EP4592616A1

EP4592616A1 - Heat pump system

Info

Publication number: EP4592616A1
Application number: EP24153633.3A
Authority: EP
Inventors: Seyed Ehsan Hajmiri; Jolien Lavens; Sijie FU; Yusuke Nakagawa; Martijn DEPREZ
Original assignee: Daikin Europe NV
Current assignee: Daikin Europe NV
Priority date: 2024-01-24
Filing date: 2024-01-24
Publication date: 2025-07-30
Also published as: EP4592617A1

Abstract

The disclosure relates to a heat pump system comprising a heat source unit (110) comprising a heat source heat (13) exchanger and a compressor (11); a plurality of usage side units (120), each comprising a sub expansion valve (122) and a usage side heat exchanger (123); a refrigerant circuit containing a refrigerant and connecting the heat source heat exchanger (13), the compressor (11), the sub expansion valves (122) and the usage side heat exchangers (123), wherein the refrigerant circuit comprises a manifold device (201) for connecting the heat source unit (110) to the usage side units (120), respectively, the manifold device (201) comprises a liquid pipe (151) and a gas pipe (152) for each of the usage side units (120); wherein each of the usage side units (120) further comprises a sensing device (126) configured to determine the temperature of the refrigerant in the respective usage side unit (120); and first and second valves (153, 154) for shutting the respective usage side unit (120) off the liquid pipe (151) and the gas pipe (152), respectively and thereby from the remainder of the refrigerant circuit; wherein the heat pump system further comprises a controller (300) for controlling the heat pump system; wherein the controller (300) has a plurality of ports each port being associated with a respective one of the usage side units (120) and the first and second valves (153, 154) of the usage side units (120) are respectively connected to a common one of the ports of the controller (300) via a wiring (155, 156), wherein the controller (300) is configured to perform an erroneous wiring connection determination operation evaluating whether the wiring (155, 156) connected to the first and second valves (153, 154) of the respective usage side unit (120) is connected to the correct port of the controller (300) based on the temperature determined by the sensing device (126) of the respective usage side unit (120); wherein the controller (300) is configured to, in the erroneous wiring connection determination operation, continue operation of the usage side units (120) and of the compressor (11).

Description

Technical Field

The present disclosure relates to heat pump systems and particularly to heat pump systems having a heat source unit and a plurality of usage side units. The heat pump system can be embodied as an air conditioning for cooling at the usage side, as air conditioning and heating system for cooling and/or heating at the usage side or as HVAC (heating, ventilation and air conditioning).

Background

Such heat pump systems known in the art comprise a heat source unit and a plurality of usage side units. The heat source unit has a heat source heat exchanger, such as an air-to-refrigerant heat source heat exchanger, a main expansion valve and a compressor. The usage side units each have a sub expansion valve and a usage side heat exchanger, such as a refrigerant-to-air usage side heat exchanger.
A refrigerant circuit containing a refrigerant connects the heat source heat exchanger, the main expansion valve, the compressor, the sub expansion valves and the usage side heat exchangers. The refrigerant circuit comprises a manifold device for connecting the heat source unit to the usage side units, respectively, the manifold device comprises a liquid pipe and a gas pipe for each of the usage side units.
Nowadays such heat pump systems often make use of flammable, highly flammable or toxic refrigerants. One example of such a refrigerant is R32.
Precautions, which may depend on certain conditions, must be taken to, in the event of leakage, prevent larger amounts of these refrigerants from entering the spaces in which the usage sides units are arranged. The precautions and conditions are regulated in certain standards such as IEC603335-2-40 (2022).
One such precaution is the provision of first and second shut-off valves for, in case of a leak in the respective usage side unit, shutting the respective usage side unit off the liquid pipe and the gas pipe, respectively and thereby from the remainder of the refrigerant circuit. Accordingly, the amount of refrigerant leaking into the space in which the respective usage side unit is arranged can be limited. Such a system is for example described in EP 3 967 942 A1 .
During installation of the heat pump system, the shut-off valves have to be wired to a controller of the heat pump system. In particular, the controller has a plurality of ports each port being associated with a respective one of the usage side units and the first and second valves of the usage side units are respectively connected to a common one of the ports of the controller via a wiring.
Yet, it may happen in the installation process, that the wiring is incorrect in that the shut-off valves connected to the respective port of the controller do not match with the usage side unit to which it is associated.
For this reason, it is necessary to perform an erroneous wiring connection determination operation. This check can be performed manually, which is however cumbersome.
Alternatively, JP 3 833 497 B suggests an erroneous wiring connection determination operation, in which only one of the usage side units is operated, whereas the remaining usage side units are switched off. In addition, the valves for shutting off the usage side units are closed for those usage side units which are switched off and opened for the sole operated usage side unit. The heat pump system of JP 3 833 497 B is operated in a heating mode and if the temperature of the usage side heat exchanger of the operated usage side unit exceeds a certain set temperature, the system concludes on a correct wiring connection of the valves.
However, the plurality of usage side units very often have different capacities, such as 3KW, 5KW or 10KW. As a result, when switching the operation of the usage side units one by one in the erroneous wiring connection determination operation, the needed capacity of the system varies and the operating load of compressor has to be adapted to the variation in capacity. However, when changing the operating load of the compressor, a certain time period is needed until the system again stabilizes so that erroneous wiring connection determination operation can be performed for the next usage side unit. Thus, the erroneous wiring connection determination operation is still considered time-consuming.

Summary

In view of the aforesaid, it is an object of the present disclosure to provide a heat pump system with an erroneous wiring connection determination operation and a method of determining erroneous wiring connection that is less time-consuming.
This object is solved by a heat pump system as defined in claim 1 and a method as defined in claim 15. Embodiments of the heat pump system and the method are defined in the dependent claims.
In an embodiment of the present disclosure it is suggested to, in the erroneous wiring connection determination operation, continue the operation of all usage side units and the compressor and, while the usage side units are operated, evaluate whether the wiring connected to the first and second valves of the respective usage side unit is connected to the correct port of the controller. During this process, only the first and second valves of the usage side unit to be evaluated may be closed. In the present disclosure the evaluation is further based on the temperature determined by a sensing device of the respective usage side unit. In a particular example, the evaluation is based on a temperature change.
According to a first aspect, the heat pump system comprises a heat source unit comprising a heat source heat exchanger and a compressor. The heat pump system may additionally comprise a main expansion valve. A main expansion valve of the heat source unit may be used in a heating operation/mode of the heat pump system mainly for regulating superheat of the refrigerant at the suction side and the discharge side of the compressor. In a cooling operation/mode, the main expansion valve may be fully open and/or be used to regulate superheat of the refrigerant at the suction side of the compressor and/or the low pressure level in the refrigerant circuit. The heat source unit can be a heat source unit of an air-to-refrigerant heat pump. The heat source unit may be located outside of the building to which the heat pump system is applied. In this case, the heat source unit may also be referred to as outdoor unit. In a particular example, the components of the heat source unit, that is the heat source heat exchanger, the compressor and the optional main expansion valve are arranged in a heat source unit casing.
Even further, the heat pump system comprises a plurality of usage side units. The usage side units may be arranged inside a space, such as a room, of the building and, hence, also be referred to as indoor units. Each of the usage side units comprises a sub expansion valve and a usage side heat exchanger. The sub expansion valves may be used to regulate the level of subcooling of the refrigerant in the usage side unit (in a heating operation/mode) and/or superheat of the refrigerant in the usage side unit (in a cooling operation/mode). The usage side units may comprise a usage side unit casing in which the components of the usage side unit are arranged, such as the sub expansion valve and the usage side heat exchanger as well as the later described sensing device, usage side fan or suction air temperature sensor. The suction air temperature sensor may be a sensor measuring the temperature of air sucked into the usage side unit by the usage side fan (suction air temperature). Such indoor temperature sensor may, however, also be arranged in the space of the respective usage side unit to be heated/cooled, i.e. conditioned.
The heat source side unit and the usage side units are connected forming a refrigerant circuit. The refrigerant circuit contains a refrigerant and connects the heat source heat exchanger, the optional main expansion valve, the compressor, the sub expansion valves and the usage side heat exchangers. The refrigerant circuit comprises a manifold device (branching points) for connecting the heat source unit to the usage side units, respectively. The manifold device comprises a liquid pipe and a gas pipe for each of the usage side units.
For example, in a so-called two pipe heat pump system, a heat source side liquid pipe and a heat source side gas pipe connect to the heat source unit. A plurality of usage side liquid pipes and usage side gas pipes branch of the heat source side liquid pipe and the heat source side gas pipe, respectively defining a manifold device or branching points. Thus, the usage side liquid pipes and the usage side gas pipes form the liquid pipe and the gas pipe of the respective usage side units.
In a so-called three pipe heat pump system, which is often referred to as three pipe heat recovery system, a heat source side liquid pipe, a heat source side high/low-pressure gas pipe and a heat source side low-pressure gas pipe extend from the heat source unit. A plurality of usage side liquid pipes branch of the heat source side liquid pipe. The usage side liquid pipes respectively form the liquid pipe of the respective usage side unit. Additionally, a plurality of usage side high/low-pressure gas pipes and usage side low-pressure gas pipes branch of the heat source side high/low-pressure gas pipe and the heat source side low-pressure gas pipe, respectively. The usage side high/low-pressure gas pipes and the usage side low-pressure gas pipes merge into a usage side gas pipe, respectively. The usage side gas pipes respectively form the gas pipe of the respective usage side unit.
Moreover, each of the usage side units further comprises a sensing device configured to determine the temperature of the refrigerant in the respective usage side unit. The sensing device may be a temperature sensor, such as a thermistor. However, the sensing device may also be a different type of sensor such as a pressure sensor which is configured to indirectly conclude on the respective temperature of the refrigerant in the respective usage side unit, such as the respective liquid pipe of the usage side unit.
Additionally, first and second valves, such as shut-off valves, for shutting the respective usage side unit off the liquid pipe and the gas pipe, respectively and thereby from the remainder of the refrigerant circuit are provided. In other words, the first and second valves define a cut-off portion inside the respective usage side unit.
The heat pump system further comprises a controller for controlling the heat pump system. The controller (control unit) may be constituted by a plurality of communicating controllers. The plurality of controllers may comprise a main controller, such as of the heat source unit, and sub controllers of the usage side units and/or the later described the valve units.
The controller or at least one of the controllers of the control unit (such as the sub controller (unit controller) of the valve unit(-s) has a plurality of ports, each port being associated with a respective one of the usage side units. In particular, the controller has ports which in the internal control logic are associated to a particular usage side unit. The first and second valves of the usage side units are respectively connected to a common one of the ports of the controller via a wiring. The first and second valves should be connected to the correct port, namely to the port associated to the usage side unit also comprising or being associated to the respective first and second valves.
In order that this correct connection or wiring can be evaluated, the controller is configured to perform an erroneous wiring connection determination operation. In the erroneous wiring connection determination operation, it is evaluated whether the wiring connected to the first and second valves of the respective usage side unit is connected to the correct port of the controller based on the temperature determined by the sensing device of the respective usage side unit.
According to the first aspect, the controller is further configured to, in the erroneous wiring connection determination operation, continue operation of the usage side units and of the compressor. In an embodiment, the operation of the usage side units and of the compressor is continuous throughout the erroneous wiring connection determination operation.
Because the usage side units and the compressor are continuously operated, variations in compressor load can be minimized and stable operation of the heat pump system can be guaranteed. Thus, a reliable erroneous wiring connection determination operation can be performed without long waiting periods until the operation of the heat pump system has stabilized.
According to a second aspect, the controller is configured to, in the erroneous wiring connection determination operation, in order to check a first port, close the first and second valves of a first usage side unit and maintain the first and second valves of the other usage side unit/-s open. The controller is further configured to subsequently conclude on the correctness of the connection of the wiring of the first and second valves of the first usage side unit to the first port based on the temperature of the refrigerant in the first usage side unit determined by the sensing device. To check a second port, the controller is further configured to subsequently open the first and second valves of the first usage side unit and close the first and second valves of a second usage side unit and then conclude on the correctness of the connection of the wiring of the first and second valves of the second usage side unit to the second port based on the temperature of the refrigerant in the second usage side unit determined by the sensing device. The opening of the first and second valves of the first usage side unit and closing of the first and second valves of the second usage side unit may be performed concurrently or with time delay, such as a few seconds.
According to this aspect, only the first and second valves of a respective usage side unit are closed to initiate the evaluation process. Thus, evaluation of the correct wiring of one usage side unit after the other may be performed without time delay caused by switching the usage side units on and off and without jeopardizing operation stability of the heat pump system.
According to a third aspect, the controller is further configured to determine a temperature difference by subtracting a refrigerant temperature determined by the sensing device at a first point in time after the first and second valves were closed from a refrigerant temperature determined by the sensing device at a second point in time after the first point in time. At the second point in time, the first and second valves are still closed. If the temperature difference is above a predetermined constant threshold, such as 3°C, conclude on a correct connection of the respective wiring.
When a particular usage side unit is shut off the remainder of the refrigerant circuit, the refrigerant temperature in the cut-off portion will assume a temperature similar to the indoor temperature (e.g. a suction air temperature) of the respective room in which the usage side unit is arranged/of the respective usage side unit. The refrigerant temperature in the cut-off portion inside the usage side unit will thus encompass a considerable change over a certain period of time. This is because no fresh "colder" (in cooling operation or mode) or "hotter" (in heating operation or mode) refrigerant is supplied into the shut off portion and the temperature of the refrigerant will over the time assume a temperature similar to the indoor temperature and thereby encompass the temperature change. To the contrary, if the first and second valves were still open because of an incorrect wiring, the refrigerant temperature or particularly the temperature difference and hence the change will be be smaller, if any. Accordingly, one may easily conclude on a correct or incorrect wiring.
According to a fourth aspect, the manifold device comprises a first manifold (first branching points) and a second manifold (second branching points), wherein the first manifold of the manifold device and the first and second valves of a first group of the usage side units are arranged in a first valve unit and the second manifold of the manifold device and the first and second valves of a second group of the usage side units are arranged in a second valve unit. The first and second valve units may respectively have valve unit casings in which at least the first and second valves are arranged.
The heat source side pipes may connect to the first and second valve units, respectively. In particular, in a two-pipe system, the heat source side liquid pipe and the heat source side gas pipe may connect to the first and second valve units, respectively. In a three-pipe system, the heat source side liquid pipe, the heat source side high/low-pressure gas pipe and the heat source side low-pressure gas pipe may connect to the first and second valve units, respectively. The merging of the heat source side high/low pressure gas pipe and the heat source side low-pressure gas pipe may be realized within the respective valve units or valve unit casings, too.
In either case, the usage side liquid and gas pipes may at least in part be arranged in the respective valve units or valve unit casings. The controller is configured to, in the erroneous wiring connection determination operation, evaluate whether the wiring is correctly connected, in parallel for the first group of usage side units in the first valve unit and the second group of usage side units in the second valve unit.
Consequently, correct wiring of two usage side units (in case of two valve units) or more (in case of more than two valve units) may be evaluated in parallel. As a result, the time for the erroneous wiring connection determination operation can be even further reduced.
Furthermore, the controller may be configured to, in the erroneous wiring connection determination operation, operate the heat pump system in a cooling operation (or cooling mode) or in a heating operation (heating mode).
According to a fifth aspect, the first and second valves are shut-off valves. A shut-off valve is a valve that safely manages the flow of fluids. Shut-off valves are also known as on-off valves either allowing the flow of fluid or cutting off the flow of fluid.
Shut-off valves are relatively cost-effective valves, reducing the overall costs of the heat pump system.
Furthermore, the sensing device may be a temperature sensor, particularly a thermistor, configured to detect the temperature of the refrigerant. In case the erroneous wiring connection determination operation is performed in cooling operation, the temperature sensor may optionally be arranged in the liquid pipe, such as downstream of the usage side heat exchanger and/or the sub expansion valve of the respective usage side unit in a/the cooling operation. In case the erroneous wiring connection determination operation is performed in heating operation, the temperature sensor may optionally be arranged and the gas pipe downstream of the usage side heat exchanger in heating operation.
The use of a temperature sensor and particularly a thermistor provides for a cost-effective and simple possibility to conclude on the temperature of the refrigerant in the usage side unit, particularly in the liquid pipe.
The liquid refrigerant supplied to the usage side unit in cooling operation/mode is expanded by the sub expansion valve upstream of the usage side heat exchanger. The temperature of the refrigerant upstream of the sub-expansion valve will, hence, not provide for an as reliable result in the evaluation process as the temperature of the refrigerant downstream of the sub-expansion valve. If the evaluation is performed in a heating operation/mode, the temperature sensor, and particularly a thermistor, used for the evaluation is arranged in the gas pipe of the respective usage side unit.
According to a sixth aspect, each of the usage side units further comprises a fan (usage side fan) driven by a fan motor and the controller is configured to, in the erroneous wiring connection determination operation, continue operation of the fan. In a particular example, the fan is operated at maximum speed. The fan may have at least two or at least three different operating states (low/high or low/medium/high). In such a case, it may be beneficial to operate the fan at the operating state "high".
Accordingly, effective heat transfer between the air in the space in which the respective usage side unit is arranged and the refrigerant in the respective usage side heat exchanger can be realized. Consequently, reliable determination of the temperature change of the refrigerant in the respective usage side unit for the evaluation of the correct wiring is realized.
According to a seventh aspect, the controller is configured to, in the erroneous wiring connection determination operation, continuously operate the compressor at maximum compressor speed. The maximum compressor speed may also be referred to as the maximum compressor operating load.
By continuously operating the compressor at the maximum compressor speed (operating load), operation of the heat pump system can be stabilized more easily and, hence, the erroneous wiring connection determination operation can be performed more reliable.
According to an eighth aspect, the heat pump system further comprises another usage side unit comprising another sub expansion valve and another usage side heat exchanger, the other usage side unit being connected to the heat source unit without shut-off valves for shutting the other usage side unit off the heat source unit or the remainder of the refrigerant circuit. The controller is further configured to, in the erroneous wiring connection determination operation, continue operation of the other usage side unit.
In the heat pump system, certain usage side units (the other user side unit/-s) may be arranged so that no valves, particularly shut-off valves, are required by the regulations as a precaution to prevent a large amount of refrigerant leaking from the other usage side unit. In the heat pump system of the present disclosure, those other usage side units will automatically be judged okay and be continuously operated. In an embodiment, the controller may comprise a main controller of the heat source unit, usage side controllers of the usage side units, (an)other usage side controller(-s) of the other usage side unit(-s) and (a) unit controller(-s) of the valve unit(-s) described earlier. The other usage side controller is directly connected to the main controller, whereas the usage side controllers are connected to the unit controller(-s) of the valve unit(-s) to which the usage side units are connected. Hence, the main controller can immediately recognize that no erroneous wiring connection determination operation needs to be performed for the other usage side unit(-s).
According to a ninth aspect, the controller is configured to in the erroneous wiring connection determination operation start the evaluation only after at least the output of the sensing devices remains in predefined range for a predetermined period. In this context, each output of the sensing devices can be required to remain in the predefined range or an average of the output of the sensing devices can be required to remain in the predefined range. The predefined range may be ±1°C and the predetermined period may be 30s.
In a more particular embodiment, more conditions may have to be met. For example, a first, second and third condition may have to be met. The first condition to be met may be that an indoor temperature distribution uniformization step has been performed for a predetermined time, such as for at least 2 or 3 minutes. In the uniformization step all usage side units may be operated and the compressor may be stopped. Subsequently, a suction air temperature may be measured by the suction air temperature sensor and a first liquid pipe temperature may be measured by the sensing device, such as the liquid pipe temperature sensor (e.g. the thermistor). The second condition to be met may be that the suction air temperature subtracted by the liquid pipe temperature of the usage side units is equal to or less than 5°C. In other words, the temperature difference between the suction air temperature and the liquid pipe temperature of the usage side units needs to be equal to or less than 5°C. After a certain period of time, such as 30 seconds, a second liquid pipe temperature will be measured by the liquid pipe temperature sensor. The third condition to be met may be that the first liquid pipe temperature subtracted by the second liquid pipe temperature is equal to or less than 1°C. In other words, the temperature between the first and second liquid pipe temperatures measured with a certain time period in between is equal to or less than 1°C. When those conditions are met, the heat pump system may be operated in cooling or heating operation for a predetermined period of time. If the average suction air temperatures of the usage side units reside in predefined range, such as between 20°C and 27°C, the controller may continue to the evaluation step.
According to this aspect, stable operation of the heat pump system forms the basis for the evaluation in the erroneous wiring connection determination operation so that the output whether the wiring is correct or not is reliable.
According to a tenth aspect, the refrigerant is a flammable and/or toxic refrigerant. In a particular example, the refrigerant may be R32.
With flammable and/or toxic refrigerants regulations have to be complied with such as IEC603335-2-40 (2022) requiring shut-off valves under certain circumstances and testing whether the shut-off valves are correctly wired.
According to an eleventh aspect, the erroneous wiring connection determination operation is manually initiated. In particular, once the heat pump system has been installed including the wiring, the erroneous wiring connection determination operation is manually started by an installer.
After installation is finished, the installer needs to be sure that the wiring is correct. One can check the wiring manually or by the erroneous wiring connection determination operation (which is not mandatory). By manually starting the erroneous wiring connection determination operation, the installer can choose.
According to a twelfth aspect, at least some of the usage side units have different capacities. In addition, the compressor may be operated at its maximum operating load during the erroneous wiring connection determination operation.
A heat pump system comprising a plurality of different usage side units as regards their capacity, the problem of changing compressor loads could arise. Yet, in the present disclosure the usage side units are continuously operated so that the change in capacity can be kept low and changes in the operation load of the compressor can be minimized.
According to a thirteenth aspect, a method of determining erroneous wiring connection in a heat pump system as described above, comprises the steps of closing the first and second valves of a first usage side unit for shutting the first usage side unit off the liquid pipe and the gas pipe and thereby from the remainder of the refrigerant circuit while maintaining the first and second valves of a second usage side unit open; determining the temperature of the refrigerant in the first usage side unit of the plurality of usage side units; and evaluating whether the wiring connected to the first and second valves of the first usage side unit is connected to the correct port of the controller based on the temperature determined by the sensing device of the first usage side unit while continuing operation of the second usage side unit and of the compressor.
Because the usage side units and the compressor are continuously operated, variations in compressor load can be minimized and stable operation of the heat pump system be guaranteed. Thus, a reliable erroneous wiring connection determination operation can be performed without long waiting periods until the operation of the heat pump system has been stabilized.
According to a fourteenth aspect, the step of evaluating comprises determining a temperature difference by subtracting a refrigerant temperature determined by the sensing device of the first usage side unit at a first point in time after the first and second valves were closed from a refrigerant temperature determined by the sensing device of the first usage side unit at a second point in time after the first point in time and concluding on a correct connection of the respective wiring if the temperature difference is above a predetermined constant threshold, such as 3°C.
According to this aspect, only the first and second valves of a respective usage side unit are closed to initiate the evaluation process. Thus, evaluation of the correct wiring of one usage side unit after the other may be performed without time delay caused by switching the usage side units on and off.

Brief Description of the Drawings

Figure 1: shows a schematic piping diagram of a heat pump system according to an embodiment of the present disclosure.
Figure 2: shows a schematic piping diagram of an example of a heat source unit of the heat pump system of figure 1.
Figure 3: shows a schematic piping diagram of a heat pump system according to another embodiment of the present disclosure.
Figure 4: shows a schematic piping diagram of an example of a heat source unit of the heat pump system of figure 3.
Figure 5A, B: show a flowchart of an erroneous wiring connection operation according to an embodiment of the present disclosure.

Detailed Description

The same reference numerals denote the same or similar elements throughout the embodiments and the description of the respect features with respect to one embodiment as well apply for the features of the other embodiment or embodiments.
The heat pump system 100 of the invention may be a device that performs cooling and/or heating of indoor spaces, such as in a building, through a vapor compression refrigeration cycle. In the heat pump system 100, a flammable and/or toxic refrigerant can be used as a refrigerant. The refrigerant may be R32.
The heat pump system 100 is a multi-heat pump system, which includes a heat source unit 110 and a plurality of usage side units 120 (which may also be referred to as utilization-side units or indoor units).
The heat pump system may have a so-called three-pipe configuration as shown in Fig. 1 and 2 or a so-called two-pipe configuration as shown in Fig. 3 and 4.

< Three Pipe Configuration >

As shown in Fig. 1, the heat pump system 100 comprises a heat source unit 110, and a plurality of usage-side units 120 connected to the heat source unit 110 via pipes defining a refrigerant circuit. The refrigerant circuit contains a refrigerant, such as R32.
The heat source unit 110 may be installed in an outside space, such as outside of a building and consequently also referred to as outdoor unit. The heat source unit 110 may for example be configured as shown in Fig. 2.
In particular, the heat source unit 110 defines an outdoor refrigerant circuit 10 that constitutes part of the refrigerant circuit. The outdoor refrigerant circuit 10 includes a compressor 11, a three-way switching valve 12, a heat source heat exchanger 13 (outdoor heat exchanger), an outdoor expansion valve 14 as main expansion valve, an accumulator 15, a liquid side closing valve 16, a suction gas side closing valve 17, a discharge gas side closing valve 18 and an outdoor fan 19 driven by an outdoor fan motor 19a.
In this embodiment, the three-way switching valve 12 is used as a mechanism for switching between a condensation operation state (cooling operation/mode), in which the heat source heat exchanger 13 functions as a condenser, and an evaporation operation state (heating operation/mode), in which the heat source heat exchanger 13 functions as an evaporator. However, a four-way switching valve or a plurality of switching valves may be used instead of a three-way switching valve 12.
The operating capacity (operating load) of the compressor 11 can be varied. In the present embodiment, the compressor 11 is a positive displacement compressor driven by a motor 11a whose rotation speed is controlled by an inverter. In the present embodiment, there is only one compressor 11. However, two or more compressors may be connected in parallel, e.g. depending on the number of connected usage side units.
The three-way switching valve 12 connects the discharge side of the compressor 11 and the gas side of the heat source heat exchanger 13 when the heat source heat exchanger 13 functions as a condenser (hereinafter referred to as cooling operation/mode). When the heat source heat exchanger 13 functions as an evaporator (hereinafter referred to as heating operation/mode), the suction side of the compressor 11 and the gas side of the heat source heat exchanger 13 are connected. Thus, the heat source heat exchanger 13 has a gas side connected to the three-way switching valve 12 and a liquid side connected to the outdoor expansion valve 14 and the liquid side closing valve 16.
A liquid (refrigerant) pipe 131 connects to the liquid side closing valve 16.
In the present embodiment, the outdoor expansion valve 14 (main expansion valve) is configured to adjust the pressure and flow rate of the refrigerant flowing in the outdoor refrigerant circuit 10. The outdoor expansion valve 14 may be an electric expansion valve (connected to the liquid side of the heat source heat exchanger 13 in this embodiment) disposed downstream of the heat source heat exchanger 13 and upstream of the liquid side closing valve 16.
A high/low-pressure gas (refrigerant) pipe 132 connects between the discharge side of the compressor 11 and the three-way switching valve 12 via a discharge gas side closing valve 18. Thereby, the high-pressure gas refrigerant compressed and discharged in the compressor 11 can be supplied to the indoor units 120 regardless of the switching operation of the three-way switching valve 12.
A low-pressure gas (refrigerant) pipe 133 is connected to the suction side of the compressor 11 (here upstream of the accumulator 15) via an intake gas side closing valve 17. As a result, low-pressure gas refrigerant returning from the indoor units 120 can be returned to the suction side of the compressor 11 regardless of the switching operation of the three-way switching valve 12.
A low pressure communication pipe 20 communicates with a pipe that connects to the low pressure gas pipe 133 and a pipe that connects to the high/low-pressure gas pipe 132. A low pressure communication valve 21 is arranged in the low pressure communication pipe 20 that can block the passage of refrigerant by closing the low pressure communication valve 21. As a result, the low-pressure gas pipe 133 and the high/low-pressure gas pipe 132 can be brought into communication with each other as necessary.
A high-pressure shut-off valve 22 is provided in the high/low-pressure gas pipe 132. The high-pressure gas refrigerant discharged from the compressor 11 can, thus, be blocked from being sent to the high/low-pressure gas pipe 132 by closing the high-pressure shut-off valve 22.
In heating operation, the high-pressure shut-off valve 22 will be opened and the low pressure communication valve 21 will be closed to send high pressure gas through the high/low-pressure gas pipe 132, which in this case is a high pressure gas pipe.
In cooling operation, the high-pressure shut-off valve 22 will be closed and the low pressure communication valve 21 will be opened to allow low pressure gas to be send to the suction side of the compressor via the low pressure gas pipe 133 and the high/low-pressure gas pipe 132, which in this case is a low pressure gas pipe.
The usage-side units 120 are divided into a plurality of unit families 121, e.g. first to third unit families 121_1, 121_2, 121_3. Yet, the number of the unit families 121 is not limited to three, and may be two, four, or more. The number of the usage-side unit 120 belonging to each of the unit families 121 is also not limited.
Each of the usage-side units 120 includes a sub-expansion valve 122 and a usage-side heat exchanger 123.
The liquid (refrigerant) pipe 131, the high/low-pressure gas (refrigerant) pipe 132, and the low-pressure gas (refrigerant) pipe 133 extend out of the heat source unit 110.
The liquid pipe 131 communicates with each of the heat source heat exchanger 24 and the usage side heat exchangers 123. The high/low-pressure gas pipe 132 communicates with a discharge port of the compressor 11. The low-pressure gas pipe 133 communicates with a suction port of the compressor 11.
The liquid pipe 131 branches into a plurality of heat source-side liquid pipes 141 towards the first to third unit families 121_1,121 _2,121_3. The high/low-pressure gas pipe 132 branches into a plurality of heat source-side high/low-pressure gas pipes 142 towards the first to third unit families 121_1, 121_2, 121_3. The low-pressure gas pipe 133 branches into a plurality of heat source-side low-pressure gas pipes 143 towards the first to third unit families 121_1, 121_2, 121_3.
For each of the unit families 121, the heat source-side liquid pipe 141 branches into a plurality of usage-side liquid pipes 151 towards the usage-side units 120 which belong to the unit family 121. For each of the unit families 121, the heat source-side high/low-pressure gas pipe 142 branches into a plurality of usage-side gas pipes 152 towards the usage-side units 120 which belong to the unit family 121. For each of the unit families 121, the heat source-side low-pressure gas pipe 143 branches towards the usage-side units 120 which belong to the unit family 121, and each of the branched pipes merges with the corresponding usage-side gas pipe 152.
For each of the usage-side units 120, the usage-side heat exchanger 123 communicates with the corresponding usage-side liquid pipe 151 and usage-side gas pipe 152.
In other words, in the heat pump system 100, a liquid refrigerant piping and a gas refrigerant piping extends between the heat source unit 110 and the usage-side units 120, while branching towards the unit families 121 and then towards the usage-side units 120 in each of the unit families 121, to form the refrigerant circuit. Thereby, it is possible to supply hot/cold heat from the heat source unit 110 to each of the usage-side units 120 by circulating refrigerant.
The heat pump system 100 further includes first to third valve units 200_1, 200_2, 200_3 for the first to third unit families 121_1, 121_2, 120_3, respectively. For each of the unit families 121, a manifold device 201 (first to third manifolds 201-1, 201_2, 201_3) including the branching points towards the corresponding usage-side units 120 is disposed in the corresponding valve unit 200. The first to third valve units 200_1, 200_2, 200_3 have substantially the same configuration.
Thus, in the following descriptions, the term "the valve unit 200" means any one of the first to third valve units 200_1, 200_2, 200_3. Further details of the valve unit 200 are explained in EP 3 967 938 A1 , the content of which is incorporated by reference.

< Two Pipe Configuration >

As previously mentioned, the heat pump system 100 may also have a so-called two-pipe configuration. The differences will be explained in the following. In the two-pipe configuration, the liquid pipe 131, the high/low-pressure gas pipe 132 and the low-pressure gas pipe 133 of the three-pipe configuration are limited to the liquid pipe 131 and the low-pressure gas pipe 133 (which in a two-pipe system is generally also referred to merely as "gas pipe") as shown in Figs. 3 and 4.
In particular, the heat source unit 110 in this case mainly includes a compressor 11 and a heat source heat exchanger 13. In addition, the heat source unit 110 includes a switching mechanism (here a four-way valve 23) that switches the operating state between a cooling operation/mode in which the heat source heat exchanger 13 functions as a condenser, and heating operation/mode in which the heat source heat exchanger 13 functions as an evaporator. The switching mechanism 23 is connected to the suction side of the compressor 11 via a suction pipe 24. The discharge side of the compressor 11 is connected to the switching mechanism 23 via a discharge pipe 25. The switching mechanism 23 is connected to the gas side of the outdoor heat exchanger 13 via a first outdoor gas pipe 26. The liquid side of the outdoor heat exchanger 13 is connected to the liquid pipe 131 via an outdoor liquid-pipe 27. An outdoor expansion valve 14, as main expansion valve, is located in the outdoor liquid-pipe 27.
The connection portion of the outdoor liquid-pipe 27 with respect to the liquid pipe 131 is provided with a liquid-side shut-off valve 28.
The switching mechanism 23 is connected to the low-pressure gas pipe (gas pipe) 133 via a second outdoor gas-pipe 29. The connection portion of the second outdoor gas-pipe 29 with respect to the low-pressure gas pipe (gas pipe) 133 is provided with a gas-side shut-off valve 30.
The liquid-side shut-off valve 28 and the gas-side shut-off valve 30 are valves that are manually opened and closed.
Hence, as compared to the three-pipe system, only a liquid (refrigerant) pipe 131 and a low-pressure gas (refrigerant) pipe (gas pipe) 133 extend out of the heat source unit 110. The liquid pipe 131 communicates with the heat source heat exchanger and each of the usage side heat exchangers. The low-pressure gas pipe (gas pipe) 133 communicates with a suction port of the compressor 11.
The liquid pipe 131 branches into a plurality of heat source-side liquid pipes 141 towards the first to third unit families 121_1, 121 _2,121_3. The low-pressure gas pipe (gas pipe) 133 branches into a plurality of heat source-side low-pressure gas pipes (heat source-side gas pipes) 143 towards the first to third unit families 121_1, 121_2, 121_3.
For each of the unit families 121, the heat source-side liquid pipe 141 branches into a plurality of usage-side liquid pipes 151 towards the usage-side units 120 which belong to the unit family 121. For each of the unit families 121, the heat source-side low-pressure gas pipe (heat source-side gas pipes) 143 branches into a plurality of usage-side gas pipes 152 towards the usage-side units 120 which belong to the unit family 121.
For each of the usage-side units 120, the usage-side heat exchanger 123 communicates with the corresponding usage-side liquid pipe 151 and usage-side gas pipe 152.
In other words, in the heat pump system 100, a liquid refrigerant piping and a gas refrigerant piping extends between the heat source unit 110 and the usage-side units 120, while branching towards the unit families 121 and then towards the usage-side units 120 in each of the unit families 121, to form the refrigerant circuit. Thereby, it is possible to supply hot/cold heat from the heat source unit 110 to each of the usage-side units 120 by circulating refrigerant.
The heat pump system 100 further includes first to third valve units 200_1, 200_2, 200_3 for the first to third unit families 121_1, 121_2, 120_3, respectively. For each of the unit families 121, a manifold device 201 (first to third manifolds 201-1, 201_2, 201_3) including the branching points towards the corresponding usage-side units 120 is disposed in the corresponding valve unit 200. The first to third valve units 200_1, 200_2, 200_3 have substantially the same configuration. Thus, in the following descriptions, the term "the valve unit 200" means any one of the first to third valve units 200_1, 200_2, 200_3. Further details of the valve unit 200 are explained in EP 3 967 938 A1 , the content of which is incorporated by reference.
Another usage side unit 400 comprising another sub expansion valve 401 and another usage side heat exchanger 402 may also be provided in the two-pipe configuration.
The other usage side unit 400 is, in the embodiment in Fig. 3 and 4, connected to the liquid pipe 131 via another usage side liquid pipe 451. Further, another usage side gas pipe 443 is connected to the low-pressure gas pipe (gas pipe) 133.
In this case, no shut-off valves (as explained later) for shutting the other usage side unit 400 off the other usage side liquid pipe 451 and the other usage side gas pipe 443 are provided.
As the usage side units 120, the other usage side unit 400 may comprise another sub expansion valve 401, another usage side heat exchanger 402, another sensing device 403, another usage side fan 406 driven by another fan motor 406a, another usage side controller 305 and wiring 404, 405 connecting the other sub expansion valve 401 to the other usage side controller 305 and the other usage side controller 305 to the main controller 301. These components may be configured in the same way as the respective components of the usage side units 120. The other sensing device 403 may comprise another liquid pipe sensing device 403-1 and another gas pipe sensing device 403-2.

< Common Features of Three-Pipe and Two-Pipe Configuration >

The following description particularly applies to both embodiments in Figs. 1 and 2 as well as Figs.3 and 4.
A first shut-off valve 153 (first valve or a liquid shut-off valve) and a second shut-off valve 154 (second valve or gas shut-off valve) are respectively located in the usage-side liquid pipes 151 and the usage-side gas pipes 152. The shut-off valves 153 and 154 define a usage side piping section (cut-off portion) which extends between the shut-off valves 153 and 154 and includes at least the usage side heat exchanger 123 and the sub expansion valve 122.
Each of the usage side units 120 has a sensing device 126 for determining the temperature of the refrigerant in the respective usage side unit 120. In the particular embodiment, the sensing device 126 is a temperature sensor in the form of a thermistor. Yet, it may also be conceivable to conclude on the temperature indirectly via a pressure sensor.
In the shown embodiments, in which the heat pump system is configured for heating and cooling, the sensing device 126 comprises a liquid pipe sensing device 126-1 and a gas pipe sensing device 126-2. In a heat pump system configured for cooling only, only the liquid pipe sensing device 126-1 may be provided and in a heat pump system configured for heating only, only the gas pipe sensing device 126-1 may be provided.
The liquid pipe sensing device 126-1 is disposed in the usage side unit 120 and measures the temperature of refrigerant in the usage side liquid pipe 151, particularly downstream of the sub expansion valve 122 in the cooling operation.
The gas sensing device 126-2 is disposed in the usage side unit 120 and measures the temperature of refrigerant in the usage side gas pipe 152.
The sensing devices 126 (126-1, 126-2) are respectively connected to the controller, e.g. the usage side controller 303.
Each usage side unit 120 also has a usage side fan 127 (indoor fan) driven by a fan motor 127a.
In addition, a suction air temperature sensor may be located in the respective spaces in which the usage side units 120 are arranged or in the usage side units 120 itself. If the suction air temperature sensor is located in the usage side unit 120 itself, it may also be a suction temperature sensor measuring the temperature of air sucked into the usage side unit 120 by the usage side fan 127 driven by the fan motor 127a.
Further, the heat source unit 110 has an outdoor temperature sensor 111.
The heat source unit 110 may have a main controller 301, each valve unit 200 may have a unit controller 302 and each usage side unit 120 may have a usage side controller 303. The usage side controller 303 is connected to the main controller 301 as well. If present (as in the two-pipe configuration), the optional other usage side controller 305 may be connected to the main controller 301. The main controller 301, the unit controllers 302, the usage side controllers 303 and the optional other usage side controller 305 may together form the controller.
The sensing devices 126 (126-1, 126-2), the outdoor temperature sensor 111 and the suction air temperature sensors 128 (and if present 428) are respectively connected to the controller. In a particular embodiment, the sensing devices 126 (and if present 403) and the suction air temperature sensors 128 (and if present 428) may be connected to the usage side controller 303(and if present the other usage side controller 305) and the outdoor temperature sensor 111 may be connected to the main controller 301.
The unit controllers 302 each have a plurality of ports, each port being associated with a respective one of the usage side units 120 and the first and second valves 153, 154 of the usage side units 120 are respectively connected to a common one of the ports of the controller by wiring 155, 156.
The usage side controller 303 is connected by wiring 124 to the respective unit controller 123 and the sub expansion valve 122 of the respective usage side unit 120 is connected to respective usage side controller 303 by wiring 125.
The main controller 301 is connected with the unit controller 302 by wiring 304, wherein the unit controllers 302 can be connected in series by the wiring 304.
The other usage side controller 305, if present, is connected with the main controller 301 by wiring 404 directly.
The controller (e.g. the main controller 301) is configured to, when a refrigerant leakage in any of the usage side units has occurred (e.g. detected by a refrigerant leakage sensor of the usage side unit), close the shut-off valves 153 and 154 associated to the usage side unit, in which the leakage has occurred. Hence, the respective usage side unit is isolated from the remainder of the refrigerant circuit. This may be a precautionary measure required by standards and regulations as previously mentioned.
During installation of the heat pump system, the shut-off valves 153, 154 have to be wired to the unit controllers 302 by the wiring 155, 156, that is by plugging the end of the respective wires 155, 156 to the associated sockets (ports). In this process, incorrect wiring can occur so that shut-off valves 153, 154 of a first usage side unit 120 are actually associated in the control unit to a second usage side unit 120.
In order to recognize such erroneous wiring, the controller is configured to perform an erroneous wiring connection determination operation, which will be explained in detail with reference to Fig. 5A and B.

< Erroneous Wiring Connection Determination Operation >

The erroneous wiring connection determination operation is manually initiated by an installer or maintenance person via the controller, particularly the main controller 301. In a particular example, the operation start signal may be communicated from the main controller 301 to the unit controllers 302 and the usage side controllers 303.
In a more general form, the erroneous wiring connection determination operation may comprise three main steps.
First, the indoor temperature distribution is made uniform (uniformization step). This can primarily be achieved by operating the usage side fans 127 (and if present 406) of the usage side units 120 (and if present 400) and not operating the compressor 11.
Second, the operation of the heat pump system is stabilized (stabilization step). Particularly, the liquid pipe temperature in the liquid pipe is stabilized. This may be achieved by operating the compressor at its maximum operating load and opening all of the shut-off valves 153, 154.
Third, it is evaluated whether each port of the controller, particularly the unit controller 302, is wired to the correct shut-off valves 153, 154 (evaluation step). The evaluation may start after continuous operation of the heat pump system in the stabilization step for a certain period of time, e.g. more than 5 minutes or between 5 minutes and 30 minutes, to stabilize the operation of the heat pump system. The evaluation is then continued until all ports have been checked/evaluated.
In the following, an example of the erroneous wiring connection determination operation is explained in more detail.

< Pre-Condition >

The erroneous wiring connection determination operation can in one example be performed in an outdoor temperature range between -2°C and 45°C. Yet, other outdoor temperature ranges are also conceivable. Thus, in a first step (S1), the controller verifies whether the temperature value delivered from the outdoor temperature sensor 111 resides within the above range. If this is not the case, the erroneous wiring connection determination operation will be ended.

< Uniformization Step >

Otherwise, the process will continue to step S2. In step S2, all usage side units are turned on. In particular, the usage side fans 127 (and if present 406) of the usage side units 120 (and if present 400) are turned on, e.g. at maximum speed. In some examples, the usage side fans 127 (and if present 406) may have three operating stages, low, middle and high. In those examples, the usage side fans are operated at the operating state "high". In step S2, the compressor 11 will be maintained in the OFF state, i.e. not operated.
The objective of step S2 is to uniformize the temperature distribution (indoor temperature distribution) inside the respective spaces in which the usage side units are arranged.
This indoor temperature distribution uniformization step (S2) will be continued until a certain condition A is met. In a particular embodiment, the condition A comprises first, second and third conditions. The condition has to be met in each of the usage side units 120 (and if present 400). Thus, the check whether the condition is met is performed for all usage side units 120 (and if present 400) individually. Only if the individual check for all usage side units 120 (and if present 400) is positive, the condition is considered to be met.
The first condition to be met is that the indoor temperature distribution uniformization step (S2) has been performed for a predetermined time, such as for 3 minutes.
Subsequently, the suction air temperature will be measured by the suction air temperature sensor 128 (and if present 428) and a first liquid pipe temperature will be measured by the liquid pipe temperature sensor 126-1 (and if present 403-1) (e.g. the thermistor).
The second condition to be met is that the suction air temperature subtracted by the liquid pipe temperature of the usage side units 120 is for all usage side units 120 (and if present 400) equal to or less than 5°C. In other words, the temperature difference between the suction air temperature and the liquid pipe temperature of the usage side units 120 (and if present 400) needs to be equal to or less than 5°C.
After a certain period of time, such as 30 seconds, a second liquid pipe temperature will be measured by the liquid pipe temperature sensor 126-1 (and if present 403-1).
The third condition to be met is that the first liquid pipe temperature subtracted by the second liquid pipe temperature is for all usage side units 120 (and if present 400) equal to or less than 1°C. In other words, the temperature between the first and second liquid pipe temperatures measured with a certain time period in between is for all usage side units 120 (and if present 400) equal to or less than 1°C.

< Stabilization Step >

In case the above condition A is met, the process continues to step S3 (stabilization step).
If the outer temperature measured by the outdoor temperature sensor is below 10°C, the heat pump system will start the heating operation, whereas if the outer temperature measured by the outdoor temperature sensor is equal to or above 10°C, the heat pump system will start the cooling operation.
This step S3 has the objective to stabilize the liquid pipe temperature of the usage side units.
In the particular example, the compressor is turned on, all usage side units are turned on, all shut-off valves are opened and all usage side fans are operated at maximum speed (e.g. the operating state "high").
In particular, in the example of the three-pipe configuration as shown in Fig. 1, the compressor 11 is turned on, all usage side units 120 are turned on, all shut-off valves 153, 154 are opened and all usage side fans 127 are operated at maximum speed (e.g. the operating state "high").
In the example of the two-pipe configuration as shown in Fig. 3, the compressor 11 is turned on, all usage side units 120, 400 are turned on, all shut-off valves 153, 154 are opened and all usage side fans 127, 406 are operated at maximum speed (e.g. the operating state "high").
This cooling or heating operation is continued for a certain period of time, such as 30 minutes and/or until at least the output of the suction air temperature sensors resides within a predetermined range. Either the output of all suction air temperature sensors 128 (and if present 428) needs to reside within the predetermined range or the average of the output of all suction air temperature sensors 128 (and if present 428) needs to reside within the predetermined range.
In particular, the controller verifies whether the indoor temperature in the spaces, in which the usage side units 120 (and if present 400) are arranged and measured by the suction temperature sensors 128 (and if present 428) resides within a predetermined range, such as between 20°C and 27°C. In example, it is checked whether the average value of all usage side units 120 (and if present 400) is within said range. In another example, the value of each of the usage side units 120 (and if present 400) has to be within said range. If this is not the case, the process ends. If this is the case, the system is assumed to be stable and the process proceeds to the evaluation.

< Evaluation Step >

Subsequently, the process continues to step S4 (evaluation step.
The evaluation step is basically the same for heating and colling operation, with the only difference, that the liquid pipe temperature is used in cooling operation and the gas pipe temperature is used in heating operation. For this reason, the evaluation step will be described in the following for the heating operation and cooling operation together.
In the evaluation step, the compressor 11 is operated at its maximum capacity or operating load. The usage side fans are all operated, e.g. at maximum speed, such as the operating stage "high".
In particular, in case of the three-pipe configuration, the compressor 11 is operated at its maximum capacity or operating load. The usage side fans 127 are all operated, e.g. at maximum speed, such as the operating stage "high".
In case of two-pipe configuration, the compressor 11 is operated at its maximum capacity or operating load. The usage side fans 127 and the other usage side fan 406 are all operated, e.g. at maximum speed, such as the operating stage "high".
Then, the first two shut-off valves 153, 154 of the first valve unit 200_1 are closed whereas the other shut-off valves 153, 154 of the first valve unit 200_1 remain open. If more than one valve unit 200 is present, first two shut-off valves 153, 154 of the respective other valve units 200_2, 200_3 are also closed, whereas the other shut-off valves 153, 154 of the respective valve units 200_2, 200_3 remain open. Thus, a plurality of two shut-off valve 153, 154 may be checked in parallel in order to reduce the checking time.
At this time, in case of cooling operation/mode, a first liquid pipe temperature measured by the liquid sensing device/-s 126-1 of the usage side unit/-s 120 to which the respectively closed shut-off valves 153, 154 should be associated is measured.
In case of heating operation/mode, a first usage side gas pipe temperature measured by the gas sensing device/-s 126-2 of the usage side unit/-s 120 to which the respectively closed shut-off valves 153, 154 should be associated is measured.
In either case, the measurement may be performed immediately after closing the shut-off valves.
After a certain period of time, such as 5 minutes, in case of cooling operation/mode, a second liquid pipe temperature is measured by the liquid sensing device/-s 126-1 of the usage side unit/-s 120 to which the respectively closed shut-off valves 153, 154 should be associated.
In case of heating operation/mode, after a certain period of time, such as 5 minutes, a second usage side gas pipe temperature is measured by the gas sensing device/-s 126-2 of the usage side unit/-s 120 to which the respectively closed shut-off valves 153, 154 should be associated.
In case of cooling operation/mode, if the temperature difference between the first and second liquid pipe temperatures is equal to or larger than 3°C, the controller concludes on a correct wiring (S6). To the contrary, if the temperature difference is smaller than 3°C, the controller concludes on a wrong wiring (S5).
In case of heating operation/mode, if the temperature difference between the first and second usage side gas pipe temperatures is equal to or larger than 3°C, the controller concludes on a correct wiring (S6). To the contrary, if the temperature difference is smaller than 3°C, the controller concludes on a wrong wiring (S5).
In this context, the controller may output a corresponding feedback of a correct or wrong wiring, e.g. on a display. In a particular embodiment, an error code may be output on a printed circuit board of the main controller 301 and/or a remote controller/a control thermostat of the respective usage side unit 120. Thus, the installer may centrally recognize that there is a wrong wiring via the main controller 301 and subsequently find the usage side unit 120 which has been wrongly wired via the remote controller/control thermostat of the respective usage side unit 120.
Subsequently, the controller verifies whether there is any other port of which the correct wiring is to be evaluated. If not, the erroneous wiring connection determination operation ends (S8). If yes, a further port check starts (S7).
In the further port check, the compressor 11 is kept operating, e.g. at the maximum operating load, and the usage side fans 127 (and if present 406) are kept operating. Subsequently, the two first shut-off valves 153, 154 of the first valve unit 200_1 and if present of the other valve units 200_2, 200_3 are opened and two second shut-off valves 153, 154 of the first valve unit 200_1 and if present of the other valve units 200_2, 200_3 are opened.
At this time, in case of cooling operation/mode, a first liquid pipe temperature measured by the liquid sensing device/-s 126-1 of the usage side unit/-s 120 to which the respectively closed shut-off valves 153, 154 should be associated is measured.
In case of heating operation/mode, a first usage side gas pipe temperature measured by the gas sensing device/-s 126-2 of the usage side unit/-s 120 to which the respectively closed shut-off valves 153, 154 should be associated is measured.
After a certain period of time, such as 5 minutes, in case of cooling operation/mode, a second liquid pipe temperature is measured by the liquid sensing device/-s 126-1 of the usage side unit/-s 120 to which the respectively closed shut-off valves 153, 154 should be associated.
In case of heating operation/mode, after a certain period of time, such as 5 minutes, a second usage side gas pipe temperature is measured by the gas sensing device/-s 126-2 of the usage side unit/-s 120 to which the respectively closed shut-off valves 153, 154 should be associated.
In case of cooling operation/mode, if the temperature difference between the first and second liquid pipe temperatures is larger than 3°C, the controller concludes on a correct wiring (S6). To the contrary, if the temperature difference is equal to or smaller than 3°C, the controller concludes on a wrong wiring (S5).
In case of heating operation/mode, if the temperature difference between the first and second usage side gas pipe temperatures is equal to or larger than 3°C, the controller concludes on a correct wiring (S6). To the contrary, if the temperature difference is smaller than 3°C, the controller concludes on a wrong wiring (S5).
In this context, the controller may output a corresponding feedback of a correct or wrong wiring, e.g. on a display. In a particular embodiment, an error code may be output on a printed circuit board of the main controller 301 and/or a remote controller/a control thermostat of the respective usage side unit 120. Thus, the installer may centrally recognize that there is a wrong wiring via the main controller 301 and subsequently find the usage side unit 120 which has been wrongly wired via the remote controller/control thermostat of the respective usage side unit 120.
Subsequently, the controller verifies whether there is any other port of which the correct wiring is to be evaluated. If not, the erroneous wiring connection determination operation ends (S8). If yes, a further port check starts (S7) and the process described above is repeated.
Because, in the two-pipe configuration described above, the other usage side unit 400 is directly connected via its other usage side controller 305 to the main controller 301, the other usage side unit 400 will automatically be checked as being correctly wired by the main controller and no port check is required for the other usage side units 400.
Because the shut-off valve 153, 154 are under certain circumstances, such as the type of refrigerant and the size of the space (volume) in which the respective usage side unit 120 is arranged, required by regulations as a precautionary safety measure in case of refrigerant leakage, correct wiring connection of the shut-off valves 153, 154 to the respectively associated usage side units 120 is obligatory. The erroneous wiring connection determination operation of the present disclosure provides for a simple and quick possibility to check the correct wiring.
Using a plurality of valve units 200 further reduces the time necessary for the erroneous wiring connection determination operation, because the correct wiring connection of two or more sets of the shut-off valves 153, 154 to the respectively associated usage side units 120 can be performed in parallel.
Because all usage side units 120 are continuously operated during the erroneous wiring connection determination operation, fluctuations in capacity can be avoided or minimized. Therefore, the heat pump system can be operated under relatively stable conditions without the need to change the operating load of the compressor. Operating the compressor at maximum operating load further stabilizes the conditions under which the heat pump system operates. Stable conditions of the heat pump system provide for a reliable erroneous wiring connection determination operation and judgment of the correct wiring.

Reference Sign List

10: outdoor refrigerant circuit
11: compressor
11a: motor of compressor
12: three-way switching valve
13: heat source heat exchanger
14: outdoor expansion valve (main expansion valve)
15: accumulator
16: liquid side closing valve
17: suction gas side closing valve
18: discharge gas side closing valve
19: outdoor fan
19a: outdoor fan motor
20: low pressure communication pipe
21: low pressure communication valve
22: high pressure shut-off valve
23: four-way valve
24: suction pipe
25: discharge pipe
26: first outdoor gas pipe
27: outdoor liquid pipe
28: liquid side valve
29: second outdoor gas pipe
30: gas side valve

110: heat source unit
111: outdoor temperature sensor

120: usage side unit
121: usage side unit family
122: sub expansion valve
123: usage side heat exchanger
124, 125: wiring
126-1: liquid pipe sensing device
126-2: gas pipe sensing device
127: usage side fan
127a: usage side fan motor
128: suction air temperature sensor

131: liquid pipe
132: high/low-pressure gas pipe
133: low-pressure gas pipe (only "gas pipe" in two-pipe configuration)

141: heat source side liquid pipe
142: heat source side high/low-pressure gas pipe
143: heat source side low-pressure gas pipe

151: usage side liquid pipe
152: usage side gas pipe
153: first shut-off valve (liquid pipe shut-off valve)
154: second shut-off valve (gas pipe shut-off valve)
155, 156: wiring

200: valve unit
201: manifold device
201_1 - 201_3: first to third manifold devices

300: control unit
301: main controller
302: unit controller
303: usage side controller
304: wiring
305: other usage side controller

400: other usage side unit
401: other sub expansion valve
402: other usage side heat exchanger
403-1: other liquid pipe sensing device
403-2: other gas pipe sensing device
404, 405: wiring
406: other usage side fan
406a: other usage side fan motor
428: other suction air temperature sensor
444: other usage side gas pipe
451: other usage side liquid pipe

Claims

Heat pump system comprising:
a heat source unit (110) comprising a heat source heat (13) exchanger and a compressor (11);

a plurality of usage side units (120), each comprising a sub expansion valve (122) and a usage side heat exchanger (123) ;

a refrigerant circuit containing a refrigerant and connecting the heat source heat exchanger (13), the compressor (11), the sub expansion valves (122) and the usage side heat exchangers (123), wherein the refrigerant circuit comprises a manifold device (201) for connecting the heat source unit (110) to the usage side units (120), respectively, the manifold device (201) comprises a liquid pipe (151) and a gas pipe (152) for each of the usage side units (120);

wherein each of the usage side units (120) further comprises
a sensing device (126) configured to determine the temperature of the refrigerant in the respective usage side unit (120); and

first and second valves (153, 154) for shutting the respective usage side unit (120) off the liquid pipe (151) and the gas pipe (152), respectively and thereby from the remainder of the refrigerant circuit;

wherein the heat pump system further comprises a controller (300) for controlling the heat pump system;

wherein the controller (300) has a plurality of ports each port being associated with a respective one of the usage side units (120) and the first and second valves (153, 154) of the usage side units (120) are respectively connected to a common one of the ports of the controller (300) via a wiring (155, 156),

wherein the controller (300) is configured to perform an erroneous wiring connection determination operation evaluating whether the wiring (155, 156) connected to the first and second valves (153, 154) of the respective usage side unit (120) is connected to the correct port of the controller (300) based on the temperature determined by the sensing device (126) of the respective usage side unit (120);

wherein the controller (300) is configured to, in the erroneous wiring connection determination operation, continue operation of the usage side units (120) and of the compressor (11).
Heat pump system according to claim 1, wherein the controller (300) is configured to, in the erroneous wiring connection determination operation,
close the first and second valves (153, 154) of a first usage side unit (120_1) and maintain the first and second valves of the other usage side unit/-s (120) open,

and then conclude on the correctness of the connection of the wiring (155, 156) of the first and second valves (153, 154) of the first usage side unit (120) based the temperature of the refrigerant in the first usage side unit (120_1) determined by the sensing device (126),

subsequently open the first and second valves (153, 154) of the first usage side unit (120_1) and close the first and second valves (153, 154) of a second usage side unit (120_2),

and then conclude on the correctness of the connection of the wiring of the first and second valves (153, 154) of the second usage side unit (120_2) based on the temperature of the refrigerant in the second usage side unit (120) determined by the sensing device (126).
Heat pump system according to claim 2, wherein the controller (300) is configured to
determine a temperature difference by subtracting a refrigerant temperature determined by the sensing device (126) at a first point in time after the first and second valves (153, 154) were closed from a refrigerant temperature determined by the sensing device (126) at a second point in time after the first point in time and

if the temperature difference is above a predetermined constant threshold, conclude on a correct connection of the respective wiring.
Heat pump system according to any one of the preceding claims,
wherein the manifold device (201) comprises a first manifold (201_1) and a second manifold (201_2), wherein the first manifold (201_1) and the first and second valves (153, 154) of a first group (121_1) of the usage side units (120) are arranged in a first valve unit (200_1) and the second manifold (201_2) and the first and second valves (153, 154) of a second group (121_2) of the usage side units (120) are arranged in a second valve unit (200_2),

wherein the controller (300) is configured to, in the erroneous wiring connection determination operation, evaluate whether the wiring (155, 156) is correctly connected, in parallel for the first group (121_1) of usage side units (120) in the first valve unit (200_1) and the second group (121_2) of usage side units (120) in the second valve unit (200_2).
Heat pump system according to any one of the preceding claims, wherein first and second valves (153, 154) are shut-off valves.
Heat pump system according to any one of the preceding claims, wherein each of the usage side units (120) further comprises a fan (127) and the controller (300) is configured to, in the erroneous wiring connection determination operation, continue operation of the fan (127).
Heat pump system according to any one of the preceding claims, wherein the controller (300) is configured to, in the erroneous wiring connection determination operation, continuously operate the compressor (11) at maximum compressor speed.
Heat pump system according to any one of the preceding claims, further comprising another usage side unit (400) comprising another sub expansion valve (401) and another usage side heat exchanger (402), the other usage side unit (400) being connected to the heat source unit (110) without shut-off valves for shutting the other usage side unit (400) off heat source unit,
wherein the controller (300) is configured to, in the erroneous wiring connection determination operation, continue operation of the other usage side unit (400).
Heat pump system according to any one of the preceding claims, wherein the controller (300) is configured to in the erroneous wiring connection determination operation start the evaluation only after at least the output of the sensing devices (126) remains in predefined range for a predetermined period.
Heat pump system according to any one of the preceding claims, wherein the refrigerant is a flammable and/or toxic refrigerant.
Heat pump system according to any one of the preceding claims, wherein the erroneous wiring connection determination operation is manually initiated.
Heat pump system according to any one of the preceding claims, wherein at least some of the usage side units (120) have different capacities.
Method of determining erroneous wiring connection in a heat pump system according to any one of the preceding claims, the method comprising the steps of:
closing the first and second valves (153, 154) of a first usage side unit (120_1) for shutting the first usage side unit off the liquid pipe (151) and the gas pipe (152) and thereby from the remainder of the refrigerant circuit while maintaining the first and second valves (153, 154) of a second usage side unit (120_2) open;

determining the temperature of the refrigerant in the first usage side unit (120_1) of the plurality of usage side units (120);

evaluating whether the wiring (155, 156) connected to the first and second valves (153, 154) of the first usage side unit (120_1) is connected to the correct port of the controller (300) based on the temperature determined by the sensing device (126) of the first usage side (120_1) unit while continuing operation of the second usage side unit (120_2) and of the compressor (11).
Method according to claim 13, wherein the step of evaluating comprises:
determining a temperature difference by subtracting a refrigerant temperature determined by the sensing device (126) of the first usage side unit (120_1) at a first point in time after the first and second valves (153, 154) were closed from a refrigerant temperature determined by the sensing device (126) of the first usage side unit (120_1) at a second point in time after the first point in time and

concluding on a correct connection of the respective wiring if the temperature difference is above a predetermined constant threshold.