CN211781362U

CN211781362U - Heating system

Info

Publication number: CN211781362U
Application number: CN202020477701.5U
Authority: CN
Inventors: 王文星; 孙立宏
Original assignee: Suzhou Manenergy Energy Saving Technology Co ltd
Current assignee: Suzhou Manenergy Energy Saving Technology Co ltd
Priority date: 2020-04-03
Filing date: 2020-04-03
Publication date: 2020-10-27
Anticipated expiration: 2030-04-03

Abstract

The utility model discloses a heating system, at least a set of muddy water unit connects on heating system's the person in charge net, mixes water unit once the side delivery pipe, once the wet return and be connected with main delivery pipe, main wet return respectively, is provided with the heat source circulating pump on heat source and the main wet return of mixing between the water unit, sets up the switching-over solenoid valve in at least a set of muddy water unit. The water mixing units are arranged in parallel, so that each user side can independently operate and control the required heating temperature, the user sides cannot be influenced mutually, and the user experience is better. The reversing electromagnetic valve is switched between two working states S1 and S2 at fixed frequency or automatically switched according to the indoor temperature of a user, the direction of water flow is switched through a certain frequency, so that the heating effect of high-rise users and low-rise users is the same, in a special time period, if no person is in the high-rise of an office building at night, the number of people on duty at the bottom is large, the direction of water flow can be switched, the mode of heating for supplying and returning the water under the whole building is changed, and the energy consumption is greatly reduced.

Description

Heating system

Technical Field

The utility model belongs to the technical field of central heating system technique and specifically relates to a heating system.

Background

The central heating is a method of supplying heat required for production, heating and life of a city (town) or a partial area with steam and hot water generated from a central heat source through a pipe network. The heat source and the heat dissipation equipment of the central heating system are respectively arranged and connected by a heat medium pipe network, and one heat source supplies heat to each room or each building through a conveying pipeline and the pipe network, so that the central heating system can be used for central heating of occasions such as residential communities, office buildings, factories, restaurants, markets, movie theaters and the like.

A plurality of traditional communities and office buildings in northern China adopt series connection type central heating of upper and lower single pipes, the industry refers to single pipe heating, namely, a heat source enters an upper pipeline of a floor along a water supply pipe, enters a high-rise user in a series mode and then enters a low-rise user, and is discharged from a lower pipeline after heat is exchanged, so that the indoor temperature of the high-rise user is generally hot, and energy is wasted when a window is opened; the indoor temperature of low-level users is low, the complaint rate is high, the upper and lower heating is unbalanced, and in order to reach the standard of the low-level heating quality, the high-level users are inevitably overheated, so that a large amount of energy is wasted; and office building upper floor nobody official working night, but the floor is very low on duty personnel's on duty heating temperature and can not be guaranteed again, and the useless waste heat supply resource causes a large amount of heat wastes. In addition, because the central heating system can not adjust the flow rate in the pipeline, the proper heating amount can not be selected according to the indoor temperature, the different temperature requirements of each user can not be met, and the control mode is single.

SUMMERY OF THE UTILITY MODEL

The applicant provides a heating system rational in infrastructure to the unbalanced heating of above-mentioned current heating system height, low floor, can't satisfy only need guarantee low floor value class room heat supply night, shortcoming such as the energy is extravagant, simple structure, and automatic operation can the fine management improve the heating quality, satisfies user's actual demand, and improves heating efficiency greatly.

The utility model discloses technical scheme and beneficial effect who adopts as follows:

a heating system is characterized in that at least one group of water mixing units are connected to a main pipe network of the heating system, a primary side water supply pipe and a primary side water return pipe of each water mixing unit are respectively connected with a main water supply pipe and a main water return pipe, a heat source circulating pump is arranged on the main water return pipe between a heat source and the water mixing units, and a reversing electromagnetic valve is arranged in at least one group of water mixing units.

In the whole heating system, part of users or all users can use the water mixing unit, and the actual requirements of different users are met. The water mixing units are arranged in parallel, so that each user side can independently operate and control the required heating temperature, the user sides cannot be influenced mutually, and the user experience is better. The reversing electromagnetic valve can be switched between two working states S1 and S2 at a fixed frequency or automatically switched according to the indoor temperature of a user, when the reversing electromagnetic valve is in an S1 working state, the direction of water flow in a user side pipe network is opposite to the direction of water flow in an S2 working state, according to actual needs, the direction of water flow is switched through a certain frequency, so that the heating effects obtained by high-rise users and low-rise users are the same, the switching of the direction of water flow in the pipeline can be realized without adding a pipeline and a plurality of electromagnetic valves, the structure is simpler, in the old heating system modification process, only a water mixing unit with variable water supply and return needs to be connected to a water supply and return pipeline of a building, the modification cost is low, and the operability is stronger.

As a further improvement of the above technical solution:

the reversing solenoid valve is a three-position four-way solenoid valve. The four-way valve branch of the three-position four-way electromagnetic valve is opened and closed in a linkage manner, and the communication states of S1 and S2 are controlled in a linkage manner, so that the problem that heating cannot be realized due to misoperation of personnel is solved. The three-position four-way electromagnetic valve also has an S3 working state, and when a certain water mixing unit needs to be overhauled and maintained, meets emergency or does not need heating, the working state can be switched to an S3 working state, and the heating of the user side corresponding to the water mixing unit is cut off.

And a main pipe network check valve is also arranged on the main water return pipe of the heat source and the heat source circulating pump. The main network check valve prevents backflow of hot water within the heat source.

A main pipe network balance pipe is arranged between the main water return pipe and the water supply pipe; one end of the main pipe network balance pipe is positioned between the heat source circulating pump and the water mixing unit, and the other end of the main pipe network balance pipe is positioned between the heat source and the water mixing unit. The main pipe network balance pipe realizes the water mixing function of the main pipe network and plays the roles of flow balancing and coupling.

A user pipe network balance pipe is connected between the joint of a primary side water supply pipe and a secondary side water supply pipe of the module A of the water mixing unit and the joint of a primary side water return pipe and a secondary side water return pipe; the upper pipe of the module B is sequentially connected with a high-level user, a low-level user and a lower pipe; a reversing solenoid valve is connected between the module A and the module B; the secondary side water supply pipe and the secondary side water return pipe are respectively communicated with the upper pipe and the lower pipe alternatively under different working states of the reversing solenoid valve.

An electric regulating valve is arranged on a primary side water return pipe of part or all of the water mixing units, and a main pipe circulating pump is arranged on a main water supply pipe between a heat source and the water mixing units. The aperture of the electric control valve can be controlled to change the water mixing coefficient of the user side, the water mixing amount of the system is adjusted, the water supply temperature of the secondary side water supply pipe is changed, and the purpose of controlling the heat supply amount of the user side can be realized by matching with the speed regulation of the user side circulating pump. Along with the change of outdoor temperature, the electric control valve can carry out corresponding adjustment, ensures that the water supply quantity of the main pipe network can just balance the heat loss of the user side.

A first temperature sensor, a second temperature sensor, a third temperature sensor and a fourth temperature sensor are sequentially arranged on the primary side water supply pipe, the secondary side water return pipe and the primary side water return pipe; when the temperature T1 measured by the primary side water supply pipe is equal to the temperature T2 measured by the secondary side water supply pipe, and the temperature T3 measured by the secondary side water return pipe is less than the temperature T4 measured by the primary side water return pipe, the water supply frequency of the water supply pipe is reduced. When T1 is T2 and T3 is less than T4, it indicates that hot water in the primary-side water supply pipe flows into the primary-side water return pipe, mixes with user-side return water, and enters the main heat source pipe, and at this time, the hot water obtained by the water mixing unit from the main heat source pipe is too much, so that heat energy cannot be fully utilized, and the water supply frequency of the primary-side pipe network circulating pump is reduced, thereby saving more energy in the system. In addition, a relation with a water mixing coefficient in a user pipe network balance pipe can be established according to the difference value delta T between T1 and T2 and between T3 and T4, so that the heating temperature of the user side can be accurately adjusted.

A primary side pipe network circulating pump is arranged on a primary side water supply pipe or a primary side water return pipe of part or all of the water mixing units. The speed of the primary side pipe network circulating pump is controlled to change the water mixing coefficient of the user side, the water mixing amount of the system is adjusted, the water supply temperature of the secondary side water supply pipe is changed, and the purpose of controlling the heat supply amount of the user side can be achieved by matching the speed regulation of the user side circulating pump. Along with the change of outdoor temperature, the primary side pipe network circulating pump can carry out corresponding adjustment, ensures that the water supply of the main pipe network can just balance the heat loss of the user side.

And a user side circulating pump is arranged on the secondary side water return pipe or the secondary side water supply pipe. The user side circulating pump provides the resource pressure of the user side, and when the outdoor temperature changes, the flow regulation of the user side pipeline can be realized through the speed regulation of the user side circulating pump, so that the heat supply amount of the user side is controlled.

A pressure sensor is arranged on the secondary side water return pipe; a user pipe network check valve is arranged on the primary side water return pipe. Pressure sensor can monitor the terminal fluid water pressure that flows of user side, and the relation of terminal pressure and indoor heating effect is out through data contrast directly perceived reaction to establish the database of liquid pressure and heating effect in the pipeline, make things convenient for the later stage to adjust and control indoor heating effect better. A user pipe network check valve is arranged on the primary side water return pipe, water flow can only flow outwards from the water mixing unit, and cold water in the main pipe network can be prevented from flowing into the water mixing unit in a reverse flow mode.

Drawings

Fig. 1 is a schematic structural diagram of the water mixing unit of the present invention.

Fig. 2 is a schematic view of the water mixing unit in fig. 1 in an S1 working state.

Fig. 3 is a schematic view of the water mixing unit in fig. 1 in an S2 working state.

Fig. 4 is a schematic structural diagram of the heating system of the present invention.

In the figure: 1. a primary side pipe network circulating pump; 2. a first temperature sensor; 3. a primary-side water supply pipe; 4. a user pipe network balance pipe; 5. a third temperature sensor; 6. a pressure sensor; 7. a user pipe network check valve; 8. a primary side water return pipe; 9. a secondary side water return pipe; 10. a user side circulation pump; 11. a control unit; 12. a secondary side water supply pipe; 13. a second temperature sensor; 14. a three-position four-way electromagnetic valve; 15. an upper pipe; 16. a lower pipe; 17. a high-level user; 18. a low-level user; 19. an electric control valve; 20. a heat source; 21. a main pipe network check valve; 22. a heat source circulating pump; 23. a main pipe network balance pipe; 24. a main water supply pipe; 25. a primary water return pipe; 26. a main pipe circulation pump; 27. a fourth temperature sensor; 28. a primary side pipe network circulating pump frequency converter; 29. and a user side circulating pump frequency converter.

Detailed Description

The following describes embodiments of the present invention with reference to the drawings.

As shown in fig. 1 and 4, the water mixing unit of the present invention includes a module a near the heat source side and a module B near the user side, wherein the module a realizes the water mixing function. One end of a primary water supply pipe 3 of the module A is connected with a main water supply pipe 24 to input hot water in a heat source pipeline, the other end is connected with a secondary water supply pipe 12, the secondary water supply pipe 12 is connected with an upper pipe 15 of the module B, one end of a secondary water return pipe 9 is connected with a lower pipe 16 of the module B, and the other end is sequentially connected with a primary water return pipe 8 and a main water return pipe 25. The upper pipe 15 of the B module is connected in sequence with a higher level user 17, a lower level user 18 and a lower pipe 16. The primary side pipe network circulating pump 1 is arranged on the primary side water supply pipe 3, the electric regulating valve 19 can be used for replacing the primary side pipe network circulating pump 1 in other embodiments, and when the outdoor temperature is increased or reduced, the primary side flow can be changed by regulating the speed of the primary side pipe network circulating pump 1 or the opening degree of the electric regulating valve 19, so that the purpose of adjusting the water mixing coefficient is achieved.

A user pipe network balance pipe 4 is connected between the joint of a primary side water supply pipe 3 and a secondary side water supply pipe 12 and the joint of a primary side water return pipe 8 and a secondary side water return pipe 9, when the user side is actively adjusted, the pressure in a user side pipe network changes, the user pipe network balance pipe 4 can maintain the flow balance between the water supply pipe and the water return pipe, the pressure of the whole main pipe network is guaranteed to be unchanged, and the heating pressure of other user sides cannot be influenced.

As shown in fig. 1, a user side circulating pump 10 and a pressure sensor 6 are further arranged on the secondary side water return pipe 9, the pressure sensor 6 can monitor the fluid water pressure flowing out from the end of the user side, on one hand, whether water leakage exists in the user side can be judged through pressure abnormity, on the other hand, the relation between the end pressure and the indoor heating effect is directly reflected through data comparison, so that a database of the liquid pressure and the heating effect in the pipeline is established, and intelligent adjustment is facilitated. The user side circulating pump 10 provides the resource pressure of the user side, and realizes the flow regulation of the user side, so that the heating temperature of the user side is changed, the actual heat supply required by the user is achieved, and meanwhile, the water supply quantity of the water supply pipe can be ensured to just balance the heat loss of the water mixing unit; when the outdoor temperature changes, the flow regulation of the user side pipeline can be realized through the speed regulation of the user side circulating pump 10, so that the heat supply quantity of the user side is controlled.

As shown in fig. 1, a first temperature sensor 2, a second temperature sensor 13, a third temperature sensor 5 and a fourth temperature sensor 27 are sequentially arranged on the primary water supply pipe 3, the secondary water supply pipe 12, the secondary water return pipe 9 and the primary water return pipe 8, a water supply temperature T1 from the main heat source pipe, a temperature T2 actually supplied to a user side, a user side end outlet water temperature T3 and an outlet water temperature T4 flowing into the main heat source pipe are respectively monitored, the direction of fluid in the water mixing unit can be judged according to T1 and T2 and a difference Δ T between T3 and T4, and when water mixing occurs in the user pipe network balance pipe 4, the four temperatures are changed. When T1 = T2 and T3= T4, it indicates that no mixing of the user pipe network balance pipe 4 occurs. When T1> T2, T3= T4, it indicates that part of the cold water in the secondary-side water return pipe 9 flows into the secondary-side water supply pipe 12 to be mixed with the hot water, and the system is in a normal operation state. And determining the water mixing coefficient in the balance pipe according to the secondary water supply temperature T2 or the secondary side water return temperature T3 or the indoor heating temperature of the user side so as to ensure that the heating temperature of the user side is in an optimal state. When T1 is T2 and T3 is less than T4, it indicates that the hot water in the primary-side water supply pipe 3 flows into the primary-side water return pipe 8, mixes with the user-side return water, and enters the main heat source pipe, and at this time, the hot water obtained by the water mixing unit from the main heat source pipe is too much, so that the heat energy cannot be fully utilized, and the water supply frequency of the primary-side pipe network circulating pump is reduced, thereby saving more energy in the system. And reducing the water supply frequency of the primary side pipe network circulating pump 1 to T3= T4, so that the system is in the most energy-saving state. In addition, a relation with the water mixing coefficient in the user pipe network balance pipe 4 can be established according to the difference value delta T between T1 and T2 and between T3 and T4, so that the heating temperature of the user side can be accurately adjusted.

As shown in fig. 1, a user pipe network check valve 7 is disposed on the primary side water return pipe 8, so that water flow can only flow out from the water mixing unit, and cold water in the main pipe network can be prevented from flowing back into the water mixing unit. The primary side pipe network circulating pump 1 and the user side circulating pump 10 are respectively connected with the control unit 11 through a primary side pipe network circulating pump frequency converter 28 and a user side circulating pump frequency converter 29, the first temperature sensor 2, the second temperature sensor 13, the pressure sensor 6, the third temperature sensor 5 and the fourth temperature sensor 27, the control center is connected with the control unit 11 through data fed back by the temperature sensors and the pressure sensors 6 for analysis and processing, control signals are fed back to the control unit 11, the control unit 11 sends control signals to the frequency converters of the primary side pipe network circulating pump 1 and the user side circulating pump 10 again, the lift and the flow of the water pump are changed by controlling the operating frequency of the water pump, the fine management of the water pump is realized by collecting and analyzing temperature and pressure data in a pipeline, on one hand, the water supply or air supply flow at higher temperature can be reduced according to the temperature data, increase water supply or air feed flow when the temperature is lower, improve heating quality, reach energy-conserving purpose, on the other hand can realize remote control, and the user can satisfy more users' demand according to actual need initiative control water pump flow.

As shown in fig. 1, a three-position four-way electromagnetic valve 14 is connected between a module a and a module B of the water mixer set, the three-position four-way electromagnetic valve 14 is connected with a control unit 11, and the control unit 11 receives an instruction from a control center, so that the three-position four-way electromagnetic valve is switched between two working states S1 and S2 at a fixed frequency or automatically switched according to the indoor temperature of a user. When the three-position four-way electromagnetic valve 14 is in the S1 working state, the water flow direction in the user-side pipe network is opposite to the flow direction in the S2 working state, and the water flow direction is switched at a certain frequency according to actual needs, so that the heating effects of the high-level users 17 and the low-level users 18 are the same, the switching of the water flow direction in the pipe can be realized without adding pipes and a plurality of electromagnetic valves, and the structure is simpler. In the existing old heating system transformation process, the water mixing unit is only required to be connected to the building entering water supply and return pipeline of a user building, the transformation cost is low, and the operability is strong. Under special circumstances, if no person is on the upper floor of office building at night, the heating is switched to supply heat from downstairs to the upper floor, and the heat is supplied to the staff on duty on the first floor as much as possible, so that a better heating target can be realized by adopting low flow, the energy consumption is greatly reduced, and the heating efficiency is improved.

As shown in fig. 4, a plurality of sets of water mixing units of the heating system of the present invention are connected in parallel to the main pipe network of the heating system, the primary water supply pipe 3 and the primary water return pipe 8 of each set of water mixing units are respectively connected to the main water supply pipe 24 and the main water return pipe 25, as shown in the second and third sets of water mixing units in fig. 4, the water mixing units in fig. 1 can be used, as shown in the first set of water mixing units in fig. 4, the electric control valve 19 can also be used to replace the primary pipe network circulation pump 1 on the primary water supply pipe 3, and at this time, the main pipe circulation pump 26 is required to be disposed on the main water supply pipe 24 between the heat source 20 and the water mixing units to provide the pipeline pressure from; a main pipe network check valve 21 and a heat source circulation pump 22 are sequentially provided in the main water return pipe 25 between the heat source 20 and the water mixing unit, and the main pipe network check valve 21 prevents the hot water in the heat source 20 from flowing backward. A main pipe network balance pipe 23 is provided between the main water return pipe 25 and the water supply pipe 24, one end of the main pipe network balance pipe 23 is positioned between the heat source circulation pump 22 and the water mixing unit, and the other end is positioned between the heat source 20 and the main pipe network circulation pump 26. The heat source circulating pump 22 is mainly used for providing pipeline pressure between the main pipe network balance pipe 23 and the heat source 20, and the main pipe network balance pipe 23 achieves the main pipe network water mixing function and plays roles in balancing flow and coupling. Three-position four-way electromagnetic valves 14 are arranged in part or all of the water mixing units in a heating system, so that the heating requirements of different users can be met; the water mixing units are arranged in parallel, so that each user side can independently operate and control the required heating temperature, the user sides cannot be influenced mutually, and the user experience is better.

The utility model discloses a muddy water unit during operation, as shown in FIG. 2, under S1 operating condition, heat source pipeline 'S hot water or steam get into once and incline delivery pipe 3, secondary side delivery pipe 12 back go into tribit four-way solenoid valve 14, in certain duty cycle, tribit four-way solenoid valve 14 switches on secondary side delivery pipe 12 and upper portion pipe 15 and secondary side wet return 9 and lower part pipe 16, so secondary side delivery pipe 12' S rivers get into upper portion pipe 15, get into indoor heat supply from high-rise user 17, flow to and follow lower part pipe 16 after low-rise user 18 in proper order, secondary side wet return 9, once incline wet return 8 and arrange into the main network wet return. As shown in fig. 3, in the operating state of S2, when the three-position four-way solenoid valve 14 is switched to connect the secondary-side water supply pipe 12 and the lower pipe 16 and the secondary-side water return pipe 9 and the upper pipe 15, hot water or hot gas in the heat source pipeline sequentially enters the primary-side water supply pipe 3, the secondary-side water supply pipe 12, and the lower pipe 16, the heat source 20 flows upward from the lower users 18 to the upper users 17, and then is sequentially discharged from the upper pipe 15, the secondary-side water return pipe 9, and the primary-side water return pipe 8 to the main pipe network water return pipe. The three-position four-way electromagnetic valve 14 also has an S3 working state, and when a certain water mixing unit needs to be overhauled and maintained, meets an emergency or does not need to be heated, the working state can be switched to an S3 working state, and heating of a user side corresponding to the water mixing unit is cut off. Three-position four-way solenoid valve 14 makes the utility model discloses can simply control can realize switching the heat source 20 flow direction in the change pipeline, make the heating of user side more balanced, also can be according to actual need, do not have one's in office building upper portion floor night, switch to from downstairs up to the upper portion heat supply, the personnel on duty heat supply of as far as possible one-storied building adopts the low flow to realize better heating target like this, greatly reduced the energy consumption, the heating efficiency who has improved. The four-way valve branch of the three-position four-way electromagnetic valve 14 is opened and closed in an interlocking manner, and the communication states of S1 and S2 are controlled in an interlocking manner, so that the problem that heating cannot be performed due to misoperation of personnel is solved.

The above description is illustrative of the present invention and is not intended to limit the present invention, and the present invention may be modified in any manner without departing from the spirit of the present invention. For example, the primary-side pipe network circulation pump 1 may be provided in the primary-side water return pipe 8 as needed, and the user-side circulation pump 10 may be provided in the secondary-side water supply pipe 12. The three-position four-way solenoid valve 14 can be a two-position four-way solenoid valve or a three-position five-way solenoid valve which is forbidden to use after one position is removed, and the purpose of the utility model can be realized by alternately communicating the reversing solenoid valves with the upper pipe 15 and the lower pipe 16 respectively under different working states.

Claims

1. A heating system, characterized in that: at least one group of water mixing units are connected to a main pipe network of the heating system, a primary side water supply pipe (3) and a primary side water return pipe (8) of each water mixing unit are respectively connected with a main water supply pipe (24) and a main water return pipe (25), a heat source circulating pump (22) is arranged on the main water return pipe (25) between a heat source (20) and the water mixing units, and reversing electromagnetic valves are arranged in the at least one group of water mixing units.

2. The heating system of claim 1, wherein: the reversing electromagnetic valve is a three-position four-way electromagnetic valve (14).

3. The heating system of claim 1, wherein: a main pipe network check valve (21) is also arranged on the main water return pipe (25) of the heat source (20) and the heat source circulating pump (22).

4. The heating system of claim 1, wherein: a main pipe network balance pipe (23) is arranged between the main water return pipe (25) and the water supply pipe (24); one end of the main pipe network balance pipe (23) is positioned between the heat source circulating pump (22) and the water mixing unit, and the other end is positioned between the heat source (20) and the water mixing unit.

5. The heating system of claim 1, wherein: a user pipe network balance pipe (4) is connected between the joint of a primary side water supply pipe (3) and a secondary side water supply pipe (12) of the module A of the water mixing unit and the joint of a primary side water return pipe (8) and a secondary side water return pipe (9); an upper pipe (15) of the module B is sequentially connected with a high-level user (17), a low-level user (18) and a lower pipe (16); a reversing solenoid valve is connected between the module A and the module B; the secondary side water supply pipe (12) and the secondary side water return pipe (9) are respectively communicated with the upper pipe (15) and the lower pipe (16) alternately under different working states of the reversing solenoid valve.

6. The heating system of claim 1, wherein: an electric control valve (19) is arranged on a primary side water return pipe (8) of part or all of the water mixing units, and a main pipe circulating pump (26) is arranged on a main water supply pipe (24) between a heat source (20) and the water mixing units.

7. The heating system according to claim 5, wherein: a first temperature sensor (2), a second temperature sensor (13), a third temperature sensor (5) and a fourth temperature sensor (27) are sequentially arranged on the primary side water supply pipe (3), the secondary side water supply pipe (12), the secondary side water return pipe (9) and the primary side water return pipe (8); when the temperature T1 measured by the primary water supply pipe (3) is equal to the temperature T2 measured by the secondary water supply pipe (12), and the temperature T3 measured by the secondary water return pipe (9) is less than the temperature T4 measured by the primary water return pipe (8), the water supply frequency of the water supply pipe is reduced.

8. The heating system of claim 1, wherein: a primary side pipe network circulating pump (1) is arranged on a primary side water supply pipe (3) or a primary side water return pipe (8) of part or all of the water mixing units.

9. The heating system according to claim 5, wherein: a user side circulation pump (10) is provided on the secondary side return pipe (9) or the secondary side water supply pipe (12).

10. The heating system according to claim 5, wherein: a pressure sensor (6) is arranged on the secondary side water return pipe (9); a user pipe network check valve (7) is arranged on the primary side water return pipe (8).