JP2016075407A - Hot water supply device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique enabling presence or absence of failure in a low temperature-side water amount sensor to be automatically determined, for a hot water supply device comprising a high temperature-side water amount sensor and the low temperature-side water amount sensor.SOLUTION: The hot water supply device according to disclosure of the present invention comprises: a mixing valve which mixes high-temperature water and low-temperature water together; a high temperature-side water amount sensor detecting a flow rate of high-temperature water flowing in the mixing valve; a low temperature-side water amount sensor detecting a flow rate of low-temperature water flowing in the mixing valve; and a control device. The control device is capable of performing fault determination processing of determining that the low temperature-side water amount sensor gets out of order. The control device determines that the low temperature-side water amount sensor gets out of order when the mixing valve has an opening at which the flow rate of the low-temperature water is larger than a flow rate of the high-temperature water and the high temperature-side water amount sensor detects the high-temperature water flowing, and the low temperature-side water amount sensor does not detect flow of the low-temperature water.SELECTED DRAWING: Figure 2

Description

  The technology disclosed in this specification relates to a hot water supply apparatus.

  Patent Document 1 includes a mixing valve that mixes high-temperature water and low-temperature water, a high-temperature water amount sensor that detects the flow rate of high-temperature water flowing into the mixing valve, and a flow rate of low-temperature water that flows into the mixing valve. A hot water supply device including a low temperature side water amount sensor to be detected and a control device is disclosed.

JP 2013-113495 A

  In the hot water supply apparatus as described above, the flow rate detected by the high temperature side water amount sensor and the flow rate detected by the low temperature side water amount sensor are added together to detect the hot water supply flow rate to the hot water supply location, and the control device acquires the hot water supply flow rate. To do. For this reason, if the low temperature side water amount sensor fails, the hot water supply flow rate cannot be detected accurately. In particular, if the opening of the mixing valve is maintained at an opening at which the flow rate of low-temperature water is larger than the flow rate of hot water, if the low-temperature water quantity sensor fails, the hot water supply flow rate is detected to be significantly lower. End up. For this reason, in spite of the fact that water is actually supplied to the hot water supply location, a situation occurs in which the control device mistakenly recognizes that the acquired hot water flow rate is too low and no hot water is being supplied. . In order to avoid such a situation, a technique capable of automatically determining the presence or absence of a failure in the low-temperature water quantity sensor is expected.

  In this specification, the technique which solves said subject is provided. The present specification provides a technology capable of automatically determining whether or not a low temperature side water amount sensor has failed in a hot water supply apparatus including a high temperature side water amount sensor and a low temperature side water amount sensor.

  The water heater disclosed in the present specification includes a mixing valve that mixes high-temperature water and low-temperature water, a high-temperature water amount sensor that detects a flow rate of high-temperature water flowing into the mixing valve, and a low-temperature water flowing into the mixing valve. A low-temperature water amount sensor for detecting the flow rate of water and a control device are provided. The control device can execute a failure determination process for determining a failure of the low temperature side water amount sensor. In the failure determination process, the controller is configured such that the opening degree of the mixing valve is such that the flow rate of the low-temperature water is larger than the flow quantity of the high-temperature water, and high-temperature water flows through the high-temperature side water amount sensor When the low temperature side water amount sensor does not detect that low temperature water is flowing, it is determined that the low temperature side water amount sensor has failed.

  If the opening of the mixing valve is such that the flow rate of the low-temperature water is larger than the flow rate of the hot water, if the hot water flows into the mixing valve, the low-temperature water will flow beyond that. Should flow into the mixing valve. Therefore, in the above hot water supply device, the opening of the mixing valve is such that the flow rate of the low-temperature water is larger than the flow rate of the high-temperature water, and high-temperature water flows through the high-temperature side water amount sensor. When the low temperature side water amount sensor does not detect that low temperature water is flowing, the control device determines that the low temperature side water amount sensor has failed. According to said hot water supply apparatus, the presence or absence of a failure of a low temperature side water quantity sensor can be determined automatically.

  The hot water supply device further includes an auxiliary heat source device that heats water downstream of the mixing valve, and the control device performs a failure determination process when the hot water supply using the auxiliary heat source device is finished. Can be configured.

  When performing hot water supply using an auxiliary heat source machine, water adjusted to a temperature lower than the hot water supply set temperature is supplied from the mixing valve to the auxiliary heat source machine in consideration of the minimum heating capacity of the auxiliary heat source machine. For this reason, in many cases, in hot water supply using an auxiliary heat source device, the flow rate of the low-temperature water flowing into the mixing valve is larger than the flow rate of the high-temperature water flowing into the mixing valve. Therefore, if the low-temperature side water quantity sensor breaks down while hot water is supplied using the auxiliary heat source machine, the hot water flow rate recognized by the controller (the flow rate detected by the low-temperature side water quantity sensor and the high-temperature side water quantity sensor is detected). Even if the hot water supply to the hot water supply location is actually continued, the control device erroneously determines that the hot water supply has ended. Therefore, in the hot water supply device described above, when the control device determines that the hot water supply using the auxiliary heat source machine has been completed, the failure determination process of the low temperature side water amount sensor is performed. With such a configuration, when a failure occurs in the low temperature side water amount sensor, the occurrence of the failure can be detected quickly.

  When the above hot water supply device determines that the low temperature side water amount sensor is malfunctioning, the opening of the mixing valve is fully opened on the low temperature side, and the hot water flow rate is detected by the water amount sensor of the auxiliary heat source unit. It can comprise so that hot water supply may be performed by the heating with an auxiliary heat source machine.

  According to the hot water supply apparatus described above, hot water supply at the hot water supply set temperature can be performed even while waiting for repair or replacement of the failed low-temperature water amount sensor.

  According to the technology disclosed in this specification, in a hot water supply apparatus including a high temperature side water amount sensor and a low temperature side water amount sensor, it is possible to automatically determine whether or not there is a failure in the low temperature side water amount sensor.

The figure which shows typically the structure of the hot water supply system 2 which concerns on an Example. The flowchart which shows the hot water supply driving | operation of the hot water supply system 2 which concerns on an Example.

(Example)
As shown in FIG. 1, the hot water supply system 2 according to this embodiment includes an HP (heat pump) unit 4, a tank unit 6, and a burner unit 8.

  The HP unit 4 is a heat source that absorbs heat from outside air and heats water. The HP unit 4 includes a compressor 10, a condenser 12, an expansion valve 14, and an evaporator 16. The compressor 10 pressurizes the refrigerant to a high temperature and a high pressure. The condenser 12 cools the refrigerant by exchanging heat with water. The expansion valve 14 depressurizes the refrigerant to low temperature and low pressure. The evaporator 16 heats the refrigerant by exchanging heat with the outside air. The HP unit 4 circulates a refrigerant (for example, a fluorocarbon refrigerant) in the order of the compressor 10, the condenser 12, the expansion valve 14, and the evaporator 16, thereby absorbing heat from outside air and heating water. The HP unit 4 further includes a circulation pump 18 that circulates water through the condenser 12, a return thermistor 20 that detects the temperature of water flowing into the condenser 12, and a forward thermistor 22 that detects the temperature of water flowing out of the condenser 12. The outside temperature thermistor 23 for detecting the outside temperature and the HP controller 24 for controlling the operation of each component of the HP unit 4 are provided.

  The tank unit 6 includes a tank 30, a mixing valve 32, and a bypass control valve 34. The tank 30 is a sealed container that is covered with a heat insulating material and stores water therein. The capacity of the tank 30 of this embodiment is, for example, 100 liters. When the circulation pump 18 of the HP unit 4 is driven, water is sucked out from the bottom of the tank 30 and sent to the condenser 12. The water heated by the condenser 12 and having a high temperature is returned from the top of the tank 30 into the tank 30. When the water heated by the HP unit 4 flows into the tank 30, a temperature stratification is formed in the tank 30 in which a high-temperature water layer is stacked on a low-temperature water layer. An upper thermistor 36 that detects the temperature of the upper water, an intermediate thermistor 37 that detects the temperature of the intermediate water, and a lower thermistor 38 that detects the temperature of the lower water are attached to the tank 30. In this embodiment, the upper thermistor 36 is disposed at a position 6 liters from the top of the tank 30, the intermediate thermistor 37 is disposed at a position 12 liters from the top of the tank 30, and the lower thermistor 38 is disposed at the tank 30. 30 liters from the top of the.

  Tap water is supplied to the tank unit 6 through the water supply path 40. In the water supply path 40, a pressure reducing valve 42 for reducing the water supply pressure and a water inlet thermistor 44 for detecting the water supply temperature are attached. The water supply path 40 branches into a tank water supply path 46 that communicates with the bottom of the tank 30 and a tank bypass path 48 that communicates with the mixing valve 32. Check valves 50 and 52 are attached to the tank water supply path 46 and the tank bypass path 48, respectively. Further, a water-side water amount sensor 54 that detects the flow rate of tap water flowing into the mixing valve 32 is attached to the tank bypass path 48. The top of the tank 30 and the mixing valve 32 communicate with each other via a tank hot water path 56. A check valve 58 and a hot water sensor 60 for detecting the flow rate of water from the tank 30 flowing into the mixing valve 32 are attached to the tank discharge path 56.

  The mixing valve 32 mixes the tap water flowing from the tank bypass passage 48 and the water from the tank 30 flowing from the tank discharge passage 56 and sends it out to the first hot water supply passage 62. The mixing valve 32 is driven by a stepping motor to adjust the opening degree on the tank bypass path 48 side (opening side on the water side) and the opening degree on the tank discharge path 56 side (opening side on the hot water side). A mixing thermistor 64 that detects the temperature of the water fed from the mixing valve 32 is attached to the first hot water supply path 62.

  Hot water is supplied from the tank unit 6 to hot water supply points such as a kitchen, a shower, and a currant through the second hot water supply path 66. A hot water supply outlet thermistor 68 that detects the temperature of water supplied to the hot water supply location and a check valve 70 are attached to the second hot water supply path 66. The first hot water supply path 62 and the second hot water supply path 66 communicate with each other through a hot water supply bypass path 72. A bypass control valve 34 is attached to the hot water supply bypass path 72.

  The tank unit 6 further includes a tank controller 74 and a remote controller 76 that can communicate with the tank controller 74. The tank controller 74 controls the operation of each component of the tank unit 6. The remote control 76 accepts various operation inputs from the user via switches, buttons, and the like. In addition, the remote controller 76 notifies the user of various types of information related to the settings and operations of the hot water supply system 2 by display and sound.

  The burner unit 8 includes a burner 80, a heat exchanger 82, a bypass servo 84, a water amount servo 86, and a hot water valve 88. The burner 80 is an auxiliary heat source machine that heats water flowing through the heat exchanger 82 by gas combustion. Water from the first hot water supply path 62 of the tank unit 6 flows into the heat exchanger 82 via the burner forward path 90. The water that has passed through the heat exchanger 82 flows out to the second hot water supply path 66 of the tank unit 6 through the burner return path 92. A water quantity servo 86 for adjusting the flow rate of water flowing through the burner forward path 90 and a water quantity sensor 91 for detecting the flow rate of water flowing through the burner forward path 90 are attached to the burner forward path 90. The burner forward path 90 and the burner return path 92 communicate with each other via a burner bypass path 94. A bypass servo 84 is attached to a connection portion between the burner forward path 90 and the burner bypass path 94. The bypass servo 84 adjusts the flow rate of water flowing from the burner forward path 90 to the burner bypass path 94. A burner hot water thermistor 96 that detects the temperature of water flowing out from the heat exchanger 82 is attached to the burner return path 92. A hot water path 98 branches off from the burner return path 92. A hot water valve 88 is attached to the hot water path 98. Hot water is poured from the burner unit 8 to the bathtub, which is a hot water supply location, via the hot water path 98. The burner unit 8 further includes a burner controller 100 that controls the operation of each component of the burner unit 8.

  The HP controller 24 and the tank controller 74 can communicate with each other. The tank controller 74 and the burner controller 100 can communicate with each other. Therefore, the hot water supply system 2 can perform various operations such as a boiling operation and a hot water supply operation by the HP controller 24, the tank controller 74, and the burner controller 100 performing control in cooperation. Hereinafter, the HP controller 24, the tank controller 74, and the burner controller 100 are collectively referred to simply as a controller.

  Below, the boiling operation and hot water supply operation which the hot water supply system 2 performs are demonstrated.

  In the boiling operation, the hot water supply system 2 drives the HP unit 4 to boil the water in the tank 30. The timing for starting the boiling operation can be set from various viewpoints. For example, the controller may determine the start timing of the boiling operation so that the boiling of the water in the tank 30 ends immediately before the time period in which cheap midnight power can be used ends. Alternatively, the controller determines the start timing of the boiling operation so that the boiling of the water in the tank 30 is completed immediately before the time when a large demand for hot water supply is expected based on the actual hot water supply results up to the previous day. Also good. Alternatively, the controller may start the boiling operation when the user instructs the boiling of water in the tank 30 via the remote controller 76.

  When the boiling operation is started, the controller drives the compressor 10 to circulate the refrigerant in the order of the compressor 10, the condenser 12, the expansion valve 14, and the evaporator 16, and drives the circulation pump 18. The water is circulated between the tank 30 and the condenser 12. As a result, the water sucked from the bottom of the tank 30 is heated to the boiling temperature in the condenser 12 and returned to the top of the tank 30. When all the water in the tank 30 is replaced with water heated to the boiling temperature, the controller ends the boiling operation.

  In the hot water supply operation, water at a hot water supply set temperature is supplied to the hot water supply location. Below, hot water supply operation is demonstrated, referring the flowchart of FIG.

  In step S2, the controller waits until the hot water supply flow rate becomes equal to or higher than the minimum operation flow rate (for example, 2.4 L / min). The hot water supply flow rate is a flow rate obtained by adding the flow rate detected by the water side water amount sensor 54 and the flow rate detected by the hot water side water amount sensor 60. When the hot water supply flow rate is equal to or higher than the minimum operation flow rate (YES in step S2), the controller determines that the hot water supply has been started by opening the hot water supply location, hot water to the bathtub, etc., and the process proceeds to step S4. move on.

  In step S4, the controller determines whether or not the temperature detected by the upper thermistor 36 is equal to or higher than the hot water supply set temperature. If the temperature detected by upper thermistor 36 is equal to or higher than the hot water supply set temperature (YES in step S4), the process proceeds to step S6.

  In step S6, the controller performs a non-combustion hot water supply operation. Specifically, the controller prohibits the combustion operation of the burner 80 and adjusts the opening of the mixing valve 32 so that the temperature detected by the mixing thermistor 64 becomes the hot water supply set temperature. After step S6, the process proceeds to step S8.

  In step S8, the controller determines whether or not the hot water supply flow rate is equal to or higher than the minimum operation flow rate. If the hot water supply flow rate is equal to or higher than the minimum operation flow rate (YES in step S8), the process returns to step S4. When the hot water supply flow rate falls below the minimum operation flow rate (NO in step S8), the controller ends the process of FIG.

  Usually, in the non-combustion hot water supply operation, the flow rate of water flowing through the tank hot water supply route 56 is larger than the flow rate of water flowing through the tank bypass route 48. Therefore, even if the water side water amount sensor 54 fails during the non-combustion hot water supply operation, the hot water supply flow rate used for the determination in step S8 (the flow rate detected by the water side water amount sensor 54 and the hot water side water amount sensor 60 is detected). The total flow rate) does not decrease so much. For this reason, when the hot water supply flow rate falls below the minimum operating flow rate in step S8, it is considered that the hot water supply has actually ended, such as closing the hot water supply location or ending the hot water supply to the bathtub. Therefore, in the hot water supply system 2 of the present embodiment, when hot water supply ends during the non-combustion hot water supply operation, failure determination processing for the water-side water amount sensor 54 described later is not performed.

  In step S4, when the temperature detected by upper thermistor 36 is less than the hot water supply set temperature (NO in step S4), the process proceeds to step S10.

  In step S10, the controller executes a combustion hot water supply operation. Specifically, the controller permits the combustion operation of the burner 80, and the temperature detected by the mixed thermistor 64 is lower than the hot water supply set temperature by the minimum heating capacity of the auxiliary heat source unit. The opening degree of the mixing valve 32 is adjusted. In this case, the high temperature water supplied from the upper part of the tank 30 and the low temperature water supplied from the water supply path 40 are mixed in the mixing valve 32 and then heated to the hot water supply set temperature by the burner 80, so Supplied to. After step S10, the process proceeds to step S12.

  In step S12, the controller determines whether or not the hot water supply flow rate is equal to or higher than the minimum operation flow rate. If the hot water supply flow rate is equal to or higher than the minimum operation flow rate (YES in step S12), the process returns to step S4. When the hot water supply flow rate falls below the minimum operation flow rate (NO in step S12), the process proceeds to step S14.

  In step S14, the controller ends the combustion hot water supply operation. Specifically, the controller ends the combustion operation of the burner 80. When the combustion hot water supply operation is terminated, the opening degree of the mixing valve 32 is maintained as it is. After step S14, the process proceeds to step S16.

  In step S <b> 16, the controller performs a failure determination process for the water-side water amount sensor 54. Usually, in the combustion hot water supply operation, the flow rate of water flowing through the tank bypass passage 48 is larger than the flow rate of water flowing through the tank discharge passage 56. Accordingly, if the water-side water amount sensor 54 fails during the combustion hot water supply operation, the hot water supply flow rate used for determination in step S12 (the flow rate detected by the water-side water amount sensor 54 and the flow rate detected by the hot-water-side water amount sensor 60 are added together. Flow rate) is significantly reduced. For this reason, it is determined in step S12 that the hot water supply flow rate is lower than the minimum operating flow rate, not only when the hot water supply is actually ended, but also the hot water supply flow rate detected due to the failure of the water-side water amount sensor 54 is greatly reduced. Cases are also conceivable. Therefore, in the hot water supply system 2 of the present embodiment, when the hot water supply is completed during the combustion hot water supply operation, a failure determination process for the water-side water amount sensor 54 is performed in step S16.

Specifically, in step S16, the controller determines that the water-side water amount sensor is in a state where the following conditions (1), (2), and (3) are satisfied for a predetermined time (for example, 10 seconds) or longer. 54 is determined to have failed.
(1) The opening degree of the mixing valve 32 is an opening degree at which the flow rate of water flowing from the tank bypass path 48 is larger than the flow rate of water flowing from the tank hot water discharge path 56. For example, when the opening degree of the mixing valve 32 sets the flow rate of water (high temperature water) flowing from the tank outlet path 56 to 1, the flow rate of water (low temperature water) flowing from the tank bypass path 48 becomes 2 or more. Opening degree.
(2) The hot water side water amount sensor 60 detects that water is flowing. For example, the flow rate detected by the hot water side water amount sensor 60 is not less than the detection lower limit flow rate (for example, 1.5 L / min) of the hot water side water amount sensor 60.
(3) The water-side water amount sensor 54 does not detect that water is flowing. For example, the flow rate detected by the water-side water amount sensor 54 is less than the detection lower limit flow rate (for example, 1.5 L / min) of the water-side water amount sensor 54.

  When the above condition (1) is satisfied, if water flows in the tank discharge passage 56, the water should flow in the tank bypass passage 48 at a higher flow rate. Therefore, if the water-side water amount sensor 54 is not malfunctioning, the above condition (3) is not satisfied when the above conditions (1) and (2) are satisfied. Therefore, in the hot water supply system 2 of the present embodiment, it is determined that the water-side water amount sensor 54 has failed when the above conditions (1), (2), and (3) are satisfied.

  In step S18, the controller determines whether or not a failure of the water-side water amount sensor 54 has been detected. When the failure of the water-side water amount sensor 54 is not detected (NO in step S18), the controller ends the process of FIG. If a failure of the water-side water amount sensor 54 is detected (YES in step S18), the process proceeds to step S20.

  In step S <b> 20, the controller notifies the user that the water-side water amount sensor 54 has failed via the remote controller 76. As a result, the user can be prompted to repair or replace the water-side water amount sensor 54. After step S20, the process proceeds to step S22.

  In step S22, the controller sets the opening of the mixing valve 32, the opening on the side of the tank bypass path 48 (opening on the water side), and the opening on the side of the tank discharge path 56 (opening on the side of hot water). In addition to being fully closed, the subsequent detection of the hot water supply flow rate is switched to the control performed by the water amount sensor 91 of the burner unit 8. As a result, even when the water-side water amount sensor 54 is out of order, the hot water supply flow rate can be accurately detected, and hot water can be supplied to the hot water supply location by the combustion hot water supply operation. After step S22, the controller ends the process of FIG.

  As described above, the hot water supply system 2 (corresponding to a hot water supply device) of the present embodiment detects the mixing valve 32 that mixes high-temperature water and low-temperature water, and the flow rate of high-temperature water that flows into the mixing valve 32. A hot water amount sensor 60 (corresponding to a high temperature side water amount sensor), a water side water amount sensor 54 (corresponding to a low temperature side water amount sensor) for detecting the flow rate of low temperature water flowing into the mixing valve 32, an HP controller 24, A controller (corresponding to a control device) including a tank controller 74 and a burner controller 100 is provided. As shown in step S <b> 16 of FIG. 2, the controller can execute a failure determination process for determining a failure of the water-side water amount sensor 54. In the failure determination process, the controller is configured such that the opening of the mixing valve 32 is such that the flow rate of the low-temperature water is larger than the flow rate of the high-temperature water. When the water side water amount sensor 54 does not detect that low temperature water is flowing, it is determined that the water side water amount sensor 54 is malfunctioning.

  The hot water supply system 2 of the present embodiment further includes a burner 80 (corresponding to an auxiliary heat source machine) that heats water downstream of the mixing valve 32. As shown in step S12 to step S16 in FIG. 2, the controller executes a failure determination process when the hot water supply using the burner 80 is finished.

  When it is determined that the water-side water amount sensor 54 has failed, the hot water supply system 2 according to the present embodiment sets the opening of the mixing valve 32 to the tank bypass path 48 side (as shown in steps S20 and S22 of FIG. The temperature of the hot water supply is detected by the water amount sensor 91 of the burner unit 8 and the hot water is supplied by heating in the burner unit 8.

  Each embodiment has 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.

  The technical elements described in this 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 exemplified in this specification or the drawings achieves a plurality of objects at the same time, and has technical utility by achieving one of the objects.

2 Hot-water supply system 4 HP unit 6 Tank unit 8 Burner unit 10 Compressor 12 Condenser 14 Expansion valve 16 Evaporator 18 Circulating pump 20 Return thermistor 22 Forward thermistor 23 Outside temperature thermistor 24 HP controller 30 Tank 32 Mixing valve 34 Bypass control valve 36 Upper thermistor 37 Middle thermistor 38 Lower thermistor 40 Water supply path 42 Pressure reducing valve 44 Water supply thermistor 46 Tank water supply path 48 Tank bypass path 50, 52 Check valve 54 Water side water amount sensor 56 Tank outlet water path 58 Check valve 60 Hot water side water amount sensor 62 First hot water supply path 64 Mixed thermistor 66 Second hot water supply path 68 Hot water supply outlet thermistor 70 Check valve 72 Hot water supply bypass path 74 Tank controller 76 Remote controller 80 Burner 82 Heat exchanger 84 Bypass servo 86 Water quantity servo 8 Yu beams valve 90 burner forward 91 water sensor 92 burner backward 94 burner bypass path 96 burner hot water thermistor 98 hot beam path 100 burner controller

Claims (3)

A mixing valve that mixes hot and cold water;
A high-temperature side water amount sensor for detecting the flow rate of high-temperature water flowing into the mixing valve;
A low-temperature side water amount sensor for detecting the flow rate of low-temperature water flowing into the mixing valve;
A hot water supply device comprising a control device,
The control device can execute a failure determination process for determining a failure of the low temperature side water amount sensor,
In the failure determination process, the controller is configured such that the opening degree of the mixing valve is such that the flow rate of the low-temperature water is larger than the flow quantity of the high-temperature water, and high-temperature water flows through the high-temperature side water amount sensor. The hot water supply apparatus which determines that the low temperature side water amount sensor has failed when the low temperature side water amount sensor does not detect that low temperature water is flowing. It further includes an auxiliary heat source machine that heats water downstream from the mixing valve,
The hot water supply apparatus according to claim 1, wherein the control device executes a failure determination process when hot water supply using the auxiliary heat source machine is terminated. If it is determined that the low-temperature water volume sensor has failed,
The hot water supply apparatus according to claim 2, wherein the opening of the mixing valve is fully opened on the low temperature side, the hot water supply flow rate is detected by a water amount sensor of the auxiliary heat source unit, and hot water is supplied by heating with the auxiliary heat source unit.

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