Heat pump heat source machine and hot water supply system

Abstract

To clean the inside of a hot water delivery pipe in addition to the inside of a tank.SOLUTION: A heat source machine controller 7 of a heat pump heat source machine 1 can execute: a hot water delivery operation for supplying clean water supplied to a heat source side water supply pipe 5 from a lower part of a tank body 20 into the tank body 20 via a second water supply branch pipe 43 and delivering the hot water in the tank body 20 from a hot water outlet 62 via a heat source side hot water delivery pipe 6 by using the supply pressure by controlling a flow of the hot water between the heat source side water supply pipe 5 and the heat source side hot water delivery pipe 6 including first and second water supply branch pipes 42, 43 and the tank body 20 a state where a first solenoid valve 36 is closed and a second solenoid valve 48 is opened; and a cleaning operation for causing the clean water supplied to the heat source side water supply pipe 5 to flow back into the heat source side hot water delivery pipe 6 via the first water supply branch pipe 42 to supply the clean water from the upper part of the tank body 20 into the tank body 20 and discharge hot water in the tank body 20 via a tank water vent pipe 4 in a state where the first solenoid valve 36 is opened and the second solenoid valve 48 is closed.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] Heat pump heat source machines are known that can heat water stored in a tank using a heat pump and supply hot water to the outside. For example, Patent Document 1 discloses an invention of a thermal device in which water stored in a hot water storage tank (tank) of a tank unit is circulated between the heat exchanger of the heat pump, heated, mixed with water, and adjusted to a set hot water supply temperature, and then hot water can be supplied from an outlet pipe. A water drainage path equipped with a drain valve is connected to the outward circulation path that circulates hot water from the tank to the heat pump. When the hot water supply system will not be used for a long period of time in winter, the drainage valve can be opened automatically or manually to drain water from the tank. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-191494 Summary of the Invention [Problem to be solved by the invention]

[0004] Since tanks can develop scale after extended use, it is advisable to periodically open the drain valve to drain the hot water and water from the tank, along with the scale, and clean it. However, although this cleaning operation can remove the limescale inside the tank, it cannot clean the hot water outlet pipe, and therefore cannot remove the limescale that has adhered to the inner surface of the hot water outlet pipe.

[0005] Therefore, an object of the present disclosure is to provide a heat pump heat source machine and a hot water supply system that can clean the inside of the hot water outlet pipe in addition to the inside of the tank. [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 water supply pipe connected to a water inlet; a heat source side outlet pipe connected between the top of the tank and the hot water outlet; a drain pipe connected to the lower part of the tank and equipped with a first opening / closing means capable of opening and closing an internal flow path; and a controller that controls the operation of the heat pump. The heat source side water supply pipe branches into a first branch pipe connected to the heat source side hot water outlet pipe, and a second branch pipe connected to the lower part of the tank and equipped with a second opening / closing means that can open and close the internal flow path. The controller controls the flow of hot and cold water between the heat source side water supply pipe including the first and second branch pipes and the heat source side hot water outlet pipe and the tank, When the first opening / closing means is in a closed state and the second opening / closing means is in an open state, clean water supplied from the water inlet to the heat source side water supply pipe is supplied into the tank from the bottom of the tank via the second branch pipe, and the hot water in the tank is discharged from the hot water outlet via the heat source side hot water outlet pipe by the supply pressure, thereby enabling a hot water discharge operation to be performed; When the first opening / closing means is in the open state and the second opening / closing means is in the closed state, clean water supplied from the water inlet to the heat source side water supply pipe is flowed back through the first branch pipe to the heat source side hot water outlet pipe and supplied into the tank from the top of the tank, and a cleaning operation can be performed in which the hot water in the tank is discharged through the water drain pipe. Another aspect of the first configuration is that, in the above configuration, a mixing valve is provided at the connection between the heat source side outlet pipe and the first branch pipe, which is controlled by the controller and can adjust the mutual communication state between the tank side of the heat source side outlet pipe, the hot water outlet side of the heat source side outlet pipe, and the first branch pipe side. Then, when the hot water dispensing operation is performed, the controller sets the mixing valve to a state in which at least the tank side and the hot water outlet side of the heat source side hot water outlet pipe are in communication with each other, When the cleaning operation is performed, the mixing valve is set to a state in which at least the tank side of the heat source side hot water outlet pipe and the first branch pipe side are in communication with each other. 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 having a first configuration; a water heater including a gas burner, a heat exchanger that exchanges heat between the 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, and a hot water outlet pipe connected to the outlet side of the heat exchanger; 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; The composition is characterized in that it comprises: Another aspect of the second configuration is that, in the above configuration, the first opening / closing means is a valve that can be manually opened and closed, a heat source side flow rate sensor that detects the flow rate of clean water supplied from the water inlet is provided in the heat source side water supply pipe; The water supply pipe is provided with a flow rate sensor that detects the flow rate of hot and cold water supplied from the connecting pipe, The controller compares the flow rate detected from the heat source side flow sensor during the hot water dispensing operation after the cleaning operation with the flow rate detected from the flow sensor, and if there is a predetermined difference between the two flow rates, stops the hot water dispensing operation. [Effects of the Invention]

[0007] According to the present disclosure, when cleaning the inside of the tank, clean water is flowed back into the heat source side hot water outlet pipe, so that the inside of the heat source side hot water outlet pipe can also be cleaned in addition to the inside of the tank. According to another aspect of the first configuration of the present disclosure, in addition to the above effects, the flow of hot and cold water can be easily controlled using a mixing valve between the heat source side water supply pipe including the first and second branch pipes and the heat source side hot water outlet pipe and the tank. According to another aspect of the second configuration of the present disclosure, in addition to the above effects, if there is a difference between the flow rate detected by the heat source side flow sensor and the flow rate detected by the water heater flow sensor during hot water discharging operation after cleaning operation, the hot water discharging operation is stopped, thereby preventing water from being wasted by performing hot water discharging operation without closing the valve after cleaning operation. [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] FIG. 4 is an explanatory diagram showing the flow of hot water during hot water supply operation. [Figure 3] 10 is a flowchart of cleaning operation control. [Figure 4] FIG. 4 is an explanatory diagram showing the flow of water during a flushing operation. [Figure 5] FIG. 10 is a schematic diagram of a modified example of the heat pump heat source machine and the hot water supply system. 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 relating to the first configuration of the present disclosure, and an example of a hot water supply system S relating to the second configuration of the present disclosure, which is configured by connecting a water heater 70 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. The tank drain pipe 4 is provided with a throttle section 35 for flow rate control. The tank drain pipe 4 branches into two branches downstream of the throttle section 35, and one of the branches is provided with a first solenoid valve 36 that opens and closes the flow path. A drain plug 37 is provided at the outlet of the other branch. The tank drain pipe 4 is an example of a drain pipe in the present disclosure. The first solenoid valve 36 and the drain plug 37 are an example of a first opening / closing means in the present disclosure, and the drain plug 37 is an example of a valve in the present disclosure. 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 first water supply branch pipe 42 is an example of the first branch pipe of the present disclosure. The second water supply branch pipe 43 is connected to the bottom of the tank body 20. A second solenoid valve 48 that opens and closes the flow path and a check valve 49 are provided in the second water supply branch pipe 43 from the upstream side. The second water supply branch pipe 43 is an example of the second branch pipe of the present disclosure. The second solenoid valve 48 is an example of the second opening / closing means of the present disclosure.

[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 that detects the outlet hot water temperature at the first partial pipe 55 is provided in the first partial pipe 55 downstream of the relief pipe 58. The first partial pipe 55 is an example of the tank side of the heat source side outlet hot water pipe of the present disclosure. 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 outlet at the second partial pipe 57. The downstream end of the second partial pipe 57 is provided with a hot water outlet 62. The second partial pipe 57 is an example of the hot water outlet side of the heat source side hot water outlet pipe of the present disclosure.

[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 is an example of a controller of the present disclosure. 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 water heater controller 73 is also an example of a controller of the present disclosure. 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] Then, when hot water dispensing operation is selected using the remote control 74, the heat source machine controller 7 opens the second solenoid valve 48 while keeping the first solenoid valve 36 closed, and switches the mixing valve 56 to a state where the first partial pipe 55 and the second partial pipe 57 are connected to each other. When the hot water tap 79 is opened in this state, clean water is supplied from the water inlet 38 to the heat-source-side water supply pipe 5. This clean water is supplied from the second water supply branch pipe 43 to the bottom of the tank body 20, as shown by the solid arrow in Figure 2. Then, the supply pressure causes the hot water in the tank body 20 to be pushed into the first partial pipe 55 of the heat-source-side hot water outlet pipe 6, and then flows directly to the second partial pipe 57 via the mixing valve 56. The hot water flowing through the second partial pipe 57 then flows via the connecting pipe 76 to the water supply pipe 75 of the water heater 70, passes through the heat exchanger 72, the hot water outlet pipe 77, and the external piping 78, and is then discharged from the hot water tap 79.

[0019] At this time, if the outlet hot water temperature detected by the outlet hot water temperature sensor 84 is lower than the set temperature set by the remote control 74, the water heater controller 73 opens the main valve and the main valve to burn the gas burner 71, heating the hot water passing through the heat exchanger 72, and adjusts the opening of the water volume control valve 83, the bypass control valve 85, and the proportional valve based on the inlet water temperature obtained from the inlet water temperature sensor 82, thereby performing outlet hot water temperature control to match the outlet hot water temperature to the set temperature. On the other hand, if the outlet hot water temperature is higher than the set temperature, the heat source machine controller 7 switches the mixing valve 56 to a state in which the first partial pipe 55, the second partial pipe 57, and the first water supply branch pipe 42 are connected, thereby increasing the amount of water supplied from the first water supply branch pipe 42. 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.

[0020] When the cleaning operation is selected by the remote control 74, the heat source machine controller 7 supplies clean water supplied from the heat source side water supply pipe 5 through the mixing valve 56 and the first partial pipe 55 into the tank body 20, and discharges it from the tank drain pipe 4. This cleaning operation control will be explained below based on the flowchart in Figure 3. When the flushing operation switch is pressed, first, in step (hereinafter simply referred to as "S") 1, it is determined whether water flow is detected by flow rate sensor 81, i.e., whether water heater 70 is in use. If water heater 70 is in use, the system waits without performing flushing operation. On the other hand, if it is determined in S1 that the water heater 70 is not in use, the cleaning operation is started in S2. Specifically, the compressor 10 of the heat pump unit 2 is stopped, and the mixing valve 56 is switched to a state in which the first water supply branch pipe 42 and the first partial pipe 55 are in communication (tank cleaning position). At the same time, the pump 25 of the tank unit 3 is operated at maximum rotation speed. At this time, the first solenoid valve 36 and the second solenoid valve 48 are both in a closed state. The display unit of the remote control 74 displays a message such as "Tank cleaning in progress." 4, 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, in S3, the circulation of hot and cold water in the tank circulation path 28 by the operation of the pump 25 is confirmed by checking whether the flow rate switch 26 is ON.

[0021] When it is confirmed in S3 that the flow rate switch 26 is ON, in S4 the pump 25 is stopped and the first solenoid valve 36 is opened. Then, based on the detection signal obtained from the heat source side flow rate sensor 40, the integration of the flow rate of clean water flowing in from the heat source side water supply pipe 5 is started. Therefore, 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 side of the first solenoid valve 36. 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 while being pressurized from above due to the force of the water as it flows in and its own weight. Therefore, limescale and the like in the tank body 20 are also discharged to the outside from the tank drain pipe 4 together with the hot and cold water.

[0022] Next, in S5, it is determined whether the cumulative flow rate of clean water flowing in from the heat source side water supply pipe 5 has reached a predetermined reached flow rate that reaches each pipe constituting the tank circulation path 28 of the tank unit 3. If it is confirmed that the target flow rate has been reached, the pump 25 is operated at the maximum rotational speed in S6, and the tank circulation path cleaning timer is started. Therefore, the hot and cold water in the tank body 20 also flows and circulates through the tank circulation path 28, cleaning each pipe. When it is confirmed in S7 that the time has expired on the tank circulation path cleaning timer, the operation of the pump 25 is stopped in S8. Then, in S9, it is determined whether the cumulative flow rate of clean water flowing in from the heat source side water supply pipe 5 has reached the flushing flow rate that has been preset for use in cleaning the inside of the tank body 20. If it is confirmed that the flushing flow rate has been reached, in S10 the first solenoid valve 36 is closed to reset the cumulative flow rate from the heat source side water supply pipe 5, and an audio notification is issued from the remote control 74 to the effect that the flushing operation has been completed.

[0023] Furthermore, when the flow rate sensor 81 of the water heater 70 confirms water flow during flushing operation, it is determined that use of the water heater 70 has begun, the first solenoid valve 36 is closed, the integrated flow rate of clean water from the heat-source-side water supply pipe 5 is reset, and the mixing valve 56 is switched to a state in which the second partial pipe 57 and the first water supply branch pipe 42 are connected. Therefore, the clean water flowing into the heat-source-side water supply pipe 5 flows from the second partial pipe 57 through the connecting pipe 76 to the water supply pipe 75, as shown by the dashed-dotted line in Figure 4, and is heated and dispensed by the water heater 70. This prevents hot water in the tank body 20 containing limescale and the like from being supplied to the water heater 70. When use of the water heater 70 ends and the flow rate sensor 81 no longer confirms water flow, processing resumes from S2. When the cleaning operation switch on the remote control 74 is pressed during cleaning operation, including during an interruption due to the use of the water heater 70, the heat source machine controller 7 cancels the cleaning operation, resets the accumulated flow rate, and issues an audio notification from the remote control 74 indicating that the cleaning operation has been canceled.

[0024] In this way, the heat source machine 1 and hot water supply system S of the above form include a tank body 20 that stores hot water, a heat pump unit 2 that heats the hot water in the tank body 20, a heat source side water supply pipe 5 connected to the water inlet 38, a heat source side hot water outlet pipe 6 connected between the top of the tank body 20 and the hot water outlet 62, a tank water drain pipe 4 connected to the bottom of the tank body 20 and equipped with a first solenoid valve 36 that can open and close the internal flow path, and a heat source machine controller 7 that controls the operation of the heat pump unit 2. The heat source side water supply pipe 5 branches into a first water supply branch pipe 42 connected to the heat source side hot water outlet pipe 6, and a second water supply branch pipe 43 connected to the lower part of the tank body 20 and equipped with a second solenoid valve 48 that can open and close the internal flow path. The heat source machine controller 7 controls the flow of hot and cold water between the heat source side water supply pipe 5 including the first and second water supply branch pipes 42, 43 and the heat source side hot water outlet pipe 6 and the tank body 20, When the first solenoid valve 36 is closed and the second solenoid valve 48 is open, clean water supplied from the water inlet 38 to the heat source side water supply pipe 5 is supplied into the tank body 20 from the bottom via the second water supply branch pipe 43, and the hot water supply pressure causes the hot water in the tank body 20 to be discharged from the hot water outlet 62 via the heat source side hot water outlet pipe 6, thereby enabling hot water discharge operation to be performed. In addition, when the first solenoid valve 36 is in the open state and the second solenoid valve 48 is in the closed state, the heat source machine controller 7 reverses the clean water supplied from the water inlet 38 to the heat source side water supply pipe 5 via the first water supply branch pipe 42 into the heat source side hot water outlet pipe 6, supplying it into the tank body 20 from the top of the tank body 20, and can perform a cleaning operation in which the hot water in the tank body 20 is discharged through the tank water drain pipe 4. According to this configuration, when cleaning the inside of the tank body 20, clean water is caused to flow back into the heat source side hot water outlet pipe 6, so that in addition to the inside of the tank body 20, the inside of the heat source side hot water outlet pipe 6 can also be cleaned.

[0025] At the connection between the heat source side hot water outlet pipe 6 and the first water supply branch pipe 42, a mixing valve 56 is provided which is controlled by the heat source machine controller 7 and can adjust the mutual communication state between the first partial pipe 55 side of the heat source side hot water outlet pipe 6, the second partial pipe 57 side of the heat source side hot water outlet pipe 6, and the first water supply branch pipe 42 side. During hot water discharge operation, the heat source machine controller 7 sets the mixing valve 56 to a state in which the first partial pipe 55 side of the heat source side hot water discharge pipe 6 is connected to the first partial pipe 42 side, and during cleaning operation, sets the mixing valve 56 to a state in which the first partial pipe 55 side of the heat source side hot water discharge pipe 6 is connected to the second partial pipe 57 side. Therefore, the flow of hot and cold water between the heat source side water supply pipe 5 including the first and second water supply branch pipes 42, 43 and the heat source side hot water outlet pipe 6 and the tank body 20 can be easily controlled using the mixing valve 56. Furthermore, the clean water used to wash the first partial pipe 55 flows into the tank body 20 in a reduced pressure state because it passes through the mixing valve 56. This prevents the supply pressure of clean water from becoming excessively high without the need for a separate component for reducing pressure. In other words, it is possible to prevent excessive load from being applied to the tank body 20 and the first partial pipe 55 connected to the tank body 20 at low cost.

[0026] Modifications of the present disclosure will be described below. In the above embodiment, the first opening / closing means employs a first solenoid valve, which is configured to open automatically during flushing operation, but the first solenoid valve may be omitted and the drain plug 37 may be opened manually during flushing operation, as shown in Fig. 5. In this case, the second opening / closing means may also be a valve that is manually opened during hot water dispensing operation and manually closed during flushing operation, instead of the second solenoid valve. In addition, if the drain valve 37 is configured to be opened during cleaning operation, the heat source machine controller 7 compares the flow rate obtained from the heat source side flow sensor 40 during hot water dispensing operation after cleaning operation with the flow rate obtained from the flow rate sensor 81 of the water heater 70, and if there is a predetermined difference between the two flow rates, it may determine that the drain valve 37 has been forgotten to be closed, stop the hot water dispensing operation, and notify this via the remote control 74. In this way, by determining whether or not the drain valve 37 has been left on based on the difference between the two flow rates, it is possible to prevent water from being wasted when the hot water dispensing operation is performed after the flushing operation with the drain valve 37 left on.

[0027] In the case of a valve, the first opening / closing means does not have to be a drain plug, and may be another valve structure. The first opening / closing means may be the first solenoid valve alone. In the above embodiment, the tank circulation path is also cleaned during the cleaning operation, but cleaning of the tank circulation path may be omitted. Mixing valves can also be configured in other ways than the T-port. In the above configuration, the flow of hot water is controlled by switching the mixing valve's flow path between the tank body, the hot water outlet, and the first water supply branch pipe during both the hot water dispensing operation and the flushing operation. However, if clean water is supplied from the bottom of the tank body during the hot water dispensing operation and from the top of the tank body during the flushing operation, switching the mixing valve's flow path for each operation is not necessary. For example, if the hot water tap on the water heater is closed, flushing operation can be performed in which clean water flows back through the heat source outlet pipe and is supplied to the top of the tank body, even if the mixing valve is connected to each of the three sides. Similarly, hot water dispensing operation can be performed in which clean water is supplied from the bottom of the tank body, causing the hot water in the tank body to flow to the heat source outlet pipe, even if the mixing valve is connected to each of the three sides. In these cases, the opening degree of the mixing valve can be changed so that when hot water dispensing operation is performed, the mixing valve is in a state that connects at least the tank body side of the heat source side hot water outlet pipe with the hot water outlet side, and when cleaning operation is performed, the mixing valve is in a state that connects at least the tank body side of the heat source side hot water outlet pipe with the first water supply branch pipe side. If the hot water dispensing operation and the cleaning operation can be performed by controlling the first and second solenoid valves and the like other than the mixing valve, the mixing valve can be omitted.

[0028] Either the heat source machine controller or the water heater controller may be omitted, and the hot water supply system may be controlled by a single controller. 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, 14··Circulation path, 20··Tank, 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 water supply pipe connected to a water inlet; a heat source side outlet pipe connected between the top of the tank and the hot water outlet; a drain pipe connected to the lower part of the tank and equipped with a first opening / closing means capable of opening and closing an internal flow path; a controller for controlling the operation of the heat pump; the heat source side water supply pipe is branched into a first branch pipe connected to the heat source side hot water outlet pipe and a second branch pipe connected to a lower part of the tank and equipped with a second opening / closing means capable of opening and closing an internal flow path, The controller controls the flow of hot and cold water between the heat source side water supply pipe including the first and second branch pipes and the heat source side hot water outlet pipe and the tank, When the first opening / closing means is in a closed state and the second opening / closing means is in an open state, clean water supplied from the water inlet to the heat source side water supply pipe is supplied into the tank from the bottom of the tank via the second branch pipe, and the hot water in the tank is discharged from the hot water outlet via the heat source side hot water outlet pipe by the supply pressure, thereby enabling a hot water discharge operation to be performed; A heat pump heat source machine characterized in that, when the first opening / closing means is in an open state and the second opening / closing means is in a closed state, a cleaning operation can be performed in which clean water supplied from the water inlet to the heat source side water supply pipe is reversed through the first branch pipe to the heat source side hot water outlet pipe and supplied into the tank from the top of the tank, and the hot water in the tank is discharged through the water drain pipe.

2. a mixing valve is provided at a connection between the heat source side outlet pipe and the first branch pipe, the mixing valve being controlled by the controller and capable of adjusting a state of communication between the tank side of the heat source side outlet pipe, the hot water outlet side of the heat source side outlet pipe, and the first branch pipe side; When the hot water dispensing operation is performed, the controller sets the mixing valve to a state in which at least the tank side and the hot water outlet side of the heat source side hot water outlet pipe are in communication with each other, The heat pump heat source machine according to claim 1, characterized in that, when the cleaning operation is performed, the mixing valve is set to a state in which at least the tank side of the heat source side hot water outlet pipe is in communication with the first branch pipe side.

3. The heat pump heat source machine according to claim 1 or 2, a water heater including a gas burner, a heat exchanger that exchanges heat between the 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, and a hot water outlet pipe connected to the outlet side of the heat exchanger; 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; A hot water system comprising:

4. the first opening / closing means is a valve that can be manually opened and closed, a heat source side flow rate sensor that detects the flow rate of clean water supplied from the water inlet is provided in the heat source side water supply pipe; The water supply pipe is provided with a flow rate sensor that detects the flow rate of hot and cold water supplied from the connecting pipe, The hot water supply system described in claim 3, characterized in that the controller compares the flow rate detected from the heat source side flow sensor during the hot water dispensing operation after the cleaning operation with the flow rate detected from the flow sensor, and if there is a predetermined difference between the two flow rates, stops the hot water dispensing operation.

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