CN109059280B

CN109059280B - Heat pump hot water system and control method thereof

Info

Publication number: CN109059280B
Application number: CN201810763510.2A
Authority: CN
Inventors: 李干春; 冯勇强; 罗金星; 高翔; 王俊
Original assignee: Guangdong PHNIX Eco Energy Solution Ltd
Current assignee: Guangdong PHNIX Eco Energy Solution Ltd
Priority date: 2018-07-11
Filing date: 2018-07-11
Publication date: 2021-01-19
Anticipated expiration: 2038-07-11
Also published as: CN109059280A

Abstract

The invention discloses a heat pump hot water system and a control method thereof, wherein the system comprises a controller, a heat pump unit, a water storage tank and a water supply pipeline; the first water outlet end of the water storage tank is communicated with the water inlet end of the heat pump unit to form a first pipeline, and the water storage tank is communicated with the water outlet end of the heat pump unit to form a second pipeline; the water storage tank, the first pipeline, the heat pump unit and the second pipeline are sequentially connected to form a circulating heating loop, and the water supply pipeline, the first pipeline, the heat pump unit and the water storage tank are sequentially connected to form a direct heating loop; the water supply pipeline is provided with a water supply pump, a first electromagnetic two-way valve, a flow sensor and a second electromagnetic two-way valve which are sequentially connected in series, and the first pipeline is provided with a circulating water pump electrically connected with the controller. The embodiment of the invention can effectively realize the integration of the circulating type and the directly-heated type heating modes of the heat pump water heater, and improve the hot water supply capacity of the heat pump water heater, thereby being beneficial to improving the use comfort of users.

Description

Heat pump hot water system and control method thereof

Technical Field

The invention relates to the technical field of heat pump water heaters, in particular to a heat pump hot water system and a control method thereof.

Background

At present, a heat pump water heater adopts a heat pump principle to lift heat energy in air to high-level heat energy, has the advantages of energy conservation and environmental protection when being used for preparing hot water, and is gradually widely applied. According to the heat supply mode of the heat pump water heater, the heat pump water heater is divided into a circulating water heater and a directly-heated water heater.

The circulating water heater continuously pumps cold water at the bottom of the water storage tank to enter the heat pump unit for heating, hot water heated by the heat pump enters the top of the water storage tank through the water outlet pipeline, and a user pumps hot water from the inside of the water storage tank through the water using end for use; the direct-heating water heater directly heats water of a tap water supply system through the heat pump unit, and hot water is stored in the water storage tank for users to use.

However, due to the circulation heating mode of the circulation type water heater, the water with higher temperature heated by the heat pump unit can be mixed with the water with lower temperature at the bottom of the water storage tank after entering the water storage tank, so that the temperature of the water inside the water storage tank is reduced, the problem of low heating speed occurs, and the use comfort of a user is further influenced. When the demand of hot water is large, the direct-heating water heater can cause the phenomenon of insufficient hot water supply, cannot meet the demand of large-flow water during the water consumption peak period of a user, and can also influence the comfort level of the user.

Disclosure of Invention

The embodiment of the invention provides a heat pump hot water system and a control method thereof, aiming at solving the technical problems that the existing circulating water heater is low in heating speed and the direct-heating water heater is insufficient in hot water supply when the hot water demand is large, so that the integration of the circulating and direct-heating modes of the heat pump water heater is effectively realized, the hot water supply capacity of the heat pump water heater is improved, and the use comfort of a user is further improved.

In order to solve the technical problem, an embodiment of the present invention provides a heat pump hot water system, including a controller, a heat pump unit, a water storage tank and a water supply pipeline; the first water outlet end of the water storage tank is communicated with the water inlet end of the heat pump unit to form a first pipeline, the water inlet end of the water storage tank is communicated with the water outlet end of the heat pump unit to form a second pipeline, and the water outlet end of the water supply pipeline is connected to the first pipeline;

the water storage tank, the first pipeline, the heat pump unit and the second pipeline are sequentially connected to form a circulating heating loop, and the water supply pipeline, the first pipeline, the heat pump unit and the water storage tank are sequentially connected to form a direct heating loop;

the water supply pipeline is provided with a water supply pump, a first electromagnetic two-way valve, a flow sensor and a second electromagnetic two-way valve which are sequentially connected in series and are respectively electrically connected with the controller, and the first pipeline is provided with a circulating water pump electrically connected with the controller; and a water level switch and a first temperature sensor which are respectively electrically connected with the controller are arranged in the water storage tank.

As a preferred scheme, the heat pump unit comprises a compressor, a four-way valve, a heat exchanger, a fan and a first electronic expansion valve which are respectively electrically connected with the controller;

an air outlet of the compressor is communicated with a D port of the four-way valve, a C port of the four-way valve is communicated with a first port of the heat exchanger, a second port of the heat exchanger is communicated with a first end of the first electronic expansion valve, a second port of the first electronic expansion valve is communicated with a first port of a fin heat exchanger where the fan is located, a second port of the fin heat exchanger where the fan is located is communicated with an E port of the four-way valve, and an S port of the four-way valve is communicated with an air return port of the compressor;

the water inlet of the heat exchanger is communicated with the water inlet end of the heat pump unit, and the water outlet of the heat exchanger is communicated with the water outlet end of the heat pump unit.

As a preferable scheme, the heat pump hot water system further comprises a water using end, a constant pressure water pump and a third electromagnetic two-way valve, a second water outlet end of the water storage tank is communicated with the water using end and a first end of the third electromagnetic two-way valve through the constant pressure water pump, and a second end of the third electromagnetic two-way valve is communicated with the water supply pipeline;

the water storage tank, the third electromagnetic two-way valve, the water supply pipeline, the first pipeline, the heat pump unit and the second pipeline are sequentially connected to form a hot water recovery loop.

In order to solve the same technical problem, an embodiment of the present invention further provides a control method for a heat pump hot water system, which is applicable to the heat pump hot water system described above, and includes the following steps:

when the heat pump hot water system operates, the heat pump unit is kept in an open state;

when the circulating heating mode is operated, a circulating water pump of the first pipeline is started, a valve of the water supply pipeline is kept in an opening state, and the current flow of the water supply pipeline is detected in real time;

when the current flow of the water supply pipeline is detected to be larger than the preset minimum flow, the circulating water pump is closed to switch to a direct heating type heating mode;

when the direct heating type heating mode is operated, opening a valve of the water supply pipeline and closing the circulating water pump;

and when the closing of the water level switch of the water storage tank is detected, the circulating water pump is started, and the valve of the water supply pipeline is closed or the opening degree of the valve of the water supply pipeline is reduced so as to switch to a circulating heating mode.

Preferably, after the step of keeping the heat pump unit in an on state when the heat pump hot water system is in operation, the method further includes:

when the water level switch is detected to be disconnected, the water storage tank is judged to be in a low water level state;

when the current hot water temperature value is smaller than a preset first target temperature value, switching to a circulating heating mode in a low water level state;

when the current hot water temperature value is greater than a preset first target temperature value, switching to a direct heating mode in a low water level state;

calculating the operation time of the direct heating mode when the direct heating mode is operated and the water storage tank keeps a low water level state;

when the running time of the direct heating type heating mode is greater than the preset first direct heating running time, judging whether the current hot water temperature value of the water storage tank is less than a preset second target temperature value or not, and if so, switching to the circulating type heating mode in a low water level state;

when the water level switch is detected to be closed, the water storage tank is judged to be in a high water level state;

when the current hot water temperature value is smaller than a preset third target temperature value, switching to a circulating heating mode in a high water level state; and the preset third target temperature value is the sum of the preset first target temperature value and a preset constant-temperature shutdown return difference value.

Preferably, the method further comprises:

when the circulating heating mode in the low water level state is operated, judging whether the current hot water temperature of the water storage tank is smaller than a preset fourth target temperature value or not; the preset fourth target temperature value is the difference between the preset first target temperature value and the direct heating mode switching return difference value;

if so, starting a compressor of the heat pump unit, starting the circulating water pump before a preset first starting time for starting the compressor, and starting a fan of the heat pump unit before a preset second starting time for starting the compressor;

when the circulating heating mode in the high water level state is operated, whether the heat pump hot water system meets a constant temperature shutdown condition is judged, if not, a compressor of the heat pump unit is started, the circulating water pump is started before the preset first starting time of the compressor, and a fan of the heat pump unit is started before the preset second starting time of the compressor.

Preferably, the method further comprises:

when the direct heating type heating mode is operated, when the water level switch is detected to be closed, the water storage tank is judged to be in a high water level state; or when the water level switch is detected to be closed, the water storage tank is judged to be in a high water level state; controlling the heat pump hot water system to switch from a direct heating mode to a circulating heating mode;

keeping a compressor and a fan of the heat pump unit in running states, and starting the circulating water pump;

detecting the state of a water flow switch on the second pipeline after the circulating water pump is started;

when the water flow switch is detected to be closed, closing a valve of the water supply pipeline after a preset third starting time after the circulating water pump is started;

when the water flow switch is detected to be switched off, starting to calculate the switching-off time of the water flow switch;

and when the off time of the water flow switch is equal to the preset first fault reporting time, fault reporting is carried out through fault reporting equipment.

Preferably, the method further comprises:

when the heat pump hot water system is started, when the current flow of the water supply pipeline is detected to be larger than the preset minimum flow, starting a direct heating type heating mode;

when the direct-heating type heating mode is operated, starting a compressor of the heat pump unit, and starting a fan of the heat pump unit and opening a valve of the water supply pipeline before a preset first starting time for starting the compressor;

after the running time of the direct heating type heating mode is judged to be greater than the first direct heating running time, whether the current hot water temperature of the water storage tank is smaller than a preset fourth target temperature value or not is judged, and if yes, the direct heating type heating mode is switched to the circulating type heating mode in a low water level state according to the disconnection of the water level switch; or the direct heating type heating mode is switched to the circulation type heating mode in the high water level state according to the closing of the water level switch.

Preferably, the method further comprises:

when the water level switch is detected to be closed, the water storage tank is judged to be in a high water level state, and the heating mode of the heat pump hot water system is a circulating heating mode in the high water level state;

when the heat pump unit is detected to be in a constant-temperature shutdown state, starting a compressor of the heat pump unit, and before a preset third starting time for starting the compressor of the heat pump unit, starting a fan of the heat pump unit and a valve of the water supply pipeline;

when the current flow of the water supply pipeline is detected to be larger than the preset minimum flow, the circulating water pump is closed, so that the circulating heating mode in the high water level state is switched to the direct heating type heating mode;

when the water level switch is detected to be turned off, the water storage tank is judged to be in a low water level state, and the heating mode of the heat pump hot water system is a circulating heating mode in the low water level state;

keeping a compressor, a fan and the circulating water pump of the heat pump unit in running states, and opening a valve of the water supply pipeline;

and when the current flow of the water supply pipeline is detected to be larger than the preset minimum flow, after a second closing time of closing a valve of the water supply pipeline, closing the circulating water pump so as to switch the circulating type heating mode in the low water level state to the direct heating type heating mode.

Preferably, the method further comprises:

when the heat pump unit is detected to be in a constant-temperature shutdown state, a compressor of the heat pump unit is started, a fan of the heat pump unit and a valve of the water supply pipeline are started before a preset third starting time for starting the compressor of the heat pump unit, and the circulating water pump is closed, so that a circulating heating mode in a high water level state is switched to a direct heating mode;

when the heat pump unit is detected to be in a non-constant temperature shutdown state, keeping a compressor and a fan of the heat pump unit in an operating state, and opening a valve of the water supply pipeline;

and when the current flow of the water supply pipeline is detected to be larger than the preset minimum flow, after the first closing time of closing the valve of the water supply pipeline, closing the circulating water pump so as to switch the circulating heating mode in the high water level state to the direct heating type heating mode.

Compared with the prior art, the embodiment of the invention has the following beneficial effects:

in this embodiment, the circulation-direct heat integrated heating function of the heat pump hot water system is realized through the circulation type heating loop and the direct heat type heating loop of the heat pump hot water system, so that the purpose of complementary advantages is achieved, the hot water supply capacity of the heat pump water heater is further improved, and the use comfort of a user is favorably improved.

The water inlet end of the water supply pipeline is communicated with an external water supply system, the water supply pipeline passes through the water supply pump and is the whole heat pump hot water system provides a water source, and water entering the heat pump hot water system through the water supply pipeline firstly flows into the heat pump unit through the first pipeline to be heated, so that water with higher temperature is obtained, and then the water with higher temperature flows into the water storage tank through the second pipeline to be stored for a user to use.

When the circulating heating mode is operated, the water storage tank, the first pipeline, the heat pump unit and the second pipeline are sequentially connected to form a circulating heating loop, water with lower temperature at the bottom of the water storage tank flows back to the heat pump unit through the first pipeline to be reheated, and the water with higher temperature flows into the water storage tank from the water inlet of the water storage tank, so that the stability of the water temperature inside the water storage tank is effectively maintained, and the water temperature requirement of a user is met.

When the direct-heating type heating mode is operated, water with lower temperature sequentially passes through the water supply pump of the water supply pipeline, the first electromagnetic two-way valve, the flow sensor and the second electromagnetic two-way valve to enter the heat pump hot water system, and enters the heat pump unit for heating through the first pipeline, water with higher temperature in the heat pump unit flows into the water storage tank through the second pipeline, full heating operation is not needed, and the phenomenon of insufficient supply when the demand of hot water is larger can be effectively avoided.

The controller switches the circulating heating mode to the direct heating type heating mode when detecting that the current flow of the water supply pipeline is larger than the preset minimum flow through the flow sensor; when the controller detects that the water level switch is closed, the direct heating type heating mode is switched to the circulating type heating mode; in the mode switching process, the switch resetting is not needed, and the problems of unstable water temperature and poor user comfort caused by frequent shutdown and startup of the heat pump unit are effectively solved.

Therefore, the embodiment can realize the unification of the circulating heating and direct heating functions, the requirement of the water temperature used by a user can be ensured, the requirement of the water consumption of the user can be met, in a circulating heating mode or a direct heating type heating mode, cold water is heated by the heat pump unit and then enters the heat storage water tank to be supplied to the user, the rapid and comfortable hot water heating is realized, and the comfort level of the user can be improved.

Drawings

Fig. 1 is a schematic structural diagram of a heat pump hot water system according to a first embodiment of the present invention;

fig. 2 is a schematic view of a circulation heating mode of a heat pump hot water system according to a first embodiment of the present invention;

fig. 3 is a schematic view of a direct heating type heating mode of a heat pump hot water system according to a first embodiment of the present invention;

fig. 4 is a schematic diagram of a hot water recovery circuit of a heat pump hot water system according to a first embodiment of the present invention;

fig. 5 is a schematic flowchart of a control method of a heat pump hot water system according to a first embodiment of the present invention;

fig. 6 is a schematic diagram illustrating mode switching of a control method of a heat pump hot water system according to a first embodiment of the present invention;

FIG. 7 is a schematic operating diagram of a circulation heating mode in a low water condition in accordance with a first embodiment of the present invention;

fig. 8 is an operation schematic view of a direct heating type heating mode of the first embodiment of the present invention;

FIG. 9 is a schematic operating diagram of the circulation heating mode in the high water level condition in accordance with the first embodiment of the present invention;

fig. 10 is an operation schematic diagram of the direct heating mode of the first embodiment of the present invention switched to the circulation heating mode in the low water level state;

fig. 11 is an operation schematic view of a circulation type heating mode in which the direct heating type heating mode of the first embodiment of the present invention is switched to a high water level state;

fig. 12 is an operation diagram of switching the circulation heating mode to the direct heating mode in the low water level state according to the first embodiment of the present invention;

fig. 13 is an operation diagram of switching the circulation heating mode to the direct heating mode in the high water level state according to the first embodiment of the present invention;

fig. 14 is an operation schematic diagram of the direct heating type heating mode of the first embodiment of the present invention switched to the mixed water heating mode;

wherein the reference numbers of the drawings in the specification are as follows:

1. a heat pump unit; 11. a water storage tank; 12. a water circulating pump; 13. a water supply pump; 14. a constant pressure water pump; 15. a water flow switch;

2. a flow sensor; 21. a water level switch; 22. a first temperature sensor; 23. a second temperature sensor;

3. a first electromagnetic two-way valve; 31. a second electromagnetic two-way valve; 32. a first check valve; 33. a second one-way valve; 34. a third check valve; 35. a third electromagnetic two-way valve;

4. carrying out water end treatment;

5. a heat exchanger; 51. a fan; 52. a compressor; 53. a first electronic expansion valve; 54. a four-way valve;

a represents a circulating heating circuit; b represents a direct-heating circuit; c denotes a hot water recovery circuit.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 1, a preferred embodiment of the present invention provides a heat pump hot water system, which includes a controller, a heat pump unit 1, a water storage tank 11 and a water supply pipeline;

the first water outlet end of the water storage tank 11 is communicated with the water inlet end of the heat pump unit 1 to form a first pipeline, the water inlet end of the water storage tank 11 is communicated with the water outlet end of the heat pump unit 1 to form a second pipeline, and the water outlet end of the water supply pipeline is connected to the first pipeline;

the water storage tank 11, the first pipeline, the heat pump unit 1 and the second pipeline are sequentially connected to form a circulating heating loop A, and the water supply pipeline, the first pipeline, the heat pump unit 1 and the water storage tank 11 are sequentially connected to form a direct heating loop;

the water supply pipeline is provided with a water supply pump 13, a first electromagnetic two-way valve 3, a flow sensor 2 and a second electromagnetic two-way valve 31 which are sequentially connected in series and are respectively electrically connected with the controller, and the first pipeline is provided with a circulating water pump 12 electrically connected with the controller; a water level switch 21 and a first temperature sensor 22 which are respectively electrically connected with the controller are arranged in the water storage tank 11.

A water level switch 21 is arranged in the water storage tank 11, and the water level switch 21 is used for detecting the water level condition of the water storage tank 11; a first temperature sensor 22 is arranged at the bottom of the water storage tank 11, and the first temperature sensor 22 is used for detecting the water temperature of the water storage tank 11; a circulating water pump 12 is arranged on the first pipeline, and a water inlet of the circulating water pump 12 is communicated with a first water outlet end of the water storage tank 11; the second water outlet end of the water storage tank 11 is connected to the water using end 4 through a constant pressure water pump 14, so that a user can obtain hot water in the water storage tank 11 for use by opening the water using end 4; and the water supply pipeline is provided with a flow sensor 2 for detecting the flow of the water supply pipeline in real time.

In this embodiment, the circulation-direct heat integrated heating function of the heat pump hot water system is realized through the circulation type heating loop a and the direct heat type heating loop B of the heat pump hot water system, so that the purpose of complementary advantages is achieved, the hot water supply capacity of the heat pump water heater is further improved, and the use comfort of a user is favorably improved.

The water inlet end of the water supply pipeline is communicated with an external water supply system, the water supply pipeline passes through the water supply pump 13 and is the whole heat pump hot water system provides a water source, and water entering the heat pump hot water system through the water supply pipeline firstly flows into the heat pump unit 1 through the first pipeline to be heated, so that water with higher temperature is obtained, and then the water with higher temperature flows into the water storage tank 11 through the second pipeline to be stored for users to use.

When the circulating heating mode is operated, the water storage tank 11, the first pipeline, the heat pump unit 1 and the second pipeline are sequentially connected to form a circulating heating loop a, water with a lower temperature at the bottom of the water storage tank 11 flows back to the heat pump unit 1 through the first pipeline to be reheated, and the water with a higher temperature flows into the water storage tank 11 from a water inlet of the water storage tank 11, so that the stability of the water temperature inside the water storage tank 11 is effectively maintained, and the water temperature requirement of a user is met.

When the direct-heating type heating mode is operated, water with lower temperature sequentially passes through the water supply pump 13 of the water supply pipeline, the first electromagnetic two-way valve 3, the flow sensor 2 and the second electromagnetic two-way valve 31 to enter the heat pump hot water system, and enters the heat pump unit 1 through the first pipeline to be heated, the water with higher temperature in the heat pump unit 1 flows into the water storage tank 11 through the second pipeline, full heating operation is not needed, and the phenomenon of insufficient supply when the demand of hot water is large can be effectively avoided.

When the controller detects that the current flow of the water supply pipeline is greater than the preset minimum flow through the flow sensor 2, the circulating heating mode is switched to the direct heating mode; when the controller detects that the water level switch 21 is closed, the direct heating mode is switched to the circulating heating mode; in the mode switching process, the switch resetting is not needed, and the problems of unstable water temperature and poor user comfort caused by frequent shutdown and startup of the heat pump unit are effectively solved.

Therefore, the embodiment can realize the unification of the circulating heating and direct heating functions, the requirement of the water temperature used by a user can be ensured, the requirement of the water consumption of the user can be met, in a circulating heating mode or a direct heating type heating mode, cold water is heated by the heat pump unit 1 and then enters the heat storage water tank to be supplied to the user, the rapid and comfortable hot water heating is realized, and the comfort level of the user can be improved.

Referring to fig. 1, in the embodiment of the present invention, the heat pump unit 1 includes a compressor 52, a four-way valve 54, a heat exchanger 5, a blower 51 and a first electronic expansion valve 53, which are electrically connected to the controller respectively;

an exhaust port of the compressor 52 is communicated with a port D of the four-way valve 54, a port C of the four-way valve 54 is communicated with a first port of the heat exchanger 5, a second port of the heat exchanger 5 is communicated with a first end of the first electronic expansion valve 53, a second port of the first electronic expansion valve 53 is communicated with a first port of a fin heat exchanger where the fan 51 is located, a second port of the fin heat exchanger where the fan 51 is located is communicated with a port E of the four-way valve 54, and a port S of the four-way valve 54 is communicated with a return air port of the compressor 52;

the water inlet of the heat exchanger 5 is communicated with the water inlet end of the heat pump unit 1, and the water outlet of the heat exchanger 5 is communicated with the water outlet end of the heat pump unit 1.

In this embodiment, the heat pump unit 1 provides a heat source for preparing hot water, and when water with a lower temperature in the first pipeline passes through the heat exchanger 5, a high-temperature refrigerant in the heat exchanger 5 exchanges heat with the water with the lower temperature, so that the water flowing into the second pipeline obtains sufficient heat to be heated and changed into water with a higher temperature, and finally the water with the higher temperature flows into the water storage tank 11 through the second pipeline to be stored or used by a user.

In the embodiment of the present invention, the heat pump hot water system further includes a water using end 4, a constant pressure water pump 14 and a third electromagnetic two-way valve 35, a second water outlet end of the water storage tank 11 is distributed by the constant pressure water pump 14 and is communicated with the water using end 4 and a first end of the third electromagnetic two-way valve 35, and a second end of the third electromagnetic two-way valve 35 is communicated with the water supply pipeline;

the water storage tank 11, the third electromagnetic two-way valve 35, the water supply pipeline, the first pipeline, the heat pump unit 1 and the second pipeline are connected in sequence to form a hot water recovery loop C.

In this embodiment, the heat pump hot water system is provided with a hot water recovery loop C, so that hot water which is not used up by a user can be recovered and heated through the hot water recovery loop C, water flowing out of the constant pressure water pump 14 returns to the water supply pipeline through the third electromagnetic two-way valve 35, and then enters the heat exchanger 5 through the water supply pipeline to be heated again, thereby effectively realizing hot water recovery, reducing heat loss, realizing energy conservation and environmental protection, and being beneficial to improving the use comfort of the user.

In the embodiment of the present invention, the heat pump hot water system further includes a second temperature sensor 23 electrically connected to the controller, and the second temperature sensor 23 is disposed on the hot water recovery circuit C between the third electromagnetic two-way valve 35 and the water supply line. The second temperature sensor 23 is used for detecting the water temperature of the hot water recovery circuit C, so that the controller can obtain the data of the return water temperature conveniently. It is understood that the flow sensor 2 includes, but is not limited to, a pulse flow meter, the first temperature sensor 22 and the second temperature sensor 23 include, but is not limited to, a temperature sensing head, and the second electromagnetic two-way valve 31 includes, but is not limited to, a warm water valve.

In the embodiment of the present invention, the heat pump hot water system further includes a first check valve 32;

the first one-way valve 32 is arranged on the first pipeline, a water inlet port of the first one-way valve 32 is communicated with a water outlet port of the circulating water pump 12, a water outlet port of the first one-way valve 32 is communicated with a water inlet end of the heat pump unit 1, and a water outlet end of the water supply pipeline is connected to the first pipeline between the first one-way valve 32 and the heat pump unit 1.

In the present embodiment, it should be noted that the first check valve 32 has a function of one-way conduction; specifically, when in the circulation heating mode, the water storage tank 11, the first pipeline, the heat pump unit 1 and the second pipeline are connected in sequence to form a circulation heating loop A, the water with lower temperature at the bottom of the water storage tank 11 flows into the first pipeline through the first water outlet end of the water storage tank 11, the circulating water pump 12 is started to convey water to the heat pump unit 1 for heating, in this process, the first check valve 32 can effectively prevent the first pipeline from generating a reverse flow phenomenon, thereby ensuring that the water with lower temperature in the water storage tank 11 flows back to the heat pump unit 1 through the first pipeline for reheating, and then the water with higher temperature flows into the water storage tank 11 from the water inlet of the water storage tank 11, so that the stability of the water temperature in the water storage tank 11 is kept, and the water temperature requirement of a user is met.

In the embodiment of the present invention, the heat pump hot water system further includes a second check valve 33; a water inlet port of the second check valve 33 is communicated with a first end of the first electromagnetic two-way valve 3, a water outlet port of the second check valve 33 is communicated with a second end of the second electromagnetic two-way valve 31, and the flow sensor 2 is connected on a water supply pipeline between the second check valve 33 and the second electromagnetic two-way valve 31.

In this embodiment, the second check valve 33 has a function of one-way conduction; specifically, the second check valve 33 can effectively prevent the running water in the water supply pipeline from flowing backwards, so as to ensure the normal operation of the heat pump hot water system.

In the embodiment of the present invention, the heat pump hot water system further includes a third check valve 34, a water inlet port of the third check valve 34 is communicated with a first end of the third electromagnetic two-way valve 35, and a water outlet port of the third check valve 34 is connected to the water supply line between the second check valve 33 and the flow sensor 2. The third check valve 34 can effectively prevent the temperature of the water end 4 from dropping when tap water in the water supply line rushes into the hot water recovery circuit C, so that water in the hot water recovery circuit C can flow into the first line through the water supply line and then be reheated and flow back into the water storage tank 11.

In the embodiment of the present invention, the heat pump hot water system further includes a water flow switch 15, the water flow switch 15 is installed on the second pipeline, and the water flow switch 15 is electrically connected to the controller.

Referring to fig. 5 and fig. 6, an embodiment of the present invention further provides a control method of a heat pump hot water system, which is suitable for the heat pump hot water system, and includes the following steps:

s11, when the heat pump hot water system runs, keeping the heat pump unit 1 in an open state;

s12, when the circulating heating mode is operated, the circulating water pump 12 of the first pipeline is started, the valve of the water supply pipeline is kept in an opening state, and the current flow of the water supply pipeline is detected in real time;

s13, when the current flow of the water supply pipeline is detected to be larger than the preset minimum flow, the circulating water pump 12 is closed to switch to the direct heating mode;

s14, when the direct heating type heating mode is operated, opening the valve of the water supply pipeline and closing the circulating water pump 12;

and S15, when the water level switch 21 of the water storage tank 11 is detected to be closed, the circulating water pump 12 is started, the valve of the water supply pipeline is closed or the opening degree of the valve of the water supply pipeline is reduced, so that the circulation heating mode is switched.

The heating mode of the heat pump hot water system is as follows:

as shown in fig. 2, when the heat pump hot water system operates in the circulation heating mode, water with a relatively low temperature in the water storage tank 1111 flows into the first pipeline through the first outlet end of the water storage tank 11, so that the water in the first pipeline is input into the heat exchanger 5 by the circulation water pump 12 for heating, and water with a relatively high temperature heated by the heat exchanger 5 flows back into the water storage tank 11 again through the second pipeline, so that the temperature of the water in the water storage tank 11 is adjusted through the circulation heating mode, the temperature of the hot water in the water storage tank 11 is prevented from being reduced due to heat dissipation, the stability of the temperature of the water in the water storage tank 11 is favorably maintained, and the use comfort of a user is favorably improved.

It should be noted that when a user uses hot water through the water end 4, the amount of water in the water storage tank 11 is reduced, so that in order to ensure the normal operation of the heat pump hot water system, when the circulation heating loop a operates in the circulation heating mode, the water is supplemented through the water supply line, so as to ensure the amount of hot water in the water storage tank 11.

In addition, because the play water end of water supply pipeline is connected on the first pipeline, the make-up water in the water supply pipeline can only pass through the first pipeline flows in heat exchanger 5 is interior to heat to avoid the lower water of temperature to directly add lead to in the water storage box 11 the water temperature of water storage box 11 descends, thereby is favorable to improving the stability of water temperature in the water storage box 11, and then is favorable to improving user's comfort level.

As shown in fig. 3, when the heat pump hot water system operates in the direct heating mode, tap water provided by an external water supply system flows into the heat pump hot water system through the water supply pipeline, water with a lower temperature in the water supply pipeline flows into the heat exchanger 5 through the first pipeline for heating, and water with a higher temperature heated by the heat exchanger 5 flows back into the water storage tank 11 through the second pipeline, so that a user can quickly obtain hot water through the water using end 4.

In addition, in the embodiment of the present invention, under a severe condition, when the flow sensor 2 of the water supply pipeline detects that the flow rate is lower than the preset minimum flow rate for a long time, the water circulation pump 12 is turned on, and the water supply pipeline is not closed, and enters a mixed water heating state;

it should be noted that: the conditions with severe working conditions comprise: the environmental temperature is lower than 0 ℃, the water inlet temperature of a tap water pipeline is lower than 4 ℃, and the environmental factors affect the heat pump unit 1, so that the working condition that the flow of the water supply pipeline is adjusted to be low is caused; or the water supply pipeline has insufficient water inflow, namely the water supply flow is very low, which belongs to the working condition of insufficient water supply.

Thus, the method further comprises:

s16, when the current environment temperature is detected to be lower than the preset lowest temperature, starting a water mixing heating mode; or the like, or, alternatively,

s17, when the water temperature of the water supply pipeline is detected to be lower than the preset minimum water supply temperature, starting a mixed water heating mode; or the like, or, alternatively,

s18, when the current flow of the water supply pipeline is detected to be smaller than the preset minimum flow, starting a water mixing and heating mode;

wherein, when the water mixing heating mode is operated, the water circulating pump 12 is started and the valve of the water supply pipeline is kept in an open state.

In order to facilitate understanding of the present invention, some preferred embodiments of a control method of a heat pump hot water system provided by the present invention will be further described below.

A. Circulation heating mode in low water level state:

referring to fig. 7, in one embodiment, after the step of keeping the heat pump unit 1 in the on state when the heat pump hot water system is running, the method further includes:

when the water level switch 21 is detected to be turned off, the water storage tank 11 is judged to be in a low water level state;

when the current hot water temperature value is less than a preset first target temperature value R02, switching to a circulating heating mode in a low water level state;

in the circulating heating mode operation in the low water level state, only when the current hot water temperature value is greater than a preset first target temperature value R02, the direct heating mode is switched to in the low water level state;

when the current hot water temperature value is greater than a preset first target temperature value R02, switching to a direct heating mode in a low water level state;

calculating the operation time of the direct heating mode when the direct heating mode is operated and the water storage tank 11 keeps a low water level state;

when the running time of the direct heating type heating mode is greater than a preset first direct heating running time R06, judging whether the current hot water temperature value of the water storage tank 11 is less than a preset second target temperature value, if so, switching to the circulating type heating mode in a low water level state;

in this embodiment, it should be noted that, after the heat pump hot water system is started, the controller first detects the state of the water level switch 21, and then determines that the water storage tank 11 is in the low water level state, and the operation mode is specifically as follows:

1. when the system is started, the current hot water temperature value is judged to be smaller than a preset first target temperature value R02, and the heat pump hot water system enters a circulating heating mode in a low water level state.

2. When the direct heating type water heater is started, the heat pump hot water system enters a direct heating type heating mode only when the current hot water temperature value is judged to be larger than a preset first target temperature value R02.

The circulating heating mode in the low water level state is switched to the direct heating mode, and the condition that the current hot water temperature value is greater than the preset first target temperature value R02 needs to be met.

And the direct heating mode is switched to the circulation heating mode in the low water level state, the condition that the current hot water temperature value of the water storage tank 11 is lower than R02-R03 needs to be met, and the preset first direct heating running time R06 should be larger than R06.

In this embodiment, it should be noted that, when the circulation heating mode in the low water level state is operated, it is determined whether the current hot water temperature of the water storage tank 11 is less than a preset fourth target temperature value; wherein the preset fourth target temperature value is a difference between the preset first target temperature value R02 and a direct heating mode switching back difference value R05;

if yes, the compressor 52 of the heat pump unit 1 is started, the circulating water pump 12 is started before a preset first start time P01 for starting the compressor 52, and the fan 51 of the heat pump unit 1 is started before a preset second start time for starting the compressor 52.

Here, the load in the circulation heating mode in the low water level state is: the compressor 52, the fan 51, the circulating water pump 12, the four-way valve 54, a crankshaft heating belt, a water pan heating belt, the first electronic expansion valve 53, an electric heater, and the alarm device. Wherein the preset first direct heating operation time R06 is 90 s.

When starting up, and judging to enter the circulating heating mode in the low water level state:

load opening sequence: the circulating water pump 12 is started in advance of the time of the compressor 52P01, the fan 51 is started in advance of the time of the compressor 5210s, the compressor 52 is started under the condition that the current hot water temperature is less than R02-R03 until the current hot water temperature is more than or equal to R02, the direct heating mode is switched, and the starting conditions of the rest loads refer to respective load descriptions.

B. Direct heating mode:

referring to fig. 8, when the water level switch 21 is detected to be closed during the operation of the direct heating mode, it is determined that the water storage tank 11 is in a high water level state; or, when the water level switch 21 is detected to be closed, the water storage tank 11 is judged to be in a high water level state; controlling the heat pump hot water system to switch from a direct heating mode to a circulating heating mode;

keeping a compressor 52 and a fan 51 of the heat pump unit 1 in running states, and starting the circulating water pump 12;

detecting the state of a water flow switch 15 on the second pipeline after the circulating water pump 12 is started;

when the water flow switch 15 is detected to be closed, closing the valve of the water supply pipeline after a preset third starting time after the circulating water pump 12 is started;

when the water flow switch 15 is detected to be turned off, starting to calculate the turn-off time of the water flow switch 15;

and when the off time of the water flow switch 15 is equal to the preset first fault reporting time, fault reporting is performed through fault reporting equipment.

Among them, the load in the direct heating mode is: the compressor 52, the fan 51, the second electromagnetic two-way valve 31, the crankshaft heating belt, the water pan heating belt, the first electronic expansion valve 53, the first electromagnetic two-way valve 3, the water supply pump 13, the electric heating and the alarm.

When the direct heating type heating mode is judged to be entered when the machine is just started:

load opening sequence: the fan 51, the first electromagnetic two-way valve 3, the tap water pump and the second electromagnetic two-way valve 31 start the compressor 5210s in advance, and after the compressor 52 is started, if the current hot water temperature value < R02-R03 is detected, the direct heat operation time meets H09, and the water level switch 21 is turned off, the circulating heating mode in the low water level state is switched; if the closing of the water level switch 21 is detected, the mode is switched to the circulation heating mode in the high water level state.

C. Circulation heating mode in high water level state:

referring to fig. 9, when the water level switch 21 is detected to be closed, it is determined that the water storage tank 11 is in a high water level state;

when the current hot water temperature value is smaller than a preset third target temperature value, switching to a circulating heating mode in a high water level state; wherein, the preset third target temperature value is the sum of the preset first target temperature value R02 and a preset constant temperature shutdown return difference value.

In this embodiment, it should be noted that, when the circulation heating mode in the high water level state is operated, it is determined whether the heat pump hot water system meets a constant temperature shutdown condition, if not, the compressor 52 of the heat pump unit 1 is started, the circulating water pump 12 is started before a preset first start time P01 for starting the compressor 52, and the fan 51 of the heat pump unit 1 is started before a preset second start time for starting the compressor 52.

In the present embodiment, it should be noted that the load in the circulation heating mode in the high water level state: the compressor 52, the fan 51, the circulating water pump 12, the four-way valve 54, a crankshaft heating belt, a water pan heating belt, the first electronic expansion valve 53, electric heating and the alarm device.

When the machine is just started and the circulating heating mode in the high water level state is judged to be entered:

load opening sequence: the circulating water pump 12 is turned on in advance of the compressor 52P01, the fan 51 is turned on in advance of the compressor 5210s, the compressor 52 is turned on under the condition that the constant-temperature shutdown is not satisfied, and the remaining load turn-on conditions refer to the respective load specifications.

D. Switching from the direct heating mode to the circulating heating mode in the low water level state:

referring to fig. 10, in one embodiment, the method further includes:

when the direct heating type heating mode is operated, a compressor 52 of the heat pump unit 1 is started, and a fan 51 of the heat pump unit 1 is started and a valve of a water supply pipeline is opened before a preset first starting time P01 for starting the compressor 52;

after the operation time of the direct heating mode is judged to be greater than the first direct heating operation time R06, whether the current hot water temperature of the water storage tank 11 is less than a preset fourth target temperature value or not is judged, and if yes, the direct heating mode is switched to the circulation type heating mode in a low water level state according to the disconnection of the water level switch 21.

In this embodiment, it should be noted that the load turn-on sequence: the compressor 52 and the fan 51 are both kept in an on state, the circulating water pump 12 is firstly turned on, the water flow switch 15 is detected, if the water flow switch 15 is turned on within 10s, the first electromagnetic two-way valve 3 and the water supply water pump 13 are turned off after the circulating water pump 12 is turned on for 10s, and the second electromagnetic two-way valve 31 is turned off; and if the water flow switch 1510s is always in an off state, reporting a water flow fault. And after the first electromagnetic two-way valve 3 is closed, the circulating heating mode in the low water level state is operated.

E. Switching from the direct heating mode to the circulating heating mode in the high water level state:

referring to fig. 11, in one embodiment, the method further includes:

after the operation time of the direct heating type heating mode is judged to be greater than the first direct heating operation time R06, whether the current hot water temperature of the water storage tank 11 is less than a preset fourth target temperature value or not is judged, and if yes, the direct heating type heating mode is switched to the circulation type heating mode in the high water level state according to the closing of the water level switch 21.

In this embodiment, it should be noted that the load turn-on sequence: the compressor 52 and the fan 51 are both kept in an on state, the circulating water pump 12 is firstly turned on, the water flow switch 15 is detected, if the water flow switch 15 is turned on within 10s, the first electromagnetic two-way valve 3 and the water supply water pump 13 are turned off after the circulating water pump 12 is turned on for 10s, and the second electromagnetic two-way valve 31 is turned off; and if the water flow switch 1510s is always in an off state, reporting a water flow fault. And after the first electromagnetic two-way valve 3 is closed, the circulating heating mode in the high water level state is operated.

F. Switching from the circulation heating mode in the low water level state to the direct heating mode:

referring to fig. 12, when it is detected that the water level switch 21 is turned off, it is determined that the water storage tank 11 is in a low water level state, and the heating mode of the heat pump hot water system is a circulation type heating mode in the low water level state;

keeping a compressor 52, a fan 51 and the circulating water pump 12 of the heat pump unit 1 in running states, and opening a valve of the water supply pipeline;

and when the current flow rate of the water supply line is detected to be greater than the preset minimum flow rate, after a second closing time for closing the valve of the water supply line, the circulation water pump 12 is turned off to switch the circulation type heating mode in the low water level state to the direct heating type heating mode.

In this embodiment, it should be noted that the load turn-on sequence: the fan 51, the compressor 52 and the circulating water pump 12 are kept on, when the first electromagnetic two-way valve 3, the water supply pump 13 and the second electromagnetic two-way valve 31 are turned on, and the flow sensor 2 in 10s detects that the flow in the water supply pipeline meets the minimum flow, the circulating water pump 12 is turned off after the first electromagnetic two-way valve 3 is turned on for 10s, and the direct heating type heating mode is operated.

G. Switching from the circulating heating mode in the high water level state to the direct heating mode:

referring to fig. 13, in one embodiment, the method further includes:

when the water level switch 21 is detected to be closed, the water storage tank 11 is judged to be in a high water level state, and the heating mode of the heat pump hot water system is a circulating heating mode in the high water level state;

when the heat pump unit 1 is detected to be in a constant-temperature shutdown state, starting a compressor 52 of the heat pump unit 1, and before a preset third starting time when the compressor 52 of the heat pump unit 1 is started, starting a fan 51 of the heat pump unit 1 and a valve of a water supply pipeline;

when the current flow of the water supply pipeline is detected to be larger than the preset minimum flow, the circulating water pump 12 is closed, so that the circulating heating mode in the high water level state is switched to the direct heating type heating mode;

preferably, in combination with the constant temperature shutdown state of the heat pump unit 1, the method further includes:

when the heat pump unit 1 is detected to be in a constant-temperature shutdown state, a compressor 52 of the heat pump unit 1 is started, and before a preset third starting time when the compressor 52 of the heat pump unit 1 is started, a fan 51 of the heat pump unit 1 and valves of the water supply pipeline are started, and the circulating water pump 12 is closed, so that a circulating heating mode in a high water level state is switched to a direct heating mode;

when detecting that the heat pump unit 1 is in a non-constant temperature shutdown state, keeping a compressor 52 and a fan 51 of the heat pump unit 1 in an operating state, and opening a valve of the water supply pipeline;

when it is detected that the current flow rate of the water supply line is greater than a preset minimum flow rate, the circulation water pump 12 is turned off after a first closing time of closing the valve of the water supply line to switch the circulation type heating mode in the high water level state to the direct heating type heating mode.

In this embodiment, it should be noted that the load turn-on sequence: if the fan 51, the first electromagnetic two-way valve 3, the water supply pump 13 and the second electromagnetic two-way valve 31 are started in advance by the compressor 5210s in the state of constant temperature shutdown, the flow sensor 2 detects that the flow in the water supply line meets the minimum flow, then the compressor 52 is started, the circulating water pump 12 is turned off, otherwise, a water flow fault is reported; if the operation is not in the constant temperature shutdown state, the fan 51, the compressor 52 and the circulating water pump 12 are kept on, the flow sensor 2 in the first electromagnetic two-way valve 3 is started, the flow sensor 2 in the first electromagnetic two-way valve 10s detects that the flow in the water supply pipeline meets the minimum flow, the circulating water pump 12 is closed after the first electromagnetic two-way valve 3 is started for 10s, and the direct heating type heating mode is operated.

H. Switching from the circulation heating mode in the high water level state to the circulation heating mode in the low water level state:

referring to fig. 14, in one embodiment, the method further includes:

in the constant temperature shutdown state, when the current hot water temperature value is less than or equal to R02-R03, switching from the circulating heating mode in the high water level state to the circulating heating mode in the low water level state;

wherein, the load opening sequence: the circulation water pump 12 is turned on in advance of the compressor 52P01, the fan 51 is turned on in advance of the compressor 5210s, the compressor 52 is turned on in the case where the current hot water temperature value < R02-R03 until the current hot water temperature value > R02, and is switched to the direct heating mode, and the remaining load turn-on conditions refer to the respective load specifications.

I. Switching from a direct heating mode to a mixed water heating mode:

in one embodiment, the method further comprises:

when the operation time of the direct heating mode is greater than the preset first direct heating operation time R06, the circulating water pump 12 is turned on to operate the mixed water heating mode.

The meanings and default values of the above parameters are shown in Table 1.

TABLE 1

In summary, an embodiment of the present invention provides a control method for a heat pump hot water system, which is applicable to the heat pump hot water system, and includes the steps of: s11, when the heat pump hot water system runs, keeping the heat pump unit 1 in an open state; s12, when the circulating heating mode is operated, the circulating water pump 12 of the first pipeline is started, the valve of the water supply pipeline is kept in an opening state, and the current flow of the water supply pipeline is detected in real time; s13, when the current flow of the water supply pipeline is detected to be larger than the preset minimum flow, the circulating water pump 12 is closed to switch to the direct heating mode; s14, when the direct heating type heating mode is operated, opening the valve of the water supply pipeline and closing the circulating water pump 12; and S15, when the water level switch 21 of the water storage tank 11 is detected to be closed, the circulating water pump 12 is started, the valve of the water supply pipeline is closed or the opening degree of the valve of the water supply pipeline is reduced, so that the circulation heating mode is switched.

(1) the system is characterized in that a circulating heating mode and a direct heating mode are fused into a heat pump hot water system, and cold water in the circulating heating mode and the direct heating mode is heated by a heat exchanger and then enters a water storage tank to be supplied to a user for use, so that quick and comfortable hot water production is realized;

(2) the system judges the mode switching by detecting the flow of the heat supply pipeline and the closing state of the water level switch, so that the instability of water temperature caused by frequent shutdown and startup for mode switching is avoided, and the comfort of a user is enhanced;

(3) the hardware and software control can realize the fast, energy-saving and comfortable hot water heating by comprehensively judging the closing state of the water level switch and the water temperature and freely switching the heat pump hot water system under four modes of low water level circular heating, high water temperature circular heating, direct heating and mixed water heating;

(4) the circulating-direct heating integrated heating function of the heat pump hot water system is realized through the circulating heating loop A and the direct heating loop B of the heat pump hot water system, so that the purpose of complementary advantages is achieved, the hot water supply capacity of the heat pump water heater is improved, and the use comfort of a user is improved; in the mode switching process, the switch resetting is not needed, and the problems of unstable water temperature and poor user comfort caused by frequent shutdown and startup of the heat pump unit are effectively solved.

(5) The water inlet end of the water supply pipeline is communicated with an external water supply system, the water supply pipeline passes through the water supply pump 13 and is the whole heat pump hot water system provides a water source, and water entering the heat pump hot water system through the water supply pipeline firstly flows into the heat pump unit 1 through the first pipeline to be heated, so that water with higher temperature is obtained, and then the water with higher temperature flows into the water storage tank 11 through the second pipeline to be stored for users to use.

(6) When the circulating heating mode is operated, the water storage tank 11, the first pipeline, the heat pump unit 1 and the second pipeline are sequentially connected to form a circulating heating loop a, water with lower temperature at the bottom of the water storage tank 11 flows back to the heat pump unit 1 through the first pipeline to be reheated, and the water with higher temperature flows into the water storage tank 11 from the water inlet of the water storage tank 11, so that the stability of the water temperature inside the water storage tank 11 is effectively maintained, and the water temperature requirement of a user is met.

When the controller detects that the current flow of the water supply pipeline is greater than the preset minimum flow through the flow sensor 2, the circulating heating mode is switched to the direct heating mode; when the controller detects that the water level switch 21 is closed, the direct heating mode is switched to the circulating heating mode.

(7) The embodiment can realize the unification of the circulation heating and the direct heating functions, can ensure the requirement of the water temperature used by a user, and can also meet the requirement of the water consumption used by the user, in the circulation heating mode or the direct heating mode, cold water is heated by the heat pump unit 1 and then enters the heat storage water tank to be supplied to the user, so that the rapid and comfortable hot water heating is realized, and the comfort level of the user is improved.

While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention.

Claims

1. A heat pump hot water system is characterized by comprising a controller, a heat pump unit, a water storage tank and a water supply pipeline; the first water outlet end of the water storage tank is communicated with the water inlet end of the heat pump unit to form a first pipeline, the water inlet end of the water storage tank is communicated with the water outlet end of the heat pump unit to form a second pipeline, and the water outlet end of the water supply pipeline is connected to the first pipeline;

the water supply pipeline is provided with a water supply pump, a first electromagnetic two-way valve, a flow sensor and a second electromagnetic two-way valve which are sequentially connected in series and are respectively electrically connected with the controller, and the first pipeline is provided with a circulating water pump electrically connected with the controller; a water level switch and a temperature sensor which are respectively and electrically connected with the controller are arranged in the water storage tank;

the heat pump hot water system also comprises a second one-way valve; the water inlet port of the second one-way valve is communicated with the first end of the first electromagnetic two-way valve, the water outlet port of the second one-way valve is communicated with the second end of the second electromagnetic two-way valve, and the flow sensor is connected to a water supply pipeline between the second one-way valve and the second electromagnetic two-way valve;

the heat pump hot water system further comprises a water using end, a constant pressure water pump and a third electromagnetic two-way valve, wherein a second water outlet end of the water storage tank is respectively communicated with the water using end and a first end of the third electromagnetic two-way valve through the constant pressure water pump, and a second end of the third electromagnetic two-way valve is communicated with the water supply pipeline;

the water storage tank, the third electromagnetic two-way valve, the water supply pipeline, the first pipeline, the heat pump unit and the second pipeline are sequentially connected to form a hot water recovery loop;

the heat pump hot water system also comprises a first one-way valve; the first one-way valve is arranged on the first pipeline, a water inlet port of the first one-way valve is communicated with a water outlet port of the circulating water pump, a water outlet port of the first one-way valve is communicated with a water inlet end of the heat pump unit, and a water outlet end of the water supply pipeline is connected to the first pipeline between the first one-way valve and the heat pump unit;

the heat pump water heating system further comprises a third one-way valve, a water inlet port of the third one-way valve is communicated with the first end of the third electromagnetic two-way valve, and a water outlet port of the third one-way valve is connected to a water supply pipeline between the second one-way valve and the flow sensor.

2. The heat pump hot water system as claimed in claim 1, wherein the heat pump unit comprises a compressor, a four-way valve, a heat exchanger, a fan and a first electronic expansion valve, which are respectively electrically connected with the controller;

3. A control method of a heat pump hot water system, which is suitable for the heat pump hot water system as claimed in any one of claims 1-2, and is characterized by comprising the following steps:

when the system is started or operated in a circulating heating mode, when the current flow of the water supply pipeline is detected to be larger than the preset minimum flow, the circulating water pump is closed so as to be switched to a direct heating mode;

when the closing of a water level switch of the water storage tank is detected, the circulating water pump is started, a valve of the water supply pipeline is closed or the opening degree of the valve of the water supply pipeline is reduced, and the circulating water pump is switched to a circulating heating mode;

after the step of maintaining the heat pump unit in an on state while the heat pump hot water system is operating, the method further comprises:

4. The method of controlling a heat pump hot water system as claimed in claim 3, further comprising:

5. The method of controlling a heat pump hot water system as claimed in claim 3, further comprising:

6. The method of controlling a heat pump hot water system as claimed in claim 3, further comprising:

7. The method of controlling a heat pump hot water system as claimed in claim 3, further comprising:

8. The method of controlling a heat pump hot water system as claimed in claim 3, further comprising: