagram illustrating an example of the configuration of a water heating device according to the present embodiment.

Referring to FIG. 1, the hot water supply device 10 according to this embodiment is shown as a hot water supply device having a hot water storage tank 150 housed in a housing 25. As described below, the hot water storage tank 150 stores high-temperature water heated by a heat generating mechanism (not shown) provided outside the hot water supply device 10. Typically, the heat generating mechanism can be a power generating mechanism that generates waste heat, such as a fuel cell or an engine generator, or a heat pump device.

The hot water supply device 10 further includes a water supply end 101, a hot water outlet end 102, external connection ends 103-110, an auxiliary heat source unit (BU heat source unit) 200, heat exchangers 210, 220, a heating tank 230, a heating pump 240, and circulation pumps 310, 315. The water supply end 101, the hot water outlet end 102, and the connection ends 103-110 are configured so that piping can be connected from outside the housing 25.

Figure 2 shows a conceptual diagram for explaining the connection relationship between the water heater 10 and other external devices.

Referring to Figures 1 and 2, the water supply end 101 is connected to a water supply pipe 81 that supplies low-temperature water. The hot water outlet end 102 is connected to a hot water supply pipe 80. A hot water tap 15 is connected to the hot water supply pipe 80, and when the hot water tap 15 is operated (opened), hot water at an appropriate temperature output from the hot water supply device 10 to the hot water outlet end 102 is supplied to the hot water supply pipe 15 via the hot water supply pipe 80. The fuel gas pipe 82 supplies fuel gas burned in the auxiliary heat source unit 200 to the hot water supply device 10.

Connection end 105 is connected to both heating device 14a and bathroom heater/dryer 14b, connection end 106 is connected to heating device 14a, and connection end 107 is connected to bathroom heater/dryer 14b. By operating heating pump 240, a first heating circuit passing through heating device 14a and a second heating circuit passing through bathroom heater/dryer 14b can be formed. The second heating circuit runs from connection end 105 through heating tank 230, heating pump 240, the secondary side of heat exchanger 210 (not shown), and connection end 107 to bathroom heater/dryer 14b. Therefore, high-temperature water heated by heat exchanger 210 is supplied to bathroom heater/dryer 14b.

On the other hand, the first heating circuit runs from the connection end 105 through the heating tank 230, the heating pump 240, and the connection end 106 to the heating device 14a. Therefore, the high-temperature water supplied to the heating device 14a is not directly heated by the heat exchanger 210 inside the hot water supply device 10.

In other words, by sharing the heat exchanger 210, a circulation path for high-temperature water (heat medium) that serves as a heat source for heating can be formed when the heating device 14a and the bathroom heater/dryer 14b are both operating. Note that below, the operation of the heating device 14a and the bathroom heater/dryer 14b will be collectively referred to as heating operation. Heating operation also includes the case where both the heating device 14a and the bathroom heater/dryer 14b are operating.

Similarly, connection ends 108 and 109 are connected to the bathtub 13. By operating a pump (not shown) built into the water heater 10, the bathtub water input from the connection end 108 to the water heater 10 passes through the secondary side (not shown) of the heat exchanger 220, and is then returned to the bathtub 13 via the connection end 109, forming a bathtub water circulation path. This allows for reheating operation in the bathtub 13. Furthermore, the connection end 110 is connected to the drain pipe 85.

The remote control 30 is an input device for operating the water heating apparatus 10, which is placed in the kitchen, bathroom, etc. The remote control 30 includes a display unit 31 for outputting information in a manner that is visible to the user, an operation switch 32 for turning the water heating apparatus 10 on and off, an operation unit 33 for accepting input setting operations by the user, etc., and a speaker 34. The display unit 31 is typically configured with a liquid crystal panel, and is configured to be able to display various information in a manner that is visible to the user. The operation unit 33 is typically configured with push buttons or touch buttons, and is configured to be able to accept setting operations for the water heating apparatus 10, such as the hot water setting temperature. The speaker 34 outputs voices, melodies, alarm sounds, etc. that the user can recognize aurally.

Referring again to FIG. 1, the hot water supply device 10 further includes a controller 20, pipes 111-114, 116-119, 119a, 119b, 121, 124-126, 130, and 132, on-off valves 215 and 225, a three-way valve 320, a heat storage switching valve 330, a mixing valve 340, a proportional valve 350, a hot water supply on-off valve 360, a flow rate adjustment valve 370, and a hot water storage switching valve 380.

The three-way valve 320, the mixing valve 340, the proportional valve 350, the flow rate adjustment valve 370, and the hot water storage switching valve 380 each have a stepping motor 321, 341, 351, 371, and 381. The stepping motors 321, 341, 351, 371, and 381 are driven by control commands from the controller 20 to control the opening degree of each of the three-way valve 320, the mixing valve 340, the proportional valve 350, the flow rate adjustment valve 370, and the hot water storage switching valve 380.

The first end of the pipe 111 is connected to the water supply end 101 and receives a supply of low-temperature water. The second end of the pipe 111 is connected to the low-temperature side port of the mixing valve 340. Hereinafter, the pipe 111 is also referred to as the low-temperature water pipe 111. A check valve 55 that prevents backflow of low-temperature water is interposed and connected to the low-temperature water pipe 111. In other words, the check valve 55 has a check function that blocks flow from the mixing valve 340 (low-temperature side port) to the water supply end 101.

The pipe 112 is connected between the low-temperature water pipe 111 and the heat storage switching valve 330. A check valve 56 is interposed and connected to the pipe 112 to prevent backflow of low-temperature water from the pipe 112 to the low-temperature water pipe 111.

The first end of the pipe 114 is connected to the primary side paths (not shown) of the heat exchangers 210 and 220 via the on-off valves 215 and 225, respectively. The second end of the pipe 114 is connected to the three-way valve 320. The pipe 113 connects between the heat storage switching valve 330 and the bottom of the hot water storage tank 150. The pipe 116 is connected between the heat storage switching valve 330 and the pipe 114.

The heat storage switching valve 330 selectively forms one of a tank water inlet path between pipes 112 and 113, a circulation side path between pipes 112 and 116, and a tank water inlet/outlet path between pipes 113 and 116 in accordance with a control command from the controller 20.

The heat storage switching valve 330 forms a tank water inlet path, and the water supply pressure of the water supply pipe 81 (Figure 2) allows low-temperature water to be introduced into the hot water storage tank 150 via the pipes 111 to 113 until the hot water storage tank 150 is filled to capacity.

The top of the hot water storage tank 150 is connected to pipes 125 and 130. Pipe 130 is connected to pipe 119a, which will be described later. Pipe 125 is connected to pipe 124, which passes through hot water storage switching valve 380 and leads to connection end 103 with a heat generation mechanism (not shown). Pipe 126 is further connected to the bottom of the hot water storage tank 150 and leads to connection end 104 with a heat generation mechanism (not shown). Multiple temperature sensors 151 to 156 are arranged at different locations in the hot water storage tank 150.

The hot water storage switching valve 380 selectively forms a bypass path that bypasses the hot water storage tank 150 and connects the pipes 124 and 126, and a hot water storage path that connects the pipes 124 and 125, according to the opening control by the controller 20 driven by the stepping motor 381. The pipes 124 and 126 are provided with temperature sensors 560 and 565, respectively.

By operating the circulation pump 315, low-temperature water in the hot water storage tank 150 can be output to the heat generating mechanism via the connection end 104, and a heating circulation path can be formed in which high-temperature water heated by the heat generating mechanism is introduced from the connection end 103. The circulation pump 315 can also be placed outside the housing 25 (for example, inside the heat generating mechanism).

When the circulation pump 315 is operating, the hot water storage switching valve 380 forms a hot water storage path, and high-temperature water heated by the heat generating mechanism is introduced into the hot water storage tank 150. This causes the temperature inside the hot water storage tank 150 to rise from the top. On the other hand, when the hot water storage switching valve 380 forms a bypass path, the high-temperature water output from the connection end 104 is reheated by the heat generating mechanism without being introduced into the hot water storage tank 150. For example, based on the temperature detected by the temperature sensor 560 (the input temperature from the connection end 103), the hot water storage switching valve 380 can form a bypass path when the temperature is low.

On the other hand, when the temperature detected by the temperature sensors 151-156 and 565 indicates that the heating of the high-temperature water in the hot water storage tank 150 has been completed, the formation of the heating circulation path is stopped by stopping the circulation pump 315. In this way, in the hot water supply device 10, the external heat generating mechanism is used as the "main heat source," and the high-temperature water heated by the main heat source is stored in the hot water storage tank 150 and used for hot water supply.

The pipe 117 connects the three-way valve 320 to the suction port 311a of the circulation pump 310. The three-way valve 320 is further connected to the pipe 130 from the top of the hot water storage tank 150 by the pipe 132 provided with a check valve 322.

Three-way valve 320 controls the flow rate ratio between path P1 leading from pipe 132 to suction port 311a of circulation pump 310 and path P2 leading from pipe 114 to suction port 311a of circulation pump 310 according to the opening control by controller 20 driven by stepping motor 321. By controlling the opening of three-way valve 320, the flow rate ratio can be controlled between 0 and 100 (%), so it is possible to realize both a state in which only path P1 or path P2 is formed, and a state in which both paths P1 and P2 are formed. Hereinafter, path P1 is also referred to as the "tank output path" and path P2 as the "circulation path".

The pipe 118 is connected to the discharge port 311b of the circulation pump 310 and the input end 201a of the auxiliary heat source unit 200. A flow rate sensor 420 is disposed on the pipe 118. The flow rate sensor 420 can detect the flow rate passing through the auxiliary heat source unit 200. The output end 201b of the auxiliary heat source unit 200 is connected to the pipe 119.

During operation, the auxiliary heat source unit 200 heats the fluid (hot water) introduced from the pipe 118 to the input end 201a using the heat of combustion of fuel, and outputs high-temperature water from the output end 201b to the pipe 119. A temperature sensor 550 is disposed in the pipe 118 for detecting the input temperature to the auxiliary heat source unit 200. A temperature sensor 555 is disposed in the pipe 119 for detecting the output temperature from the auxiliary heat source unit 200. The auxiliary heat source unit 200 corresponds to one embodiment of a "heat source unit."

At node Nb, pipe 119 branches into pipe 119a which leads to the high temperature port of mixing valve 340, and pipe 119b which leads to the primary side (not shown) of heat exchangers 210 and 220.

During heating operation, the on-off valve 215 is opened while the circulation pump 310 is operating, thereby forming a "high-temperature water circulation path" including the auxiliary heat source unit 200, pipes 119, 119b, the heat exchanger 210, pipes 114, 117, the circulation pump 310, and pipe 118. As a result, when the auxiliary heat source unit 200 is operating, the high-temperature water from the auxiliary heat source unit 200 can heat the fluid (heat medium for heating) in the circulation path formed between the heating device 14a and/or the bathroom heater/dryer 14b and the heat exchanger 210 (secondary side).

Similarly, during reheating operation, the auxiliary heat source unit 200 is operated, and the on-off valve 225 is opened together with the operation of the circulation pump 310, thereby forming a high-temperature water circulation path including the auxiliary heat source unit 200, pipes 119, 119b, heat exchanger 220, pipes 114, 117, circulation pump 310, and pipe 118. This allows the high-temperature water from the auxiliary heat source unit 200 to heat the bath water flowing through the circulation path between the heat exchanger 220 (secondary side) and the bathtub 13. The temperature sensor 590 can detect the temperature of the high-temperature water after it has passed through the heat exchangers 210, 220 (primary side).

On the other hand, when both on-off valves 215 and 225 are closed, a circulation path for high-temperature water via pipe 119b is not formed.

The pipe 119a is connected to the pipe 130 from the hot water tank 150 at a node Nc located downstream of the node Nb. Furthermore, a proportional valve 350 is disposed between the node Nb and the node Nc, which are included in the circulation path formed when the circulation pump 310 is operated. The opening degree of the proportional valve 350 is controlled by the controller 20 using a stepping motor 351 as a drive source.

By controlling the opening degree of the proportional valve 350, the flow rate of high-temperature water output from the pipe 119 via the pipe 119a to the mixing valve 340 for hot water supply purposes can be controlled. Hereinafter, the pipe 119a is also referred to as the high-temperature water pipe 119a.

In particular, when the on-off valves 215 and/or 225 are open, the ratio of the flow rate (for hot water supply) to the mixing valve 340 via the high-temperature water pipe 119a and the flow rate (for heating/reheating) to the circulation path including the pipe 119b can be controlled by the opening degree of the proportional valve 350 for the high-temperature water from the auxiliary heat source unit 200. It is also possible to fully close the proportional valve 350 (opening degree = 0) and use the entire amount of high-temperature water from the auxiliary heat source unit 200 for heating/reheating.

The output end of the mixing valve 340 is connected to a pipe 121 leading to the hot water outlet end 102. Hereinafter, the pipe 121 is also referred to as the hot water outlet pipe 121. As a result, the mixing valve 340 mixes high-temperature water from the high-temperature side port connected to the high-temperature water pipe 119a and low-temperature water from the low-temperature side port connected to the low-temperature water pipe 111, and outputs the mixed water to the output port connected to the hot water outlet pipe 121. The high-temperature side port corresponds to the "first port", the low-temperature side port corresponds to the "second port", and the output port corresponds to the "third port".

The opening of the mixing valve 340 is controlled by the controller 20 using the stepping motor 341 as a drive source. By controlling the opening of the mixing valve 340, the flow state between the high-temperature side port (high-temperature water pipe 119a) and the low-temperature side port (low-temperature water pipe 111) and the output port (hot water outlet pipe 121), i.e., the mixing ratio of high-temperature water and low-temperature water, is controlled. Specifically, the mixing valve 340 is controlled to one of a fully closed state (high-temperature water 0 (%)) in which only the low-temperature side port flows with the output port, a fully open state (high-temperature water 100 (%)) in which only the high-temperature side port flows with the output port, and an intermediate opening in which both the low-temperature side port and the high-temperature side port flow with the output port. The intermediate opening includes multiple openings with stepwise different mixing ratios within a range in which the ratio of high-temperature water is greater than 0 (%) and less than 100 (%).

A temperature sensor 510 for detecting the temperature of the low-temperature water is disposed in the low-temperature water pipe 111. The temperature sensor 510 is disposed upstream of the check valve 55 (the water supply end 101 side), i.e., between the check valve 55 and the water supply end 101. In particular, by disposing the temperature sensor 510 upstream of the node Nx where the low-temperature water pipe 111 and the pipe 112 branch off, both the temperature of the low-temperature water introduced into the mixing valve 340 and the temperature of the low-temperature water introduced into the hot water storage tank 150 via the heat storage switching valve 330 (tank water inlet path) and the pipes 112 and 113 can be detected by a single temperature sensor 510.

A temperature sensor 520 for detecting the temperature of the hot water outlet pipe 121 is disposed downstream of the mixing valve 340. Furthermore, in addition to the above-mentioned temperature sensor 555, a temperature sensor 530 is disposed in the high-temperature water pipe 119a. The temperature sensor 530 is disposed to detect the temperature of the high-temperature water input to the mixing valve 340.

The mixing ratio of low-temperature water by the mixing valve 340 can be controlled, for example, based on the temperatures detected by the temperature sensors 510, 520, and 530. This allows the output temperature (i.e., the hot water outlet temperature) from the mixing valve 340 to the hot water outlet pipe 121 to be controlled to a temperature set by the user.

Furthermore, it is preferable to place a high temperature avoidance solenoid valve 365 between the low temperature water pipe 111 and the vicinity of the mixing valve 340 of the hot water outlet pipe 121. The high temperature avoidance solenoid valve 365 is opened by the controller 20 when the hot water outlet temperature detected by the temperature sensor 520 is detected as being excessively high.

A flow sensor 430 and a flow control valve 370 are arranged in the hot water outlet pipe 121. The flow sensor 430 can detect the hot water outlet flow rate through the hot water outlet pipe 121. The flow control valve 370 can throttle the hot water outlet flow rate according to the opening control by the controller 20, which uses a stepping motor 371 as a drive source. For example, when the hot water outlet temperature does not rise, a significant drop in the hot water outlet temperature can be suppressed by controlling the flow control valve 370. It is also possible to further arrange a temperature sensor 525 in the hot water outlet pipe 121 for control purposes to prevent freezing.

A hot water supply pipe 301 branches off from the hot water outlet pipe 121 and reaches the connection end 109. A hot water supply opening/closing valve 360 and a flow rate sensor 410 are arranged on the hot water supply pipe 301. The hot water supply opening/closing valve 360 is composed of an electromagnetic valve, and opens and closes according to control commands from the controller 20. By opening the hot water supply opening/closing valve 360, the hot water output to the pipe 121 and controlled to the hot water supply setting temperature can be used to fill the bathtub 13 (Figure 2). Furthermore, the amount of hot water supplied to the bathtub 13 can be calculated by integrating the detection value of the flow rate sensor 410.

A temperature sensor 580 and a pressure relief valve 390 are further arranged on the piping 116. The pressure relief valve 390 can prevent overpressure from occurring in the circulation path of the high-temperature water from the auxiliary heat source unit 200.

In addition, by opening the valve 110x provided at the connection end 110, the water stored in the hot water tank 150 can be forcibly discharged from the connection end 110 to the drain pipe 85 (Figure 2).

In this way, the water heater 10 can perform hot water supply operations, including pouring hot water into the bathtub 13, by either supplying hot water using high-temperature water stored in the hot water storage tank 150 (hereinafter also referred to as "tank hot water supply") or supplying hot water using high-temperature water from the auxiliary heat source unit 200 in operation (hereinafter also referred to as "BU hot water supply"). That is, in this embodiment, "hot water supply" includes both tank hot water supply and BU hot water supply. Furthermore, by passing high-temperature water through a circulation path including the auxiliary heat source unit 200 and the heat exchangers 210 and 220, heating operation and reheating operation can be further performed.

The controller 20 can typically be configured with a microcomputer. The controller 20 controls the operation of various devices, including controlling the opening degree of each valve driven by a stepping motor and controlling the opening and closing of each on-off valve, based on the detection values of each sensor (temperature sensor, flow rate sensor, etc.), so that the water heating device 10 operates according to user instructions input to the remote control 30. The controller 20 corresponds to one embodiment of a "control device."

(Operation of the hot water supply device)
Next, the operation of the water heater 10 according to the present embodiment will be described with reference to Fig. 3. In Fig. 3, a state in which at least one of the heating operation and the reheating operation is on is indicated as "heating/reheating on", while a state in which both the heating operation and the reheating operation are off is indicated as "heating/reheating off". As shown in Fig. 3, the water heater 10 can be set to heating/reheating on or heating/reheating off in each of the tank hot water supply and the BU hot water supply.

Referring to FIG. 3, when the heating/reheating of the tank hot water supply is turned off, the operation (combustion) of the auxiliary heat source unit 200 is turned off, the proportional valve 350 is fully closed, and the circulation pump 310 is also stopped. Furthermore, the heat storage switching valve 330 is controlled to form a tank water inlet path, that is, a path from pipe 112 to 113. In this state, when the hot water tap 15 connected to the hot water supply pipe 80 is opened, low-temperature water flows into the hot water storage tank 150 via pipes 112 and 113 due to the water supply pressure to the water supply end 101, and high-temperature water in the hot water storage tank 150 is output to pipe 130. Regardless of whether the three-way valve 320 forms path P1 or P2, high-temperature water is output from the hot water storage tank 150.

The high-temperature water output to the pipe 130 is input from the high-temperature water pipe 119a to the mixing valve 340 via the node Nc. Therefore, tank hot water supply is performed by mixing the high-temperature water output from the hot water storage tank 150 with the low-temperature water from the low-temperature water pipe 111.

When heating/reheating is turned on during tank hot water supply, the three-way valve 320 forms path P2 (circulation path) and the on-off valves 215 and/or 225 are opened. The heat storage switching valve 330 forms a tank water inlet path to output high-temperature water for hot water supply from the hot water storage tank 150 to the piping 130.

Furthermore, when the circulation pump 310 and the auxiliary heat source unit 200 are operated, a high-temperature water circulation path can be formed that includes the auxiliary heat source unit 200, the pipes 119, 119b, the primary side of the heat exchanger 210 and/or 220, and the pipes 114, 117. The high-temperature water in the circulation path can heat the circulating water (heat medium) of the heating device 14a and the bathroom heater/dryer 14b, and/or the bath water, which flows through the secondary side of the heat exchanger 210 and/or 220.

During hot water supply operation, if tank hot water supply is not possible due to a drop in temperature inside the hot water storage tank 150, BU hot water supply is performed. In BU hot water supply, the auxiliary heat source unit 200 operates. When heating/reheating is off, the heat storage switching valve 330 forms the tank water inlet path, and the three-way valve 320 forms path P1, and the circulation pump 310 operates.

As a result, the hot water in the hot water storage tank 150 is heated by the auxiliary heat source unit 200 via the piping 132, via the circulation pump 310, and output to the piping 119. At this time, the flow rate of the circulation pump 310 is controlled so that the pressure of the high-temperature water flowing through the high-temperature water piping 119a via the proportional valve 350 is set higher than the fluid pressure output from the hot water storage tank 150 to the high-temperature water piping 119a (node Nc) via the piping 130. As a result, while utilizing the preheat in the hot water storage tank 150, high-temperature water equivalent to that during tank hot water supply can be supplied from the high-temperature water piping 119a to the high-temperature side of the mixing valve 340.

When heating/reheating is turned on during BU hot water supply, the on-off valves 215 and/or 225 are opened. Furthermore, the three-way valve 320 forms the path P2, and the heat storage switching valve 330 is controlled to form a circulation path, so that the low-temperature water introduced from the low-temperature water pipe 111 and the circulating high-temperature water flowing through the heat exchanger 210 and/or 220 are mixed and input from the circulation pump 310 to the auxiliary heat source unit 200. The high-temperature water output from the auxiliary heat source unit 200 is divided into a path from the high-temperature water pipe 119a to the mixing valve 340 and a path from the pipe 119b to the heat exchangers 210 and 220 at a ratio according to the opening degree of the proportional valve 350. Therefore, when the opening degree of the proportional valve 350 is increased, the supply ratio of high-temperature water for hot water supply increases, while when the opening degree of the proportional valve 350 is decreased, the supply ratio of high-temperature water for heating/reheating increases.

Alternatively, when the BU hot water supply heating/reheating is on, the heat storage switching valve 330 is set to the tank water inlet side, and the three-way valve 320 controls the ratio of paths P1 and P2, so that preheating of the hot water storage tank 150 can be utilized. However, in this case, the flow rate ratio is variably controlled by both the three-way valve 320 and the proportional valve 350, which may complicate the control.

In the hot water supply device 10, in addition to tank hot water supply using high-temperature water from the hot water storage tank 150, BU hot water supply using the circulation pump 310 and the auxiliary heat source unit 200 is possible. Even when the hot water supply operation is stopped, the proportional valve 350 can be controlled to be fully closed, the three-way valve 320 can be controlled to route P2, and the circulation pump 310 can be operated, so that the opening and closing valves 215 and/or 225 can be opened to form a circulation path that flows the high-temperature water heated by the auxiliary heat source unit 200 to the heat exchanger 210 and/or 220.

In this manner, in the hot water supply device 10 according to this embodiment, when the hot water tap 15 is opened, the mixing valve 340 mixes the high temperature water in the high temperature water pipe 119a and the low temperature water in the low temperature water pipe 111, thereby outputting hot water at the appropriate temperature to the hot water outlet pipe 121.

As described above, the check valve 55 is disposed in the low-temperature water pipe 111. When the check function of the check valve 55 is normal, flow from the low-temperature side port of the mixing valve 340 to the water supply end 101 is blocked. In contrast, if an open failure occurs in the check valve 55 and the check function is lost, there is a risk of high-temperature water backflowing from the high-temperature side port to the low-temperature side port of the mixing valve 340 while hot water supply is stopped (when the hot water tap 15 is closed). Specifically, when the pressure of the high-temperature side port of the mixing valve 340 is rising due to the operation of the circulation pump 310, etc., if the mixing valve 340 is controlled to an opening degree that mixes high-temperature water and low-temperature water, there is a risk of high-temperature water in the high-temperature water pipe 119a backflowing into the low-temperature water pipe 111 via the low-temperature side port of the mixing valve 340.

For example, there is concern that the above-mentioned backflow may occur while the re-discharge standby control shown in Figure 4 is being executed.

Figure 4 shows a flowchart explaining the control process for the re-discharge standby control. The control process shown in Figure 4 can be executed by the controller 20.

As shown in FIG. 4, the controller 20 detects the timing to end hot water supply in step (hereinafter simply referred to as "S") 110. For example, based on the flow rate detection value by the flow rate sensor 430, it is periodically determined whether the water heating device 10 is supplying hot water or is not supplying hot water, and if the state changes from supplying hot water in the previous cycle to not supplying hot water in the current cycle, S110 is judged as YES in that cycle, and the timing to end hot water supply is detected. In all other cases, S110 is judged as NO, and the processing from S120 onwards is not started.

When the controller 20 detects the end of hot water supply (YES at S110), it sets the mixing valve 340 to a predetermined intermediate opening at S120 and controls the proportional valve 350 to a predetermined opening that is not fully closed until a predetermined time T1 has elapsed from the end of hot water supply (NO at S120), creating a hot water re-discharge standby state.

In the hot water re-discharge standby state, the proportional valve 350 forms a path from the auxiliary heat source unit 200 to the high temperature side port of the mixing valve 340, and the mixing valve 340 is in a state where both the high temperature side port and the low temperature side port are in communication with the hot water discharge pipe 121. Therefore, when hot water supply is started by opening the hot water tap 15, the high temperature water remaining in the high temperature water pipe 119a can be used for hot water supply immediately, and the high temperature water from the auxiliary heat source unit 200 can also be quickly introduced into the mixing valve 340. As a result, when hot water supply is resumed in a short time after the hot water supply is stopped, the hot water supply temperature can be quickly increased. Note that if hot water supply is started during the processing of S120 to S130, the processing of FIG. 4 is forcibly returned to S110, and the controller 20 monitors the next hot water supply end timing.

When the predetermined time T1 has elapsed without hot water supply being resumed (YES in S120), the controller 20 controls the proportional valve 350 to be fully closed and the mixing valve 340 to be fully closed (high temperature water 0 (%)) in S140.

Here, assume that a hot water re-discharge standby state is formed by S130 during heating operation or reheating operation. In this case, the high-temperature water output from the auxiliary heat source unit 200 via the proportional valve 350 is pressurized by the operation of the circulation pump 310 and reaches the high-temperature side port of the mixing valve 340. In this state, if an open failure occurs in the check valve 55 of the low-temperature water pipe 111, if the pressure of the high-temperature water introduced into the mixing valve 340 is greater than the water supply pressure from the water supply end 101, there is a risk of high-temperature water backflowing through the high-temperature side port and low-temperature side port of the mixing valve 340 to the low-temperature water pipe 111 and pipe 112. In this state of hot water re-discharge standby where such backflow occurs, high-temperature water is present in both the high-temperature side port and the low-temperature side port of the mixing valve 340, so if hot water supply is started from this state, there is a concern that the hot water supply temperature immediately after the start of hot water supply will rise more than expected.

(Check valve open failure detection)
Therefore, in order to avoid the above-mentioned problems in hot water temperature control, the hot water supply device according to this embodiment is provided with a function for detecting an open failure of check valve 55.

Figures 5 to 7 show a flowchart explaining the check valve failure diagnosis process in the hot water supply device according to this embodiment. The control process shown in Figures 5 to 7 can be executed by the controller 20.

When hot water supply is stopped (YES at S210), the controller 20 executes fault diagnosis according to S220 to S240. On the other hand, when hot water is being supplied (NO at S210), the fault diagnosis is not executed. The determination in S210 of whether hot water supply is in progress or stopped can be made based on the detection value by the flow rate sensor 430, as described above.

In S220, the controller 20 compares the temperature Tw detected by the temperature sensor 510 with the reference temperature Tref. If Tw>Tref (YES in S220), an open failure of the check valve 55 is detected in S230. On the other hand, if Tw≦Tref (NO in S220), an open failure of the check valve 55 is not detected in S240.

The reference temperature Tref is set according to the temperature of the low-temperature water introduced into the water supply end 101 so that backflow of high-temperature water to the upstream side (the water supply end 101 side) of the check valve 55 can be detected. Specifically, it needs to be set between the inlet water temperature from the water supply end 101 and the temperature of the high-temperature water. It is assumed that the inlet water temperature changes depending on the ambient temperature of the hot water supply device 10 (the water supply end 101). Therefore, the reference temperature Tref can be variably set inside the controller 20 by inputting the temperature detected by the ambient temperature detector (not shown) to the controller 20. Alternatively, the reference temperature Tref can be input from outside the controller 20 (for example, a server connected to the controller 20).

The reference temperature Tref can also be set using the actual temperature during hot water supply, as shown in Figure 6.

Referring to FIG. 6, the controller 20 detects the timing to start supplying hot water in S250. For example, contrary to S110 (FIG. 4), if hot water supply was stopped in the previous cycle and changes to hot water supply being started in the current cycle, S250 is judged as YES in that cycle, and the timing to start supplying hot water is detected. In other cases, S250 is judged as NO, and the processing from S260 onwards is not started.

When the controller 20 detects the timing to start supplying hot water (YES in S250), and a predetermined time Td has passed since the timing to start supplying hot water (YES in S260), the controller 20 acquires the detected temperature Tw of the temperature sensor 510 for a certain period of time in S270, and sets the reference temperature Tref based on the average value TW0 of the acquired detected temperatures Tw. For example, the reference temperature Tref can be calculated by adding a predetermined margin value α to the average value (Tref = TW0 + α). Meanwhile, the process of S270 is put on hold until the predetermined time Td has passed since the timing to start supplying hot water (NO in S260).

In this way, when S210 in FIG. 5 is judged as YES, the reference temperature Tref used in S220 can be set using the actual value of the detected temperature Tw of the temperature sensor 510 during the immediately preceding hot water supply operation. This can improve the accuracy of detecting an open failure of the check valve 55.

Alternatively, in order to prevent erroneous detection of open circuit faults, it is possible to limit the opportunities for fault diagnosis according to S220 to S240 in FIG. 5.

Figure 7 shows the control process that is added to limit the opportunities for fault diagnosis.

As shown in FIG. 7, when S210 is judged as YES, i.e., when hot water supply is stopped, the controller 20 executes the additional judgment of S215, which includes S215a and S215b.

In S215a, the controller 20 determines whether the auxiliary heat source unit 200 is in combustion operation (BU combustion) and whether the circulation pump 310 is operating. Furthermore, in S215b, the controller 20 determines whether the mixing valve 340 is at an intermediate opening. Note that in S215b, it may also be determined whether the water heater 10 is in a re-discharge standby state (S130).

If both S215a and S215b are judged as YES while hot water supply is stopped (YES judgment in S210), the controller 20 advances the process to S220 (FIG. 5) and executes a fault diagnosis using the detected temperature Tw (temperature sensor 510). On the other hand, if at least one of S215a and S215b is judged as NO, the process advances to S240 and an open fault of the check valve 55 is not detected.

That is, by the additional determination in FIG. 7, the failure diagnosis by S220 is executed only when the high temperature side port and the low temperature side port of the mixing valve 340 are connected and the internal state is such that pressurized high temperature water (BU combustion) is input to the high temperature side port of the mixing valve 340. As a result, failure detection is executed in response to an increase in the detected temperature Tw due to the backflow, limited to the internal state in which an open failure of the check valve 55 is likely to cause a backflow of high temperature water. As a result, it is possible to prevent an open failure of the check valve 55 from being erroneously detected due to the influence of noise in the output value of the temperature sensor 510, etc.

In this way, one embodiment of the "fault diagnosis unit" can be configured by the controller 20 executing the control processes shown in Figures 5 to 7.

(Control when check valve open failure is detected)
Next, the control for responding to an open failure of the check valve 55 detected by the control process described in Figures 5 to 7 will be described with reference to Figures 8 and 9. This control is for avoiding the discharge of high-temperature hot water caused by starting hot water supply from a state in which high-temperature water is present in both the high-temperature side port and the low-temperature side port of the mixing valve 340. The control process shown in Figures 8 and 9 can also be executed by the controller 20.

According to the first control example shown in FIG. 8, the controller 20 determines in S310 whether an open failure of the check valve 55 has been detected. That is, S310 is determined to be YES in conjunction with S230 in FIG. 5.

When an open failure of the check valve 55 is detected (YES in S310), the controller 20 outputs a message to notify the user that a failure (open failure) has occurred in the check valve 55 and to request that repairs be arranged. The notification message can be output in a manner that is visually or audibly recognizable to the user, for example, using the display unit 31 and/or speaker 34 of the remote control 30. When an open failure of the check valve 55 is not detected (NO in S310), the processing from S320 onwards is not executed.

Furthermore, in S330, the controller 20 controls the mixing valve 340 to be fully closed (high temperature water 0 (%)) in response to the error state of the check valve 55. That is, the hot water outlet temperature control is not executed and the mixing valve 340 is controlled to be fully closed. Furthermore, when the check valve 55 enters an error state, there is a risk that the low-temperature water pipe 111 will also be at a high temperature. Therefore, in order to prevent the hot water tap 15 from being opened and high-temperature hot water being discharged, the flow rate adjustment valve 370 is further controlled to be fully closed. This prevents high-temperature hot water from being discharged when the check valve 55 fails to open.

The controller 20 maintains the control of the mixing valve 340 to be fully closed by S330 until the error state of the check valve 55 is released by S340 (NO at S340). For example, the error state is released in response to an operation input by a service technician when the replacement work of the failed check valve 55 is completed.

When the error code is cleared (YES in S340), the controller 20 releases the control of the full closure of the mixing valve 340 and the flow rate control valve 370. After this, the opening control of the mixing valve 340 by controlling the hot water outlet temperature, i.e., the control of the mixing ratio of high-temperature water and low-temperature water, is resumed, and hot water can be discharged by flowing through the hot water outlet pipe 121.

According to the first control example in FIG. 8, when an open failure of the check valve 55 is detected, the mixing valve 340 is controlled to be fully closed, blocking the path from the high-temperature water pipe 119a to the hot water outlet pipe 121, thereby preventing continuous hot water from being discharged at high temperatures. In this way, one embodiment of a "failure response control unit" can be configured by the controller 20 executing the control process shown in FIG. 8.

In the second control example shown in FIG. 9, after steps S310 and S320 similar to those in FIG. 7, the controller 20 calculates in step S400 the amount of increase (temperature increase) Twup of the detected temperature Tw of the temperature sensor 510 relative to the reference temperature Tref (Twup=Tw-Tref). In the second control example in FIG. 9, the action for the open circuit fault is executed in stages according to the amount of temperature increase Twup.

When the temperature rise amount Twup is lower than a predetermined judgment value Tr (YES judgment in S410), the controller 20 controls the proportional valve 350 to be fully closed in S420 to cut off the supply of high-temperature water from the auxiliary heat source unit 200 to the mixing valve 340. On the other hand, the mixing valve 340 is not controlled to be fully closed, and opening control continues. Furthermore, unlike S330, the flow rate adjustment valve 370 is not controlled to be fully closed in order to allow flow through the hot water outlet pipe 121. This allows tank hot water supply using high-temperature water stored in the hot water storage tank 150 to continue.

Normally, the temperature of the high-temperature water stored in the hot water storage tank 150 is lower than the temperature of the high-temperature water output from the auxiliary heat source unit 200. Therefore, in the range where the temperature rise Twup is small, the rise in the hot water temperature is expected to be small as well, and so the tank hot water supply is permitted to continue. For example, it is possible to determine whether or not to continue the tank hot water supply based on the detected temperature (temperature sensors 151-156) of the hot water stored in the hot water storage tank 150.

When the error is cleared in the same manner as S340 in FIG. 8 (YES at S430), processing proceeds to S440 and the control of the proportional valve 350 to be fully closed at S420 is released. On the other hand, until the error is cleared (NO at S430), processing returns to S400. In other words, if the amount of temperature rise is small (Twup<Tr) after an open failure of the check valve 55 is detected, S420 is executed continuously and hot water supply to the tank is permitted.

On the other hand, if the amount of temperature rise Twup is equal to or greater than the judgment value Tr after detecting an open failure of the check valve 55 (NO in S410), the controller 20 executes S330 to S350 similar to those in FIG. 8. As a result, if an open failure of the check valve 55 is detected and the amount of temperature rise Twup due to backflow is large, the controller 20 executes control similar to that in FIG. 8, in which the mixing valve 340 and the flow rate adjustment valve 370 are fully closed.

In the second control example of FIG. 9, even if an open failure occurs in the check valve 55, tank operation can be continued within a range in which the temperature rise amount Twup is small, thereby improving user convenience. In FIG. 9, an embodiment of a "first failure response control unit" is realized by executing the process of S420 when the determination of S410 is YES, and an embodiment of a "second failure response control unit" is realized by executing the process of S330 when the determination of S410 is NO.

When the hot water supply device 10 shown in FIG. 1 is stopped, the circulation pump 310 and the auxiliary heat source unit 200 are operating, and the mixing valve 340 is controlled to an opening (medium opening) that allows hot water to flow between both the high-temperature side port and the low-temperature side port (first and second ports) and the output port (third port), and an open failure of the check valve 55 occurs, there may be a case where a hot water circulation path is formed from the low-temperature water pipe 111 through the pipe 112. In order to detect an open failure of the check valve 55 in this case, it is preferable that the temperature sensor 510 is located upstream of the check valve 55 and is included in the hot water circulation path from the low-temperature water pipe 111 through the pipe 112. However, even if the temperature sensor 510 is not located on the hot water circulation path, it can be used to detect an open failure of the check valve 55 by arranging it near the node Nx as exemplified in this embodiment.

In addition, in this embodiment, the detection of a check valve failure has been described using a hot water storage and hot water supply device with a hot water storage tank as an example, but the configuration of the hot water supply device 10 is not limited to the example in Figure 1. That is, like this embodiment, the open failure detection of the check valve according to this embodiment can be applied to a hot water supply device configured with a mixing valve for high-temperature water and low-temperature water, and a check valve arranged in the water inlet path to the low-temperature water port of the mixing valve.

The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is indicated by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims.

10 hot water supply device, 13 bathtub, 14a heating device, 14b bathroom heater/dryer, 15 hot water tap, 20 controller, 25 housing, 30 remote control, 31 display unit, 32 operation switch, 33 operation unit, 34 speaker, 55, 56, 322 check valve, 80 hot water supply pipe, 81 water supply pipe, 82 fuel gas pipe, 85 drain pipe, 101 water supply end, 102 hot water outlet end, 103 to 110 connection end, 111 low temperature water pipe, 119a high temperature water pipe, 121 hot water outlet pipe, 150 hot water storage tank, 151 to 156, 510, 520, 525, 530, 550, 555, 560, 580, 590 temperature sensor, 200 auxiliary heat source unit, 201a input end, 201b Output end, 210, 220 heat exchanger, 215, 225 on-off valve, 230 heating tank, 240 heating pump, 301 hot water supply pipe, 310, 315 circulation pump, 311a intake port, 311b discharge port, 320 three-way valve, 321, 341, 351, 371, 381 stepping motor, 330 heat storage switching valve, 340 mixing valve, 350 proportional valve, 360 hot water supply on-off valve, 365 high temperature avoidance solenoid valve, 370 flow rate adjustment valve, 380 hot water storage switching valve, 390 pressure relief valve, 410, 420, 430 flow rate sensor, Nb, Nc, Nx node, Tref reference temperature, Tw detected temperature, Twup temperature rise amount.

Claims (5)

A hot water supply device, comprising:
A high-temperature water pipe for supplying high-temperature water;
a low-temperature water pipe for supplying low-temperature water from a water supply end;
A tapping pipe connected to the tapping end;
a mixing valve having a first port connected to the high-temperature water pipe, a second port connected to the low-temperature water pipe, and a third port connected to the hot water outlet pipe;
a control device that controls a mixing ratio of hot and cold water flowing from the first port to the third port and hot and cold water flowing from the second port to the third port according to an opening degree of the mixing valve;
a check valve that is connected to the low-temperature water pipe and has a check function for preventing a flow from the second port toward the water supply end;
a temperature detector disposed in a path of the low-temperature water between the water supply end and the check valve;
The control device includes:
a fault diagnosis unit that detects an open fault in which the check valve loses its check function when the temperature detected by the temperature detector rises above a reference temperature that is set according to the temperature of the low-temperature water introduced into the water supply end ,
The fault diagnosis unit sets the reference temperature according to the detected temperature of the temperature detector while the hot water supply device is supplying hot water, and when the detected temperature by the temperature detector rises above the reference temperature set from the detected temperature during the previous hot water supply while the hot water supply device is stopped, detects the open fault of the check valve . The hot water supply device includes:
A circulation pump;
A circulation path for the high-temperature water formed in response to operation of the circulation pump;
A heat source machine included in the circulation path;
a proportional valve connected between the circulation path and the high-temperature water pipe,
The hot water supply device of claim 1, wherein the failure diagnosis unit detects the open failure of the check valve when the detected temperature by the temperature detector rises above the reference temperature while the hot water supply of the hot water supply device is stopped, the circulation pump and the heat source unit are operating, and the mixing valve is controlled to an opening degree that allows flow between both the first and second ports and the third port. The hot water supply apparatus according to claim 2 , wherein the high-temperature water in the circulation path is used to heat a heat medium supplied to a heating appliance connected to the hot water supply apparatus. Further comprising a flow rate control valve connected to the hot water outlet pipe,
The control device includes:
The hot water supply device according to any one of claims 1 to 3, further comprising a failure response control unit that controls the opening degree of the mixing valve so that flow between the first port and the third port is blocked while flow is allowed through the second port and the third port when the open failure of the check valve is detected, and that controls the flow control valve to be fully closed. A circulation pump;
A high-temperature water circulation path formed in response to operation of the circulation pump;
A heat source machine included in the circulation path;
a proportional valve connected between the circulation path and the high-temperature water pipe;
A flow rate control valve connected to the hot water outlet pipe;
Further comprising a hot water storage tank;
an output end of the hot water storage tank is connected to the high-temperature water pipe at a position closer to the first port of the mixing valve than the proportional valve;
The control device includes:
a first failure response control unit which, when an open failure of the check valve is detected and an increase in the detected temperature by the temperature detector with respect to the reference temperature is lower than a predetermined judgment value, controls an aperture of the proportional valve so as to block a path between the circulation path and the high-temperature water pipe, while controlling an aperture of the mixing valve in accordance with a hot water outlet temperature in the hot water outlet pipe, and controls the flow rate control valve to be fully closed;
The hot water supply device of claim 1, further comprising a second failure response control unit for controlling the opening degree of the mixing valve so that flow between the first port and the third port is blocked while flow is allowed through the second port and the third port when the open failure of the check valve is detected and the amount of increase is equal to or greater than the judgment value , and for controlling the flow control valve to allow flow through the hot water outlet piping.

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