Liquid heating device

Abstract

The invention provides a liquid heating device. The present invention suppresses erroneous detection of liquid leakage in a heating path of a liquid heating device. An inflow-side on-off valve is provided on the inflow side of a heating path in which a liquid flowing in from upstream is heated by a heating unit and then flows out downstream, and an outflow-side on-off valve is provided on the outflow side of the heating path. A pressure sensor for detecting the pressure of the liquid is provided between the two on-off valves of the heating path. The control unit controls execution of a liquid leak detection process in which, after the outflow-side on-off valve and the inflow-side on-off valve are closed to seal the heating path, a liquid leak in the heating path is detected on the basis of a decrease in the detection pressure of the pressure sensor. The control unit executes a liquid leak detection process after a predetermined temperature stabilization condition is satisfied, in which the temperature of the liquid in the heating path is estimated to be reduced and stabilized. Therefore, the influence of temperature change on the liquid pressure of the sealed heating path can be reduced, and false detection of liquid leakage of the heating path caused by temperature reduction can be inhibited.

Description

Technical Field

[0001] The present invention relates to a liquid heating device having a heating path in which liquid flowing in from upstream is heated by a heating unit and then flows out to downstream, and more particularly to a technology for detecting liquid leakage in the heating path. Background Art

[0002] As a liquid heating device for heating a liquid, there is known a liquid heating device having a heating path through which the liquid to be heated flows, and in the heating path, the liquid flowing in from the upstream is heated by a heating unit such as a heat exchanger and then flows out to the downstream.

[0003] In such a liquid heating device, the following scheme has been proposed (for example, Patent Document 1): on-off valves are respectively provided on the inflow side and the outflow side of the heating path, and a pressure sensor for detecting the pressure of the liquid is provided between the two on-off valves on the heating path. After the two on-off valves are closed to seal the heating path, liquid leakage in the heating path is detected based on the decrease in the detected pressure obtained by the pressure sensor.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2002-174458 Summary of the invention

[0007] Problem that the invention aims to solve

[0008] However, in a liquid heating device that detects liquid leakage in a heating path as described above, the pressure of the liquid in the closed heating path is easily affected by temperature changes, so there is a problem that even if no liquid leakage actually occurs, the pressure drop caused by the temperature drop may sometimes lead to erroneous detection of liquid leakage.

[0009] The present invention has been made in response to the above-mentioned problems in the prior art, and an object of the present invention is to provide a technology capable of suppressing erroneous detection of liquid leakage in a heating path in a liquid heating device.

[0010] Solutions for solving problems

[0011] In order to solve the above problems, the liquid heating device of the present invention adopts the following structure. That is,

[0012] A liquid heating device has a heating path, in which liquid flowing in from upstream is heated by a heating unit and then flows out to downstream, wherein the liquid heating device is characterized by comprising:

[0013] an inflow-side opening and closing valve that opens and closes the inflow side of the heating path;

[0014] an outflow-side opening and closing valve that opens and closes the outflow side of the heating path;

[0015] a pressure sensor disposed between the inflow-side on-off valve and the outflow-side on-off valve on the heating path and capable of detecting the pressure of the liquid; and

[0016] a control unit for controlling execution of a liquid leakage detection process in which, after the heating path is sealed by closing the outflow-side on-off valve and the inflow-side on-off valve, liquid leakage in the heating path is detected based on a decrease in a detection pressure of the pressure sensor,

[0017] The control unit executes the liquid leakage detection process after a predetermined temperature stabilization condition is satisfied, in which it is estimated that the temperature of the liquid in the heating path has dropped and stabilized.

[0018] In a liquid heating device of the present invention as shown above, by waiting for the temperature stabilization condition to be established before executing the liquid leakage detection process, the effect of temperature changes on the pressure of the liquid in the closed heating path can be reduced compared to a case where the temperature stabilization condition is not set, thereby suppressing false detection of liquid leakage in the heating path caused by temperature drop.

[0019] In the above-mentioned liquid heating device of the present invention, it can also be set as follows. First, in the heating unit, when the flow rate of hot water in the heating path is less than a specified flow rate, heating is stopped. Moreover, the temperature stabilization condition is that a specified stabilization time has passed in a state where the flow of the liquid in the heating path is stopped.

[0020] In a liquid heating device constructed in this way, if the flow of liquid in the heating path stops, the heating in the heating section stops, and heated liquid does not flow into the heating path from elsewhere. Therefore, in this state, the temperature of the liquid in the heating path decreases and stabilizes due to heat dissipation until the stabilization time has passed, thereby suppressing erroneous detection in the liquid leakage detection process performed later.

[0021] In addition, the temperature stabilization condition in the liquid heating device of the present invention described above may be that a stabilization time has elapsed in a state where the flow of the liquid in the heating path is stopped by closing the outflow-side on-off valve.

[0022] In the liquid heating device configured as above, when the outflow side opening and closing valve is closed, the outflow of the liquid from the heating path is cut off, so the flow of the liquid in the heating path stops. Moreover, the outflow side opening and closing valve is already closed at the time point when the stabilization time has passed, and the heating path can be sealed by only closing the inflow side opening and closing valve, so the liquid leakage detection process can be performed quickly.

[0023] In such a liquid heating device of the present invention, it is also possible that, when a prescribed pre-stabilization time shorter than the stabilization time has passed while the flow of liquid in the heating path has stopped, the liquid leakage detection process is performed in advance, and if no liquid leakage in the heating path is detected, the liquid leakage detection process after the stabilization time has passed is omitted. Conversely, when there is a possibility of liquid leakage in the heating path, the sealing of the heating path is temporarily released and the liquid leakage detection process is re-executed after the stabilization time has passed.

[0024] In the liquid heating device configured as above, if no liquid leakage is detected in the liquid leakage detection process executed in advance, the subsequent liquid leakage detection process is omitted, thereby enabling early recovery to normal use even when the use is restricted until the liquid leakage detection process is completed. On the other hand, even if there is a possibility of liquid leakage, it is suspected that it is caused by a drop in temperature, so waiting for the stabilization time to pass before executing the liquid leakage detection process again can suppress false detection.

[0025] In such a liquid heating device of the present invention, it can also be configured to have a temperature sensor that can detect the temperature of the liquid in the heating path, and interrupt the liquid leakage detection process when the detected temperature of the temperature sensor changes by more than a prescribed allowable value during the execution of the liquid leakage detection process despite the establishment of a temperature stability condition.

[0026] In a liquid heating device constructed in this way, if the temperature of the liquid in the heating path is estimated to be stabilized based on the establishment of the temperature stabilization condition, but the temperature sensor actually confirms that the temperature has not yet stabilized, the pressure of the liquid in the heating path is affected by the temperature change, so it is possible to suppress false detection by interrupting the liquid leakage detection process being executed. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 1 is an explanatory diagram showing the overall structure of a connected hot water system 1 according to the present embodiment as an example of a liquid heating device.

[0028] Figure 2 1 is an explanatory diagram showing the structure of the water heater 10 of this embodiment.

[0029] Figure 31 is a flowchart of the water leakage detection control process executed by the controller 29 of the “slave” water heater 10 of the present embodiment.

[0030] Figure 4 1 is a flowchart of the temperature stable condition monitoring process of the present embodiment executed in the water leakage detection control process.

[0031] Figure 5 This is a flowchart of most of the water leakage detection process of this embodiment executed in the water leakage detection control process.

[0032] Figure 6 4 is a flowchart of the remaining part of the water leakage detection process of this embodiment executed in the water leakage detection control process.

[0033] Figure 7 4 is a flowchart of the pre-water leakage detection process of this embodiment executed in the water leakage detection control process.

[0034] Figure 8 It is an explanatory diagram showing a configuration of another example including the hot water storage tank 30 .

[0035] Fig. 9 It is an explanatory diagram showing the structure of another example including the filter unit 40 . DETAILED DESCRIPTION

[0036] Figure 1 1 is an explanatory diagram showing the overall structure of a connected hot water system 1 of the present embodiment as an example of a liquid heating device. In the connected hot water system 1 shown in the figure, two water heaters 10 that burn fuel gas to generate hot water are connected, and a gas pipe 2 for supplying fuel gas to each water heater 10, a water supply pipe 3 for supplying tap water to each water heater 10, and a hot water outlet pipe 4 for guiding the hot water heated by each water heater 10 are provided.

[0037] The details of the water heater 10 will be described later using other drawings. The two water heaters 10a and 10b are basically of the same specifications, can operate in the same manner, and are connected in parallel. That is, the gas pipe 2 for supplying fuel gas is connected to the two water heaters 10a and 10b in a branched manner, and similarly, the water supply pipe 3 for supplying tap water is connected to the two water heaters 10a and 10b in a branched manner. In addition, the hot water outlet pipes 4 extending from the two water heaters 10a and 10b are merged into one to guide the hot water.

[0038] A plurality of (three in the illustrated example) hot water taps 5 (so-called faucets) are connected to the hot water outlet pipe 4 at a position downstream of the confluence point. In addition, the portion of the hot water outlet pipe 4 downstream of the connection point of the hot water tap 5 is connected to the portion of the water supply pipe 3 upstream of the branch point via a circulation pipe 6, and a circulation pump 7 for conveying hot water from the hot water outlet pipe 4 side to the water supply pipe 3 side is provided in the circulation pipe 6. The connected hot water system 1 of this embodiment has a so-called instant hot water function, and when the hot water tap 5 is closed and the hot water is not consumed, the hot water can be circulated in the circulation pipe 6 from the hot water outlet pipe 4 side to the water supply pipe 3 side by operating the circulation pump 7, while the water heater 10 is heated to keep the water warm, so that hot water can be supplied immediately once the hot water tap 5 is opened.

[0039] Furthermore, the two water heaters 10a and 10b are connected in a communication-capable manner, and are set in a master-slave relationship in which one water heater 10 is set as the "master" and the other water heater 10 is set as the "slave". If the consumption of hot water is small, only the "master" water heater 10 is operated, and the "slave" water heater 10 is in a standby state. Furthermore, if the consumption of hot water increases, not only the "master" water heater 10 is operated, but also the "slave" water heater 10 is operated. In addition, the master-slave relationship of the two water heaters 10a and 10b is periodically replaced. In addition, the number of connected water heaters 10 is not limited to two, but may be three or more, in which case one is the "master" and the others are "slaves".

[0040] Furthermore, a remote controller 8 operable by a manager of the connected hot water system 1 is connected to each water heater 10 in a manner capable of communicating by wire or wirelessly. The remote controller 8 includes an operation unit 8a provided with various switches for performing various settings such as the temperature of the supplied hot water, switching on / off of various functions, or resetting, and includes a display unit 8b capable of displaying the setting status and operating status of the connected hot water system 1, information on the water heater 10, and the like.

[0041] Figure 2 1 is an explanatory diagram showing the structure of the water heater 10 of the present embodiment. As shown in the figure, the water heater 10 is provided with a burner 12 which is housed in a combustion chamber 11 and burns fuel gas, and a combustion fan 13 which blows combustion air from below toward the burner 12. The fuel gas is supplied to the burner 12 through the above-mentioned gas piping 2. The gas piping 2 in the water heater 10 is provided with a main valve 14 for opening and closing the gas piping 2, and a proportional valve 15 for adjusting the flow rate of the fuel gas flowing through the gas piping 2. In addition, the combustion chamber 11 is provided with a spark plug 16 for igniting the burner 12 by spark discharge, a flame rod 17 for detecting the combustion state in the burner 12, and the like.

[0042] A heat exchanger 18 is provided above the burner 12. The high-temperature combustion exhaust gas generated by the combustion in the burner 12 passes through the heat exchanger 18 and is discharged to the outside from an exhaust port 19 provided at the upper part of the water heater 10. A water supply pipe 3 is connected to one end (upstream side) of the heat exchanger 18, and a hot water outlet pipe 4 is connected to the other end (downstream side). The water supply pipe 3 in the water heater 10 is provided with a water volume servo 20 for opening and closing the water supply pipe 3 and controlling the flow rate, a flow sensor 21 for detecting the flow rate of hot water supplied to the heat exchanger 18, an inflow side temperature sensor 22 for detecting the temperature (inflow side temperature) of the hot water flowing into the heat exchanger 18, and a pressure sensor 23 for detecting the pressure of the hot water in the water supply pipe 3 in order from the upstream side. In addition, the water volume servo 20 of this embodiment corresponds to the "inflow side opening and closing valve" of the present invention.

[0043] The hot water flowing into the heat exchanger 18 in the open state of the water quantity servo 20 is heated by heat exchange between the heat exchanger 18 and the combustion exhaust gas from the burner 12, and then flows out to the hot water outlet pipe 4. The hot water outlet pipe 4 in the water heater 10 is provided with an outflow side temperature sensor 24 for detecting the temperature of the hot water flowing out of the heat exchanger 18 (outflow side temperature) and a hot water quantity servo 25 for opening and closing the hot water outlet pipe 4 and controlling the flow rate in sequence toward the downstream side. In addition, the burner 12 and the heat exchanger 18 of this embodiment are equivalent to the "heating unit" of the present invention. In addition, the hot water quantity servo 25 of this embodiment is equivalent to the "outflow side opening and closing valve" of the present invention, and the outflow side temperature sensor 24 of this embodiment is equivalent to the "temperature sensor" of the present invention.

[0044] In the water heater 10 of the present embodiment, a position of the water supply pipe 3 on the upstream side of the water quantity servo 20 and a position of the hot water outlet pipe 4 on the downstream side of the hot water quantity servo 25 are connected by a bypass pipe 26. The bypass pipe 26 is provided with a bypass servo 27 for opening and closing the bypass pipe 26 and controlling the flow rate. A part of the hot water supplied to the water heater 10 through the water supply pipe 3 is not supplied to the heat exchanger 18 but can pass through the bypass pipe 26, and the rest is supplied to the heat exchanger 18. Then, the hot water heated by the heat exchanger 18 and the hot water passing through the bypass pipe 26 are mixed and supplied to the hot water tap 5. The mixing ratio of the hot water heated by the heat exchanger 18 and the hot water passing through the bypass pipe 26 can be changed by the opening degree of the bypass servo 27, the hot water quantity servo 25, and the water quantity servo 20.

[0045] A hot water supply temperature sensor 28 for detecting the temperature of hot water supplied to the hot water faucet 5 (hot water supply temperature) is provided on the hot water outlet pipe 4 at a position downstream of the connection point of the bypass pipe 26. Since the bypass pipe 26 is connected as described above, the temperature detected by the hot water supply temperature sensor 28 becomes lower than the temperature detected by the outflow side temperature sensor 24 located upstream, and the temperature variation of the hot water supplied to the hot water faucet 5 can be suppressed by adjusting the mixing ratio. In addition, the various temperature sensors of this embodiment use thermistors whose resistance changes according to the change of temperature.

[0046] In addition, the water heater 10 is separately equipped with a controller 29 for controlling the entire device, and the above-mentioned combustion fan 13, main valve 14, proportional valve 15, spark plug 16, flame rod 17, water volume servo 20, flow sensor 21, inflow side temperature sensor 22, pressure sensor 23, outflow side temperature sensor 24, hot water volume servo 25, hot water supply temperature sensor 28, etc. are electrically connected to the controller 29. The controller 29 controls the opening and closing of the water volume servo 20 and the hot water volume servo 25, and controls the combustion volume (heating volume) of the burner 12 according to the detected flow rate in the flow sensor 21, the detected temperature in the inflow side temperature sensor 22, etc., and stops the combustion in the burner 12 when the detected flow rate in the flow sensor 21 is less than the specified flow rate.

[0047] In addition, the controllers 29 of the two water heaters 10a and 10b are electrically connected to each other and to the circulation pump 7 of the circulation pipe 6. As described above, a master-slave relationship is set for the two water heaters 10a and 10b, and the controller 29 of the "master" water heater 10 controls the operation of the circulation pump 7 and gives instructions to the controller 29 of the "slave" water heater 10. For the "slave" water heater 10 in this embodiment, when it becomes a standby state, the hot water quantity servo 25 is completely closed, and the flow of hot water on the upstream side of the hot water quantity servo 25 is stopped (the flow rate detected by the flow sensor 21 is less than the specified flow rate), so that combustion is not performed in the burner 12, and heated hot water does not flow from the "master" water heater 10 through the water quantity servo 20 during the circulation process. In addition, for the "slave" water heater 10 in the standby state, the bypass servo 27 is also completely closed in advance in conjunction with the complete closing of the hot water quantity servo 25, and the flow of hot water in the standby state is cut off in this way. In addition, for the "main" water heater 10, even in the standby state (the state in which combustion in the burner 12 is stopped), the hot water quantity servo 25 and the bypass servo 27 are set to the open state (the opening degree corresponding to the set temperature in the remote control 8, the detection temperature of various temperature sensors, etc.) to ensure the circulation of hot water.

[0048] In the connected hot water system 1 of the present embodiment as described above, in the "slave" water heater 10 in the standby state, not only the hot water quantity servo 25 but also the water quantity servo 20 is completely closed to seal the path from the water quantity servo 20 to the hot water quantity servo 25 (hereinafter referred to as the heating path), thereby making it possible to detect water leakage in the heating path based on the decrease in the detected pressure in the pressure sensor 23. However, the pressure of hot water in the sealed heating path is easily affected by temperature changes, so sometimes, for example, the pressure of the hot water is reduced due to the temperature drop caused by the residual heat cooling in the heat exchanger 18, resulting in a false detection of a water leakage in the heating path. Therefore, in the connected hot water system 1 of the present embodiment, the controller 29 of the "slave" water heater 10 performs the following water leakage detection control processing, so that water leakage in the heating path can be detected and false detection can be suppressed. In addition, the controller 29 of the present embodiment is equivalent to the "control unit" of the present invention.

[0049] Figure 3 1 is a flowchart of the water leakage detection control process executed by the controller 29 of the "slave" water heater 10 of the present embodiment. When the power supply connected to the hot water system 1 is turned on, the water leakage detection control process is repeatedly executed at a predetermined cycle in the water heater 10 set as the "slave". As shown in the figure, when the water leakage detection control process of the present embodiment is started, first, a process of monitoring whether a predetermined temperature stabilization condition is satisfied (temperature stabilization condition monitoring process) is executed to estimate that the temperature of the hot water in the heating path has decreased and stabilized (step 1). The temperature stabilization condition in the present embodiment is set to "a predetermined stabilization time (e.g., 90 minutes) has passed in a state where the hot water quantity servo 25 is completely closed and the flow of hot water in the heating path has stopped."

[0050] Figure 4 1 is a flow chart of the temperature stabilization condition monitoring process of the present embodiment executed in the water leakage detection control process. In the temperature stabilization condition monitoring process, first, it is determined which condition establishment flag of the temperature stabilization condition establishment flag and the pre-temperature stabilization condition establishment flag is set to ON (step 10). As described later, the temperature stabilization condition establishment flag is a flag indicating that the temperature stabilization condition has been established, and the pre-temperature stabilization condition establishment flag is a flag indicating that the pre-temperature stabilization condition has been established before the temperature stabilization condition has been established. In addition, a storage area for the flag is ensured in the storage unit (not shown) of the controller 29.

[0051] When both the temperature stabilization condition establishment flag and the pre-temperature stabilization condition establishment flag are set to OFF (step 10: "No"), it is then determined whether or not the stabilization time standby timer and the pre-stabilization time standby timer are timing (step 11). These stabilization time standby timer and the pre-stabilization time standby timer are timers for measuring the elapsed time when the hot water quantity server 25 is completely turned off. The time (pre-stabilization time) measured by the pre-stabilization time standby timer is shorter than the time (stabilization time) measured by the stabilization time standby timer as described later. Then, when the stabilization time standby timer and the pre-stabilization time standby timer are not timing (step 11: "No"), it is then determined whether or not 24 hours have passed since the last determination of the presence or absence of water leakage in the heating path (step 12). In each water heater 10 of the present embodiment, the frequency of performing the process of detecting water leakage in the heating path (water leakage detection process) is performed after at least 24 hours have passed since the last determination of the presence or absence of water leakage. Therefore, if 24 hours have not passed since the last water leakage determination (step 12: No), the water leakage detection process will not be performed regardless of whether the temperature stability condition is met, and the process is temporarily terminated as is. Figure 4 The temperature stability condition is monitored during processing and returned to Figure 3 Water leakage detection and control processing.

[0052] On the other hand, if 24 hours have passed since the last water leakage determination (step 12: Yes), it is determined whether the hot water quantity servo 25 is completely closed (step 13). If the hot water quantity servo 25 is not completely closed but is in the open state (step 13: No), the "slave" water heater 10 is not in the standby state, the burner 12 is burning, and the temperature stabilization condition is not satisfied, so the operation is temporarily terminated. Figure 4 The temperature stability condition is monitored during processing and returned to Figure 3 Water leakage detection and control processing.

[0053] On the other hand, when the hot water quantity servo 25 is completely closed (step 13: Yes), it is determined that the "slave" water heater 10 is in the standby state and the burner 12 is not burning, so the above-mentioned stable time standby timer and the preceding stable time standby timer start timing (step 14). When the timing by the stable time standby timer and the preceding stable time standby timer is started in this way, it is determined whether the hot water quantity servo 25 is set to the open state after the timing starts (step 15). In addition, when it is determined in step 11 that the stable time standby timer and the preceding stable time standby timer are already timing (step 11: Yes), the processing of steps 12 to 14 is omitted, and it is determined whether the hot water quantity servo 25 is set to the open state (step 15). Then, when the hot water quantity servo 25 is turned on (step 15: Yes), the standby state of the "slave" water heater 10 is released, and combustion is started in the burner 12. Therefore, after resetting (stopping) the stabilization time standby timer and the preceding stabilization time standby timer (step 16), the process is temporarily terminated. Figure 4 The temperature stability condition is monitored during processing and returned to Figure 3 In addition, it is also possible to limit the use of the "slave" water heater 10 before the end of the water leakage detection process and maintain the hot water quantity servo 25 in a completely closed state.

[0054] On the other hand, when the hot water quantity servo 25 remains in the completely closed state (step 15: No), the stabilization time standby timer determines whether a predetermined stabilization time (90 minutes in this embodiment) has passed (step 17). If the stabilization time has not passed (step 17: No), the preceding stabilization time standby timer determines whether a predetermined preceding stabilization time (15 minutes in this embodiment) shorter than the stabilization time has passed (step 18). Then, if the preceding stabilization time has not passed (step 18: No), the process is temporarily terminated as it is. Figure 4 The temperature stability condition is monitored during processing and returned to Figure 3 Water leakage detection and control processing.

[0055] After that, repeat the Figure 3 If the pre-stabilization time standby timer determines that the pre-stabilization time has elapsed during the water leakage detection control process (step 18: "Yes"), the pre-temperature stabilization condition establishment flag indicating that the pre-temperature stabilization condition has been established is set to ON (step 19) because the pre-stabilization time has elapsed while the hot water quantity server 25 is completely closed. In addition, the pre-stabilization time standby timer is automatically reset when the pre-stabilization time has elapsed. After that, the process is temporarily terminated. Figure 4 The temperature stability condition is monitored during processing and returned to Figure 3 Water leakage detection and control processing.

[0056] In addition, when repeatedly executing Figure 3 If the stabilization time standby timer determines that the stabilization time has passed during the water leakage detection control process (step 17: "Yes"), it means that the temperature stabilization condition of this embodiment has been met, so the temperature stabilization condition establishment flag indicating that the temperature stabilization condition has been met is set to ON (step 20). In addition, the stabilization time standby timer is automatically reset when the stabilization time has passed. When the temperature stabilization condition establishment flag is set to ON in this way, the process is temporarily terminated. Figure 4 The temperature stability condition is monitored during processing and returned to Figure 3 Water leakage detection and control processing.

[0057] Then, in Figure 4 In the judgment of step 10 immediately after the start of the temperature stabilization condition monitoring process, if any one of the temperature stabilization condition establishment flag and the pre-temperature stabilization condition establishment flag has been set to ON (step 10: "Yes"), it is judged whether the hot water quantity server 25 is set to the open state (step 21). Then, if the hot water quantity server 25 remains in the completely closed state (step 21: "No"), the temperature stabilization condition establishment flag or the pre-temperature stabilization condition establishment flag that has been set to ON is kept set to ON, and the process is temporarily terminated. Figure 4 The temperature stability condition is monitored during processing and returned to Figure 3 Water leakage detection and control processing.

[0058] On the other hand, when the hot water quantity servo 25 is turned on (step 21: Yes), it means that the standby state of the water heater 10 is released and the burner 12 starts to burn. Therefore, after the temperature stabilization condition establishment flag and the pre-temperature stabilization condition establishment flag that have been set to ON are set to OFF (step 22), the process is temporarily terminated. Figure 4 The temperature stability condition is monitored during processing and returned to Figure 3 Water leakage detection and control processing.

[0059] In the water leakage detection control process, when returning from the temperature stability condition monitoring process (step 1), it is determined whether the temperature stability condition establishment flag is set to ON (step 2). Then, if the temperature stability condition establishment flag is set to ON (step 2: "Yes"), the following water leakage detection process is executed (step 3). In addition, after the leakage detection process is completed, the water leakage detection process is temporarily terminated. Figure 3 The water leakage detection control process is executed again at a specified period. Figure 3In addition, the water leakage detection process of this embodiment is equivalent to the "liquid leakage detection process" of the present invention.

[0060] Figure 5 and Figure 6 This is a flow chart of the water leakage detection process of the present embodiment executed in the water leakage detection control process. In the water leakage detection process, first, it is determined whether the water quantity servo 20 is completely closed (step 30). The water quantity servo 20 of the present embodiment is basically in an open state. When detecting a water leakage in the heating path, in order to seal the heating path, not only the hot water quantity servo 25 but also the water quantity servo 20 is completely closed. Therefore, in the case where the water quantity servo 20 is not completely closed but in an open state (step 30: "No"), after the water quantity servo 20 is completely closed and the heating path is sealed (step 31), the temperature of the hot water in the hot water pipe 4 (the outflow side temperature) is detected by the outflow side temperature sensor 24 arranged in the heating path, and the pressure of the hot water in the water supply pipe 3 is detected by the pressure sensor 23 also arranged in the heating path (step 32).

[0061] When the outflow temperature and pressure of the hot water in the closed heating path are detected in this way, the outflow temperature (the temperature of the hot water in the heating path) detected by the outflow temperature sensor 24 is monitored, and it is determined whether the outflow temperature detected in the process of step 32 has changed by a predetermined allowable value (1 degree in this embodiment) or more (step 33). If the change in the outflow temperature is less than 1 degree (step 33: "No"), it is then determined whether the determination time has passed (step 34). In the water leakage detection process of this embodiment, a determination time is set for the period from when the water volume servo 20 is completely closed until the presence or absence of water leakage in the heating path is determined. The determination time is set according to the pressure of the hot water detected in the process of step 32, and the determination time is set longer if the detected pressure is high. For example, when the detected pressure is 200 kPa, the determination time is set to 3 seconds, while when the detected pressure is 600 kPa, the determination time is set to 20 seconds.

[0062] If the determination time has not elapsed (step 34: No), the heating path is kept sealed and the process is temporarily terminated. Figure 5 and Figure 6 The water leakage detection process is returned to Figure 3 After that, if the temperature stability condition is satisfied flag is set to ON, the control will be executed again at a specified cycle. Figure 5 and Figure 6In the water leakage detection process, in the judgment of step 30, the water volume server 20 has been completely closed (step 30: "Yes"), so the processing of steps 31 and 32 is omitted, and it is judged again whether the outflow side temperature has changed by more than 1 degree (step 33).

[0063] Then, if the outflow temperature changes by more than 1 degree before the judgment time has passed (step 33: Yes), the temperature of the hot water in the heating path is not yet stable, so no water leakage is detected, and the temperature stability condition is satisfied flag is set to OFF (step 35). In addition, the water volume servo 20 is opened to release the sealing of the heating path (step 36). Then, when the stabilization time standby timer and the pre-stabilization time standby timer start timing again in order to wait for the temperature stabilization condition or the pre-stabilization condition to be satisfied again (step 37), the temporary end Figure 5 and Figure 6 The water leakage detection process is returned to Figure 3 In the water leakage detection control process of the present embodiment, the change of the outflow side temperature is monitored from before the judgment time has passed, but it is also possible to determine whether the change of the outflow side temperature during the judgment time is more than 1 degree at the time point after the judgment time has passed.

[0064] On the other hand, if the outflow side temperature does not change by more than 1 degree (step 33: No), and the determination time has passed (step 34: Yes), the temperature of the hot water in the heating path has stabilized, so it is determined whether the pressure of the hot water in the water supply pipe 3 (sealed heating path) detected by the pressure sensor 23 is greater than or equal to a predetermined reference pressure (30 kPa in this embodiment) (step 38). Then, if the detected pressure is greater than or equal to 30 kPa (step 38: Yes), the pressure of the hot water in the sealed heating path is sufficient, so it is determined that there is no water leakage (step 39).

[0065] When it is determined that there is no water leakage, the temperature stability condition satisfaction flag is set to OFF (step 40), and then the water volume servo 20 is opened to release the sealing of the heating path (step 41). Figure 4 When the judgment completion timer for counting the time from when it is judged that there is no water leakage is operated (step 42), the process ends. Figure 5 and Figure 6 The water leakage detection process is returned to Figure 3 Water leakage detection and control processing.

[0066] On the other hand, if the detection pressure of the pressure sensor 23 is lower than 30 kPa in the judgment of step 38 (step 38: No), the water leakage detection counter is incremented by "1" ( Figure 6 The water leakage detection counter is a counter that stores the number of times the detection pressure of the pressure sensor 23 is lower than 30 kPa and the possibility of water leakage is confirmed. In the water leakage detection process of this embodiment, even if the detection pressure of the pressure sensor 23 is lower than 30 kPa, it is not immediately determined that there is a water leakage, but the confirmation is repeated until the upper limit number (three times in this embodiment) is reached. Therefore, when "1" is added to the water leakage detection counter, it is next determined whether the water leakage detection counter has reached "3" (step 44).

[0067] If the water leakage detection counter has not reached "3" (step 44: "No"), the water volume servo 20 is opened to temporarily release the sealing of the heating path (step 45). As a result, hot water is supplied to the heating path to apply pressure. After that, the process is temporarily terminated. Figure 5 and Figure 6 The water leakage detection process is returned to Figure 3 At this time, the temperature stability condition satisfaction flag is not set to OFF, so it is executed again at a specified cycle. Figure 5 and Figure 6 The water leakage detection process is repeated in the above steps 30 to 38. That is, after the water volume server 20 is completely closed to seal the heating path, the temperature change on the hot water outlet side is monitored, and the decrease in the detection pressure of the pressure sensor 23 is determined when the determination time has passed. If it is lower than 30 kPa (step 38: "No"), the water leakage detection counter is further increased by "1" (step 43). In addition, the water leakage detection counter is reset when the temperature stability condition establishment flag is set to OFF.

[0068] When the water leakage detection counter reaches the upper limit of "3" during the repetition of the process (step 44: "Yes"), since the pressure of the hot water in the closed heating path is repeatedly confirmed to be reduced, it is determined that there is a water leakage (step 46), and a notification is given to indicate that a water leakage has been detected (step 47). The notification of the water leakage in this embodiment is performed by displaying it on the display unit 8b of the remote controller 8. In addition, the notification method is not limited to this, and the notification may also be performed by sound output from a speaker (not shown) built into the remote controller 8. After that, the process ends. Figure 5 and Figure 6 The water leakage detection process is returned to Figure 3 Water leakage detection and control processing.

[0069] The above describes the processing to be performed when the temperature stabilization condition establishment flag is set to ON in step 2 of the water leakage detection control process (step 2: "Yes"). On the other hand, when the temperature stabilization condition establishment flag is set to OFF (step 2: "No"), it is next determined whether the pre-temperature stabilization condition establishment flag is set to ON (step 4). As described above, the pre-temperature stabilization condition establishment flag indicates that the pre-temperature stabilization condition has been established because the pre-stabilization time (15 minutes in this embodiment) has passed in the state where the hot water quantity server 25 is completely closed. Then, when the pre-temperature stabilization condition establishment flag is not set to ON (step 4: "No"), the process is temporarily terminated as it is. Figure 3 The water leakage detection control process is executed again at a specified period. Figure 3 Water leakage detection and control processing.

[0070] On the other hand, when the pre-temperature stability condition establishment flag is set to ON (step 4: "Yes"), the following pre-leakage detection process is executed (step 5). In addition, after the pre-leakage detection process is completed, the Figure 3 The water leakage detection control process is executed again at a specified period. Figure 3 In addition, there are many common parts between the pre-leakage detection process and the above-mentioned leakage detection process, so the common contents are briefly described.

[0071] Figure 7 1 is a flow chart of the pre-leakage detection process of the present embodiment executed in the water leakage detection control process. In the pre-leakage detection process, first, it is determined whether the water volume servo 20 is completely closed (step 50). When the water volume servo 20 is not completely closed but is in an open state (step 50: No), after the water volume servo 20 is completely closed to seal the heating path (step 51), the pressure sensor 23 arranged on the heating path detects the pressure of the hot water in the water supply pipe 3 (step 52).

[0072] When the pressure of the hot water in the sealed heating path is detected in this way, it is determined whether the determination time has passed (step 53). The determination time is set according to the pressure of the hot water detected by the process of step 52. If the detected pressure is high, the determination time is set to be long. If the determination time has not passed (step 53: "No"), the heating path is kept sealed and the process is temporarily terminated. Figure 7 The pre-leakage detection process is returned to Figure 3 After that, when the water leakage detection control process is executed again at a specified period Figure 7During the pre-leakage detection process, since the water volume server 20 has been completely closed in the judgment of step 50 (step 50: "Yes"), the processing of steps 51 and 52 is omitted, and it is judged again whether the judgment time has passed (step 53).

[0073] Then, when the determination time has passed (step 53: "Yes"), it is determined whether the pressure of the hot water in the water supply pipe 3 (sealed heating path) detected by the pressure sensor 23 is greater than a predetermined reference pressure (30 kPa in this embodiment) (step 54). At this time, when the detected pressure is greater than 30 kPa (step 54: "Yes"), the pressure of the hot water in the sealed heating path is sufficient to remain, and it is determined that there is no water leakage (step 55).

[0074] When it is determined that there is no water leakage, the pre-temperature stabilization condition satisfaction flag is set to OFF (step 56), and the water volume servo 20 is opened to release the sealing of the heating path (step 57). In addition, in this embodiment, the pre-water leakage detection process is performed at the time point when the pre-stabilization time (15 minutes) shorter than the stabilization time (90 minutes) has passed. Figure 7 ), when it is determined that there is no water leakage, the water leakage detection process after the stabilization time has passed is omitted ( Figure 5 , Figure 6 ). Therefore, the stabilization time standby timer that is timing is reset (stopped) (step 58). And when the judgment completion timer that counts the time from when it is judged that there is no water leakage is started (step 59), the process ends. Figure 7 The pre-leakage detection process is returned to Figure 3 Water leakage detection and control processing.

[0075] On the other hand, if the detected pressure of the pressure sensor 23 is lower than 30 kPa in the judgment of step 54 (step 54: "No"), the pressure of the hot water in the closed heating path is reduced, and there is a possibility of water leakage. However, in the pre-leakage detection processing ( Figure 7 ) is not determined to be leaking, and the final determination is made by subsequent leak detection processing ( Figure 5 , Figure 6 ). In addition, the pre-leakage detection process can be repeatedly performed every time the pre-stabilization time (15 minutes) passes until the stabilization time (90 minutes) passes.

[0076] Therefore, after the pre-temperature stabilization condition establishment flag is set to OFF (step 60), the water volume servo 20 is opened to release the sealing of the heating path (step 61). Then, when the pre-stabilization time standby timer starts again to wait for the pre-stabilization condition to be established again (step 62), the process ends. Figure 7The pre-leakage detection process is returned to Figure 3 After that, as the pre-stabilization time standby timer passes the pre-stabilization time again, the pre-temperature stabilization condition establishment flag is set to ON (refer to Figure 4 Step 19) of Figure 7 In addition, if it is not determined that there is no water leakage in the pre-leakage detection process, the stabilization time standby timer also continues to count, so the temperature stabilization condition establishment flag is set to ON as the stabilization time passes (refer to Figure 4 Step 20), execute Figure 5 and Figure 6 The water leakage detection process determines whether there is a water leakage as described above.

[0077] As described above, in the linked hot water system 1 of the present embodiment, in the "slave" water heater 10 in the standby state, the following processing (water leakage detection processing) can be performed: after the hot water quantity servo 25 and the water quantity servo 20 are completely closed to seal the path (heating path) from the water quantity servo 20 to the hot water quantity servo 25, water leakage in the heating path is detected based on the decrease in the detection pressure of the pressure sensor 23. In addition, the water leakage detection processing is performed after a predetermined temperature stabilization condition is satisfied, in which it is estimated that the temperature of the hot water in the heating path has decreased and stabilized.

[0078] According to the connected hot water system 1 of this embodiment, the water leakage detection process is performed after waiting for the temperature stabilization condition to be established. This can reduce the impact of temperature changes on the pressure of hot water in the closed heating path compared to the case where the temperature stabilization condition is not set, thereby suppressing the false detection of water leakage in the heating path caused by temperature drop.

[0079] In addition, in the coupled hot water system 1 of the present embodiment, the temperature stabilization condition is set to "the prescribed stabilization time (90 minutes) has passed with the flow of hot water in the heating path stopped" on the premise that the combustion of the burner 12 is stopped when the flow rate detected by the flow sensor 21 on the heating path is less than the prescribed flow rate. If the flow of hot water in the heating path has stopped, the combustion of the burner 12 stops, and the heated hot water does not flow in from elsewhere (for example, the "main" water heater 10), so in this state, the temperature of the hot water in the heating path decreases and stabilizes due to heat dissipation until the stabilization time has passed, thereby suppressing erroneous detection in the water leakage detection process performed later.

[0080] In particular, in the coupled hot water system 1 of the present embodiment, "a predetermined stabilization time has passed in a state where the flow of hot water in the heating path has been stopped by completely closing the hot water quantity servo 25" is set as a temperature stabilization condition. If the hot water quantity servo 25 is completely closed, the outflow of hot water from the heating path is cut off, and thus the flow of hot water in the heating path is stopped. Moreover, at the time point when the stabilization time has passed, the hot water quantity servo 25 has been completely closed, and the heating path can be sealed only by completely closing the water quantity servo 20, so that the water leakage detection process can be performed quickly. In addition, even if the flow of hot water in the heating path can be stopped by completely closing the water quantity servo 20, in this case, after the stabilization time has passed (when the water leakage detection process is started), in order to apply pressure to the heating path by supplying hot water, it is necessary to temporarily open the water quantity servo 20, and then completely close the water quantity servo 20 again in a state where the hot water quantity servo 25 is completely closed.

[0081] Furthermore, in the connected hot water system 1 of the present embodiment, when the flow of hot water in the heating path stops and a predetermined pre-stabilization time (15 minutes) shorter than the stabilization time (90 minutes) has passed, the pre-leakage detection process is performed before the water leakage detection process (a part of the water leakage detection process is performed in advance), and if no water leakage in the heating path is detected, the water leakage detection process after the stabilization time has passed is omitted. On the other hand, if there is a possibility of water leakage in the heating path, the sealing of the heating path is temporarily released and the water leakage detection process is performed after the stabilization time has passed. Thus, if no water leakage is detected by the pre-leakage detection process performed before the water leakage detection process, the subsequent water leakage detection process is omitted, thereby enabling early recovery to normal use even in the case of limiting the use of the water heater 10 until the end of the water leakage detection process. On the other hand, even if there is a possibility of water leakage, since it is suspected that it is caused by a drop in temperature, the water leakage detection process is re-executed after waiting for the stabilization time to pass, thereby suppressing false detection.

[0082] Furthermore, in the interconnected hot water system 1 of the present embodiment, the water leakage detection process is interrupted when the outflow-side temperature detected by the outflow-side temperature sensor 24 changes by a predetermined allowable value (1 degree) or more during the execution of the water leakage detection process despite the establishment of the temperature stabilization condition. Although the temperature of the hot water in the heating path is estimated to be stabilized due to the establishment of the temperature stabilization condition, if the outflow-side temperature sensor 24 confirms that the temperature is not yet stabilized, the pressure of the hot water in the heating path is affected by the temperature change, so it is possible to suppress false detection by interrupting the water leakage detection process being executed.

[0083] As mentioned above, the interconnected hot water system 1 of this embodiment has been described as a liquid heating device, but the present invention is not limited to the above-mentioned embodiment, and can be implemented in various forms within the scope not departing from the gist of the present invention.

[0084] For example, the temperature stabilization condition of the above-mentioned embodiment is set to "a prescribed stabilization time (90 minutes) has passed in a state where the hot water quantity servo 25 is completely closed and the flow of hot water in the heating path is stopped." However, the temperature stabilization condition is not limited to this, and any condition may be used as long as it is estimated that the temperature of the hot water in the heating path has dropped and stabilized. For example, instead of confirming that the hot water quantity servo 25 is completely closed, the stop of the flow of hot water in the heating path may be confirmed based on the detected flow rate in the flow sensor 21. In addition, the stabilization time of the present embodiment is set to 90 minutes based on natural heat dissipation. However, since the combustion fan 13 continues to blow air after the combustion in the burner 12 is stopped (so-called post-purge), the temperature of the hot water in the heating path (mainly the heat exchanger 18) is promoted to drop by forced cooling, the stabilization time may be shortened (for example, set to 10 minutes).

[0085] In addition, "the outflow side temperature detected by the outflow side temperature sensor 24 drops to a predetermined temperature" may be set as a temperature stabilization condition, and the predetermined temperature may be set based on the outside temperature. Alternatively, "the amount of change in the outflow side temperature detected by the outflow side temperature sensor 24 at a certain period (for example, every 5 minutes) is less than a predetermined value (for example, 1 degree)" may be set as a temperature stabilization condition.

[0086] In addition, in the above-mentioned embodiment, as an example of a liquid heating device, a connected hot water system 1 in which two water heaters 10 are connected and have a circulating instant hot water function is described. However, the liquid heating device is not limited to this, and may be a single water heater 10, or may be a non-circulating type without an instant hot water function (a structure in which the water heater 10 starts heating as the hot water tap 5 is opened and hot water flows out) by omitting the circulating pipe 6 and the circulating pump 7. Of course, the liquid heating device is not limited to such a hot water system, and may be a heating system that circulates the heated liquid for heating. In this case, the heated liquid is not limited to hot water, and silicone oil or the like may be used.

[0087] Furthermore, in the above-mentioned embodiment, if Figure 1 As shown in FIG. 1 , the hot water outlet pipe 4 connected to the hot water system 1 is directly connected to the hot water valve 5. Figure 8As shown in FIG. 1 , a hot water storage tank 30 for storing hot water may be provided between the hot water outlet pipe 4 and the hot water tap 5. That is, the downstream side of the hot water outlet pipe 4 is connected to the hot water storage tank 30 to supply hot water, and the upstream side of the circulation pipe 6 is connected to the hot water storage tank 30 to return the hot water in the hot water storage tank 30 to the water supply pipe 3 by operating the circulation pump 7 to circulate, and the water is kept warm by heating by the water heater 10. In addition to this circulation, the upstream and downstream sides of the hot water supply circulation pipe 31 are connected to the hot water storage tank 30, and the hot water in the hot water storage tank 30 is circulated in the hot water supply circulation pipe 31 by operating the hot water supply circulation pump 32 provided in the hot water supply circulation pipe 31. Then, by connecting the hot water tap 5 to the hot water supply circulation pipe 31, the hot water in the hot water storage tank 30 can be immediately supplied once the hot water tap 5 is opened.

[0088] And, if Fig. 9 As shown, the downstream side of the hot water outlet pipe 4 may be connected to the upstream side of the circulation pipe 6 via the filter unit 40. That is, the filter unit 40 and the bath water circulation pump 43 are provided in the bath water circulation pipe 42 for circulating the hot water in the bathtub 41, and the hot water drawn from the bathtub 41 by the operation of the bath water circulation pump 43 is filtered by the filter unit 40 and then returned to the bathtub 41 again. At this time, the hot water supplied from the hot water outlet pipe 4 is returned to the water supply pipe 3 through the circulation pipe 6 via the filter unit 40 by the operation of the circulation pump 7, and is circulated and heated by the water heater 10. Thus, the hot water of the bathtub 41 circulating in the bath water circulation pipe 42 is reheated by liquid-liquid heat exchange through the filter unit 40 (so-called follow-up incineration).

[0089] Here, in the linked hot water system 1 of the above-mentioned embodiment, when the "slave" water heater 10 of the two linked water heaters 10 is in a standby state (a state in which the combustion of the burner 12 is stopped), the hot water quantity servo 25 and the bypass servo 27 are set to be completely closed. Figure 8 The type with hot water storage tank 30, Fig. 9 In the type with the filter unit 40, the heating amount (number of units) of the water heater 10 is sometimes predetermined according to the heat required by the hot water storage tank 30 and the filter unit 40, and the "master" water heater 10 and the "slave" water heater 10 are operated synchronously. In this case, even if the "slave" water heater 10 becomes a standby state, the hot water amount server 25 and the bypass server 27 are kept in the open state (the opening degree corresponding to the set temperature of the remote controller 8, the detected temperature of various temperature sensors, etc.) like the "master" water heater 10. Therefore, if the above-mentioned processing is applied to these types ( Figure 3 to Figure 7 ), it is necessary to start timing by the stabilization time standby timer and the preceding stabilization time standby timer ( Figure 4Before step 14), the hot water volume servo 25 and the bypass servo 27 are completely closed. Furthermore, it is assumed that when it is determined that there is no water leakage, the water volume servo 20 is opened ( Figure 5 Step 41, Figure 7 In step 57), the hot water quantity servo 25 and the bypass servo 27 are also turned on. In addition, in the case of a separate water heater 10, when a water leak is detected in the "main" water heater 10, the hot water quantity servo 25 and the bypass servo 27 are kept turned on in the standby state, so the same is true.

[0090] In addition, Figure 8 The type with hot water storage tank 30, Fig. 9 In the type equipped with the filter unit 40, it is desirable to execute the standby and water leakage detection processing until the temperature stabilization condition is satisfied between the connected water heaters 10 (if there are two water heaters, each of the "master" and "slave" water heaters, if there are three or more water heaters, each of the "master" and a plurality of "slave" water heaters) one by one so that the execution timing does not overlap. In this way, the number of water heaters 10 that cannot be used due to the complete shutdown of the hot water quantity server 25 can be limited to a minimum, so that the use of the system can be maintained by the remaining water heaters 10.

[0091] In the above-mentioned embodiment, the outflow side temperature sensor 24 detects the change of the outflow side temperature during the water leakage detection process after the temperature stabilization condition is satisfied ( Figure 5 However, such confirmation of the change in the outflow side temperature is not essential and may be omitted (see Figure 7 In this case, in the process of step 32, the outflow side temperature is not detected by the outflow side temperature sensor 24, but only the pressure of the hot water is detected by the pressure sensor 23. However, by confirming the change of the outflow side temperature as in the above-mentioned embodiment, the influence of the temperature change on the pressure of the hot water in the closed heating path can be eliminated, thereby improving the effect of suppressing the false detection of water leakage.

[0092] In addition, in the above-mentioned embodiment, the water quantity servo 20 is completely closed from the state where the hot water quantity servo 25 is completely closed first to seal the heating path. However, the order of completely closing the hot water quantity servo 25 and the water quantity servo 20 when sealing the heating path is not limited to this. For example, in the case of a single water heater 10 and a non-circulating type, as long as the hot water valve 5 is closed, the flow of hot water in the heating path is stopped even if the hot water quantity servo 25 is in the open state. Therefore, the stop of the flow of hot water is confirmed based on the flow detected by the flow sensor 21, and after the temperature stabilization condition is met according to the passage of the stabilization time, either the hot water quantity servo 25 or the water quantity servo 20 can be completely closed first, or both can be completely closed at approximately the same time.

[0093] In the above-mentioned embodiment, the position of the water supply pipe 3 upstream of the water volume server 20 is connected to the position of the hot water outlet pipe 4 downstream of the hot water volume server 25 by the bypass pipe 26. Figure 2 However, it is also possible to connect the position of the water supply pipe 3 on the downstream side of the water quantity server 20 and the position of the hot water outlet pipe 4 on the upstream side of the hot water quantity server 25 through the bypass pipe 26, and include the bypass pipe 26 in the heating path to be detected for water leakage. In this case, the mixing ratio of the hot water heated by the heat exchanger 18 and the hot water passing through the bypass pipe 26 can be changed by the opening degree of the bypass server 27. In addition, as the hot water quantity server 25 is completely closed, the flow of hot water in the bypass pipe 26 is also stopped, so it is not necessary to completely close the bypass server 27 in conjunction with the complete closing of the hot water quantity server 25.

[0094] In addition, in the above-mentioned embodiment, the controller 29 of the "master" water heater 10 gives instructions to the controller 29 of the "slave" water heater 10. However, it is also possible to have a system controller (not shown) for controlling the entire connected hot water system 1, and to connect the remote control 8 and the controllers 29 of each water heater 10 to the system controller in a manner that allows for wired or wireless communication, and to electrically connect the circulating pump 7. Moreover, it is also possible to have the following structure: the system controller controls the operation of the circulating pump 7, and allocates the master-slave relationship of multiple water heaters 10, or gives operation instructions to the controller 29 of each water heater 10. In this case, if the controller 29 in the "slave" water heater 10 determines that there is a water leak ( Figure 6 In step 46), the water leakage notification (step 47) can be carried out by displaying it on the display unit 8b of the remote controller 8 through the system controller.

[0095] Description of Reference Numerals

[0096] 1: Connect to hot water system; 2: Gas piping; 3: Water supply piping; 4: Hot water outlet piping; 5: Hot water faucet; 6: Circulation piping; 7: Circulation pump; 8: Remote controller; 8a: Operation unit; 8b: Display unit; 10: Water heater; 11: Combustion chamber; 12: Burner; 13: Combustion fan; 14: Main valve; 15: Proportional valve; 16: Spark plug; 17: Flame rod; 18: Heat exchanger; 19: Exhaust port; 20: Water volume server; 2 1: Flow sensor; 22: Inflow side temperature sensor; 23: Pressure sensor; 24: Outflow side temperature sensor; 25: Hot water quantity server; 26: Bypass piping; 27: Bypass server; 28: Hot water supply temperature sensor; 29: Controller; 30: Hot water storage tank; 31: Hot water supply circulation piping; 32: Hot water supply circulation pump; 40: Filter unit; 41: Bathtub; 42: Bath water circulation piping; 43: Bath water circulation pump.

Claims

1. A liquid heating device having a heating path, in which liquid flowing in from upstream is heated by a heating unit and then flows out to downstream, the liquid heating device being characterized by comprising: an inflow-side opening and closing valve that opens and closes the inflow side of the heating path; an outflow-side opening and closing valve that opens and closes the outflow side of the heating path; a pressure sensor disposed between the inflow-side on-off valve and the outflow-side on-off valve on the heating path and capable of detecting the pressure of the liquid; and a control unit for controlling execution of a liquid leakage detection process in which, after the heating path is sealed by closing the outflow-side on-off valve and the inflow-side on-off valve, liquid leakage in the heating path is detected based on a decrease in a detection pressure of the pressure sensor, in, The control unit executes the liquid leakage detection process after a predetermined temperature stabilization condition is satisfied, in which it is estimated that the temperature of the liquid in the heating path has dropped and stabilized.

2. The liquid heating device according to claim 1, characterized in that: In the heating unit, when the flow rate of the liquid in the heating path is less than a predetermined flow rate, heating is stopped. The temperature stabilization condition is that a predetermined stabilization time has elapsed in a state where the flow of the liquid in the heating path is stopped.

3. The liquid heating device according to claim 2, characterized in that: The temperature stabilization condition is that the stabilization time has elapsed in a state where the flow of the liquid in the heating path is stopped due to the closing of the outflow-side on-off valve.

4. The liquid heating device according to claim 2 or 3, characterized in that: When the flow of the liquid in the heating path stops for a prescribed pre-stabilization time shorter than the stabilization time, the control unit executes the liquid leakage detection process in advance. If no liquid leakage in the heating path is detected, the liquid leakage detection process after the stabilization time is omitted. Conversely, when there is a possibility of liquid leakage in the heating path, the sealing of the heating path is temporarily released and the liquid leakage detection process is re-executed after the stabilization time has passed.

5. The liquid heating device according to any one of claims 1 to 3, characterized in that: further comprising a temperature sensor capable of detecting the temperature of the liquid in the heating path, The control unit interrupts the liquid leakage detection process when the temperature detected by the temperature sensor varies by a predetermined allowable value or more during the execution of the liquid leakage detection process despite the satisfaction of the temperature stabilization condition.

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