Heat pump heat source machine and hot water supply system

Abstract

To suppress overshoot of rising and wasteful consumption of fuel gas by preventing unnecessary or excessive combustion of a gas burner in a water heater to which hot water is supplied.SOLUTION: A heat pump heat source machine (1) comprises a tank unit (3) for storing hot water, a heat pump unit (2) for heating the hot water in the tank unit (3), a heat source-side hot water discharge pipe (6) connected between the tank unit (3) and a hot water outlet (62), and a heat source machine controller (7) for controlling the heat pump unit (2), wherein the heat source machine controller (7) can perform hot water discharge control in a first hot water discharge mode for controlling the temperature of the hot water discharged from the heat source-side hot water discharge pipe (6) to a set temperature and in a second hot water discharge mode for controlling the temperature of the hot water discharged from the heat source-side hot water discharge pipe (6) to a limit temperature lower than the set temperature.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a heat pump heat source machine that heats water stored in a tank using a heat pump, and a hot water supply system that supplies hot water heated by the heat pump heat source machine via a water heater. [Background technology]

[0002] BACKGROUND ART Conventionally, a heat pump-type hot water supply system has been put into practical use, which includes a heat pump and a tank for storing hot water heated by the heat pump, and supplies the hot water in the tank to a kitchen, bathroom, etc. In this hot water supply system, the heat pump operates during times when hot water usage is relatively low to heat the water in the tank, and when the hot water tap is opened or a command is given to fill the bathtub, hot water is supplied from the tank. Therefore, in order to supply the required amount of hot water to the bathtub, the tank needs to be sized to store a large amount of hot water. Therefore, Patent Document 1 discloses an invention for a hybrid hot water supply system in which a burner heating device, which is a water heater, is installed in a supply line downstream of a tank that stores hot water heated by a heat pump, which is a heat source unit, and the burner heating device is activated when the temperature of the water supplied from the tank is lower than the hot water supply set temperature or when there is little hot water in the tank when filling it with water. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-224762 Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-mentioned hot water supply system, communication between the water heater and the heat source machine (for example, communication between the controllers of the two) is enabled, and information from the heat source machine (for example, the temperature of the hot water being dispensed) is sent to the water heater, and the water heater determines the amount of combustion in the gas burner based on the received information. However, if a new heat source unit is connected to an existing water heater that does not have communication capabilities, or if a communication failure occurs between the water heater and heat source unit even if communication is possible, the water heater will not be able to obtain information from the heat source unit. Normally, when a water heater detects water flowing through the appliance, it will activate the gas burner at a preset combustion rate. Therefore, if hot water at the same temperature as the set temperature is supplied to the water heater, the gas burner will burn at an unnecessary or excessive combustion rate. This can result in water overshooting at the start of the water heater, which can worsen the water discharge characteristics and also lead to wasteful consumption of fuel gas.

[0005] Therefore, the present disclosure aims to provide a heat pump heat source machine and hot water supply system that can prevent unnecessary or excessive gas burner combustion in a water heater to which hot water is supplied, thereby suppressing start-up overshoot and wasteful consumption of fuel gas. [Means for solving the problem]

[0006] In order to achieve the above object, a first configuration of the present disclosure is a heat pump heat source machine, A tank for storing hot water, a heat pump that heats the hot water in the tank; a heat source side outlet pipe connected between the tank and the hot water outlet; a heat source machine controller that controls the heat pump, The heat source machine controller is characterized by being capable of controlling the hot water discharge between a first hot water discharge mode in which the temperature of the hot water discharged from the heat source side hot water discharge pipe is controlled to a predetermined first temperature, and a second hot water discharge mode in which the temperature of the hot water discharged from the heat source side hot water discharge pipe is controlled to a predetermined second temperature or lower that is lower than the first temperature. Another aspect of the first configuration is that, in the above configuration, the heat source machine controller has a communication function with a water heater controller of an external water heater, and when communication is established with the water heater controller, the first temperature is used as the set temperature in the water heater and hot water discharge control is performed in the first hot water discharge mode, and when communication is not established with the water heater controller, the hot water discharge control is performed in the second hot water discharge mode. Another aspect of the first configuration is that, in the above configuration, a mode selection means is provided that can select either of the two hot water discharge modes, and the heat source machine controller controls hot water discharge in the hot water discharge mode selected by the mode selection means. Another aspect of the first configuration is characterized in that, in the above configuration, in the second hot water dispensing mode, the second temperature can be selected from multiple stages, and the heat source machine controller is provided with a temperature selection means that can select any of the multiple stages of temperature. In order to achieve the above object, a second configuration of the present disclosure is a hot water supply system, A heat pump heat source machine of a first configuration in which a heat source machine controller has a communication function; a water heater including a gas burner, a heat exchanger that exchanges heat between water flowing therethrough and the combustion exhaust heat of the gas burner, a water supply pipe connected to the inlet side of the heat exchanger, a hot water outlet pipe connected to the outlet side of the heat exchanger, and a water heater controller that controls the gas burner and has a communication function with a heat source machine controller of the heat pump heat source machine; and a connecting pipe that connects the hot water outlet of the heat pump heat source machine to the upstream end of the water supply pipe of the water heater. [Effects of the Invention]

[0007] According to the present disclosure, the temperature of hot water supplied from a heat pump heat source can be limited, thereby preventing unnecessary or excessive gas burner combustion in the water heater to which hot water is supplied, thereby suppressing start-up overshoot and wasteful consumption of fuel gas. According to another aspect of the present disclosure, in addition to the above effects, when communication is established with the water heater, the heat source machine controller controls the water discharge in the first water discharge mode with the first temperature as the set temperature of the water heater, and when communication is not established with the water heater, controls the water discharge in the second water discharge mode.This means that the first water discharge mode and the second water discharge mode can be selected automatically, and by setting the first temperature as the set temperature, combustion of the gas burner can be suppressed and fuel gas can be saved. According to another aspect of the present disclosure, in addition to the above-mentioned effects, by providing a mode selection means, the heat source machine controller can arbitrarily select the second hot water dispensing mode. Therefore, even if the water heater does not have a communication function or if the communication function is not established due to a malfunction or the like, unnecessary or excessive gas burner combustion in the water heater can be prevented, thereby suppressing start-up overshoot and unnecessary consumption of fuel gas. According to another aspect of the present disclosure, in addition to the above effects, the heat source machine controller is equipped with a temperature selection means that can select from multiple levels of second temperatures, so that a second temperature that is appropriate for each water heater that has a different lower limit for the temperature that can be set can be set. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic diagram of a heat pump heat source machine and a hot water supply system. [Figure 2] 10 is a flowchart of hot water dispensing operation control. [Figure 3] FIG. 10 is a schematic diagram of a heat pump heat source machine and a hot water supply system according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Figure 1 is a schematic diagram showing an example of a heat pump heat source machine (hereinafter simply referred to as a "heat source machine") 1 according to the first configuration of the present disclosure and an example of a hot water supply system S according to the second configuration of the present disclosure, in which a water heater 70 is connected to the heat source machine 1. The heat source unit 1 includes a heat pump unit 2, a tank unit 3, a tank drain pipe 4, a heat source side water supply pipe 5, a heat source side hot water outlet pipe 6, and a heat source unit controller 7 within a housing not shown. The heat pump unit 2 includes a compressor 10, a water heat exchanger 11, an expansion valve 12, a heat absorption unit 13, and a loop-shaped circulation path 14 that connects these in series. A heat medium (e.g., a chlorofluorocarbon alternative) can circulate through the circulation path 14. The heat pump unit 2 is an example of the heat pump of the present disclosure. The compressor 10 compresses the heat medium that has absorbed heat in the heat absorption section 13, turns it into high-temperature, high-pressure liquid, and sends it to the water heat exchange section 11. The water heat exchange section 11 is equipped with a heat side piping 15 and a water side piping 16. The heat side piping 15 is incorporated into the circulation path 14. The water side piping 16 is incorporated into a tank circulation path 28, which will be described later. The expansion valve 12 reduces the pressure of the heat medium from which heat has been absorbed in the water heat exchange section 11, turns it into low-temperature, low-pressure liquid, and sends it to the heat absorption section 13. The heat absorption section 13 exchanges heat between the outside air and the heat medium.

[0010] The tank unit 3 includes a tank body 20, a tank supply pipe 21, and a tank return pipe 22. Tank body 20 can store a predetermined volume (for example, 50 L) of hot water, and is provided therein with a tank temperature sensor 23 that detects the temperature of the hot water. Tank body 20 is an example of the tank of the present disclosure. The tank supply pipe 21 is connected to the upper part of the tank body 20. The tank supply pipe 21 is connected to the downstream end of the water-side pipe 16 of the water heat exchange section 11 of the heat pump unit 2. The tank supply pipe 21 is provided with a supply temperature sensor 24 that detects the temperature of the hot and cold water. The tank return pipe 22 is connected to the lower part of the tank body 20. The tank return pipe 22 is connected to the upstream end of the water side piping 16. The tank return pipe 22 is provided with a pump 25, a flow rate switch 26 that detects the flow of water, and a return temperature sensor 27 that detects the temperature of the hot and cold water. The tank supply pipe 21, the tank return pipe 22, and the water-side pipe 16 form a tank circulation path 28 through which hot and cold water circulates within the tank body 20. A drain pipe 29 for the return pipe is connected to the tank return pipe 22 on the upstream side of the pump 25. A drain plug 30 is provided at the downstream end of the drain pipe 29 for the return pipe.

[0011] The tank drain pipe 4 is connected to the bottom of the tank body 20. A throttle section 35 for flow rate control is provided in the tank drain pipe 4. The tank drain pipe 4 branches into two branches downstream of the throttle section 35, and a first solenoid valve 36 for opening and closing the flow path is provided in one of the branch pipes. A drain plug 37 is provided at the outlet of the other branch pipe. The upstream end of the heat source-side water supply pipe 5 is connected to a water inlet 38 provided in the housing. An external water pipe (not shown) is connected to the water inlet 38. From the upstream side, the heat source-side water supply pipe 5 is provided with a pressure reducing valve 39 that adjusts the inlet water pressure to the tank body 20, a heat source-side flow rate sensor 40 that detects the amount of water flowing, and a heat source-side inlet water temperature sensor 41 that detects the temperature of the water.

[0012] The heat source side water supply pipe 5 branches into a first water supply branch pipe 42 and a second water supply branch pipe 43 downstream of the heat source side inlet water temperature sensor 41. The first water supply branch pipe 42 is connected to a mixing valve 56 (described later) provided on the heat source side hot water outlet pipe 6. The first water supply branch pipe 42 is provided with a check valve 44 and a throttle section 45 for flow rate control. A water supply pipe drain pipe 46 is connected between the check valve 44 and the throttle section 45. A drain plug 47 is provided at the downstream end of the water supply pipe drain pipe 46. The second water supply branch pipe 43 is connected to the bottom of the tank body 20. From the upstream side, the second water supply branch pipe 43 is provided with a second solenoid valve 48 that opens and closes the flow path, and a check valve 49. The second solenoid valve 48 is closed in the standby state before the hot water dispensing operation.

[0013] The heat source side hot water outlet pipe 6 includes a first partial pipe 55 , a mixing valve 56 , and a second partial pipe 57 . The upstream end of the first partial pipe 55 is connected to the top of the tank body 20, and the downstream end is connected to the first inlet of the mixing valve 56. A relief pipe 58 equipped with a relief valve 59 is connected to the first partial pipe 55. An upstream temperature sensor 60 is provided in the first partial pipe 55 downstream of the relief pipe 58 to detect the temperature of the hot water at the outlet of the first partial pipe 55. The mixing valve 56 is an electrically operated valve that can adjust the opening degree of the flow path as well as switch the flow path by driving the valve element of the T port with a motor. The downstream end of the first water supply branch pipe 42 is connected to the second inlet of the mixing valve 56. The upstream end of the second partial pipe 57 is connected to the outlet of the mixing valve 56. The second partial pipe 57 is provided with a downstream temperature sensor 61 that detects the temperature of the hot water being discharged at the second partial pipe 57. The downstream end of the second partial pipe 57 is provided with a hot water outlet 62. Before the hot water dispensing operation, the mixing valve 56 is in a standby position that connects the first water supply branch pipe 42 and the second partial pipe 57.

[0014] The heat source machine controller 7 includes a CPU and a memory connected to the CPU. The heat source machine controller 7 is electrically connected to the compressor 10 of the heat pump unit 2, the expansion valve 12, a fan (not shown), and a temperature sensor (not shown) provided in the circulation path 14. The heat source machine controller 7 is electrically connected to the pump 25, the first and second solenoid valves 36, 48, and the mixing valve 56 to control the operation of each component, and also receives detection signals from each sensor and switch. The heat source machine controller 7 controls the operation of the heat pump unit 2 and the hot water discharge operation in the tank body 20, as well as a cleaning operation for cleaning the tank body 20 and the first partial pipe 55, in accordance with a program stored in a non-transitory computer-readable storage medium including a memory connected to the CPU, based on operation commands set by a remote control 74 described below and each detection signal. Note that the first solenoid valve 36 of the tank drain pipe 4 is closed except during the cleaning operation.

[0015] Water heater 70 has gas burner 71, heat exchanger 72, water heater controller 73, and remote control 74. A water supply pipe 75 is connected to the inlet end of the heat transfer pipe of heat exchanger 72. The upstream end of water supply pipe 75 is connected to hot water outlet 62 of heat source unit 1 via connecting pipe 76. An outlet hot water pipe 77 is connected to the outlet end of the heat exchanger 72. An external pipe 78 having a hot water tap 79 is connected to the downstream end of the outlet hot water pipe 77. A bypass pipe 80 that bypasses the heat exchanger 72 is connected between the water supply pipe 75 and the outlet hot water pipe 77. Upstream of the bypass pipe 80, the water supply pipe 75 is provided with a flow rate sensor 81 that detects the flow of water, an inlet water temperature sensor 82 that detects the water temperature, and a water volume control valve 83 that controls the flow rate in the water supply pipe 75. The outlet hot water pipe 77 is provided with an outlet hot water temperature sensor 84 that detects the outlet hot water temperature. The bypass pipe 80 is provided with a bypass control valve 85 that controls the bypass amount. A gas pipe that supplies fuel gas to the gas burner 71 is provided with a main valve, a proportional valve, and a main valve (none of which are shown) from the upstream side.

[0016] The water heater controller 73 includes a CPU and a memory connected to the CPU. The water heater controller 73 is electrically connected to the water volume control valve 83, the bypass control valve 85, the valves of the gas pipe, the igniter for ignition, and a fan (not shown) to control the operation of each component, and also receives detection signals from each sensor. The water heater controller 73 controls the operation of the water heater 70 based on operation commands set by the remote control 74 and each detection signal, in accordance with a program stored in a non-transitory computer-readable storage medium including a memory connected to the CPU. The water heater controller 73 is electrically connected to the heat source machine controller 7, enabling mutual communication. The remote control 74 can instruct the hot water supply system S to perform heat retention operation, hot water supply operation, and cleaning operation using switches (not shown). Heat retention operation is an operation that operates the heat pump unit 2 to heat and keep the hot water in the tank body 20 warm. Hot water supply operation is an operation that supplies hot water in the tank body 20 via the water heater 70. Cleaning operation is an operation that discharges hot water from the tank body 20 and cleans the first partial pipe 55 of the heat source side hot water outlet pipe 6 and the tank body 20.

[0017] In the hot water supply system S configured as described above, when the heat source machine controller 7 receives an instruction from the remote control 74 to perform heat retention operation on the heat pump unit 2, it operates the compressor 10 and expansion valve 12 of the heat pump unit 2 and the pump 25 of the tank unit 3. Then, in the heat pump unit 2, the heat medium is compressed by the compressor 10 to become high temperature and high pressure, releases heat in the water heat exchange section 11, becomes low temperature and low pressure in the expansion valve 12, and circulates through the circulation path 14 while absorbing heat in the heat absorption section 13. Meanwhile, in the tank unit 3, operation of the pump 25 causes the hot water in the tank body 20 to circulate through the tank circulation path 28. That is, the hot water repeats a cycle of passing from the tank return pipe 22 through the water-side piping 16 of the water heat exchanger 11 and returning to the tank body 20 through the tank supply pipe 21. Thus, in the water heat exchanger 11, heat exchange occurs between the heat medium flowing in the heat-side piping 15 and the hot water flowing in the water-side piping 16, heating the hot water in the tank body 20. After the hot water in the tank body 20 is once heated to a high temperature (e.g., 75°C), the compressor 10 is turned on and off based on the temperature detected by the return temperature sensor 27, thereby maintaining the hot water at a predetermined temperature (e.g., 65°C).

[0018] During hot water dispensing operation, the heat source machine controller 7 can execute hot water dispensing operation control to select one of two hot water dispensing modes with different temperatures for the hot water dispensed from the hot water outlet 62, based on the state of communication with the water heater controller 73. This hot water dispensing operation control will be explained below with reference to the flowchart in Figure 2. First, in step (hereinafter referred to as "S") 1, when the heat source side flow sensor 40 detects the flow of water inside the equipment due to the opening of the hot water tap 79, the heat source equipment controller 7 opens the second solenoid valve 48 in S2 and switches the mixing valve 56 to the hot water outlet position which connects the first partial pipe 55 and the second partial pipe 57. Therefore, clean water supplied from water inlet 38 to heat source side water supply pipe 5 is supplied from second water supply branch pipe 43 to the bottom of tank body 20, as shown by the solid arrow in Figure 1. Then, this supply pressure pushes the hot water in tank body 20 into first partial pipe 55 of heat source side hot water outlet pipe 6, and flows directly through mixing valve 56 to second partial pipe 57 and is discharged from hot water outlet 62.

[0019] Next, in S3, the heat source machine controller 7 determines whether or not information on the set temperature selected by the remote control 74 has been obtained from the water heater controller 73. If the determination is YES, i.e., if it is confirmed that information on the set temperature has been obtained, the heat source machine controller 7 determines that communication with the water heater controller 73 has been established, and executes the first hot water dispensing mode. In the first hot water outlet mode, in S4, the heat source machine controller 7 performs temperature control by adjusting the opening of the mixing valve 56 so that the hot water temperature (heat source side hot water outlet temperature) detected by the downstream temperature sensor 61 matches or approaches the set temperature. Specifically, if the heat source side hot water outlet temperature is higher than the set temperature, the mixing valve 56 is switched to the mixing position in which the first partial pipe 55, the second partial pipe 57, and the first water supply branch pipe 42 are in communication, thereby increasing the amount of water supplied from the first water supply branch pipe 42. If the heat source side hot water outlet temperature is lower than the set temperature, the hot water outlet position of the mixing valve 56 is maintained. The set temperature is an example of the first temperature in the present disclosure.

[0020] On the other hand, if the result of S3 is NO, i.e., if the information on the set temperature is not obtained from the water heater controller 73, the heat source machine controller 7 determines that communication with the water heater controller 73 has not been established and executes the second hot water dispensing mode. In the second hot water outlet mode, in S5, the heat source machine controller 7 controls the temperature by adjusting the opening of the mixing valve 56 so that the heat source side hot water outlet temperature detected by the downstream temperature sensor 61 matches or approaches a predetermined limit temperature. The limit temperature must be below the minimum temperature that can be set in the water heater 70 (for example, 35°C), so it is set to around 30°C. Therefore, in S5, if the heat source side hot water outlet temperature is higher than the limit temperature, the mixing valve 56 is switched to the mixing position where the first partial pipe 55, the second partial pipe 57 and the first branch water supply pipe 42 are in communication with each other, thereby increasing the amount of water supplied from the first branch water supply pipe 42. If the heat source side hot water outlet temperature is lower than the limit temperature, the hot water outlet position of the mixing valve 56 is maintained. The limit temperature is an example of the second temperature in the present disclosure.

[0021] The hot water thus dispensed from hot water outlet 62 flows into water supply pipe 75 of water heater 70 via connecting pipe 76. When communication is established between water heater controller 73 and heat source machine controller 7, water heater controller 73 can obtain information on the heat source side outlet hot water temperature from heat source machine controller 7. Therefore, if the heat source side outlet hot water temperature is lower than the set temperature, a feedforward control amount corresponding to the temperature difference is calculated to adjust the opening of the proportional valve, and the master valve and main valve are opened to cause gas burner 71 to combust. On the other hand, if communication with the heat source machine controller 7 is not established, the water heater controller 73 calculates a feedforward control amount according to the temperature difference between the inlet water temperature detected by the inlet water temperature sensor 82 and the set temperature, and burns the gas burner 71. The hot water thus entering the water heater 70 is heated by the heat exchanger 72, passes through the hot water outlet pipe 77 and external piping 78, and is discharged from the hot water tap 79. If there is a difference between the outlet hot water temperature detected by the outlet hot water temperature sensor 84 and the set temperature, the water heater controller 73 adjusts the opening of the water volume control valve 83, the bypass control valve 85, and the proportional valve to perform outlet hot water temperature control so that the outlet hot water temperature matches the set temperature.

[0022] When the hot water tap 79 is closed and the water heater controller 73 detects that water flow has stopped in the water heater 70 using the flow sensor 81, the water heater controller 73 closes the main valve and the main valve to stop combustion in the gas burner 71. On the other hand, in either the first hot water dispensing mode or the second hot water dispensing mode, when the heat source machine controller 7 detects in S6 that water flow within the device has stopped due to the hot water tap 79 being closed, it closes the second solenoid valve 48 in S7, sets the mixing valve 56 to the standby position, and ends the hot water dispensing operation control. If the determination in S6 does not detect that water flow has stopped, it returns to S3 and executes the first hot water dispensing mode or the second hot water dispensing mode depending on whether or not information about the set temperature is available.

[0023] When the cleaning operation is selected by the remote control 74, the heat source machine controller 7 stops the compressor 10 of the heat pump unit 2 if the water heater 70 is not in use, and switches the mixing valve 56 to a state (tank cleaning position) in which the first water supply branch pipe 42 and the first partial pipe 55 are in communication with each other. At this time, the first solenoid valve 36 and the second solenoid valve 48 are both closed. 1, clean water flowing into the heat source side water supply pipe 5 flows back through the first partial pipe 55 from the first water supply branch pipe 42 via the mixing valve 56 and into the upper part of the tank body 20. This backflowing water discharges scale and the like on the inner surface of the first partial pipe 55 into the tank body 20. Next, the first solenoid valve 36 is opened, and the hot and cold water in the tank body 20 is discharged to the outside from the tank drain pipe 4 through the branch pipe on the first solenoid valve 36 side. At this time, clean water is flowing in from the top of the tank body 20, so the hot and cold water in the tank body 20 is discharged from above under pressure due to the force of the water as it flows in and its own weight. Therefore, scale and the like in the tank body 20 are also discharged to the outside from the tank drain pipe 4 along with the hot and cold water. When it is confirmed that the cumulative flow rate of clean water flowing in from the heat source side water supply pipe 5 has reached the flushing flow rate preset for flushing the inside of the tank body 20, the first solenoid valve 36 is closed, and the flushing operation is terminated.

[0024] Thus, the heat source machine 1 of the above form includes a tank body 20 for storing hot water, a heat pump unit 2 for heating the hot water in the tank body 20, a heat source side hot water outlet pipe 6 connected between the tank body 20 and the hot water outlet 62, and a heat source machine controller 7 for controlling the heat pump unit 2. The heat source machine controller 7 is capable of controlling the hot water discharge between a first hot water discharge mode in which the temperature of the hot water discharged from the heat source side hot water discharge pipe 6 is controlled to a set temperature, and a second hot water discharge mode in which the temperature of the hot water discharged from the heat source side hot water discharge pipe 6 is controlled to a limit temperature that is lower than the set temperature. The hot water supply system S of the above embodiment includes a heat source machine 1, a water heater 70 including a gas burner 71, a heat exchanger 72 that exchanges heat between the water flowing therethrough and the combustion exhaust heat of the gas burner 71, a water supply pipe 75 connected to the inlet side of the heat exchanger 72, a hot water outlet pipe 77 connected to the outlet side of the heat exchanger 72, and a water heater controller 73 that controls the gas burner 71 and has a communication function with the heat source machine controller 7 of the heat source machine 1; and a connecting pipe 76 that connects the hot water outlet 62 of the heat source unit 1 and the upstream end of the water supply pipe 75 of the water heater 70. According to this heat source machine 1 and hot water supply system S, the temperature of the hot water supplied from the heat source machine 1 can be limited, thereby preventing unnecessary or excessive combustion of the gas burner 71 in the water heater 70 to which the hot water is supplied, thereby suppressing start-up overshoot and wasteful consumption of fuel gas.

[0025] The heat source machine controller 7 has a communication function with the water heater controller 73 of the external water heater 70, and when communication with the water heater controller 73 is established, the first temperature is set as the set temperature in the water heater 70 and hot water discharge control is performed in the first hot water discharge mode, and when communication with the water heater controller 73 is not established, the hot water discharge control is performed in the second hot water discharge mode. Therefore, the first and second water dispense modes can be selected automatically, and by setting the first temperature as the set temperature, combustion of the gas burner 71 can be suppressed, thereby saving fuel gas.

[0026] Modifications of the present disclosure will be described below. In the above embodiment, when set temperature information is received from the water heater, the first hot water dispensing mode is automatically executed, with the first temperature set as the set temperature, and when set temperature information is not received, the second hot water dispensing mode is automatically executed, with the second temperature set as the limit temperature. However, the hot water dispensing mode may also be selected by the heat source machine controller. FIG. 3 shows an example in which a mode selection switch 8 is provided on the heat source machine controller 7. By operating this mode selection switch 8, one of the first hot water dispensing mode and the second hot water dispensing mode can be selected. A specific example of the mode selection switch 8 is one in which the display of the hot water dispensing mode changes each time the switch is pressed, allowing one of the modes to be selected. Alternatively, a separate switch may be provided for each hot water dispensing mode, allowing one of the modes to be selected. The mode selection switch 8 is an example of a mode selection means of the present disclosure. In this way, by providing a mode selection switch 8 that can select either of the two hot water dispensing modes and configuring the heat source machine controller 7 to control hot water dispensing in the hot water dispensing mode selected by the mode selection switch 8, the second hot water dispensing mode can be selected at will by the heat source machine controller 7. Therefore, even if the water heater controller 73 does not have a communication function, or if it has a communication function but communication is not established due to a malfunction or the like, unnecessary or excessive combustion of the gas burner 71 in the water heater 70 can be prevented, thereby suppressing start-up overshoot and wasteful consumption of fuel gas.

[0027] Furthermore, the second temperature does not have to be fixed to one, but can be selectable from multiple levels. FIG. 3 also shows an example in which a temperature selection switch 9 for selecting the second temperature is provided together with the mode selection switch 8. This temperature selection switch 9 may, for example, be configured such that each time the switch is pressed, multiple temperature levels prepared in advance are displayed on the display unit in sequence, allowing one of the temperatures to be selected. Alternatively, a separate switch may be provided for each of the multiple temperature levels, allowing one of the temperatures to be selected. The temperature selection switch 9 is an example of a temperature selection means of the present disclosure. In this way, in the second hot water mode, the second temperature can be selected in multiple stages, and by providing the heat source machine controller 7 with a temperature selection switch 9 that can select any of the multiple temperatures, it is possible to set a second temperature that is appropriate for each water heater that has a different lower limit for the temperature that can be set. The heat source machine controller 7 may be provided with only the temperature selection switch 9, rather than both the mode selection switch 8 and the temperature selection switch 9. In addition, the first temperature may also be selectable in multiple stages, not just the second temperature.

[0028] The heat source machine is not limited to one that supplies clean water from the bottom of the tank body during hot water dispensing operation. Also, the heat source machine may not perform a cleaning operation. The mixing valve can be configured in a way other than a T-port. However, if the hot water dispensing operation can be performed by controlling the first and second solenoid valves other than the mixing valve, the mixing valve can be omitted. The capacity of the tank is not limited to 50 L as in the above embodiment, and may be increased or decreased as appropriate. The heat exchanger of the water heater may be a combination of a primary heat exchanger that recovers sensible heat and a secondary heat exchanger that recovers latent heat. A drop pipe leading to the bathtub can be branched off from the hot water outlet pipe of the water heater, and the bathtub can be filled with hot water using an on-off valve installed on the drop pipe. In this case, a bath heater can be installed next to the hot water supply unit so that the hot water in the bathtub can be reheated by the bath heater. [Explanation of symbols]

[0029] 1··Heat pump heat source unit, 2··Heat pump unit, 3··Tank unit, 4··Tank drain pipe, 5··Heat source side water supply pipe, 6··Heat source side hot water outlet pipe, 7··Heat source unit controller, 8··Mode selection switch, 9··Temperature selection switch, 20··Tank body, 25··Pump, 28··Tank circulation path, 36··First solenoid valve, 38··Water inlet, 42··First water supply branch pipe, 43··Second water supply branch pipe, 48··Second solenoid valve, 55··First partial pipe, 56··Mixing valve, 57··Second partial pipe, 62··Hot water outlet, 70··Water heater, 71··Gas burner, 72··Heat exchanger, 73··Water heater controller, 74··Remote control, 79··Hot water tap, S··Hot water supply system.

Claims

1. A tank for storing hot water, a heat pump that heats the hot water in the tank; a heat source side outlet pipe connected between the tank and the hot water outlet; a heat source machine controller that controls the heat pump, The heat source machine controller is a heat pump heat source machine capable of controlling the hot water discharge between a first hot water discharge mode in which the temperature of the hot water discharged from the heat source side hot water discharge pipe is controlled to a predetermined first temperature, and a second hot water discharge mode in which the temperature of the hot water discharged from the heat source side hot water discharge pipe is controlled to a predetermined second temperature or lower than the first temperature.

2. The heat pump heat source machine described in claim 1, wherein the heat source machine controller has a communication function with a water heater controller of an external water heater, and when communication with the water heater controller is established, the heat source machine controller controls the water discharge in the first water discharge mode with the first temperature as the set temperature of the water heater, and when communication with the water heater controller is not established, the heat pump heat source machine controls the water discharge in the second water discharge mode.

3. The heat pump heat source machine according to claim 1, further comprising a mode selection means capable of selecting one of the two hot water discharge modes, and the heat source machine controller controls the hot water discharge in the hot water discharge mode selected by the mode selection means.

4. The heat pump heat source machine of claim 1, wherein in the second hot water outlet mode, the second temperature can be selected from a plurality of levels, and the heat source machine controller is provided with a temperature selection means that can select any one of the plurality of levels.

5. The heat pump heat source machine according to claim 2; A gas burner and a heat exchanger that exchanges heat between the water passing therethrough and the combustion exhaust heat of the gas burner; a water supply pipe connected to the inlet side of the heat exchanger; an outlet pipe connected to the outlet side of the heat exchanger; a water heater controller that controls the gas burner and has a communication function with a heat source controller of the heat pump heat source machine; a connecting pipe connecting the hot water outlet of the heat pump heat source machine and the upstream end of the water supply pipe of the water heater.

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