JP5107759B2 - Hot water storage hot water supply system - Google Patents

Description

  The present invention relates to a hot water storage type hot water supply system.

  The hot water storage type hot water supply system stores heated hot water in a hot water storage tank, and supplies hot water stored in the hot water storage tank as needed. The hot water storage type hot water supply system is employed in, for example, a cogeneration system that uses generated heat generated by power generation as a heat source for hot water supply. Some hot water storage systems use hot water stored in hot water storage tanks as a heat source not only for hot water supply but also for heating and bathing. In such a hot water storage type hot water supply system, high temperature hot water is sent out from the upper part of the hot water storage tank, and the hot water and the heat medium are exchanged in the heat exchanger to return the low temperature hot water to the lower part of the hot water storage tank. Since the hot water stored in the hot water tank is used as it is for hot water supply, it must be kept clean.

  The heat exchanger through which hot water stored in the hot water tank circulates is damaged, and the space between the water side path through which hot water from the hot water tank passes and the heat medium side path through which the heating medium for heating and bathing passes passes. There may be a hole in the partition wall. Even if there is a hole in the partition between the water side path and the heat medium side path in the heat exchanger, if the water pressure in the water side path is maintained, the heat medium in the heat medium side path will enter the water side path. There is no end to it. However, when the water supply pressure to the hot water storage tank decreases due to water breakage or the like, the water pressure in the water side path of the heat exchanger also decreases, and the heat medium in the heat medium side path may enter the water side path. Since the hot water in the water-side path is then returned to the hot water storage tank, the hot water stored in the hot water storage tank may be contaminated.

  Patent Document 1 discloses a technique for preventing contamination of hot water in a hot water tank when a heat exchanger is damaged. In the technique of Patent Document 1, on-off valves are provided on the upstream side and the downstream side of the heat exchanger that circulates hot water between the hot water tanks, and the on-off valve on the upstream side and the on-off valve on the downstream side are closed when water is shut off. Separate the water-side path of the heat exchanger from the hot water tank. This prevents contamination of hot water stored in the hot water tank.

JP 2004-53054 A

  The technique of Patent Document 1 can prevent the hot water stored in the hot water tank from being contaminated, but the hot water existing between the upstream side open / close valve and the downstream side open / close valve is contaminated and the upstream side open / closed valve is opened. The piping between the valve and the downstream on-off valve becomes dirty. In this case, when the hot water supply system is restored, it is not enough to repair the heat exchanger, and the piping that has become dirty due to the infiltration of the heat medium must also be cleaned. If not only the contamination of the hot water stored in the hot water tank is prevented, but also the heat medium in the heat exchanger can be prevented from entering the water side path, the piping between the hot water tank and the heat exchanger will be It won't get dirty. In this case, when the hot water supply system is restored, it is only necessary to repair the heat exchanger. A technique for preventing the heat medium from entering from the heat medium side path to the water side path in the heat exchanger is awaited.

  The present invention solves the above problems. The present invention provides a technology capable of preventing the heat medium from entering the water-side path even when the heat exchanger that circulates hot water between the hot water storage tanks is damaged in the hot water storage hot water supply system. To do.

  The present invention is embodied as a hot water storage type hot water supply system. The hot water storage hot water system includes a hot water storage tank, a water supply path for supplying water to the hot water storage tank, a hot water supply path for supplying hot water from the hot water storage tank, a water side path through which water passes, and a heat medium side path through which the heat medium passes. A heat exchanger that exchanges heat between water in the water side path and a heat medium in the heat medium side path, a heat exchanger circuit that circulates water between the hot water storage tank and the heat exchanger, and heat in the heat exchanger circuit A circulation pump provided upstream of the exchanger, an on-off valve provided downstream of the heat exchanger in the heat exchanger circulation path, and detection means for detecting a decrease in water supply pressure in the water supply path are provided. In the hot water storage type hot water supply system, when the detecting means detects a decrease in the water supply pressure, the open / close valve is closed to drive the circulation pump.

  In the hot water storage type hot water supply system described above, when a decrease in water supply pressure in the water supply path is detected, the circulation pump is driven with the on-off valve closed. As a result, the water pressure in the water-side path of the heat exchanger existing between the circulation pump and the on-off valve is kept high, and the infiltration of the heat medium from the heat-medium side path can be prevented. It is possible to prevent the water in the hot water tank from being contaminated. Moreover, since the penetration of the heat medium into the heat exchanger circuit is prevented, it is possible to prevent the piping of the heat exchanger circuit from being contaminated by the heat medium.

  The hot water storage type hot water supply system further includes a second on-off valve provided between the circulation pump and the heat exchanger, and when the detecting means detects a decrease in the water supply pressure, the on-off valve is closed to turn off the circulation pump. After driving, it is preferable to close the second on-off valve and stop the circulation pump.

  In the hot water storage hot water system described above, the water pressure in the water side path of the heat exchanger is increased by driving the circulation pump, and then the water in the water side path of the heat exchanger is increased by closing the second on-off valve. Seal as it is. Without continuing to drive the circulation pump, the water in the water side path of the heat exchanger can be maintained at a high pressure to prevent the heat medium from entering from the heat medium side path.

  Another hot water storage type hot water supply system of the present invention includes a hot water storage tank, a water supply path for supplying water to the hot water storage tank, a hot water supply path for supplying hot water from the hot water storage tank, a water side path through which water passes, and a heat medium through which a heat medium passes. A heat exchanger that exchanges heat between the water in the water path and the heat medium in the heat medium side path, a heat exchanger circuit that circulates water between the hot water tank and the heat exchanger, and a hot water storage A heat source device for heating the water in the tank, a water supply valve provided in the water supply path, a hot water supply valve provided in the hot water supply path, and detection means for detecting a decrease in the water supply pressure in the water supply path are provided. In the hot water storage type hot water supply system, when the detecting means detects a decrease in the water supply pressure, the water supply valve and the hot water supply valve are closed to drive the heat source machine.

  In the hot water storage type hot water supply system, when a decrease in the water supply pressure in the water supply path is detected, the heat source device is driven with the water supply valve and the hot water supply valve closed. Thereby, the temperature of the water in the hot water tank rises, and the pressure of the water in the hot water tank, the heat exchanger circuit, and the water side path of the heat exchanger rises. The water pressure in the water-side path of the heat exchanger is maintained high, and the heat medium can be prevented from entering from the heat-medium side path. It is possible to prevent the water in the hot water tank from being contaminated. Moreover, since the penetration of the heat medium into the heat exchanger circuit is prevented, it is possible to prevent the piping of the heat exchanger circuit from being contaminated by the heat medium.

  According to the hot water storage type hot water supply system of the present invention, even when the heat exchanger that circulates hot water between the hot water storage tanks is damaged, the heat medium can be prevented from entering the water side path.

Hereinafter, preferred embodiments of the present invention will be described.
(Mode 1) A hot water storage hot water supply system is incorporated in a cogeneration system.

  An embodiment embodying the present invention will be described with reference to the drawings. As shown in FIG. 1, the cogeneration system 2 of this embodiment includes a power generation unit 150, a hot water supply unit 10, and a thermal load 108.

  The power generation unit 150 includes a fuel cell (not shown), a reformer (not shown), a heat medium circulation path 152, and a heat recovery heat exchanger 154. The fuel cell generates power by reacting hydrogen gas generated in the reformer with oxygen in the air. Generated heat is generated along with power generation, and the heat medium in the heat medium circulation path 152 is heated by the generated heat. The heat medium heated by the generated heat passes through the heat medium side path of the heat recovery heat exchanger 154 and is cooled.

  The hot water supply unit 10 includes a hot water storage unit 12, a burner unit 68, a heating heat exchanger 114, a bath heat exchanger 124, various flow paths, a controller 146, and the like.

  The controller 146 stores a control program. The controller 146 receives operation signals from the remote controller 148, detection signals from various flow sensors described below, detection signals from various thermistors, and the like. The remote controller 148 is disposed in a bathroom, a washroom, a kitchen, and the like. The controller 146 processes the input signal with a control program, and controls various pumps, various valves, a burner, and the like described below.

  The hot water storage section 12 includes a hot water storage tank 14, a tank upper thermistor 15, a first tank thermistor 16, a second tank thermistor 18, a third tank thermistor 20, and a fourth tank thermistor 22. The hot water storage tank 14 is a sealed container that can store hot water therein. The tank upper thermistor 15 is inserted into the hot water storage tank 14 from the top, and directly detects the temperature of hot water at a position of 5 liters from the hot water storage tank 14. The 1st tank thermistor 16, the 2nd tank thermistor 18, the 3rd tank thermistor 20, and the 4th tank thermistor 22 are provided in the outer wall surface of the hot water storage tank 14, respectively, 45 liters, 85 liters, 125 from the top part of a hot water tank. The temperature of hot water at the position of liters and 165 liters is detected. Detection signals from the tank upper thermistor 15, the first tank thermistor 16, the second tank thermistor 18, the third tank thermistor 20, and the fourth tank thermistor 22 are output to the controller 146.

  A water supply path 24 for supplying tap water to the hot water storage tank 14 is connected to the bottom of the hot water storage tank 14. A pressure reducing valve 26, a water supply thermistor 28, a water supply amount sensor 30, a water supply amount servo 32, a mixing servo 34, and a pressure switch 33 are interposed in the water supply path 24. The pressure reducing valve 26 is disposed in the vicinity of the upstream end of the water supply path 24. The pressure reducing valve 26 adjusts the feed water pressure. When the pressure on the downstream side of the pressure reducing valve 26 decreases, the pressure reducing valve 26 opens and tries to maintain the pressure at a predetermined pressure regulation value. For this reason, when the hot water in the hot water storage tank 14 decreases or the mixing servo 34 described later opens, tap water is supplied by the action of the pressure reducing valve 26. The water supply thermistor 28 detects the temperature of the tap water supplied. The water supply amount sensor 30 detects the flow rate of tap water supplied. The detection signal of the water supply thermistor 28 and the detection signal of the water supply amount sensor 30 are output to the controller 146. Each of the water supply amount servo 32 and the mixing servo 34 has a built-in stepping motor, and when this is driven, the opening degree is adjusted to change the flow rate. The water supply amount servo 32 adjusts the flow rate of the tap water supplied. The opening degree of the water supply servo 32 is controlled by the controller 146. The mixing servo 34 is disposed at a connection portion between the water supply path 24 and the mixing path 36. The mixing servo 34 will be described in detail later. The pressure switch 33 is provided between the water supply amount servo 32 and the mixing servo 34 in the water supply path 24 and outputs an ON signal when the water pressure is equal to or higher than the specified pressure, and outputs an OFF signal when the water pressure falls below the specified pressure. Output. An output signal of the pressure switch 33 is output to the controller 146.

  A drainage path 38 is connected to the downstream side of the mixing servo 34 in the water supply path 24. The other end of the drainage path 38 is connected to the pressure release path 42. The pressure release path 42 is open to the outside of the cogeneration system. A drain valve 40 is interposed in the drain path 38. The drain valve 40 is manually opened and closed. When the drain valve 40 is opened, the hot water in the hot water storage tank 14 is drained through the drain path 38 and the pressure release path 42.

  A hot water supply path 46 for supplying hot water in the hot water storage tank 14 to the hot water tap 44 is connected to the top of the hot water storage tank 14. The hot-water tap 44 is disposed in a bathroom, a washroom, a kitchen, or the like. In the hot water supply path 46, a pressure relief valve 48, a hot water solenoid valve 50, a high temperature thermistor 52, and a hot water supply thermistor 54 are interposed. The hot water supply path 46 is connected to the mixing path 36 described above. The mixing path 36 is downstream of the hot water solenoid valve 50 and is connected between the high temperature thermistor 52 and the hot water supply thermistor 54.

  The pressure relief valve 48 is connected to the pressure release path 42. Hot water solenoid valve 50 is opened when hot water supply is started and closed when hot water supply is completed. Whether or not hot water supply has been started is determined by the controller 146 based on the flow rate detected by the water supply amount sensor 30. The high temperature thermistor 52 detects the temperature of the hot water sent out from the hot water storage tank 14. The hot water supply thermistor 54 detects the temperature of the mixed water of the hot water from the hot water supply path 46 and the tap water from the mixing path 36. Detection signals from the high temperature thermistor 52 and the hot water supply thermistor 54 are output to the controller 146. The mixing ratio of the hot water from the hot water supply path 46 and the tap water from the mixing path 36 is adjusted by the opening degree of the mixing servo 34. The hot water supply temperature can be adjusted by adjusting the opening of the mixing servo 34. The opening degree of the mixing servo 34 is instructed by the controller 146 based on the detected temperature of the water supply thermistor 28 and the detected temperature of the hot water supply thermistor 54.

  The hot water storage tank 14 and the power generation unit 150 are connected by a heat recovery circulation path 56. The heat recovery circulation path 56 is disposed so as to pass through the water side path of the heat recovery heat exchanger 154. In the heat recovery circulation path 56, a path from the hot water storage tank 14 to the heat recovery heat exchanger 154 is a heat recovery circulation forward path 56a, and a path from the heat recovery heat exchanger 154 to the hot water storage tank 14 is a heat recovery circulation return path 56b. It is.

  The heat recovery circulation forward path 56 a connects the bottom of the hot water storage tank 14 and the upstream end of the heat recovery heat exchanger 154. A heat recovery circulation pump 58 and a circulation outward path thermistor 60 are interposed in the heat recovery circulation path 56a. The heat recovery circulation pump 58 circulates hot water in the heat recovery circulation path 56. The heat recovery circulation pump 58 is driven during the power generation operation or during the freeze prevention operation of the hot water in the heat recovery circulation path 56. The drive of the heat recovery circulation pump 58 is controlled by the controller 146. The circulation outward thermistor 60 is disposed in the vicinity of the hot water storage tank 14 and detects the temperature of the hot water delivered from the hot water storage tank 14. A detection signal from the circulation forward thermistor 60 is output to the controller 146.

  The heat recovery circulation return path 56 b connects the downstream end of the heat recovery heat exchanger 154 and the top of the hot water storage tank 14. A circulation return thermistor 62 and a heat recovery three-way valve 64 are interposed in the heat recovery circulation return path 56b. The circulation return thermistor 62 is disposed upstream of the heat recovery three-way valve 64 and detects the temperature of the hot water after passing through the heat recovery heat exchanger 154. A detection signal of the circulation return thermistor 62 is output to the controller 146. The heat recovery three-way valve 64 has an inlet 64a and two outlets 64b and 64c. The upstream portion of the heat recovery circulation return path 56b is connected to the inlet 64a, and the downstream portion of the heat recovery circulation return path 56b is connected to the outlet 64c. One end of a tank bypass path 66 is connected to the outlet 64 b of the heat recovery three-way valve 64. The other end of the tank bypass path 66 is connected to the middle of the heat recovery circulation path 56a. When the inlet 64a and the outlet 64c of the heat recovery three-way valve 64 communicate with each other, a circulation path is formed through the power generation unit 150 and the hot water storage tank 14, and when the inlet 64a and the outlet 64b of the heat recovery three-way valve 64 communicate with each other, the power generation unit 150 is connected. A circulation path that bypasses the hot water storage tank 14 is formed. Switching of the heat recovery three-way valve 64 is controlled by the controller 146.

  The burner unit 68 includes a burner 70, a latent heat exchanger 72, and a sensible heat exchanger 74. The burner 70 burns using gas as fuel. The hot water in the latent heat exchanger 72 is preheated by the heat of the combustion exhaust gas generated in the burner 70. At this time, due to the temperature drop of the combustion exhaust gas, water vapor in the combustion exhaust gas is condensed, and acidic drain in which nitrogen oxides are dissolved is generated. The hot water preheated by the latent heat exchanger 72 is reheated by the combustion heat of the burner 70 by the sensible heat exchanger 74.

  A drain path 92 for discharging or collecting the drain is connected to the latent heat exchanger 72. The drain path 92 is connected to the pressure release path 42. A neutralizer 94 is interposed in the drain path 92. The neutralizer 94 is filled with calcium carbonate. The acidic drain is neutralized to pH 6 to 7 by calcium carbonate while passing through the neutralizer 94. An overflow path 98 is connected to the drain path 92 on the downstream side of the neutralizer 94. The other end of the overflow path 98 is connected to the cistern 100, and when the hot water in the cistern 100 exceeds a predetermined water level, the hot water corresponding to the predetermined water level is discharged from the cistern 100.

  The hot water storage tank 14 and the burner unit 68 are connected by a burner circulation path 76. The burner circulation path 76 is disposed so as to pass through the latent heat exchanger 72 and the sensible heat exchanger 74 in the burner section 68 in order. In the burner circulation path 76, the path from the hot water storage tank 14 to the burner section 68 is a burner circulation forward path 76a, and the path from the burner section 68 to the hot water storage tank 14 is a burner circulation return path 76b.

  The burner circulation outward path 76 a includes a first burner circulation outward path 77 connected to an intermediate part of the hot water storage tank 14 (intermediate between the tank upper thermistor 15 and the first tank thermistor 16), and a water supply path 24 communicating with the lower part of the hot water storage tank 14. A second burner circulation forward path 79 to be connected, and a burner circulation three-way valve 78 provided at a location where the first burner circulation forward path 77 and the second burner circulation forward path 79 join are provided. The burner circulation three-way valve 78 has two inlets 78a and 78b and an outlet 78c. One end of a second burner circulation forward path 79 is connected to the inlet 78 a of the burner circulation three-way valve 78. One end of the first burner circulation forward path 77 is connected to the inlet 78 b of the burner circulation three-way valve 78. An outlet 78 c of the burner circulation three-way valve 78 communicates with the upstream end of the latent heat exchanger 72. When the inlet 78a and the outlet 78c of the burner circulation three-way valve 78 communicate with each other, a path from the lower part of the hot water storage tank 14 toward the burner portion 68 is formed, and when the inlet 78b and the outlet 78c of the burner circulation three-way valve 78 communicate with each other, A path from the intermediate portion toward the burner portion 68 is formed. Switching of the burner circulation three-way valve 78 is controlled by the controller 146.

  A burner circulation pump 80, a burner circulation water amount sensor 82, a burner circulation water amount servo 84, and a burner inlet thermistor 83 are provided downstream of the burner circulation outward passage 76a from the burner circulation three-way valve 78. The burner circulation pump 80 circulates hot water in the burner circulation path 76. The drive of the burner circulation pump 80 is controlled by the controller 146. The burner circulation water amount sensor 82 detects the flow rate of hot water in the burner circulation path 76. A detection signal of the burner circulating water amount sensor 82 is output to the controller 146. The burner circulating water amount servo 84 has a built-in stepping motor, and when this is driven, the opening degree is adjusted to change the flow rate. The burner circulation water amount servo 84 adjusts the flow rate of hot water in the burner circulation path 76. The opening degree of the burner circulation water amount servo 84 is controlled by the controller 146. The burner inlet thermistor 83 detects the temperature of hot water flowing into the burner section 68. A detection signal from the burner inlet thermistor 83 is output to the controller 146.

  A burner outlet thermistor 88 is interposed in the vicinity of the outlet of the burner portion 68 of the burner circulation return path 76b. The burner outlet thermistor 88 detects the temperature of the hot water after passing through the burner portion 68. The burner circulation return path 76 b is branched downstream of the burner outlet thermistor 88 into a heating bypass path 172 and a heating heat exchange path 174. The heating bypass path 172 is connected to the top of the hot water storage tank 14. The heating heat exchange path 174 joins the heating bypass path 172 via the water side path of the heating heat exchanger 114. A heat exchanger outlet thermistor 90 is interposed in the heating heat exchange path 174. The heat exchanger outlet thermistor 90 is disposed downstream of the heating heat exchanger 114 and detects the temperature of the hot water after passing through the heating heat exchanger 114. The detection signal from the burner outlet thermistor 88 and the detection signal from the heat exchanger outlet thermistor 90 are output to the controller 146.

  One end of the second tank bypass path 166 is connected downstream of the heat exchanger outlet thermistor 90 in the heating heat exchange path 174. The other end of the second tank bypass path 166 is connected between the burner circulation three-way valve 78 and the burner circulation pump 80 in the burner circulation forward path 76a.

  One end of the second burner circulation return path 168 is connected downstream of the heat exchanger outlet thermistor 90 in the heating heat exchange path 174. The other end of the second burner circulation return path 168 is connected to the lower part of the hot water storage tank 14.

  A first control valve 170 is provided in the heating bypass path 172. A second control valve 160 is provided downstream of the connection point of the second burner circulation return path 168 and the second tank bypass path 166 of the heating heat exchange path 174. A third control valve 162 is provided in the second tank bypass path 166. A fourth control valve 164 is provided in the second burner circulation return path 168. The controller 146 controls opening and closing of the first control valve 170, the second control valve 160, the third control valve 162, and the fourth control valve 164. The hot water circulates in the burner circulation path 76 by driving the burner circulation pump 80 with any of the first control valve 170, the second control valve 160, the third control valve 162, and the fourth control valve 164 opened. .

  From the hot water supply path 46, a systern water supply path 102 branches off. A negative pressure valve 104 and a cistern water supply valve 106 are interposed in the cistern water supply path 102. The negative pressure valve 104 is opened when the water supply path 24 becomes negative pressure due to a water interruption or the like, and sucks the air to prevent the hot water storage tank 14 from being damaged due to the negative pressure. The cistern water supply valve 106 is opened when hot water from the hot water storage tank 14 is supplied to the cistern 100. The water level of the hot water in the cistern 100 is monitored by a water level sensor (not shown). When the water level of the hot water in the cistern 100 is within a predetermined water level range, the cistern water supply valve 106 is closed. When it is determined that the water level has deviated from the predetermined water level range, the cistern water supply valve 106 is opened. Opening and closing of the cistern water supply valve 106 is controlled by the controller 146. The hot water in the cistern 100 is used as a heating medium for heating and bathing.

  In this embodiment, the thermal load 108 includes a heating device, a bath device, and a hot water supply device. As a terminal of the heating device, it has an air conditioner and a floor heater. In FIG. 1, an air conditioner and a floor heater are shown as a heating terminal 110. The systern 100 and the heating terminal 110 are connected by a heating circulation path 112. In the heating circulation path 112, a path from the systern 100 to the heating terminal 110 is a heating circulation forward path 112a, and a path from the heating terminal 110 to the systern 100 is a heating circulation return path 112b. The heating circulation forward path 112 a is disposed so as to pass through the heat medium side path of the heating heat exchanger 114. A heating circulation pump 116 and a heating circulation thermistor 118 are interposed in the heating circulation forward path 112a. The heating circulation pump 116 circulates the heat medium (hot water in the cistern 100) in the heating circulation path 112. The heating circulation pump 116 is driven in accordance with the operation of the switch of the remote controller 148. The driving of the heating circulation pump 116 is controlled by the controller 146. The heating circulation thermistor 118 is arranged on the downstream side of the heating heat exchanger 114 and detects the temperature of the heat medium after passing through the heating heat exchanger 114. A detection signal from the heating circulation thermistor 118 is output to the controller 146. A heating thermal valve 120 is interposed in the heating circulation path 112 in the heating terminal 110. The heating / heat valve 120 opens and closes according to the operation of the switch of the remote controller 148. The controller 146 controls the opening / closing of the heating / thermal valve 120.

  On the downstream side of the heating circulation path 112a, the reheating path 122 branches off from the downstream side of the heating circulation thermistor 118. The downstream end of the tracking path 122 is connected to the vicinity of the cistern 100 of the heating circulation return path 112b. The chasing path 122 is arranged so as to pass through the bath heat exchanger 124. The heat of the heating medium in the heating circulation path 112a is input to the bath heat exchanger 124. A tracking heat valve 126 is interposed in the tracking path 122. The reheating heat valve 126 opens and closes when the bath reheating switch is operated. Opening and closing of the reheating heat valve 126 is controlled by the controller 146.

  A bath circulation path 130 is connected to the bath tub 128. The bath circulation path 130 is disposed so as to pass through the bath heat exchanger 124. In the bath circulation path 130, a path from the bathtub 128 to the bath heat exchanger 124 is a bath circulation forward path 130a, and a path from the bath heat exchanger 124 to the bathtub 128 is a bath circulation return path 130b. A bath water level sensor 132, a bath circulation pump 134, a bath water flow switch 136, and a bath circulation thermistor 138 are interposed in the bath circulation outward path 130a. The bath water level sensor 132 detects the water pressure of the hot water in the bath circulation path 130. A detection signal of the bath water level sensor 132 is output to the controller 146. The water pressure detected by the bath water level sensor 132 is used to estimate the hot water level in the bathtub 128. The bath circulation pump 134 circulates hot water in the bath circulation path 130. The bath circulation pump 134 is driven in accordance with the operation of the switch of the remote controller 148. The driving of the bath circulation pump 134 is controlled by the controller 146. The bath water flow switch 136 is turned on when hot water flows in the bath circulation path 130. An on / off signal of the bath water flow switch 136 is output to the controller 146. The bath circulation thermistor 138 is arranged on the upstream side of the bath heat exchanger 124 and detects the temperature of warm water entering the bath heat exchanger 124. A detection signal from the bath circulation thermistor 138 is output to the controller 146.

  The hot water supply path 46 and the bath circulation path 130 are connected by a hot water supply path 140. The upstream end of the hot water supply route 140 is connected to the downstream side of the hot water supply thermistor 54 of the hot water supply route 46, and the downstream end of the hot water supply route 140 is a bath circulation pump 134 and a bath water flow switch of the bath circulation outward route 130 a of the bath circulation route 130. 136. A hot water filling amount sensor 142 and a pouring electromagnetic valve 144 are interposed in the hot water filling route 140. The hot water filling amount sensor 142 detects the flow rate of hot water passing through the hot water filling route 140. The detection signal of the hot water filling amount sensor 142 is output to the controller 146. The hot water solenoid valve 144 is opened and closed by operating the switch of the remote controller 148 or the level of hot water in the bathtub 128. Opening and closing of the pouring solenoid valve 144 is controlled by the controller 146.

  Hereinafter, various operations such as a power generation heat recovery operation, a hot water supply operation, a heating operation, a bath hot water operation, a bath reheating operation, a first protection operation, and a second protection operation performed by the hot water supply unit 10 will be described.

(Generation heat recovery operation)
An outline of the power generation heat recovery operation will be described. When the power generation operation is performed in the power generation unit 150, the heat medium in the heat medium circulation path 152 circulates, and the high-temperature heat medium flows into the heat medium side path of the heat exchanger for heat recovery 154. In the hot water supply unit 10, the heat recovery circulation pump 58 is driven, and the hot water in the hot water storage tank 14 is sucked out from the bottom of the hot water storage tank 14 to the heat recovery circulation forward path 56a. The hot water in the heat recovery circulation path 56a flows into the water side path of the heat recovery heat exchanger 154 and is heated. The heated hot water is returned to the top of the hot water storage tank 14 through the heat recovery circulation return path 56b. As a result, the generated heat generated by the power generation in the power generation unit 150 is collected into the hot water storage tank 14 and stored.

(Hot water operation)
An outline of the hot water supply operation will be described. When the hot-water tap 44 is opened and the amount of water detected by the water supply amount sensor 30 is 2.7 liters / min or more, it is determined that a hot water supply request has been made and the hot water supply operation is started. The hot water solenoid valve 50 is opened and the hot water in the upper part of the hot water storage tank 14 is sent to the hot water supply path 46. The opening degree of the mixing servo 34 is adjusted so that the detected temperature of the hot water supply thermistor 54 becomes the hot water supply set temperature. As a result, the hot water sent from the upper part of the hot water storage tank 14 to the hot water supply path 46 is adjusted to a hot water supply set temperature by mixing with tap water and supplied to the hot water tap 44.

  When the detected temperature of the tank upper thermistor 15 is high, hot water can be supplied at a hot water supply set temperature without heating the hot water in the hot water storage tank 14. In this case, a non-combustion hot water supply operation is performed. In the non-combustion hot water supply operation, hot water in the upper part of the hot water storage tank 14 is supplied without circulating heat. That is, in the non-combustion hot water supply operation, the burner 70 is not burned and the burner circulation pump 80 is not driven.

  When the detected temperature of the tank upper thermistor 15 is low, it is considered that the hot water in the hot water storage tank 14 needs to be heated in order to supply hot water at the hot water supply set temperature. In this case, a combustion hot water supply operation is performed. In the combustion hot water supply operation, the hot water in the upper part of the hot water storage tank 14 is circulated and heated in parallel with the hot water supply to the hot water tap 44. The first control valve 170 is opened, the burner circulation pump 80 is driven, and the burner 70 is burned to circulate and heat the hot water in the upper part of the hot water storage tank 14.

  When the detected flow rate of the water supply amount sensor 30 becomes 2.0 liter / min or less during hot water supply, it is determined that the hot water tap 44 is closed. When the combustion hot water supply operation is performed, the burner 70 is extinguished and the burner circulation pump 80 is stopped. Thereafter, the hot water solenoid valve 50 is closed to end the hot water supply operation.

(Heating operation)
An outline of the heating operation will be described. When an operation request for the heating terminal 110 is made by operating a switch of the remote controller 148, the burner circulation pump 80 is driven and hot water is sent to the burner unit 68. The hot water sent to the burner unit 68 is heated as necessary, and sent to the water-side path of the heating heat exchanger 114. The hot water cooled by heat exchange in the heating heat exchanger 114 may be returned to the upper part of the hot water storage tank 14 by opening the second control valve 160 according to the temperature detected by the heat exchanger outlet thermistor 90. The fourth control valve 164 may be opened and returned to the lower part of the hot water storage tank 14, or the third control valve 162 may be opened to bypass the hot water storage tank 14 and returned to the burner unit 68.

  Further, the heating heat valve 120 of the heating terminal 110 is opened, the heating circulation pump 116 is driven, and the heat medium in the cistern 100 is sent out to the heat medium side path of the heating heat exchanger 114. The heat medium heated by heat exchange in the heating heat exchanger 114 is used for heating in the heating terminal 110. The heat medium that has passed through the heating terminal 110 returns to the cistern 100.

  When the operation stop of the heating terminal 110 is requested by operating the switch of the remote controller 148, the burner 70 is extinguished if it is burning, the burner circulation pump 80 is stopped, the heating thermal valve 120 is closed, and the heating circulation is performed. The pump 116 is stopped and the heating operation is finished.

(Bath bathing operation)
An outline of bathing operation of a bath will be described. When a bath filling request is made by operating the switch of the remote controller 148, the hot water solenoid valve 144 is opened and the hot water solenoid valve 50 is opened. Thereafter, similarly to the hot water supply operation, hot water having a hot water filling set temperature is supplied into the bathtub 128 through the hot water supply passage 46, the hot water filling passage 140, and the bath circulation passage 130.

  When the integrated flow rate of the hot water filling amount sensor 142 from the start of hot water filling reaches the hot water filling set water amount, the hot water electromagnetic valve 144 is closed and the hot water electromagnetic valve 50 is closed, and the hot water filling operation is completed.

(Bath bathing operation)
The outline of the bath chasing operation will be described. When there is a bath renewal request by operating the switch of the remote controller 148, the burner circulation pump 80 is driven and hot water is sent to the burner unit 68. The hot water sent to the burner unit 68 is heated as necessary, and sent to the water-side path of the heating heat exchanger 114. The hot water cooled by heat exchange in the heating heat exchanger 114 may be returned to the upper part of the hot water storage tank 14 by opening the second control valve 160 according to the temperature detected by the heat exchanger outlet thermistor 90. The fourth control valve 164 may be opened and returned to the lower part of the hot water storage tank 14, or the third control valve 162 may be opened to bypass the hot water storage tank 14 and returned to the burner unit 68.

  Further, the reheating heat valve 126 is opened, the heating circulation pump 116 is driven, and the heat medium in the cistern 100 is sent out to the heat medium side path of the heat exchanger 114 for heating. The heat medium heated by the heat exchange in the heating heat exchanger 114 is sent to the bath heat exchanger 124. The heat medium cooled by heat exchange in the bath heat exchanger 124 is returned to the cistern 100.

  Further, the bath circulation pump 134 is driven, and the hot water in the bathtub 128 passes through the bath heat exchanger 124 and is returned to the bathtub 128. The hot water sucked out of the bathtub 128 is heated by heat exchange in the bath heat exchanger 124 and returned to the bathtub 128.

  When the detected temperature of the bath circulation thermistor 138 reaches the reheating set temperature, the temperature of the hot water in the bathtub 128 is regarded as the reheating set temperature, and if the burner 70 is burning, the fire is extinguished and the burner circulation pump 80 is stopped. Then, the reheating heat valve 126 is closed, the heating circulation pump 116 is stopped, the bath circulation pump 134 is stopped, and the bath renewal operation is completed.

  In the present embodiment, the hot water in the hot water storage tank 14 is sent to the burner 70, and the hot medium heated in the burner 70 is returned to the hot water storage tank 14 by using the burner circulation path 76, so that the heat medium in the heating circulation path 112 is supplied. Can be heated. Further, the hot water in the bath circulation path 130 connected to the bathtub 128 can be heated using the bath retreat path 122 branched from the heating circulation path 112. Since one circulation path (burner circulation path 76) can be used in various ways, the system configuration can be simplified and the system can be made compact.

  In the present embodiment, the return destination of the hot water passing through the burner circulation return path 76 b can be switched according to the temperature detected by the heat exchanger outlet thermistor 90. Depending on the temperature detected by the heat exchanger outlet thermistor 90, the return destination of the hot water should be the upper part of the hot water storage tank 14, the lower part of the hot water storage tank 14, or the hot water storage tank 14 may be bypassed to become the burner circulation forward path 76a. Can do. By switching the return destination of the hot water in this way, the temperature stratification state formed in the hot water storage tank 14 is not destroyed.

(First protection operation)
The water supply pressure in the water supply path 24 may decrease due to water interruption or the like. When the water pressure in the water supply path 24 decreases, the water pressure in the hot water storage tank 14 decreases accordingly, and the water pressure in the burner circulation path 76 communicating with the hot water storage tank 14 also decreases. If there is a hole in the partition wall between the water side path and the heat medium side path of the heat exchanger 114 for heating, the water pressure in the water side path is reduced, so that the heat medium in the heat medium side path (that is, heating) Water from the cistern 100 used as a heating medium for driving and bathing operation) enters the water-side path, and the hot water in the water-side path is contaminated. When the hot water in the water-side path of the heating heat exchanger 114 is contaminated, the hot water in the hot water storage tank 14 is also contaminated, which may hinder subsequent hot water supply. Therefore, in the cogeneration system 2 of this embodiment, when the pressure switch 33 detects a decrease in the water supply pressure in the water supply path 24, either the first protection operation or the second protection operation is performed, and the hot water storage tank 14 is communicated. Contamination of hot water in the burner circulation path 76 is prevented. The user can select in advance either the first protection operation or the second protection operation by operating the remote controller 148.

  Hereinafter, the first protection operation will be described with reference to the flowchart of FIG.

  In step S202, the first control valve 170, the second control valve 160, the third control valve 162, and the fourth control valve 164 are all closed. In step S204, the burner circulating water amount servo 84 is fully opened. In step S206, the burner circulation pump 80 is driven. Since the first control valve 170, the second control valve 160, the third control valve 162, and the fourth control valve 164 are all closed in step S202, the hot water in the hot water storage tank 14 is circulated even if the burner circulation pump 80 is driven. The hot water downstream of the burner circulation pump 80 and upstream of the first control valve 170, the second control valve 160, the third control valve 162, and the fourth control valve 164 is discharged from the burner circulation pump 80. Pressurized by pressure, the water pressure gradually increases.

  In step S208, while the burner circulation pump 80 is driven, the process waits for 10 seconds. As a result, the discharge pressure of the burner circulation pump 80 is stabilized, and the pressure of hot water between the burner circulation pump 80 and the first control valve 170, the second control valve 160, the third control valve 162, and the fourth control valve 164. Is stable.

  In step S210, the burner circulation water amount servo 84 is fully closed. In step S212, the burner circulation pump 80 is stopped. Since the burner circulation water amount servo 84 is closed in step S210, even if the burner circulation pump 80 is stopped in step S212, the burner circulation water amount servo 84, the first control valve 170, the second control valve 160, and the third control valve. The hot water between 162 and the fourth control valve 164 is sealed while maintaining a high pressure. Even when there is a hole in the partition between the water side path and the heat medium side path of the heat exchanger 114 for heating, the water pressure in the water side path is maintained high. Water from the cistern 100 does not enter the water-side path.

  In step S214, it is determined from the detection signal of the pressure switch 33 whether or not the water supply pressure in the water supply path 24 has recovered. When the supply water pressure remains low and has not recovered (in the case of NO), the process proceeds to step S216.

  In step S216, it is determined whether or not the elapsed time since the burner circulation water amount servo 84 is fully closed has reached 30 minutes. When the elapsed time reaches 30 minutes (in the case of YES), the process returns to step S204, the burner circulation water amount servo 84 using the burner circulation pump 80, the first control valve 170, the second control valve 160, and the third control valve 162. The hot water between the fourth control valves 164 is pressurized again. When the elapsed time since the burner circulation water amount servo 84 is fully closed is less than 30 minutes (in the case of NO), the process returns to step S214.

  When the water supply pressure in the water supply path 24 has been recovered in step S214 (in the case of YES), the process proceeds to step S218. In step S218, the burner circulation water amount servo 84 is returned to the normal standby position, and the burner circulation water amount servo 84 and the first control valve 170, the second control valve 160, the third control valve 162, and the fourth control valve 164 are connected. The hot water pressure is released and the first protection operation is terminated.

  By performing the first protection operation described above, the water pressure in the water-side path of the heating heat exchanger 114 can be maintained high while the water supply pressure in the water supply path 24 is reduced due to water interruption or the like. Even if there is a hole in the partition wall between the water side path and the heat medium side path of the heat exchanger 114 for heating, the heat medium (water from the cistern 100) enters the water side path. It is possible to prevent contamination of the hot water in the water path. Contamination of hot water stored in the hot water storage tank 14 can be prevented. Moreover, it can prevent that the piping of the burner circulation path | route 76 gets dirty with a heat medium.

  It is also possible to prevent the heat medium from entering the water side path in the heat recovery circulation path 56 in the same manner as described above. In this case, control valves are provided downstream of the heat recovery heat exchanger 154 and between the heat recovery circulation pump 58 and the heat recovery heat exchanger 154, respectively. When a decrease in the feed water pressure in the feed water path 24 is detected, the heat recovery circulation pump 58 is driven with the control valve on the downstream side of the heat recovery heat exchanger 154 closed, and then the heat recovery circulation pump 58 and the heat By closing the control valve between the recovery heat exchangers 154, the water pressure in the water-side path of the heat recovery heat exchanger 154 can be maintained high. It is possible to prevent the heat medium from entering the water-side path of the heat recovery heat exchanger 154.

(Second protection operation)
Hereinafter, the second protection operation will be described with reference to FIG.

  In step S302, the mixing servo 34 is fully opened on the water side. In step S304, the hot water solenoid valve 50 is closed. Accordingly, the hot water storage tank 14, the heat recovery circulation path 56, and the burner circulation path 76 form a sealed hot water circuit.

  In step S306, the burner circulation three-way valve 78 is switched to a state where the inlet 78a and the outlet 78c are in communication and the inlet 78b is not in communication.

  In step S308, it is determined whether or not the detected temperature of the tank upper thermistor 15 is below 60 ° C. When the detected temperature of the tank upper thermistor 15 is lower than 60 ° C. (in the case of YES), the process proceeds to step S310 and the first control valve 170 is opened. When the detected temperature of the tank upper thermistor 15 is 60 ° C. or higher (in the case of NO), the process proceeds to step S312 and the fourth control valve 164 is opened.

  In step S314, the burner circulation water amount servo 84 is fully opened. In step S316, the burner circulation pump 80 is driven. Accordingly, hot water is sent from the lower part of the hot water storage tank 14 to the burner unit 68. The hot water that has passed through the burner section 68 flows into the upper part of the hot water storage tank 14 if the first control valve 170 is opened in step S310, and the hot water in the hot water storage tank 14 if the fourth control valve 164 is opened in step S312. Flows into the bottom.

  In step S318, the process waits until the detected flow rate of the burner circulating water amount sensor 82 reaches 2.7 liters / min.

  In step S320, the burner 70 is ignited. The hot water circulating in the burner circulation path 76 is heated, and the temperature of the hot water in the hot water storage tank 14 rises. Since the hot water storage tank 14, the heat recovery circulation path 56, and the burner circulation path 76 form a sealed hot water circuit, the pressure of the hot water increases as the temperature of the hot water rises.

  In step S322, it is determined whether the detected temperature of the burner outlet thermistor 88 is 75 ° C. or higher. If the detected temperature of the burner outlet thermistor 88 is less than 75 ° C. (in the case of YES), the process proceeds to step S324. If the detected temperature of the burner outlet thermistor 88 is 75 ° C. or higher in step S322 (in the case of YES), the process proceeds to step S326.

  In step S324, it is determined whether 10 minutes have elapsed since the burner 70 was ignited in step S320. When 10 minutes have elapsed since the burner 70 was ignited (in the case of YES), the process proceeds to step S326. If 10 minutes have not elapsed (NO), the process returns to step S322.

  Heating by the burner 70 is performed until the detected temperature of the burner outlet thermistor 88 becomes 75 ° C. or higher in step S322 or until 10 minutes elapses after the burner 70 is ignited in step S324. As a result, the temperature of the hot water in the hot water storage tank 14 rises sufficiently, and the pressure of the hot water rises accordingly.

  In step S326, the burner 70 is extinguished. In step S328, the burner circulation pump 80 is stopped. Since the water pressure in the hot water storage tank 14, the heat recovery circulation path 56 and the burner circulation path 76 has already increased, the water-side path of the heating heat exchanger 114 and the heat after the circulation heating using the burner 70 is completed. The water side path of the recovery heat exchanger 154 is maintained at a high water pressure. Even when there is a hole in the partition between the water side path and the heat medium side path of the heat exchanger 114 for heating, the water pressure in the water side path is maintained high. Water from the cistern 100 does not enter the water-side path. Further, even when there is a hole in the partition between the water side path and the heat medium side path of the heat exchanger 154 for heat recovery, the water pressure in the water side path is maintained high. The heat medium does not enter the water side path.

  In step S330, the temperature of the tank upper thermistor 15 is stored.

  In step S332, it is determined from the detection signal of the pressure switch 33 whether or not the water supply pressure in the water supply path 24 has recovered. If the supply water pressure remains low and not recovered (in the case of NO), the process proceeds to step S334.

  In step S334, it is determined whether the detected temperature of the tank upper thermistor 15 has dropped by 5 ° C. or more. When the temperature of the hot water in the hot water storage tank 14 is lowered, the water pressure is also lowered accordingly. Therefore, when a temperature drop is detected by the tank upper thermistor 15, circulation heating by the burner 70 is performed again. If the detected temperature of the tank upper thermistor 15 has decreased by 5 ° C. or more (in the case of YES), the process returns to step S308, and the pressure is raised again by circulating heating using the burner 70. If the detected temperature of the tank upper thermistor 15 has not decreased by 5 ° C. or more (in the case of NO), the process returns to step S332.

  If the water supply pressure in the water supply path 24 has recovered in step S332 (in the case of YES), the process proceeds to step S336. In step S336, the opening degree of the mixing servo 34 is returned to the normal standby position, the pressure of the hot water in the hot water storage tank 14, the heat recovery circulation path 56 and the burner circulation path 76 is released, and the second protection operation is ended.

  By performing the above-mentioned second protection operation, while the water supply pressure in the water supply path 24 is lowered due to water interruption or the like, the water side path of the heating heat exchanger 114 and the water side path of the heat recovery heat exchanger 154 The water pressure can be kept high. If there is a hole in the partition between the water side path and the heat medium side path of the heating heat exchanger 114, or there is a hole in the partition between the water side path and the heat medium side path of the heat recovery heat exchanger 154, Even if it is open, the heat medium in the heat medium side path does not enter the water side path, and contamination of the hot water in the water side path can be prevented. Contamination of hot water stored in the hot water storage tank 14 can be prevented. Further, it is possible to prevent the piping of the burner circulation path 76 and the heat recovery circulation path 56 from being contaminated by the heat medium.

  In the second protection operation, the hot water may be heated by the power generation operation of the power generation unit 150 instead of heating the hot water by the combustion of the burner 70. Also in this case, as the temperature of the hot water in the hot water storage tank 14 rises, the pressure of the hot water rises, and the water side path of the heating heat exchanger 114 and the water side path of the heat recovery heat exchanger 154 are at high water pressure. Maintained. It is possible to prevent the heat medium from entering the water side path of the heating heat exchanger 114 and the water side path of the heat recovery heat exchanger 154.

Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.
In addition, the technical elements described in the present specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology illustrated in the present specification or the drawings achieves a plurality of objects at the same time, and has technical utility by achieving one of the objects.

FIG. 1 is a system diagram of a cogeneration system according to an embodiment of the present invention. FIG. 2 is a flowchart for explaining the operation of the first protection operation. FIG. 3 is a flowchart for explaining the operation of the second protection operation.

Explanation of symbols

2 Cogeneration System 10 Hot Water Supply Unit 12 Hot Water Storage Unit 14 Hot Water Storage Tank 15 Tank Upper Thermistor 16 First Tank Thermistor 18 Second Tank Thermistor 20 Third Tank Thermistor 22 Fourth Tank Thermistor 24 Water Supply Path 26 Pressure Reducing Valve 28 Water Supply Thermistor 30 Water Supply Sensor 32 Water supply amount servo 33 Pressure switch 34 Mixing servo 36 Mixing path 38 Drainage path 40 Drainage valve 42 Pressure release path 44 Hot water tap 46 Hot water supply path 48 Pressure relief valve 50 Hot water solenoid valve 52 High temperature thermistor 54 Hot water thermistor 56 Heat recovery circulation path 56a Heat Recovery circulation forward path 56b Heat recovery circulation return path 58 Heat recovery circulation pump 60 Circulation forward path thermistor 62 Circulation return path thermistor 64 Heat recovery three-way valve 64a Inlet 64b, 64c Outlet 66 Tank bypass path 68 Burner section 70 Burner 7 Latent heat exchanger 74 Sensible heat exchanger 76 Burner circulation path 76a Burner circulation outbound path 76b Burner circulation return path 77 First burner circulation outbound path 78 Burner circulation three-way valve 78a, 78b Inlet 78c Outlet 79 Second burner circulation outbound path 80 Burner circulation pump 82 Burner circulating water sensor 83 Burner inlet thermistor 84 Burner circulating water servo 88 Burner outlet thermistor 90 Heat exchanger outlet thermistor 92 Drain path 94 Neutralizer 98 Overflow path 100 cistern 102 cistern water supply path 104 negative pressure valve 106 cistern water supply valve 108 thermal load 110 Heating terminal 112 Heating circulation path 112a Heating circulation forward path 112b Heating circulation return path 114 Heating heat exchanger 116 Heating circulation pump 118 Heating circulation thermistor 120 Heating thermal valve 122 Reheating path 124 Bath heat exchanger 26 Heating valve 128 Bath 130 Bath circulation path 130a Bath circulation outbound path 130b Bath circulation return path 132 Bath water level sensor 134 Bath circulation pump 136 Bath water flow switch 138 Bath circulation thermistor 140 Hot water path 142 Hot water volume sensor 144 Hot water solenoid valve 146 Controller 148 Remote control 150 Power generation unit 152 Heat medium circulation path 154 Heat recovery heat exchanger 160 Second control valve 162 Third control valve 164 Fourth control valve 166 Second tank bypass path 168 Second burner circulation return path 170 First control Valve 172 Heating bypass path 174 Heating heat exchange path

Claims (3)

A hot water tank,
A water supply route for supplying water to the hot water tank,
A hot water supply route for supplying hot water from a hot water tank,
A heat exchanger that has a water-side path through which water passes and a heat-medium side path through which the heat medium passes, and that exchanges heat between the water in the water-side path and the heat medium in the heat-medium side path;
A heat exchanger circuit for circulating water between the hot water tank and the heat exchanger;
A circulation pump provided upstream of the heat exchanger in the heat exchanger circuit;
An on-off valve provided downstream of the heat exchanger in the heat exchanger circuit;
It has a detection means to detect a drop in the water supply pressure in the water supply path,
A hot water storage type hot water supply system that closes the on-off valve and drives the circulation pump when the detecting means detects a decrease in the water supply pressure. A second on-off valve provided between the circulation pump and the heat exchanger;
The hot water storage hot water supply system according to claim 1, wherein when the detecting means detects a decrease in the water supply pressure, the on-off valve is closed to drive the circulation pump, and then the second on-off valve is closed to stop the circulation pump. A hot water tank,
A water supply route for supplying water to the hot water tank,
A hot water supply route for supplying hot water from a hot water tank,
A heat exchanger that has a water-side path through which water passes and a heat-medium side path through which the heat medium passes, and that exchanges heat between the water in the water-side path and the heat medium in the heat-medium side path;
A heat exchanger circuit for circulating water between the hot water tank and the heat exchanger;
A heat source machine for heating the water in the hot water tank,
A water supply valve provided in the water supply path;
A hot water supply valve provided in the hot water supply path;
It has a detection means to detect a drop in the water supply pressure in the water supply path,
A hot water storage hot water supply system that closes the water supply valve and the hot water supply valve to drive the heat source device when the detection means detects a decrease in the water supply pressure.

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