The present invention relates to a heat pump system and a module of such a system for heating water flows, for a housing complex or stables, and a heat pump module.

Heat pumps for heating water for the central heating of houses are already known from US 3, 959, 986 A. Here a heat pump system for space heating of a house by means of hot water using the outside air as a heat source is described. This system consists of an air cooler that acts as an expansion cooler, a compressor, a condenser, a hot water storage tank and room radiators that receive the hot water from the storage tank. This system is twofold. It can cool as well as heat. The expansion cooler can cool the water in the storage tank when it is warm outside. However, the installation can also heat the water in the storage tank, using heat that is extracted from the outside air by the air cooler. The water is circulated along the condenser for heating so that the heat can be transferred to the water by the condenser. However, such installations generally have a low energy output, which means that they cannot be used for residential complexes such as apartment buildings. If after installation a system does not appear to provide sufficient capacity, the capacity of the system cannot be further increased. If one of the parts of the system breaks down, the entire system is no longer able to heat or cool.

The present invention seeks to overcome at least one of the above drawbacks or at least provide an alternative.

Therefore, the present invention provides a first aspect of a modular heat pump system for receiving and heating a water flow, such as for a central heating system, for a housing complex, such as an apartment building:

- a plurality of heat pump modules where each heat pump module of the plurality of heat pump modules comprises a processing unit (4) for controlling the heat pump module, wherein the plurality of heat pump modules (3.1, 3.2) are fluidly connected and communicatively sequentially connected to each other to automatically distribute the water flow among themselves, such as evenly distributing, wherein the system is arranged such that the control of the system as a whole is separately controllable via the processing unit of each of the modules of the plurality of heat pump modules (3.1, 3.2) . An advantage is that the modular nature of the system does not necessarily break down completely in the event of a defect. Furthermore, the system can be expanded if the demand for energy increases or turns out to be higher than the system could initially handle. Each module is effectively a self-contained heat pump that works in tandem with other self-contained heat pumps .

Optionally, each heat pump module of the plurality of heat pump modules includes a first heating circuit and a second heating circuit. The second heating circuit is connected to the first heating circuit by means of a cascade exchanger. The system is further designed to be switchable between heating the water flow by means of the first circuit only, and the combination of the first and the second circuit. This allows the system to achieve higher water temperatures or to extract heat from the outside air under colder outdoor air conditions.

Optionally, the first heating circuit comprises a first compressor. The second heating circuit comprises a second compressor. The first and second compressors are each placed separately or jointly within a soundproof enclosure. In this manner, the system can be placed within a residential area without noise nuisance.

Optionally, the casing is designed for supplying air from above by means of a fan and discharging air from below. This has the advantage that the compressors are cooled while diverting the noise from the fans to the floor.

Optionally, the first and second circuits are provided at least in part within a common heat exchanger. The first and second circuits each have a cooling section, the common heat exchanger being adapted to perform simultaneous defrosting of the cooling sections through the supply of compressed gas. The advantage of this is that any sublimation of ambient moisture on the cooling parts can be removed simultaneously. Compressed gas will be understood as the relevant refrigerants of the circuits, which refrigerants are supplied to the heat exchanger in gas form for internal condensation. Optionally, the system comprises at least one temperature sensor for measuring the outside temperature. This sensor can, for example, be communicatively coupled to a module of the plurality of modules, in particular to its processing unit. The system is further designed to switch, on the basis of the measured outside temperature, between heating the water flow by means of the first circuit only, and the combination of the first and the second circuit. An advantage is that the system is designed in an energy-efficient manner to switch to a two- stage heating at a low outside temperature without the intervention of an operator, and to a single-stage heating at a high outside temperature.

Preferably, the first circuit and the second circuit each comprise a refrigerant that is highly flammable at room temperature, such as propane and isobutane respectively, and wherein the system is designed with a casing comprising upright walls and a passage labyrinth, whereby fresh air can be supplied through a bottom or an opening of the upright walls. This makes it possible to safely use a flammable refrigerant in a residential environment. Because of the labyrinth, the sound remains muffled, while a good air exchange can take place, so that the fire risk is low. The upright walls of the casing may also be sound-absorbing.

Optionally, each module of the plurality of heat pump modules is also individually encased, wherein the individual encasement is configured with at least one other fan, and wherein the at least one other fan is configured with at least one cover valve, and wherein the at least one cover valve is arranged to cover the at least one other fan during simultaneous defrosting of the cooling parts. An advantage is that thawing of ice buildup on the cooling parts can take place more quickly. Optionally, electrical components, such as the processing unit of each module of the plurality of heat pump modules, are cast in an electrically insulating material. This prevents any electrical components from being an ignition source for the refrigerants in the event of a leak.

Optionally, the system is designed to recognize a defect of and/or maintenance to a module of the plurality of heat pump modules and to switch it off on the basis of the recognized defect of and/or maintenance to the module wherein the defect was recognized, and to redistribute the waterflow over the other modules of the plurality of heat pump modules. An advantage is that the system can continue to function despite the defect.

Optionally, each module of the plurality of heat pump modules comprises a supply duct for supplying the water flow and which supply duct is designed to be connectable to a supply duct of at least one other module of the plurality of heat pump modules, and wherein each module of the plurality of heat pump modules is arranged to take water from its own supply duct. Alternatively or in addition to the foregoing, each module of the plurality of heat pump modules may comprise a discharge duct for discharging the water flow and which discharge duct is formed connectable to a discharge duct of at least one other module of the plurality of heat pump modules, and wherein each module of the plurality of heat pump modules is designed to discharge water through its own discharge duct. An advantage is that each module can be connected without having to be connected to existing manifolds. Due to the mutual connection between supply and/or discharge ducts, the system can be expanded immediately. An end module in a coupling sequence of the plurality of modules can then for instance be provided with blind flanges for sealing the supply and/or discharge ducts thereof.

Optionally, each module of the plurality of heat pump modules comprises a flow meter communicatively connected to the processing unit of the module for measuring a water flow rate associated with that module and wherein each module of the plurality of heat pump modules comprises a control valve for controlling through the processing unit the water flow rate associated with the heat pump, and wherein the system is arranged in such a way that the modules mutually communicate the measured values for evenly distributing the water flow. An advantage is that in this way the system is controlled in a decentralized manner and is therefore not dependent on just a single processing unit. The flow meter may be arranged to measure the water flow rate from the module supply duct, and the control valve may be arranged in the supply duct or in a branch duct of the supply duct for taking water from the water flow through the module for heating .

Optionally, the modules are each arranged to provide a nominal capacity of 150-350 kW, preferably 200-300 kW, such as 250 kW .

According to a second aspect of the invention, a heat pump module may be taken from the plurality of heat pump modules as described according to a first aspect of the invention. Such a module is then designed for such a coupling instead of being coupled .

Accordingly there is described herein a heat pump (system) that functions 1-2 stagewise on the basis of natural refrigerants, such as propane and isobutane, wherein the system is set up in a residential environment with modularity through the coupling of several units. The heat pump is constructed as a cascade system which automatically divides the hydraulic water flow over the number of installed units. By communicating flow measurement per unit with the total units present, the installation will distribute the total supplied flow evenly over the number of installed units. The units communicate with each other at the moment of connection of the mutual plug communication. The coupling makes it possible to choose to place 1 unit or to choose at any time to connect several units and the distribution of flow of the units will be activated automatically. This makes modularity very strong. The units can be easily expanded by placing the units one behind the other. A central supply and return duct runs in the unit, where the heat pump consumption and supply are realized internally on the unit. The flow over the heat pump is then controlled by an electronically controlled control valve based on measured flow. A coupling tube is supplied as standard with the units for the water-side coupling and a communication cable which is connected by means of plugs. This is also referred to here as plug & play. The yellow ducts below show the connection from the 1st unit to the 2nd unit. Blind flanges are then placed on the last unit if no further coupling takes place. The unit is designed plug & play in such a way that for the installer only a power supply (current) needs to be connected to the unit and a supply and return duct needs to be fitted to the flanges. Due to the plug- in connection for several units, the installation is Plug & Play for the installer with this type of large heat pump on this scale. A giga joule measurement is also placed in these units to measure the total heat emitted and to display it on the SIMSERPC visualization system. The visualization system is integrated with every heat pump unit, which makes it possible for multiple units to monitor a total overview of the entire setup on each heat pump. Each unit is electrically and technically decentralized to guarantee operational reliability per unit. Due to the mutual communication with the units, data is shared and the units will be controlled by the PLC software of each unit, based on temperature, by the PLC software programmed in Siemens. This eliminates such central control, so that operational reliability remains high at all times. The Programmable logic controller (PLC) software has been programmed in such a way that it is known per heat pump unit, also known as module, how many units have been installed and connected in total through mutual communication and the sharing of mutual data, such as valve positions and measured liquid flows. This is then determined per unit, so that the flow measurements per unit are also shared through data traffic, so that the units each add up the total flow of all units together and divide this by the number of connected units installed. This is then calculated per unit in order to have the same flow flowing through each unit, so that an even load is distributed among the installed units. If a unit can no longer actively participate during maintenance work or malfunction, this will automatically be communicated to the other units, so that the flow is distributed over the currently active units. The heat pump cooler that is included in this unit, which ensures that ambient air is converted into final warm central heating water of a maximum of 85 degrees, has been specially designed to achieve the lowest possible noise production with the best possible performance. The design has been converted from a traditional cooler block to a v-bank principle with a specially built-in defrosting cover and sound-absorbing housing. Due to the construction of the special cooler included in the heat pump unit, it is possible to achieve the highest possible performance with a very low sound power. Due to the extremely large surface area, the fans can run at a very low speed on a very small footprint. In the heat pump unit, excess heat is blown away from the unit for safety of components with regard to heat in the unit and for added safety related to flammable refrigerants and a relatively enclosed space, this warm air is reused on the cooler to improve efficiency. The cooler is equipped with special outlet covers that close during the defrosting cycle and are kept ice-free during winter conditions when stationary to avoid start-up problems in snowfall and humid weather conditions around freezing point. The heat pump unit is composed in the cold technical portion (portion where refrigerant is located, so combustible refrigerant) by a housing completely closed by sound-reducing material. The compressors that form the largest noise source are equipped with a specially designed sound box with extra air cooling which is blown into the top of the sound box with cool air which is discharged from the heat pump cooler and subsequently discharged below the compressor in the closed heat pump unit. This warm air is then ultimately discharged with excess pressure from a ventilation facility with waste heat from the switch panel towards the heat pump cooler in order to again optimize it .

A special sound wall arrangement is provided around the entire installation of the heat pump or several heat pumps with a special suction option to provide the heat pump cooler with sufficient air without sound escaping the installation wall. The installation wall is constructed in such a way that natural passage is possible at all times in order to guarantee refreshment in the installation in the event of a possible minimal leakage of the combustible refrigerant, (by arrows in the sketch the passage holes are indicated for the natural passage) The figures show how air suction through a labyrinth is possible without noise pollution. The defrosting principle is based on a heat exchanger with 2 circuits, which allows defrosting in 1 stage. The heat from the central heating water is then used to pump compressed gas through 1 stage in the cooler to defrost. This allows the second stage to stop during defrosting which is a significant noise source reduction. During defrosting, the valves on the fans will close and the special defrosting cover will ensure that the heat that is pumped into the cooler also remains in the cooler to allow the defrosting process to proceed as quickly as possible and not to be dependent on wind influences by the possible weather conditions at that time. The use of the 2-circuit heat exchanger makes it possible to automatically switch from 1 stage to 2 stages. Due to the choice that is automatically calculated in the programmed PLC software based on outside temperature, the central heating water will be heated to a desired water temperature. Depending on this temperature, the heat pump will run in 1 stage or 2 stages. At a relatively low central heating water temperature and an outside temperature above 0 degrees, the installation can heat the water to +55 degrees in 1 step. If a winter situation arises with the need for warmer water above 55 degrees, the installation will automatically switch to a 2-stage system. In 2 stages, the 1st stage (propane system) runs through a cascade exchanger to the 2nd stage (isobutane system) and the central heating water is then heated by the second stage. Fire safety of the unit is additionally guaranteed by eliminating all possible ignition sources by using EX equipment and by casting electrical components. Because detection applies to suction, safety is guaranteed during a standstill. During operation there is a continuous air flow in the installation so that any leakage is immediately discharged to the cooler and dilution of the mixture takes place immediately. What we are now going to install is a heat pump that is basically of equivalent value in terms of technology for heating, but the technology has now been improved/adapted to be able to place it in residential areas. The circuit /cont rol has been completely adapted to the heat demand of an apartment building, and the outdoor cooler that extracts the heat from the air has been completely redesigned to extract the full capacity from the environment with a minimal set-up with the noise of the machine still within the norms. The defrosting principle of the air cooler is also completely different in terms of cooling technology. The installation is also suitable to function as 1 stage or 2 stage installation so that a low central heating water temperature can be generated during the summer with the best energetic performance. The machine is built with an extra noise-reducing machine housing and because flammable refrigerant is used, it is unique due to the reasonably closed construction of the machine. With flammable refrigerant, the refrigerant that could leak could accumulate, causing an explosion hazard. These construction facilities ensure that the machine is still safely constructed. The total unit set-up, that is to say the entire system, can be set up in such a way at an apartment building that, together with the noise-reducing means on the property boundary, will at most reach 35 dba. The concept consists of a unit with a nominal capacity of approximately 250 kW and can be set up in a cascade to provide apartment buildings with the required heat requirement. Unit is currently suitable for linking up to, for example, 4 units, so that we can supply a heating capacity of 1000 kW. There are only a few apartment buildings in the Netherlands where this heat requirement of 1000 kW is present and the remained are lower and have an average of 500 kW. Each unit is equipped with its own hydraulic module and a special control to automatically coordinate the distribution of water flow. It is built as a true plug & play setup, so installers only need to provide the unit with a power cable and provide a supply and return duct on the water side, (actually, just connect it to the existing central heating system and that's it) This also makes it possible for installers in the field to scale up such set-ups. This is definitely different from machine delivered to chick hatcheries. Those are truly custom-made products that can hardly be scaled up and the coolers that extract the heat from the outside air are also set up separately from the machine. The current heat pump consists of 1 total unit in which all components are located to be considered a plug & play unit. Due to this design of the machine, it is quite easy to make the entire housing construction, especially apartment buildings and a central heating supply, gas-free.

There are about 30, 000 objects in the Netherlands where these configurations can be realized. An arrangement within a residential environment with natural refrigerants (combustible refrigerants) is also very unique. Everything that is installed now is a synthetic refrigerant. A standard heat pump setup to an apartment building instead of all separate heat pump units also provides a better energy flow for the energy supplier. Think of less power peaks because the heating is centrally controlled. This plug & play concept also ensures that when an apartment building is demolished after, for example, 10 years, the heat pump installation can be moved to a new location.

The invention is further described herein with reference to the figures.

Figure 1 shows a modular heat pump system 1 for receiving and heating a water flow. Such a water flow is supplied to the system 1 with a feed pump (not shown, but conventional) . The feed pump may be part of the system. More specifically, the water flow can be supplied from a central water storage tank (not shown, but conventional) for the central heating of a residential complex 2, in this example an apartment building. The system may also separately from this example be placed adjacent to the residential complex 2. The system has a plurality of heat pump modules 3.1, 3.2. In this example, the plurality of heat pump modules comprises a first heat pump module 3.1 and a second heat pump module 3.2. Each heat pump module, i.e. the first and second heat pump modules, of the plurality of heat pump modules is provided with a processing unit (not shown, but usual) , such as a computer, optionally with a visual display and/or human interface, for controlling the heat pump module. The plurality of heat pump modules 3.1, 3.2 are fluidly and communicatively connected to each other sequentially to automatically divide the water flow among themselves, such as evenly distributing it. In this example, the first module 3.1 receives the water flow and takes a portion of it to heat it. The remained of the water flow is passed on to the second module 3.2 which takes the remaining portion of the water flow to heat it. The systems are designed to be communicative in order to make the distribution of the water flow evenly across the modules. To this end, each module is therefore equipped with a flow meter (not shown, but customary) for measuring the taken water flow for heating and a control valve (not shown, but customary) which is adjustable by means of the processing unit for tuning the water flow that is taken. The processing units of the modules are communicatively connected so that the control valves of the modules are tuned so that approximately the same fluid flow is measured by the flow meters of the modules. The system is also further arranged in such a way that the control of the system as a whole via the processing unit of each of the modules of the plurality of heat pump modules is separately controllable. The processing units of the modules form, as it were, an overarching processing unit by means of the communicative connection. The control system is therefore also modular. In this example, each heat pump module 3.1, 3.2 of the plurality of heat pump modules has a first heating circuit (not shown, but customary) and a second heating circuit (not shown, but customary) , the second heating circuit being connected by means of a cascade exchanger (not shown, but customary) with the first heating circuit. The system is designed to be switchable between heating the water flow, i.e. each water flow taken by the modules from the original water flow, by means of the first circuit by itself, and the combination of the first and the second circuit. Figures 1 and 2 further show that each module of the plurality of heat pump modules is individually encased. That is to say that they are each placed in their own casing 10, also known as a housing. The individual housing is designed with at least one fan 12, in this example three fans.

The at least one fan 12 can be seen in more detail in Figure 3 where it is also shown that each fan 12 is provided with a cover valve 14. The cover valve has a first and second cover wing, such as semi-circular covers, that each have cover other halves attached on the same side of the fan. The cover valve is open in Figure 3, and can be held open, for example, by an air flow, but can fall closed when the fan generates no air flow or an insufficiently large air flow. The cover valve is designed to cover the at least one other fan during simultaneous defrosting of, for example, cooling parts. These parts cool the air, and thus extract heat from the air. These cooling parts are further described herein below. When heat is removed from the outside air, ice can collect on the cooling parts and the build-up of ice can hinder its functioning. The valve can, for instance, close during a defrosting because the fan 12 is switched off. The at least one fan can then be controlled by the processing unit of the relevant module. In this example, the first and second circuits are provided, at least partly, within a common heat exchanger. That is to say, the cooling parts 16.1, 16.2 of the first and second circuits are arranged within a common heat exchanger 18. Figure 3 shows a V-bank of the module, where V- bank means that the heat exchanger has both a first side and a second side is angled to a floor. The first and the second circuit each have a cooling section 16.1, 16.2, wherein the common heat exchanger is designed to perform simultaneous defrosting of the cooling sections, optionally by means of a defrost cover for the supply of compressed gas. In this case, compressed gas is simply the first and/or second refrigerant in gaseous form. That is to say, by means of the first circuit and/or the second circuit, the refrigerant of the relevant circuit can be condensed on the common heat exchanger. When the gaseous refrigerant is allowed to condense, the part of the cooler that is in contact with the outside air defrosts. The cooler thus temporarily becomes a condenser. In the summer, if necessary, defrosting can also be done with ambient air by means of a supply of ambient air.

The system is designed with a further casing 20 which is visible in Figure 4. This casing 20 has upright walls 22 and a passage labyrinth 24, wherein fresh air can be supplied from an underside or an opening of the upright walls 22. This housing functions as an additional protection because the first circuit and the second circuit are each designed with a refrigerant that is highly flammable at room temperature. In this example this is propane and isobutane respectively. The upright walls can be made sound-absorbing, i.e. also separately from this example, made of a sound-absorbing material and/or comprise a soundabsorbing internal profile. In this example, the labyrinth consists of an upright inner wall 22.1 with a first passage 23.1 and an upright outer wall 22.2 with a second passage 23.1, and wherein the first and second passages are not at the same height in the respective upright walls. Figure 5 shows the upright walls 22 without the modules. Figure 6 shows the upright walls 22 together with the modules 3.1, 3.2 and a roof part 26. Some electrical components, such as the processing unit of each module of the plurality of heat pump modules, are cast in an electrically insulating material to prevent electrical ignition from taking place of refrigerants in the event of a leak.

A first heating circuit is provided with a first compressor (not shown, but customary) and the second heating circuit is provided with a second compressor (not shown, but customary) . The first and second compressors are each placed separately or jointly within a soundproof housing 30. This housing 30, which again is a kind of encasing, is visible in Figure 7. This encasing is optional. The encasing in question is designed for supplying air from above by means of a fan and discharging air from below. The white arrow 50 shows how the air flow is blown into the encasing 30, also known as the sound box, and how it is blown out again at the bottom of the sound box) . The enclosure 30 is shown in Figure 7 in exploded form, which is in two parts laterally offset in opposite directions. The enclosure 30 has an inlet at the top for aspirating air. On the underside, the casing is provided with openings, such as openings in a floor part of the casing, for the passage of air therethrough. The system further comprises at least one temperature sensor (not shown, but customary) for measuring the outside temperature. That is to say, the temperature outside of the system. The system is designed to switch, on the basis of the measured outside temperature, between heating the water flow by means of the first circuit only, and the combination of the first and the second circuit. In this example, the temperature sensor is communicatively connected to a processing unit of one of the modules. The system is further arranged to recognize a defect of and/or maintenance to a module of the plurality of heat pump modules and to switch it off on the basis of the recognized defect of and/or maintenance to the relevant module in which the defect is recognized and to redistribute the water flow over the other modules of the plurality of heat pump modules. When the flow sensor of a module becomes defective during use, the system is arranged to close the associated control valve and to redistribute the water flow to the other modules that do not exhibit the defect. Optionally, each module of the plurality of modules has a sensor for detecting a leak, such as a sensor measuring the pressure drop of water across the module. When the measured value of the pressure drop falls outside a predetermined range, a processing unit arranged communicatively with such a sensor decides to close the module from the water flow by closing the control valve. Figure 8 shows that the water supply and discharge are centrally controlled per module. That is to say, each module of the plurality of heat pump modules comprises a supply duct 40 for supplying the water flow and which supply duct is formed connectable to a supply duct of at least one other module of the plurality of heat pump modules, and wherein each module of the plurality of heat pump modules is arranged to take water from its own supply duct and wherein each module of the plurality of heat pump modules comprises a discharge duct 42 for discharging the water flow and which discharge duct is designed to be coupled to a discharge duct of at least one other module of the plurality of heat pump modules, and wherein each module of the plurality of heat pump modules is designed to discharge water via its own discharge duct. In this manner, the system can be expanded modularly without the need for an additional manifold for supply or discharge. The modules can therefore be linked to each other via supply and discharge.

Figure 8 further shows a switch panel 60 for operating the module via the processing unit, a central heating section 70, i.e. a section to which water is supplied and discharged from the module, a refrigeration section 80 and the heat pump cooler 90.

Each module of the heat pump modules has a nominal capacity of 250 kW in this example. This brings the total capacity of the system according to the example to 500 kW. This system can be expanded by connecting a third module to the second module, and optionally even connecting a fourth module to the third module. The link is therefore consecutive. The system can be expanded to, for example, 1000 kW.

Figure 9 shows a flow diagram of the system 1. The overview here is based only on a single heat pump module 3.1. In practice, these are coupled together for receiving and distributing the water flow. The first stage T1 and the second stage T2 are shown herein. Figure 10 shows the legend of the elements according to Figure 9. These elements are as follows:

Thus, Figure 9 shows the system in which the second circuit comprises a liquid separator for separating refrigerant condensed to liquid from an internal gas stream within the second circuit, and optionally wherein the separated liquid is gradually evaporated to be supplied to the compressor of the second circuit.

Figure 9 shows only one condenser in the system which is arranged as double-sided whereby it is able in the first stage, that is to say with the first circuit, heat the central heating water, and in the second stage, that is to with the second heating circuit, heat the central heating water. This exchanger has a double refrigeration side, so that one can cool both circuits on the same condenser.

During a defrosting of the condenser, because moisture from the environment sublimates on it during use, the second stage will be completely stopped and cold gas will be evaporated with the first circuit on exchanger-2 to create the heat needed to defrost the condenser, also called the outdoor cooler, also called the v-bank, with compressed gas.

Figure 11 shows more particularly the arrangement of a first module 3.1 according to the invention. In this example, it can be seen that the individual housing 10 is provided with a number of outside air intake ports 10.1. The outside air is drawn in by means of fans 12. These fans close before defrosting, so that rising warm air cannot leave the housing by rising and is thus forced to exchange heat with the common heat exchanger, as also shown in Figure 3. However, during normal functioning, i.e. during one or two-stage heating of central heating water, the fans 12 are in operation. The fans 12, also apart from this example, can be designed to direct at least a part of the extracted air further within the housing to compressors for cooling the compressors. This is also visible in Figure 12. The heat exchanger 18 absorbs heat from the air while heating central heating water, so that the fans cool the air during normal use, all use except defrosting. This cooled air can be fed to the compressors of the first and/or the second circuit. In this example both. The compressors are each located in their respective sound box 30. This cooled air then cools the compressors, but is itself heated again. The air heated by the compressors is then released back into the same room and used to heat the heat exchanger.

In Figure 13 it can be seen that the housing 10 is designed with a partition 10.2 so that the common heat exchanger is located in a space separated from the compressors. The housing is further provided with a ventilation duct 10.3 for capturing air at a first height in the space in which the compressors in sound boxes are located, and introducing air at a second height in the space where the common heat exchanger is located, and where the first height is higher than the second height. In this manner, warm air can be captured from compressors so that it can be reused at the heat exchanger. This increases the energetic efficiency of the system. Figure 14 shows that the warm air at the bottom can be mixed with the drawn-in outside air.

Figures 15 and 16 together show one flow diagram of an alternative system 1 ' according to the invention. Here too, the overview is based on a single heat pump module 3.1 ' . In the following, only differences with respect to the system 1 according to Figure 9 are discussed. The part of the system 1 ' shown in Figure 15 connects to the part of the system 1 ' shown in Figure 16. A dotted line indicates the transition between Figure 15 and Figure 16. In this system 1 ' , the number of expansion valves 10014 has been reduced due to the strategic placement of additional check valves in the system 10011. In the diagram it is visible through comparison where this change has been implemented. Due to this adjustment, fewer expansion valves are required, which means that the investment costs for the system are lower. One can think of an installation technique and electrotechnical reduction of labor and material. The manner of operation of system 1 ' is hereby unchanged. Furthermore, the system has been expanded as a so-called "four-duct system", which makes the possibility of cooling and heating through the central heating system possible. The four-duct system is just one example of how the cooler can be connected to the heat exchangers in the two-stage system to switch between heating and cooling. In this system 1 ' , the cooler 10021 can be operated in two different modes. This means that the heat pump module 3.1 ' can be operated in two different modes. In a first mode, also called the central heating mode, heat from a cooling water of the third exchanger 10027 is used for central heating by means of the second exchanger 10023. A first exchanger 10013 serves to exchange heat between the first and second circuits, i.e. between the two stages of the system Tl, T2. In the second mode, also known as the cooling mode, heat from the second exchanger is transferred to the cooling water from the third heat exchanger for central cooling. The second exchanger 10023 is flowed through by central heating water that is brought up to temperature by the system for heating or cooling. The central heating water can also be divided over different pump modules. This means that the central heating water can be used to both cool and heat the house, depending on the momentary need. In the first mode, the cooler 10021 only uses three of the four ducts it is connected to, in the second mode, the cooler uses all four ducts .

Figures 15 and 16 show that the cooler is connected to the plurality of heat exchangers such that the cooler can be operated in the second mode both when

- the system is switched to heat the water flow only through the first circuit; and

- the system is switched to heat the water flow by means of a combination of the first and the second circuit. If there is no heat demand or need, but for example there is a cooling demand, the heat is removed through the cooler V-bank cooler, which will then function as a condenser. Due to this application, the system 1 ' can be used as a whole as an air/water heat pump, but also as a water/water heat pump. This makes this product even more versatile. Apart from this example, different modules 3.1, 3.2 can each be operated simultaneously in mutually different modes. For example, the different modules can each heat or cool different central heating flows. In this example, the first module 3.1 ' and the second module (not shown) can be operated simultaneously in different modes. One can then cool a central heating water flow and the other can then heat a central heating water flow. Apart from this example, it is also possible to have two first modules for mutually distributing a water flow to be heated and two second modules for mutually distributing a water flow to be cooled.

Figure 17 shows the legend of the system 1 ' according to Figures 15 and 16. Only differences compared to Figure 10 are indicated here:

Figure 18 further shows a more specific embodiment of the valves 14, which can also be seen in Figure 12 as a cover for the fans 12. The valves 14 in Figure 18 are electronically controlled motor louvered valves. This provides an improved reduction of noise from, among other things, the fans, even when the valves are open. The valves close automatically during defrosting. To this end, the valves may be communicatively connected to other parts of the system, such as at least one module of the plurality of heat pump modules.