CN204285677U - Heat recovery system - Google Patents

Abstract

The utility model discloses a heat recovery system, which comprises an air-conditioning system, a full heat recovery hot water system and a solar water heater system. According to different operation modes of the heat recovery system, the opening and closing of four solenoid valves are controlled so that the solar water heater system can assist in heating, which can greatly shorten the hot water making time in the air-conditioning heating mode or the hot water making mode, ensure sufficient heating amount in the air-conditioning system, and effectively prevent frost on the outdoor heat exchanger, so that the air-conditioning system can operate stably, save energy, be environmentally friendly and have high economic benefits.

Description

heat recovery system

technical field

The utility model relates to the field of heat recovery, in particular to a heat recovery system.

Background technique

At present, referring to FIG. 1 , a common air-conditioning system 10 generally adds a heat recovery heat exchanger 12 on the exhaust side of the compressor 11 to recover and utilize the condensation heat of the air conditioner, so as to obtain hot water. However, in winter, when the air conditioner is heating, the heat recovery heat exchanger 12 produces insufficient heat due to poor heat exchange efficiency, resulting in too low hot water temperature and insufficient heat exchange, and it is easy to cause the outdoor heat exchanger 13 Frosting affects the operation of the entire air conditioning system 10 .

Utility model content

The main purpose of the utility model is to provide an energy-saving and environment-friendly heat recovery system with high heat recovery efficiency.

To achieve the above object, the utility model provides a heat recovery system, which includes an air conditioning system, a total heat recovery hot water system and a solar water heater system.

The air conditioning system includes a compressor, an oil separator, a first four-way valve, a second four-way valve, a first heat exchanger, a refrigerant regulating device, a second heat exchanger, and a gas-liquid circuit that are connected in sequence to form a refrigerant circulation loop. For the separator, the first heat exchanger is provided with a first water inlet and a first water outlet; the second heat exchanger is provided with a second water inlet and a second water outlet.

The total heat recovery hot water system includes a third heat exchanger connected between the second four-way valve and the refrigerant regulating device, and the third heat exchanger is provided with a third water inlet and a third water outlet .

The solar water heater system includes a solar heat collector, and the solar heat collector has a fourth water inlet and a fourth water outlet.

The first water inlet communicates with the second water outlet and the third water outlet respectively, the first water outlet communicates with the fourth water inlet; the fourth water outlet communicates with the second water inlet respectively , the third water inlet is connected; and a first solenoid valve is provided between the third water inlet and the fourth water outlet, and a first electromagnetic valve is provided between the fourth water outlet and the second water inlet. Two solenoid valves, the first solenoid valve and the second solenoid valve are opened or closed according to different operation modes of the heat recovery system.

Preferably, a third solenoid valve is provided between the first water inlet and the third water outlet, and a fourth solenoid valve is provided between the first water inlet and the second water outlet, so The opening or closing state of the third electromagnetic valve is consistent with that of the first electromagnetic valve, and the opening or closing state of the fourth electromagnetic valve is consistent with that of the second electromagnetic valve.

Preferably, when the heat recovery system operates in cooling mode, the first solenoid valve, the third solenoid valve, the second solenoid valve and the fourth solenoid valve are closed.

Preferably, when the heat recovery system operates in the heating mode, the first solenoid valve and the third solenoid valve are closed, and the second solenoid valve and the fourth solenoid valve are opened.

Preferably, when the heat recovery system operates in the hot water heating mode, the first solenoid valve and the third solenoid valve are opened, and the second solenoid valve and the fourth solenoid valve are closed.

Preferably, when the heat recovery system operates in cooling and hot water heating mode, the controller controls the opening of the first solenoid valve and the third solenoid valve, controls the opening of the second solenoid valve and the fourth solenoid valve closure.

Preferably, the total heat recovery hot water system further includes a water storage tank, and the water storage tank is respectively communicated with the third water inlet and the third water outlet; when the heat recovery system operates in the heating and hot water heating modes When it is down, the first solenoid valve and the third solenoid valve are opened, and the second solenoid valve and the fourth solenoid valve are closed. When the temperature of the water storage tank reaches a preset value, the first solenoid valve and the second solenoid valve The three solenoid valves are closed, and the second solenoid valve and the fourth solenoid valve are opened.

Preferably, the refrigerant regulating device includes a liquid reservoir and a thermal expansion valve. During the operation of the air conditioning system, the refrigerant flows in from the liquid reservoir and flows out from the thermal expansion valve; A first one-way valve and a second one-way valve that flow to the liquid reservoir are sequentially provided between the heat exchanger and the liquid reservoir, and sequentially provided between the second heat exchanger and the liquid reservoir There are a third one-way valve and a fourth one-way valve that flow to the liquid reservoir, and a fifth one-way valve that flows to the first heat exchanger is sequentially provided between the thermal expansion valve and the first heat exchanger. valve and the fifth solenoid valve, between the thermal expansion valve and the second heat exchanger, a sixth one-way valve and a sixth solenoid valve that flow to the second heat exchanger are sequentially provided, and between the third heat exchanger A seventh one-way valve flowing to the liquid reservoir is provided between the heater and the liquid reservoir.

Preferably, when the heat recovery system operates in the heating mode, hot water mode, heating and hot water mode, the fifth solenoid valve is opened; when the heat recovery system operates in the cooling mode, cooling and the hot water heating mode, the fifth solenoid valve is closed.

Preferably, when the heat recovery system operates in cooling mode, cooling and hot water mode, the sixth solenoid valve is opened; when the heat recovery system operates in heating mode, hot water mode, heating and the hot water heating mode, the sixth solenoid valve is closed.

A heat recovery system provided by the utility model, the heat recovery system includes an air conditioning system, a full heat recovery hot water system, and a solar water heater system, and controls the opening and closing of four solenoid valves according to different operating modes of the heat recovery system , so that the solar water heating system can assist heating, which can greatly shorten the heating time of the air conditioner in the heating mode or hot water mode, ensure sufficient heating capacity in the air conditioning system, and effectively prevent the outdoor heat exchanger from frosting. The air-conditioning system operates stably, is energy-saving and environmentally friendly, and has high economic benefits.

Description of drawings

Fig. 1 is the connection diagram of air-conditioning system in the prior art;

Fig. 2 is a schematic diagram of the system connection of the first embodiment of the present invention.

The realization of the purpose of the utility model, functional features and advantages will be further described in conjunction with the embodiments and with reference to the accompanying drawings.

Detailed ways

It should be understood that the specific embodiments described here are only used to explain the utility model, and are not intended to limit the utility model.

The utility model provides a heat recovery system.

Referring to Fig. 2, Fig. 2 is a schematic diagram of the system connection of the first embodiment of the present utility model.

In this utility model embodiment, the heat recovery system includes an air conditioning system 100, a total heat recovery hot water system 200, and a solar water heater system 300. The air conditioning system 100 includes a compressor 110, an oil separator 120, a first four A through valve 130, a second four-way valve 140, a first heat exchanger 170, a second heat exchanger 180 and a gas-liquid separator 190, the first heat exchanger 170 is provided with a first water inlet 171 and a first A water outlet 172, a second water inlet 181 and a second water outlet 182 are provided on the second heat exchanger 180; the total heat recovery hot water system 200 includes a The third heat exchanger 210, the third heat exchanger 210 is provided with a third water inlet 211 and a third water outlet 212; the solar water heater system 300 includes a solar heat collector 310, the solar heat collector It has a fourth water inlet 311 and a fourth water outlet 312 .

The first water inlet 171 communicates with the second water outlet 182 and the third water outlet 212 respectively, and the first water outlet 172 communicates with the fourth water inlet 311; the fourth water outlet 312 communicates with the fourth water outlet 312 respectively. The second water inlet 181 and the third water inlet 211 are connected; and a first solenoid valve 002 is provided between the third water inlet 211 and the fourth water outlet 312 , and the fourth water outlet 312 A second solenoid valve 004 is provided between the second water inlet 181, and the first solenoid valve 002 and the second solenoid valve 004 are opened or closed according to different operation modes of the heat recovery system.

When the first solenoid valve 002 is opened and the second solenoid valve 004 is closed, at this time, the solar water heater system 300 operates, the solar heat collector 310 heats the water flowing through, and the heated hot water flows from the fourth water outlet 312 outflow, through the first electromagnetic valve 002 to the third water inlet 211 of the third heat exchanger 210, mixed with the water in the original water storage tank 220, and after exchanging heat with the refrigerant in the third heat exchanger 210, the The water outlet of the third heat exchanger 210 flows out, flows to the first water inlet 171 of the first heat exchanger 170, exchanges heat with the refrigerant in the first heat exchanger 170, flows out from the first water outlet 172, and Back to the fourth water inlet 311 of the solar water heater system 300 to form a hot water heating cycle. Through this cycle, the temperature of hot water in the total heat recovery hot water system 200 can be increased, thereby accelerating the hot water heating process of the third heat exchanger 210, reducing the time of hot water heating, saving energy and electricity, and having high economical efficiency At the same time, the first heat exchanger 170 is an outdoor heat exchanger, preferably a finned heat exchanger. The hot water in this cycle can also prevent the first heat exchanger 170 from frosting and keep the unit running stably.

When the first solenoid valve 002 is closed and the second solenoid valve 004 is opened, at this time, the solar collector 310 heats the water flowing through, and the heated hot water flows out from the fourth water outlet 312 and passes through the second solenoid valve 004. Flow to the second water inlet 181 of the second heat exchanger 180, mix with the original water in the second heat exchanger 180, and exchange heat with the refrigerant in the second heat exchanger 180. The water outlet flows out, flows to the first water inlet 171 of the first heat exchanger 170, exchanges heat with the refrigerant in the first heat exchanger 170, flows out from the first water outlet 172, and returns to the solar water heater The fourth water inlet 311 of the system 300 forms a heating and hot water cycle. The second heat exchanger 180 is an indoor air-conditioning heat exchanger. Through this cycle, the water in the second heat exchanger 180 can be continuously heated, thereby accelerating the process of heating water in the second heat exchanger 180, reducing The hot water heating time saves energy and electricity, and ensures that the hot water in the second heat exchanger 180 can fully exchange heat with the refrigerant, which is very economical; at the same time, the hot water in this cycle can also prevent the first heat exchanger from 170 frost, keep the unit running stably.

Further, a third solenoid valve 001 is provided between the first water inlet 171 and the third water outlet 212 , and a third electromagnetic valve 001 is provided between the first water inlet 171 and the second water outlet 182 . Four solenoid valves 003 , the opening or closing state of the third solenoid valve 001 is consistent with that of the first solenoid valve 002 , and the opening or closing state of the fourth solenoid valve 003 is consistent with that of the second solenoid valve 004 .

Further, when the heat recovery system operates in cooling mode, the first solenoid valve 002, the third solenoid valve 001, the second solenoid valve 004, and the fourth solenoid valve 003 are closed.

Specifically, the refrigerant regulating device includes a liquid reservoir 150 and a thermal expansion valve 160. During the operation of the air conditioning system 100, refrigerant flows in from the liquid reservoir 150 and flows out from the thermal expansion valve 160; and Between the first heat exchanger 170 and the liquid reservoir 150, a first one-way valve 005 and a second one-way valve 006 that flow to the liquid reservoir 150 are sequentially provided. 180 and the liquid reservoir 150 are sequentially provided with a third one-way valve 009 and a fourth one-way valve 010 flowing to the liquid reservoir 150, between the thermal expansion valve 160 and the first heat exchanger 170 are sequentially provided with a fifth one-way valve 011 and a fifth solenoid valve 012 that flow to the first heat exchanger 170, and between the thermal expansion valve 160 and the second heat exchanger 180 are sequentially provided that flow to the first heat exchanger 170. The sixth one-way valve 007 and the sixth solenoid valve 008 of the second heat exchanger 180 are provided with a seventh check valve flowing to the liquid reservoir 150 between the third heat exchanger 210 and the liquid reservoir 150. to valve 013.

Moreover, the first heat exchanger 170 is also provided with a first refrigerant port 173 and a second refrigerant port 174, and the second heat exchanger 180 is also provided with a third refrigerant port 183 and a fourth refrigerant port 184, and the third heat exchanger 180 is also provided with a third refrigerant port 183 and a fourth refrigerant port 184. The heater 210 is further provided with a fifth refrigerant port 213 and a sixth refrigerant port 214 .

When the heat recovery system is running in cooling mode, at this time, the sixth solenoid valve 008 is opened, the fifth solenoid valve 012 is closed, and the refrigerant flow direction is compressor 110→oil separator 120→first four-way valve 130→second four-way valve Through valve 140→first refrigerant port 173→second refrigerant port 174→first one-way valve 005→second one-way valve 006→liquid receiver 150→thermal expansion valve 160→sixth one-way valve 007→sixth electromagnetic Valve 008→third refrigerant port 183→fourth refrigerant port 184→first four-way valve 130→gas-liquid separator 190→compressor 110. In this mode, generally the external environment temperature is relatively high, and there is no need to heat water for the first heat exchanger 170 (ie, the outdoor heat exchanger), because the temperature of the first heat exchanger 170 itself is also high, and it is easy to use water if the water is added. The first heat exchanger 170 burns out; the heat exchange with the refrigerant in the second heat exchanger 180 (that is, the indoor heat exchanger) is cooling water, and the second heat exchanger 180 does not need to heat water, so the third solenoid valve 001, the first solenoid valve 002, the fourth solenoid valve 003 and the second solenoid valve 004 are all closed. At this time, neither the total heat recovery hot water system 200 nor the solar water heater system 300 is in operation.

Further, when the heat recovery system operates in the heating mode, the first solenoid valve 002 and the third solenoid valve 001 are closed, and the second solenoid valve 004 and the fourth solenoid valve 003 are opened.

When the heat recovery system is running in the heating mode, at this time, the sixth solenoid valve 008 is closed, the fifth solenoid valve 012 is opened, and the flow direction of the refrigerant is compressor 110→oil separator 120→first four-way valve 130→fourth Refrigerant port 184→third refrigerant port 183→third check valve 009→fourth check valve 010→liquid receiver 150→thermal expansion valve 160→fifth check valve 011→fifth solenoid valve 012→second refrigerant Port 174 →first refrigerant port 173 →second four-way valve 140 →gas-liquid separator 190 →compressor 110 . In this mode, generally the ambient temperature is low, and the first heat exchanger 170 (ie, the outdoor heat exchanger) is prone to frost, which affects the function of the first heat exchanger 170; in order to stabilize the first heat exchanger 170 At this time, the fourth solenoid valve 003 and the second solenoid valve 004 are opened, and the solar water heater system 300 communicates with the first heat exchanger 170 and the second heat exchanger 180 to form a water cycle, so that the first heat exchanger 170 can There is continuous hot water circulation, thereby effectively preventing the first heat exchanger 170 from frosting and maintaining the stable operation of the first heat exchanger 170; During the cycle, the solar water heater system 300 continues to heat the second heat exchanger 180, which greatly reduces the heating time of the second heat exchanger 180 and makes the heating effect more stable.

Further, when the heat recovery system operates in the hot water heating mode, the first solenoid valve 002 and the third solenoid valve 001 are opened, and the second solenoid valve 004 and the fourth solenoid valve 003 are closed.

When the heat recovery system is running in the hot water heating mode, at this time, the sixth solenoid valve 008 is closed, the fifth solenoid valve 012 is opened, and the flow direction of the refrigerant is compressor 110→oil separator 120→first four-way valve 130→second Two four-way valve 140→fifth refrigerant port 213→sixth refrigerant port 214→seventh one-way valve 013→liquid receiver 150→thermal expansion valve 160→fifth one-way valve 011→fifth solenoid valve 012→second Refrigerant port 174 →first refrigerant port 173 →second four-way valve 140 →gas-liquid separator 190 →compressor 110 .

Further, when the heat recovery system operates in cooling and hot water heating modes, the first solenoid valve 002 and the third solenoid valve 001 are opened, and the second solenoid valve 004 and the fourth solenoid valve 003 are closed.

When the heat recovery system is running in cooling and hot water heating mode, at this time, the sixth solenoid valve 008 is opened, the fifth solenoid valve 012 is closed, and the refrigerant flow direction is compressor 110 → oil separator 120 → first four-way valve 130 →Second four-way valve 140→Fifth refrigerant port 213→Sixth refrigerant port 214→Seventh one-way valve 013→Accumulator 150→Thermal expansion valve 160→Fifth one-way valve 011→Sixth solenoid valve 008→ Third refrigerant port 183→fourth refrigerant port 184→first four-way valve 130→gas-liquid separator 190→compressor 110. In this mode, in order to obtain high-temperature domestic hot water, the total heat recovery hot water system 200 starts to operate. At this time, the third solenoid valve 001 and the first solenoid valve 002 are opened, and the solar heat collector 310 convects the water flowing through it. Heating is carried out, and then sent to the third heat exchanger 210 for heat exchange with the refrigerant, which can greatly shorten the time for heating water in the third heat exchanger 210, improve the efficiency of heating water, and save energy and protect the environment. At the same time, the temperature of the external environment is generally low, and the first heat exchanger 170 (that is, the outdoor heat exchanger) is prone to frost. The water circulation makes the first heat exchanger 170 have continuous hot water circulation, thereby effectively preventing the first heat exchanger 170 from frosting, and also maintaining the stable operation of the first heat exchanger 170.

Further, the total heat recovery hot water system 200 also includes a water storage tank 220, and the water storage tank 220 communicates with the third water inlet 211 and the third water outlet 212 respectively; and hot water heating mode, the first solenoid valve 002 and the third solenoid valve 001 are opened, the second solenoid valve 004 and the fourth solenoid valve 003 are closed, when the temperature of the water storage tank 220 reaches the preset value , the first solenoid valve 002 and the third solenoid valve 001 are closed, and the second solenoid valve 004 and the fourth solenoid valve 003 are opened.

When the heat recovery system operates in the heating and hot water heating mode, at this time, the sixth solenoid valve 008 is closed, and the fifth solenoid valve 012 is opened. At this time, the heat recovery system gives priority to the hot water heating mode, and when the temperature of the hot water in the water storage tank 220 reaches a preset value, the heat recovery system automatically enters the heating mode.

The direction of refrigerant flow is compressor 110→oil separator 120→first four-way valve 130→second four-way valve 140→fifth refrigerant port 213→sixth refrigerant port 214→seventh one-way valve 013→accumulator 150 → thermal expansion valve 160 → fifth one-way valve 011 → fifth solenoid valve 012 → second refrigerant port 174 → first refrigerant port 173 → second four-way valve 140 → gas-liquid separator 190 → compressor 110; at this time , open the third solenoid valve 001 and the first solenoid valve 002, the solar water heater system 300 communicates with the first heat exchanger 170 and the third heat exchanger 210 to form a water cycle, and the solar heat collector 310 is used to conduct water flow through it. heating, and then sent to the third heat exchanger 210 to exchange heat with the refrigerant, which can greatly shorten the time for heating hot water in the third heat exchanger 210, so that the water temperature in the water storage tank 220 can quickly reach the preset value, prompting The system quickly enters heating mode.

In the heating mode, the refrigerant flow direction is compressor 110→oil separator 120→first four-way valve 130→fourth refrigerant port 184→third refrigerant port 183→third one-way valve 009→fourth one-way valve 010→storage Liquid tank 150→thermal expansion valve 160→fifth one-way valve 011→fifth solenoid valve 012→second refrigerant port 174→first refrigerant port 173→second four-way valve 140→gas-liquid separator 190→compressor 110 . At this time, open the fourth solenoid valve 003 and the second solenoid valve 004, the solar water heater system 300 communicates with the first heat exchanger 170 and the second heat exchanger 180 and forms a water cycle, so that the solar water heater system 300 The second heat exchanger 180 (that is, the indoor heat exchanger) continues to heat, which greatly reduces the time for the second heat exchanger 180 to heat water, so that the heating effect is stable.

During the whole operation process, the first heat exchanger 170 (that is, the outdoor heat exchanger) is always in the hot water circulation, thereby effectively preventing the first heat exchanger 170 from frosting and maintaining the stable operation of the first heat exchanger 170; In this mode, combined with the solar hot water system, it can not only generate stable heating capacity to meet the heating needs of users, but also use the total heat recovery hot water system 200 to recover heat for hot water heating and generate hot water with a higher temperature It can be used by users in daily life and has high economic benefits.

The above are only preferred embodiments of the present utility model, and are not intended to limit the patent scope of the present utility model. Any equivalent structure or equivalent process conversion made by using the description of the utility model and the contents of the accompanying drawings, or directly or indirectly used in other related All technical fields are all included in the scope of patent protection of the utility model in the same way.

Claims (10)

1. A heat recovery system, characterized in that the heat recovery system comprises an air conditioning system, a total heat recovery hot water system and a solar water heater system; The air conditioning system includes a compressor, an oil separator, a first four-way valve, a second four-way valve, a first heat exchanger, a refrigerant regulating device, a second heat exchanger, and a gas-liquid circuit that are connected in sequence to form a refrigerant circulation loop. A separator, the first heat exchanger is provided with a first water inlet and a first water outlet; the second heat exchanger is provided with a second water inlet and a second water outlet; The total heat recovery hot water system includes a third heat exchanger connected between the second four-way valve and the refrigerant regulating device, and the third heat exchanger is provided with a third water inlet and a third water outlet ; The solar water heater system includes a solar heat collector, and the solar heat collector has a fourth water inlet and a fourth water outlet; The first water inlet communicates with the second water outlet and the third water outlet respectively, the first water outlet communicates with the fourth water inlet; the fourth water outlet communicates with the second water inlet respectively , the third water inlet is connected; and a first solenoid valve is provided between the third water inlet and the fourth water outlet, and a first electromagnetic valve is provided between the fourth water outlet and the second water inlet. Two solenoid valves, the first solenoid valve and the second solenoid valve are opened or closed according to different operation modes of the heat recovery system. 2. The heat recovery system according to claim 1, wherein a third solenoid valve is provided between the first water inlet and the third water outlet, and a third solenoid valve is provided between the first water inlet and the third water outlet. A fourth solenoid valve is arranged between the second water outlets, the opening or closing state of the third solenoid valve is consistent with the opening or closing state of the first solenoid valve, and the opening or closing state of the fourth solenoid valve is consistent with the opening or closing state of the second solenoid valve. The state is consistent. 3. The heat recovery system according to claim 2, wherein when the heat recovery system operates in cooling mode, the first solenoid valve and the third solenoid valve, the second solenoid valve and the fourth solenoid valve The valve is closed. 4. The heat recovery system according to claim 2, wherein when the heat recovery system operates in heating mode, the first solenoid valve and the third solenoid valve are closed, and the second solenoid valve And the fourth electromagnetic valve is opened. 5. The heat recovery system according to claim 2, wherein when the heat recovery system operates in the hot water heating mode, the first solenoid valve and the third solenoid valve are opened, and the second solenoid valve valve and the fourth solenoid valve are closed. 6. The heat recovery system according to claim 2, wherein when the heat recovery system operates in cooling and hot water heating modes, the first solenoid valve and the third solenoid valve are opened, and the second solenoid valve is opened. The second solenoid valve and the fourth solenoid valve are closed. 7. The heat recovery system according to claim 2, wherein the total heat recovery hot water system further comprises a water storage tank, and the water storage tank is connected to the third water inlet and the third water outlet respectively; When the heat recovery system operates in the heating and hot water heating modes, the first solenoid valve and the third solenoid valve are opened, the second solenoid valve and the fourth solenoid valve are closed, and when the temperature of the water storage tank When the preset value is reached, the first solenoid valve and the third solenoid valve are closed, and the second solenoid valve and the fourth solenoid valve are opened. 8. The heat recovery system according to claim 1, wherein the refrigerant regulating device includes a liquid reservoir and a thermal expansion valve, and during the operation of the air conditioning system, the refrigerant flows in from the liquid reservoir and from The thermal expansion valve flows out; and between the first heat exchanger and the liquid reservoir, a first one-way valve and a second one-way valve flowing to the liquid reservoir are sequentially provided, and in the first Between the second heat exchanger and the liquid reservoir, a third one-way valve and a fourth one-way valve flowing to the liquid reservoir are sequentially provided, and between the thermal expansion valve and the first heat exchanger A fifth one-way valve and a fifth solenoid valve that flow to the first heat exchanger are sequentially provided, and a sixth one-way valve that flows to the second heat exchanger is sequentially provided between the thermal expansion valve and the second heat exchanger. A directional valve and a sixth electromagnetic valve, and a seventh one-way valve flowing to the liquid reservoir is provided between the third heat exchanger and the liquid reservoir. 9. The heat recovery system according to claim 8, wherein when the heat recovery system operates in heating mode, hot water mode, heating and hot water mode, the fifth solenoid valve Open; when the heat recovery system operates in cooling mode, cooling and hot water heating mode, the fifth solenoid valve is closed. 10. The heat recovery system according to claim 8, characterized in that, when the heat recovery system operates in cooling mode, cooling and hot water mode, the sixth solenoid valve is opened; When the system operates in heating mode, hot water heating mode, heating and hot water heating mode, the sixth electromagnetic valve is closed.