EP4658959A1

EP4658959A1 - An integrated water circuit for a heat pump

Info

Publication number: EP4658959A1
Application number: EP23832990.8A
Authority: EP
Inventors: Finn Mathiesen Høj
Original assignee: Grundfos Holdings AS
Current assignee: Grundfos Holdings AS
Priority date: 2023-01-31
Filing date: 2023-12-12
Publication date: 2025-12-10
Also published as: WO2024160432A1; CN120604087A

Abstract

Described and claimed is an integrated water circuit for a heat pump. The integrated water circuit comprises an electric backup heater with a composite housing defining a cavity for heating water using electric heating elements arranged in the cavity, a condenser connector, a first direct water connector and a first pump support. All connectors are formed integrally with the composite housing. The condenser connector is configured for connecting the electric backup heater to a return flow of a condenser of a heat pump. A first water pump is mounted via a distributor/collector unit to the first pump support so that an inlet of the first water pump is in fluid connection with the first distributor/collector unit. The first direct water connector is provided for supplying water from the cavity to an external water circuit.

Description

Applicant: GRUNDFOS HOLDING A/S Title: An integrated water circuit for a heat pump Our Ref.: GP 3692 WO Description [01] The present invention is directed to an integrated water circuit for a heat pump. The integrated water circuit comprises an electric backup heater, a first water pump for a first external water circuit and a first dis- tributor/collector unit. 5 [02] Heat pumps use thermal energy from the outside of a building to generate hot water for radiators, underground heating or for providing domestic hot water. The thermal energy collected outside the building is transferred via a heat transfer fluid to a condenser where water for the respective building circuits is heated. Depending on various factors such10 as the dimensions of the heat pump, the outside temperature, the ther- mal insulation of the building and the required water temperature, the water temperatures generated using the condenser may not be suffi- cient. Therefore, most heat pumps for domestic use include an electric backup heater which can be used to further increase the temperature15 of the water provided by the heat pump. [03] In case the heat pump is used for multiple water circuits in parallel, the water heated by the condenser and the electric backup heater has to be distributed among the multiple water circuits and may also have to be provided to the circuits at different supply temperatures. For exam- 20 ple, an underfloor heating circuit may require a supply temperature of 35°C, a radiator water circuit may require a supply temperature of 50°C and a domestic hot water circuit may require a water temperature of 27°C. In order to supply water to the different circuits, corresponding Patentanwälte Vollmann Hemmer Lindfeld GP 3692 WO, 12/12/2023 valves and manifolds need to be installed at the heat pump and dedi- cated water pumps have to be provided. [04] For domestic installations it is essential that all components re- quired for distributing the water among the multiple circuits can be inte- 5 grated into a single compact housing. EP 2312224 B1 discloses a heat pump with a hydraulics module that comprises an integrated electric backup heater with two three-way valves. The hydraulics module can be used to distribute water from the condenser of a heat pump between a heating water circuit and a domestic hot water circuit. 10 [05] While the hydraulics module integrates several parts of an internal water circuit, the resulting internal water circuit is not particularly com- pact due to the low degree of integration. Further, the hydraulics module is very limited in its use as it cannot be flexibly adapted to different num- bers of external water circuits and different supply temperatures. 15 [06] In view of the above, it can be considered an object of the pre- sent invention to provide an improved compact and flexible integrated water circuit for a heat pump that allows a compact design of the heat pump and can be flexibly adapted used for different purposes. [07] The present invention provides an integrated water circuit for a20 heat pump according to claim 1. Preferred embodiments are the sub- ject matter of the dependent claims. [08] According to the present invention, an integrated water circuit for a heat pump is provided. The integrated water circuit comprises an elec- tric backup heater, a first water pump for a first external water circuit and 25 a first distributor/collector unit. The electric backup heater comprises a composite housing defining a cavity for heating water using at least one Patentanwälte Vollmann Hemmer Lindfeld GP 3692 WO, 12/12/2023 electrical heating element arranged in the cavity. The electric backup heater further comprises a condenser connector, a first direct water con- nector and a first pump support which are all integrally formed with the composite housing. The condenser connector is configured for connect- 5 ing the electric backup heater to a return flow of a condenser of a heat pump. The first water pump is mounted via the distributor/collector unit to the first pump support so that an inlet of the water pump is in fluid connection with the first distributor/collector unit. The first water con- nector is provided for supplying water from the cavity to the first external 10 water circuit. [09] In other words, the integrated water circuit is based on an electric backup heater which serves at the same time as a manifold and a struc- tural support for a distributor/collector unit and a first pump. This enables a particularly compact design of the integrated water circuit and still al-15 lows a flexible adaptation of the integrated water circuit to many differ- ent uses as will be explained in the following. [10] The integrated water circuit is based on the composite housing of the electric backup heater. The composite housing is, for example, pref- erably made from polyamide 66 (PA66) with 30% glass fiber (GF) using 20 plastic injection molding. Further, the composite housing is preferably produced as a single piece. This reduces the number of parts that need be manufactured and also the number of parts that need to be assem- bled. [11] The composite housing surrounds a cavity in which at least one 25 and preferably a plurality of electric heating elements is arranged. The electric heating elements which are made, for example, from copper can be used to additionally warm-up water in case the water heated using the condenser of the heat pump is not warm enough. The cavity Patentanwälte Vollmann Hemmer Lindfeld GP 3692 WO, 12/12/2023 may, for example, have a generally cylindrical shape and extend in a longitudinal direction. [12] The composite housing of the electric backup heater comprises at least two connectors: a condenser connector and a first direct water 5 connector. The condenser connector is a connector which is provided for connecting the backflow of the condenser of the heat pump to the electric backup heater. In other words, the electric backup heater is sup- plied with water through the condenser connector. The condenser con- nector is formed integrally with the composite housing, i.e., it is formed in10 one piece with the housing so that manufacturing of the electric backup heater no connectors need to be soldered or welded or attached in any other way to the electric backup heater. [13] The first direct water connector is formed so that water can be directly supplied from this connector to an external water circuit, i.e., the 15 direct external water connector is used to supply water from the electric backup heater to the external water circuit. The external water circuit may, for example, be a domestic hot water circuit, a water circuit sup- plying hot water to radiators or an underfloor heating circuit. The con- nector is referred to as a direct water connector at it is intended that no20 pumps or valves of the internal heat pump water circuit are placed be- tween the connector and the external water circuit, at least not inside the housing holding the integrated water circuit. [14] Furthermore, the composite housing also includes a first pump sup- port to which a first water pump is mounted using a distributor/collector 25 unit. The first pump support is again integrally formed with the composite housing. For example, when the composite housing is manufactured us- ing plastic injection molding, the housing defining the cavity, the con- denser connector, the first direct water connector and the first pump support are all manufactured in the same manufacturing step. Patentanwälte Vollmann Hemmer Lindfeld GP 3692 WO, 12/12/2023 [15] The first water pump which is preferably a centrifugal pump is at- tached to the composite housing using the first pump support and a dis- tributor/collector unit which is placed between the pump support and the first water pump. The distributor/collector unit may be a passive de- 5 vice that only forwards one flow to the first water pump, combines multi- ple flows on their way to the first water pump, i.e., collects multiple flows, or splits multiple a single supply flow into multiple outgoing flows, i.e., dis- tribute the supply flow to multiple outgoing flows. Alternatively, the dis- tributor/collector unit may be formed as a three-way valve which ac- 10 tively mixes two incoming flows, i.e., a three-way valve which is operated as a collector, or distributes a single incoming flow selectively among two outgoing flows, i.e., a three-way valve which is operated as a distributor. [16] Preferably, the distributor/collector unit has a housing which is formed as a single plastic injection molded piece, for example, from15 PA66 with 30% GF. This housing may be used as passive distributor/collec- tor unit but could be reconfigured as a three-way valve by installing an insert in the housing holding the components of the valve. Thereby, irre- spective of the configuration of the distributor/collector required for op- erating the integrated water circuit, the first water pump can always be20 attached to the first pump support using the same part. [17] The distributor/collector unit thus advantageously has multiple purposes. It provides an inlet connection for the first water pump and serves as an attachment means for mounting the first water pump to the first pump support. Hence, the distributor/collector unit is not only a con- 25 duit for water but also part of the structural support for the first water pump. [18] In a preferred embodiment, a housing of the first distributor/col- lector unit and a pump housing of the first water pump are formed as single piece. For example, the two parts may be molded as a single Patentanwälte Vollmann Hemmer Lindfeld GP 3692 WO, 12/12/2023 piece with a bracket interconnecting the housing of the distributor/col- lector unit and the pump housing. Thus, by attaching the distributor/col- lector unit to the first pump support, the first water pump is mounted to the first pump support via the first distributor/collector unit. 5 [19] The integrated water circuit thus advantageously may be used in multiple different set ups or configurations. The electric backup heater of the integrated water circuit serves both as a manifold for distributing the heated water at least via the first direct water connector and further connectors to multiple external water circuits, and also provides an ad-10 ditional heat source for the heat pump. [20] As the first water pump is mounted via the distributor/collector unit to the first pump support on the composite housing of the electric backup heater, a particularly compact arrangement of the compo- nents of the water circuit can be achieved. Further, the number of addi-15 tional conduits required for completing the integrated water circuit is re- duced which simplifies assembly of the integrated water circuit as only a limited number of parts need to be connected. Also, reusing parts for multiple configurations reduced the overall number of parts that are re- quired which also reduced the production costs per unit. 20 [21] In a preferred embodiment the integrated water circuit comprises a second water pump for a second external water circuit and a second distributor/collector unit. The electric backup heater comprises a second pump support integrally formed with the composite housing opposite of the first pump support. The water pump is mounted via the second dis- 25 tributor/collector unit to the second pump support so that an inlet of the second water pump is in fluid connection with the second distributor/col- lector unit. Patentanwälte Vollmann Hemmer Lindfeld GP 3692 WO, 12/12/2023 [22] Thus, in the preferred embodiment the electric backup heater supports a second external water circuit. To this end, a second pump support is formed as part of the composite housing of the electric backup heater. Th pump support and the composite housing are formed 5 as a single piece which simplifies the assembly of the integrated water circuit as no additional parts need to be mounted to the composite housing to provide the second pump support. Preferably, the second pump is already formed when the composite housing is manufactured using, for example, plastic injection molding. 10 [23] On the second pump support a second water pump for the sec- ond external water circuit is mounted. Like the first water pump, the sec- ond water pump is preferably also a centrifugal pump which is attached to the second pump support using the second distributor/collector unit. This second distributor/collector unit can also be a passive connection 15 for one or more supply lines at least for the second water pump or be provided as an active three-way valve that at least controls the flow to the second water pump. [24] In a preferred embodiment, a pump housing of the second water pump is formed integrally with a housing of the second distributor/collec-20 tor unit. [25] Preferably, the first and second distributor/collector unit have an identical housing which can either be fitted with already discussed inserts to turn them into three-way valves for actively mixing or diverting one or more flows or be used without an insert as a passive distributor/collector. 25 Using identical parts as the first and second distributor/collector unit fur- ther simplifies assembly of the integrated water circuit as less different parts are required. Further, by having to manufacture fewer different parts, the cost of providing the parts that are required to form the inte- grated water circuit for a heat pump are further reduced. Patentanwälte Vollmann Hemmer Lindfeld GP 3692 WO, 12/12/2023 [26] In a preferred embodiment, a pump housing of the first water pump is formed integrally with a housing of the first distributor/collector unit. Likewise, a pump housing of the second water pump is formed inte- grally with a housing of the second distributor/collector unit. By forming 5 the pump housing and the respective distributor/collector units from a single piece, the production costs are reduced as only a single tool is required for plastic injection molding the combined part. Further, during assembly it is not necessary to attach the parts to one another. [27] Preferably, with respect to a center plane of the composite hous- 10 ing, the first pump support is formed opposite the second pump support, the first distributor/collector unit is arranged opposite the second distrib- utor/collector unit and the first water pump is arranged opposite the sec- ond water pump. Thus, according to the preferred embodiment the first water pump is mounted via the first distributor/collector unit and the first 15 pump support on an opposite side of a center plane of the composite housing as the second water pump which is mounted to the composite housing via the second distributor/collector unit and the second pump support. Arranging the water pump and the distributor/collector unit pro- vided for the first external water circuit opposite to the water pump and20 the distributor/collector unit provided for the second external water cir- cuit allows providing a particularly compact integrated water circuit. Fur- ther, when the integrated water circuit is mounted in a building in an intended operating position, the center plane could, for example, ex- tend vertically. 25 [28] It is further preferred that the first distributor/collector unit is ar- ranged at same distance and on the same side of a base plane of the composite housing as the second distributor/collector unit. Further, the first water pump is preferably arranged at the same distance and in a same side of the base plane of the electric backup heater as the water 30 pump. The base plane extends perfect to the center plane. Patentanwälte Vollmann Hemmer Lindfeld GP 3692 WO, 12/12/2023 [29] Thus, in the preferred embodiment the components provided for the first external water circuit are arranged at a same distance from the base plane then those components of the integrated water circuit pro- vided for the second external water circuit. Again, this arrangement of 5 the distributor/collector unit and the water pump facilitate a particularly compact integrated water circuit. [30] In a particularly preferred embodiment, the first pump support, the first water pump and the first distributor/collector unit are arranged sym- metrically with respect to the center plane to the second pump support, 10 the second water pump and the second distributor/collector unit. [31] In a preferred embodiment, the second pump supports forms a conduit establishing a fluid connection between the cavity of the elec- tric backup heater and the second distributor/collector unit so that an inlet of the second water pump is in fluid connection via the second dis- 15 tributor/collector unit with the cavity of the electric backup heater. [32] In other words, in the preferred embodiment the second pump support is at least partially hollow so that it can connect the interior of the distributor/collector unit attached thereto to the inside of the cavity of the electric backup heater. Thereby, a direct fluid connection be- 20 tween the cavity of the electric backup heater and the second water pump can be established. [33] Providing a second pump support which also serves as a fluid con- nection between the cavity and the second water pump facilitates the use of the integrated water circuit for supplying heated water to external25 water circuits that are connected to the pressure outlet of the second water pump, For example, when the integrated water circuit shall be used to supply hot water to an underfloor heating circuit, this underfloor heating circuit requires water at significantly lower temperatures than a Patentanwälte Vollmann Hemmer Lindfeld GP 3692 WO, 12/12/2023 first external water circuit which is used, for example, to provide domestic hot water. To lower the temperature of the water provided to the under- floor heating circuit, the hot water taken from the cavity of the electric backup heater may be mixed in the second distributor/collector unit with 5 return flow from the underfloor heating. In this example, the second dis- tributor/collector unit is preferably configured as a three-way valve so that the mixing of water from the cavity of the electric backup heater and the return flow from the underfloor heating can be actively con- trolled to allow setting the temperature of the water provided to the un- 10 derfloor heating. By enabling the second water pump to draw the water directly from the cavity via the second pump support, advantageously no additional piping has to be provided which simplifies assembly of the integrated water circuit. [34] In a further preferred embodiment, the first distributor/collector 15 unit is connected to the second distributor/collector unit via a bypass connector. The bypass connector may be formed as single part and may comprise a conduit for establishing a fluid connection between the first distributor/collector unit and the second distributor/collector unit. [35] Thus, a bypass connector between the two distributor/collector20 units is provided which may be used to establish a fluid connection be- tween the second distributor/collector unit and the first distributor/col- lector unit. Such a connection can, for example, be used when the sec- ond water pump is used as a booster pump for the first water pump when high flows are required. 25 [36] For example, in case the first water pump is used to supply water both for a conventional radiator circuit and a domestic hot water circuit, i.e., for two external water circuits, the return flow of the radiator circuit may be attached to the second distributor/collector unit and the return flow from the domestic hot water circuit could be connected to the first Patentanwälte Vollmann Hemmer Lindfeld GP 3692 WO, 12/12/2023 distributor/collector unit. The first distributor/collector unit would further be configured as a three-way valve which allows controlling the amount of flow that is drawn from the radiator circuit and the domestic hot water circuit which in turn controls the amount of water or flow provided to the 5 respective external water circuit. [37] The second distributor/collector unit could serve as a passive dis- tributor which only distributes return flow from the radiator circuit to the first distributor/collector unit or the second water pump. The amount of water that is drawn in the respective directions depends on the opera-10 tion of the water pumps and the configuration of the first distributor/col- lector unit. In this configuration, the pressure side outlets of both water pumps are both connected to condenser. [38] Hence, in this exemplary embodiment the bypass connector al- lows using the second pump as a booster pump without having to signif- 15 icantly modify the remainder of the integrated water circuit. Further, since the first and second distributor/collector units are preferably ar- ranged at a same distance from the base plane, a simple direct con- nection can be provided using the bypass connector. Hence, the bypass connector also improves the rigidity of the integrated water circuit as it20 provides a structural connection between the first and second distribu- tor/collector unit. [39] In a preferred embodiment, the first distributor/collector unit is structurally connected to the second distributor/collector unit via a con- necting element. The connecting element has a return flow interface for25 a return flow of an external water circuit. An external water circuit con- nected to the return flow interface is in fluid communication with either the first or the second distributor/collector unit via the connecting ele- Patentanwälte Vollmann Hemmer Lindfeld GP 3692 WO, 12/12/2023 ment. No fluid connection is provided between the first distributor/col- lector unit and the second distributor/collector unit by the connecting element. The connecting element is preferably formed as a single piece. [40] In other words, in the preferred embodiment instead of the bypass 5 connector a connecting element is provided which attaches the first dis- tributor/collector unit to the second distributor/collector unit and further provides a connector for attaching a return flow from an external water circuit. The return flow is directed to either the first distributor/collector unit or the second distributor/collector unit. 10 [41] A return flow interface could, for example, be used for attaching the return flow of an underfloor heating circuit to the integrated water circuit so that the return flow from the underfloor heating can be mixed in the second distributor/collector unit with hot water from the cavity of the electric backup heater. To this end, the second distributor/collector 15 unit is preferably configured as a three-way valve operating in a mixing mode so that the return flow from the underfloor heating can be mixed with the hot water from the cavity of the electric backup heater. The preferred embodiment thus provides a particularly compact design as the return flow conduit attached to the return flow interface is arranged 20 between the first water pump and the second water pump to use every available space in the integrated water circuit. [42] In a preferred embodiment, the first pump support further defines a return flow connector for the first external water circuit. When a return flow of the first external water circuit is connected to the return flow con- 25 nector of the first pump support, the return flow of the first external water circuit is in fluid communication via a conduit formed by the first pump support with the first distributor/collector unit. The cavity defined by the composite housing is not in fluid communication with the first distribu- tor/collector unit via the first pump support. Patentanwälte Vollmann Hemmer Lindfeld GP 3692 WO, 12/12/2023 [43] In other words, the first pump support is also hollow so that it can serve as part of the integrated water circuit and not only as a structure for supporting the first distributor/collector unit and the first water pump. The conduit through the first pump support allows connecting the return 5 flow of one of the external water circuits to the first distributor/collector unit and through the first distributor/collector unit to the first water pump. Thereby, an additional connector for the first distributor/collector unit is provided so that multiple connectors are available for the first distribu- tor/collector unit. Using the first pump support for connecting the return10 flow of an external water circuit to the first distributor collector unit pro- vides a particularly compact arrangement of the connector. [44] This is particularly relevant in case the first water pump is used to drive two external water circuits such as a conventional radiator circuit and a domestic hot water circuit. Here, the return flow of one of the ex- 15 ternal water circuits can be connected via the first pump support to the first distributor/collector unit and the second return flow can be directly connected directly to the first distributor/collector unit. In case the first distributor/collector unit is configured as a three-way valve operating in a mixing mode, this allows the first water pump to drive both water cir- 20 cuits at the same time or alternatively separately. [45] As previously mentioned, the first and/or a second distributor/col- lector unit may be a three-way valve. The three-way valve can prefera- bly be operated in a diverter mode or a mixing mode. Thus, the distribu- tor/collector units are preferably based on a housing or casing serving as 25 a passive distributor/collector unit into which a valve insert can be mounted for transforming the passive distributor/collector unit into an ac- tive three-way valve. Patentanwälte Vollmann Hemmer Lindfeld GP 3692 WO, 12/12/2023 [46] The distributor/collector unit may, for example, comprise four con- nectors and one opening for installing a valve insert in the distributor col- lector unit. One of the four connectors could be an outflow connector of the distributor/collector unit which is connected to the input port of 5 the water pump supported on the respective distributor/collector unit. The outflow connector is always used for an outgoing flow to the at- tached water pump. [47] Another one of the four connectors could be a support connector of the distributor connector unit is attached to a pump support of the10 electric backup heater. The support connector could be used for receiv- ing either a return flow from an external water circuit connected to a return flow connector at the pump support or for receiving a flow from the cavity of the electric backup heater. The outflow connector and the support connector are preferably aligned and extend in opposite direc- 15 tions but parallel to the central plane when the distributor/collector unit has been attached to a pump support. [48] The third and fourth connectors of the four connectors are lateral connectors extending perpendicular to the outflow connector and the support connector and in opposite directions. The lateral connector20 could, for example, be used for attaching a bypass connector and con- necting two distributor/collector units or be used for connecting a return flow of an external water circuit to the distributor/collector unit. The lat- eral connector could, thus, depending on the configuration of the inte- grated water circuit be used for incoming or outgoing flows. 25 [49] In a preferred embodiment, the integrated water circuit com- prises an input condenser connector for connecting at least an outlet of the first water pump to a condenser of a heat pump. The input conden- ser thus supplies water to the condenser and could also be referred to as a condenser supply. Patentanwälte Vollmann Hemmer Lindfeld GP 3692 WO, 12/12/2023 [50] In a preferred embodiment, the cavity of the electric backup heater has a generally cylindrical shape. Thus, the composite housing has the shape of a tube or cylinder to which the different connectors and the pump supports are attached on various positions. Preferred ex- 5 emplary positions of the connector and support will be described in the following. A cylindrical cavity is both particularly efficient for heating the water using electric heating elements inserted thereto along the longitu- dinal direction of the cavity. Also, the cylindrical shape allows for an even distribution of the water flowing into the cavity through the condenser10 connector to the different outlets. Furthermore, a tube structure is inher- ently rigid which allows supporting the relatively heavy distributor/collec- tor units and the water pumps on the housing of the electric backup heater. [51] In a preferred embodiment, the condenser connector and the 15 first direct water condenser extend in opposite directions away from the cavity defined by the composite housing. The condenser connector and the first direct water connector extend preferably in the center plane. For example, the condenser connector could extend in the center plane parallel to the direction in which the arrangement of the distributor, slash 20 connectors units and the water pumps extend away from the cavity and the first direct water connector could extend in the opposite direction, i.e., away from the distributor/collector units and the water pumps. The first direct water connector and the condenser connector are, however, not aligned. Rather, the direct water connector is arranged so that water 25 from the condenser connector has to flow along most or the entirety of the electric heating elements in the cavity so that energy is transferred from the heating element to the passing water for sufficient energy trans- fer. [52] Further, the return flow connector of the first pump support prefer- 30 ably extends away from the first pump support in a direction extending Patentanwälte Vollmann Hemmer Lindfeld GP 3692 WO, 12/12/2023 parallel to the first direct water connection. The return flow connector and the first direct water connector are provided for connecting water circuits which are not part of the integrated water circuit, i.e., external thereto. Thus, having the water circuits extending in the same direction 5 allows a simple coupling of all external connections to the electric backup heater. Such a connection could, for example, be established via a bottom cover of a housing of the integrated water circuits where the connectors terminate and merge into coupling for external water circuits. 10 [53] In the latter case the connector could also form a structure sup- port supporting the entire integrated water circuit on the bottom cover of the housing of the integrated water circuit. Hence, in the exemplary embodiment the integrated water circuit at least partially rests on the external water connector and the return flow connector of the electric15 backup heater. Since these parts are formed integrally with the compo- site housing of the electric backup heater, no or only a limited number of additional parts is required for supporting the integrated water circuit in its housing. [54] In a further preferred exemplary embodiment, a support beam or 20 support shaft is provided on the second pump support. The support beam extends parallel to the return flow connector and the first direct water connector and is provided for further supporting the integrated water circuit on a bottom cover of a housing of the integrated water circuit. 25 [55] In a further preferred embodiment, the first pump support extends generally perpendicular to the center plane away from the cavity de- fined by the composite housing. Hence, the first pump support extends preferably parallel to the base plane. It is further preferred that the first pump support is formed so that a first water pump mounted to the first Patentanwälte Vollmann Hemmer Lindfeld GP 3692 WO, 12/12/2023 pump support is arranged on a side of the electric backup heater to- wards which the condenser connector extends. Again, this serves for providing a particularly compact integrated water circuit where all inter- nal connections are provided on one side of the base plane of the elec- 5 tric backup heater whereas all connections to external parts are pro- vided on a lower side of the external backup heater. [56] In a preferred embodiment the electric backup heater comprises a combined fill/drain connector which is integrally formed with the com- posite housing. The combined fill/drain connector preferably 10 extends parallel to the at least one direct water connector away from the cavity defined by the composite housing. The combined fill/drain connector can be used to fill the integrated water circuit as well as the attached external water circuits with water. Further, water can be drained out of these circuits using the integrated fill/drain connector. In 15 case the fill/drain connector extends parallel to the at least one direct water connector it can be used as a further support of the entire inte- grated water circuit provided that it rests, for example, on a bottom cover of a housing of the integrated water circuit. [57] In a preferred embodiment, the integrated water circuit is ar- 20 ranged in a housing comprising a bottom cover. The integrated water circuit is supported by the first direct water connector on the bottom cover. Preferably, the integrated water circuit is further supported by the combined fill/drain connector on the bottom cover. [58] In an exemplary aspect an electric backup heater for an inte-25 grated water circuit for a heat pump is provided. The following exem- plary embodiments of the electric backup heater form an independent inventive concept. The previous detailed embodiments discussed with regard to the electric backup heater as part of an integrated water cir- cuit also apply to the electric backup heater itself. Therefore, for the sake Patentanwälte Vollmann Hemmer Lindfeld GP 3692 WO, 12/12/2023 of brevity, a repetition of the discussion of individual parts and embodi- ments of the electric backup heater is not repeated. Instead, reference is made to the preceding description of the electric backup heater as a part of the integrated water circuit-. [59] Preferably, the electric backup heater comprises a composite housing defining a cavity for heating water and receiving at least one electric heating element. Further, the electric backup heater comprises a condenser connector for connecting the electric backup heater to a return flow of condenser of a heat pump, one or more direct water con- nectors, and a first pump support. The condenser connector, the first di- rect water connector and the first pump support are formed integrally with the composite housing. The one or more direct water connectors are each configured for providing water from the cavity directly to an external water circuit connected to the respective direct water con- nector. The first pump support is provided for mounting a first water pump for an external water circuit to the composite housing. [60] In a preferred embodiment the wherein the electric backup heater further comprises a second pump support, The second pump sup- port is formed integrally with the composite housing. The second pump support is provided for mounting a second water pump for an external water circuit to the composite housing. The first pump support and the second pump support are preferably formed on opposite sides of the composite housing. [61] Preferably, at least one of the first pump support and the second pump support defines a conduit facilitating a fluid connection between a water pump mounted to the respective pump support and the cavity. Patentanwälte Vollmann Hemmer Lindfeld GP 3692 WO, 12/12/2023 [62] The electric backup heater further preferably comprises two direct water connectors integrally formed with the composite housing. Each of the direct water connectors is configured for providing water from the cavity directly to an external water circuit. 5 [63] In a preferred embodiment the cavity has a generally cylindrical shape. [64] At least one of the first pump support and the second pump sup- port preferably comprises a return flow connector for connecting a re- turn flow from an external water circuit. The return flow connector is10 formed integrally with the pump housing and facilitates a fluid connec- tion between an external water circuit connected to the return flow con- nector and a water pump mounted to the respective pump support. [65] In a preferred embodiment the condenser connector and the at least one direct water connector extend in a vertical plane in opposite15 directions away from the cavity defined by the composite housing. [66] The vertical plane is preferably identical to the central plane. In a preferred embodiment, the return flow connector extends away from the respective pump support in a direction extending parallel to the ver- tical plane and facing in the same direction as the at least one water20 connector. [67] The first pump support extends generally perpendicular to the ver- tical plane away from the cavity defined by the composite housing. The first pump support is further preferably formed so that a first water pump mounted to the first pump support is arranged on a side of the electric 25 backup heater towards which the condenser connector extends. Patentanwälte Vollmann Hemmer Lindfeld GP 3692 WO, 12/12/2023 [68] In a preferred embodiment, the electric backup heater comprises a combined fill/drain connector which is integrally formed with the com- posite housing. The combined fill/drain connector preferably extends parallel to the at least one direct water connector away from the cavity 5 defined by the composite housing. [69] In so far as in any of the preceding embodiments of an electric backup heater for an integrated water circuit a first and/or second wa- ter pump is mentioned, this water pump is preferably a centrifugal water pump. 10 [70] In the following the invention will be described in more detail with reference to the drawings wherein: Figure 1 shows an exemplarily embodiment of a heat pump used for providing hot water to multiple external water circuits, 15 Figure 2 shows a schematic circuit diagram of the water circuit of the heat pump shown in figure 1, Figure 3 shows a perspective drawing of an integrated water circuit for a heat pump comprising an exemplarily embodiment of an electric heat exchanger, 20 Figure 4 shows another perspective drawing of the exemplarily em- bodiment of figure 3, Figure 5 shows a partial exploded view of the exemplarily embodi- ment of figure 3, Figure 6 shows a first sectional view of the exemplarily embodiment25 of figure 3, Figure 7 shows a further perspective view of the exemplarily embod- iment of figure 3, Figure 8 shows a second sectional view of the exemplarily embodi- ment of figure 3, Patentanwälte Vollmann Hemmer Lindfeld GP 3692 WO, 12/12/2023 Figure 9 shows a perspective view of the exemplarily embodiment of an electric backup heater of figure 3 Figure 10 shows a sectional view of the exemplarily embodiment of an electric backup heater of figure 9, 5 Figure 11 shows a top view of the exemplarily embodiment of an electric backup heater of figure 9, Figure 12 shows a bottom view of the exemplarily embodiment of an electric backup heater of figure 9, Figure 13 shows a second exemplarily embodiment of an integrated 10 water circuit for a heat pump, Figure 14 shows a schematic drawing of the integrated water circuit of figure 13 and two external water circuits, Figure 15 shows a third exemplarily embodiment of an integrated water circuit for a heat pump, and 15 Figure 16 shows a schematic drawing of the exemplarily embodi- ment of an integrated water circuit of figure 15 used to pro- vide hot water to two external water circuits. [71] Figure 1 shows an exemplarily embodiment of the heat pump 1 which is used to supply hot water to multiple external water circuits 2, 3, 20 4. The first external water circuit 2 is an underfloor heating circuit 5. The second external water circuit 3 is a conventional radiator heating circuit 6 and the third external circuit 4 is a domestic hot water circuit 7. [72] Only one radiator 8 of the radiator heating circuit 6 and a single loop of heating tubes 9 of the underfloor heating circuit 5 are shown in 25 figure 1 to exemplify the use of the respective circuits 5,6. Further, a warm water buffer 10 is shown in figure 1 which provides water supply for do- mestic hot water. The warm water buffer 10 may also be referred to as a hot water tank 10 or hot water storage 10. Patentanwälte Vollmann Hemmer Lindfeld GP 3692 WO, 12/12/2023 [73] The heat pump 1 comprises an external heat exchanger unit 11 which includes a fan (not shown) for heating a refrigerant and a con- denser (not shown) where the refrigerant is used to heat water for the external water circuits 2, 3, 4. The external heat exchanger unit 11 is con- 5 nected via a supply line 12 and return flow line 13 to an exemplarily em- bodiment of an integrated water circuit 14. The integrated water circuit 14 is arranged in a housing 15 which also holds an expansion tank or ex- pansion vessel 16. [74] The integrated water circuit 14 as well as the general layout of the 10 system shown in figure 1 will now be described in more detail with regard to figure 2. For the sake of completeness is should be noted that the in- tegrated water circuit 14 could be used with different types of heat pumps, for example, a heat pump where all parts are located in a single housing or a heat pump where the condenser is arranged in the same 15 housing as the integrated water circuit. The heat pump 1 shown in figure 1 is an air-source heat pump. However, the integrated water circuit 14 could also, for example, be used with a ground-source heat pump, an exhaust heat air pump or a water-source air pump. [75] In figure 2 the fan 17 and the condenser 18 of the heat pump 1 20 are shown as separate parts with a conduit 19 for a refrigerant extending between the two parts 17, 18 of the heat pump 1. Water heated in the condenser 18 flows via a return flow line 13 past a temperature sensor 20 to an electric backup heater 21. Both the temperature sensor 20 and the electric backup heater 21 are part of the integrated water circuit 14. In 25 figure 2 all components that are inside the dashed line indicated with reference numeral 14 are part of the integrated water circuit 14. [76] The temperature sensor 20 is provided for measuring the water temperature in the return flow line 13 from the condenser 18. In case the temperature is lower as required, electric heating elements 22 arranged Patentanwälte Vollmann Hemmer Lindfeld GP 3692 WO, 12/12/2023 in a cavity 23 of the electric backup heater 21 is activated to increase the temperature of the water. In order to measure the temperature of the water in the cavity 23 a further temperature sensor 24 is provided. For example, the electric backup heater 21 may comprise a plurality of elec- 5 tric heating elements 22 which can be selectively activated and deac- tivated to increase the amount by which the return flow from the con- denser 18 is heated in the electric backup heater 21. [77] The integrated water circuit 14 provides heated water to three ex- ternal water circuits 2, 3, 4. The first external water circuit 2 is as previously10 discussed an underfloor heating circuit 5. The second external water cir- cuit 3 is a conventional radiator circuit 6 and the third external water cir- cuit is used for providing domestic hot water 7. Also shown in figure 2 is the expansion vessel 16 which is also not part of the integrated water circuit 14 although it may be arranged in the same housing 15 as shown 15 in figure 1. [78] As can be seen in figure 2 the second and third external water circuits 3, 4 are directly supplied with water from the cavity 23 of the elec- tric backup heater 21. This is indicated by the arrows 25, 26 pointing in the flow direction of the water. Thus, a supply or inlet temperature of the20 second and third external water circuit 3, 4 corresponds to the tempera- ture of the water in the cavity 23 of the electric backup heater 21. [79] The return flows of the second and third external water circuit 3, 4 are collected or combined at a three-way valve 27 which is part of the integrated water circuit 14. The three-way valve 27 is operated as a mix-25 ing valve selectively joining the return flows of the two external water cir- cuits 3, 4. The outflow of the three-way valve 27 flows past the expansion vessel 16 towards a first water pump 28. The first water pump 28 is a cen- trifugal pump. From the first water pump 28 the water flows past a check Patentanwälte Vollmann Hemmer Lindfeld GP 3692 WO, 12/12/2023 valve or non-return valve 29 and a temperature sensor 30 to the conden- ser 18 of the heat pump 1. [80] As the first external water circuit 2 is an underfloor heating circuit 5, it requires a lower supply temperature than the second and third external 5 water circuits 3, 4. Therefore, water drawn from the electric backup heater 21 is not directly supplied to the first external water circuit 2 but instead mixed at a second three-way valve 31 with a return flow from the underfloor heating circuit 5. The outflow of the second three-way valve 31 is pumped by a second water pump 32 into the first external water 10 circuit 2. Further, a temperature sensor 33 is arranged at the outflow of the second pump 32 to measure the supply temperature of the first water circuit 2. Depending on the temperature measured by the temperature sensor 33, the mixing of the return flow from the first external water circuit 2 and the water drawn from the cavity 23 of the electric backup heater 15 21 is modified. [81] The remaining water from the first external water circuit 2 which is not mixed at the second three-way valve 31, flows past a second check valve 34 towards the condenser 18 of the heat pump 1. This amount of water corresponds to the amount of water taken from the cavity 23 of 20 the electric backup heater 21 and mixed at the second three-way valve 31. Ahead of the temperature sensor 30, the return flows of the two three external water circuits 2, 3, 4 are combined. The second three-way valve 31 as well as the second water pump 32 (which is also a centrifugal pump), the temperature sensor 30 and the second return valve 34 are all 25 part of the integrated water circuit 14. [82] An exemplary embodiment of an integrated water circuit 14 will now be described with reference to figures 3 to 8. Each of figures 3 to 8 shows the same integrated water circuit 14 which is based on an electric backup heater 21 shown in detail in figures 9 to 12. The electric backup Patentanwälte Vollmann Hemmer Lindfeld GP 3692 WO, 12/12/2023 heater 21 comprised a composite housing 35 which has been manufac- tured using plastic injection molding from polyamide 66 with 30% glass fiber (PA66 GF30). The entire composite housing 35 is made from a single piece and defines a cavity 23. The inside of the cavity 23 is only visible in 5 figures 5, 6, and 10. [83] The cavity 23 has a generally circular cross-section and thus an about cylindrical shape. Inside the cavity 23 a heating insert 36 or heat- ing module 36 has been placed which can be inserted through an open- ing 23a. The heating insert 36 comprises twelve electric heating elements 10 37 out of which only selected heating elements have been designated with reference numerals to keep the figure intelligible. The heating ele- ments 37 are arranged inside the cavity 23 to heat or warm-up water. Note that the individual heating elements 37 are only visible in figures 5, 6, and 10. In the remaining figures, only a flange 38 which is used to at- 15 tach the heating insert 36 to the composite housing 35 of the electric backup heater 21 is visible. The flange 38 is secured to the composite housing 35 using four bolts 39. Only selected bolts 39 have been desig- nated in the drawings with reference numerals. [84] The heating inserts 36 further comprises for each of the heating 20 elements 37 are power connector 40 which protrudes to the outside of the cavity 23. The power connectors 40 of which again only selected have designated with reference numerals are provided for supplying electric power to the heating elements 37. [85] The electric backup heater 21 comprises three connectors 41, 42, 25 43 at its bottom. The first connector 41 and the second connector 42 are direct water connectors 41, 42 which are used to supply water directly from the cavity 23 of the electric backup heater 21 to an external water circuit 3, 4. In the exemplarily embodiments shown in figures 1 and 2 the Patentanwälte Vollmann Hemmer Lindfeld GP 3692 WO, 12/12/2023 first direct water connector 41 is used to supply water to the second ex- ternal water circuit 3 which is a conventional radiator circuit 6 and the second direct water connector 42 provides water to the third external water circuit 4 which is a domestic hot water circuit 7. 5 [86] The third connector 43 at the bottom of the electric backup heater 21 is a combined fill/drain connector 43 which can be used to fill the integrated water circuit 14 with water or drain the water from the circuit 14. As can be seen best in figure 6 and 10, the first direct water connector 41, the second direct water connector 42 and the fill/drain 10 connector 43 are each formed integrally with the composite housing 35, i.e., are formed as a single piece with the composite housing 35. [87] In order to attach the connectors to outside piping, ducts or con- duits, couplings 44, 45, 46 with outer threads have been placed in the connectors 41, 42, 43. Here, the couplings 44, 45, 46 are locked in place 15 using metal brackets 47. The metal brackets 47 can be seen, for example in figures 3, 4 and 5 as well as figures 9 and 12 where at least one of the brackets 47 has been designated with a reference numeral. To summa- rize, the electric backup heater comprises three connectors 41, 42, 43 at its bottom which may be used to supply water to a conventional radiator 20 circuit 6 via the first coupling 44, to supply water to a domestic hot water circuit 7 via the second coupling 45 and to fill or drain the integrated water circuit 14 using the third coupling 46. [88] As can be seen best in figures 6, 7, and 10, the first, second and third connector 41, 42, 43 are all arranged on a center plane 49 of the 25 electric backup heater 21. Figure 6 shows a cut though the integrated water circuit 14 along the center plane 49. Figure 10 shows the corre- sponding cut through the electric backup heater 21 alone. In addition to serving as ducts for water, the connectors 41, 42, 43 structurally support the electric backup heater 21 and, therefore, the entire integrated water Patentanwälte Vollmann Hemmer Lindfeld GP 3692 WO, 12/12/2023 circuit 14 on a bottom cover 48 of the housing 15 of the integrated water circuit 14. Thus, the connectors 41, 42, 43 are not only used as conduits for water but also as support structure for the entire integrated water cir- cuit. 5 [89] Note that in figures 3 to 8 only the bottom cover 48 of housing 15 of the integrated water circuit 14 is shown. The remainder of the housing 15 is partially depicted in figure 1. [90] The electric backup heater 21 further comprises two pump sup- ports 50, 51. On the first pump support 50 a first water pump 28 is mounted10 via a first distributor/collector unit 53. The second pump support 51 sup- ports the second water pump 32 via the second distributor/collector unit 55. [91] The first and second water pumps 28, 32 are centrifugal pumps. In figure 5, a pump housing 56 of the pumps 28, 32 including an impeller 15 chamber 56a is shown separately from a motor housing 57 which also comprises an electronics unit. The first and second water pump 28, 32 are preferably identical. [92] The first and second distributor/collector units 53, 55 are identical and comprise a casing or housing 58 which by itself already forms a con-20 duit for water. The housing 58 can be used for passively combining mul- tiple incoming flows or distributing one incoming flow to multiple out- going flows. In the exemplary embodiment, the housing 58 of the first dis- tributor/collector unit 53 is formed integrally with the pump housing 56 of the first water pump 28. Likewise, the housing 58 of the second distribu- 25 tor/collector unit 55 is formed integrally with the pump housing 56 of the second water pump 32. In other words, the pump housing 56 of each pump 28, 32 is formed in one piece with the housing 58 of the respective distributor/collector unit 53, 55 that supports the respective pump 28, 32 Patentanwälte Vollmann Hemmer Lindfeld GP 3692 WO, 12/12/2023 as can be seen best in figure 5. This allows molding the pump housing 56 and the housing 58 of the distributor/collector unit 53, 55 with a single tool whereby the manufacturing cost for the individual pieces is reduced. Fur- ther, since less parts need to be assembled, the assembly time and cost 5 is also reduced. [93] By installing an insert 59 (figure 5) through an opening 58a in the casing 58 of the distributor/collector units 53, 55, the distributor/collector units 53, 55 are turned into three-way valves 27, 31. Operation of the three-way valves can be controlled for actively mixing or distributing 10 flows. [94] Details of the inside of the three-way valves 27, 31 are shown in figure 8 which shows a cut through the integrated water circuit 14 per- pendicular to the center plane 49 through the distributor/collector units 53, 55 looking down towards the electric backup heater 21. Since three-15 way valves 27, 31 are well known to skilled person, a further detailed de- scription is omitted. [95] The first distributor/collector unit 53 and the first water pump 28 are in fluid communication via a dedicated conduit 52. The conduit 52 con- nects an outflow 53a of the first distributor/collector unit 53 with a suction 20 port 28a of the first water pump 28. Further, a temperature sensor 52a is provided in the conduit 52. Likewise, the second distributor/collector unit 55 and the second water pump 32 are in fluid communication via a ded- icated conduit 54. The conduit 54 connects an outflow 55a of the sec- ond distributor/collector unit 55 with a suction port 32a of the second25 water pump 32. Further, a temperature sensor 54a is provided in the con- duit 54 for measuring the water temperature at the suction port 32a of the second water pump 32. The conduits 52, 54 fluidly connecting the distributor/collector units 53, 55 to the water pumps 28, 32 are identical. Patentanwälte Vollmann Hemmer Lindfeld GP 3692 WO, 12/12/2023 [96] The first pump support 50 has at its bottom end facing towards the bottom cover 48 of the housing 15 of the integrated water circuit 14 a return flow connector 62 to which the return flow of an external water circuit can be connected. In the exemplarily embodiment shown in fig- 5 ure 2 the return flow of the second external water circuit 3 which provides water for a conventional radiator circuit 6 is connected to the return flow 62 of the first pump support 50. [97] The return flow connector 62 formed at the first pump support 50 extends parallel to the center plane 49 and thus parallel to the first and 10 second direct water connectors 41, 42 and the fill/drain connector 43. Attached to the return flow connector 62 is a coupling 63 with an outer thread that matches the couplings 44, 45, 46 which are provided at the direct water connectors 41, 42 and the fill/drain connector 43. [98] The return flow connector 62 also supports the integrated water 15 circuit 14 on the bottom cover 48 of the housing 15 of the integrated water circuit 14. Water flowing through the return flow connector 62 into the first pump support 50 is guided to the first distributor/collector unit 53 which is implemented as a three-way valve 27 in the exemplarily embod- iments shown in figures 3 to 8. Here, the water from the return flow con- 20 nector 62 of the first pump support 50 is mixed with water from a second return flow collector 64 which provides water directly to the first distribu- tor/collector unit 53. [99] The second return flow connector 64 can be used, for example, to connect the return flow of a domestic hot water circuit 7 as shown in 25 figure 2. The water from the first return flow connector 62 and the second return flow connector 64 is mixed at the three-way valve 27 and contin- uous to flow through the conduit 52 to the first water pump 28. The pres- sure side outlet 65 of the first water pump 28 is connected to a supply line Patentanwälte Vollmann Hemmer Lindfeld GP 3692 WO, 12/12/2023 66 for the condenser 18. Integrated into the supply line 66 is a tempera- ture sensor 67. Inside the tube 65a connecting the pressure side outlet 65 of the first water pump 28 to the supply line 66 the first check valve 29 is integrated. 5 [100] As can be seen best in figure 7, the second return flow connector 64 is formed similar to the first return flow connector 62, the direct water connectors 41, 42 and the fill/drain valve 43 in that a coupling 64a with an outer thread for external piping is attached to an inlet end of the re- turn flow connector 64. The rigid return flow connector 64 also provides 10 a structural support of the integrated water circuit 14 from the bottom cover 48 of the housing 15 of the integrated water circuit 14. [101] The fluid connection between the first pump support 50 and the first distributor/collector unit 53 can be seen in figure 11 at the reference numeral 68. The second pump support 51 has a similar connection 69 15 which protrudes upwards from the second pump support 51 parallel to the center plane 49 towards the second distributor/collector unit 55. The first and second connection 68, 69 between the first and second pump support 50, 51 and the respective distributor/collector units 53, 55 thus extend in the opposite direction of the first and second direct water con- 20 nectors 41, 42 and the fill/drain connector 43. The second pump support 51 provides a fluid communication between the cavity 23 of the electric backup heater 21 and the second distributor/collector unit 55 so that water can be drawn directly out of the cavity 23 into the second distrib- utor/collector unit 55 by the second water pump 32. 25 [102] The first and second pump support 50, 51 extend on opposite sides of the center plane 49 away from the composite housing 35 of the elec- tric backup heater 21. The pump supports 50, 51 including the connec- tions 68, 69 are integrally formed with the composite housing 35. While the first pump support 50 is supported on the bottom cover 48 of the Patentanwälte Vollmann Hemmer Lindfeld GP 3692 WO, 12/12/2023 housing 15 of the integrated water circuit 14 via the first return flow con- nector 62, a stud 70 is provided at the second pump support 51. The stud 70 is the only dedicated support element of the electric backup heater 21 which serves for supporting the electric backup heater 21 on the bot- 5 tom cover 48 and, therefore, also the entire integrated water circuit 14 on the bottom cover 48. All other support is provided by the connectors 41, 42, 43, 62 which also carry water. Further, all of these connectors 41, 42, 43, 62 including in particular also the return flow connector 62 are formed integrally with the composite housing 35 of the electric backup 10 heater 21 which simplifies manufacturing and assembly of the integrated water circuit 14. [103] At the second distributor/collector unit 55 which is also configured as a three-way valve 31 water from the cavity 23 of the electric backup heater 21 is mixed with a return flow from an external water circuit 2. The15 external water circuit is in the exemplarily embodiment in figure 2 an un- derfloor heating circuit 5. At the bottom cover 48 of the housing 15 of the integrated water circuit 14 a corresponding coupling 71 is provided which is connected via tubing 72 to a connecting element 73 which con- nects the first and second distributor/collector unit 53, 55. 20 [104] In the embodiment shown in figures 3 to 8, the connecting ele- ment 73 holds the distributor/collector units 53, 55 together. Further, the return flow received via the tubing 72 is directed to the second distribu- tor/collector unit 55 by the connecting element 73 where it is mixed with heated water taken directly out of the cavity 23. From the second dis- 25 tributor/collector unit 55, the second water pump 32 forwards the water via its pressure outlet 74 and a tube 75 attached thereto to an external water circuit which may, for example be, the first external water circuit 2 of figure 2, i.e., the underfloor heating circuit 5. At the bottom cover 48 of the housing 15 a coupling 76 corresponding to the other couplings is30 provided for attaching the additional external water circuit. Patentanwälte Vollmann Hemmer Lindfeld GP 3692 WO, 12/12/2023 [105] The tubing 72 carrying the return flow from this external water cir- cuit 2 to the second distributor/collector unit 55 comprises a diverter 77 where a part of the return flow which is not mixed at the second three- way valve 31 flows also into the supply line 66 for the condenser 18 of the 5 heat pump 1. The diverter 77 includes at its end towards the supply line 66 the second check valve 34. [106] The electric backup heater 21 also comprises a condenser con- nector 78 to which a return flow of the condenser 18 of the heat pump 1 is connected via a condenser return flow tube 79. Further, on the top of10 the housing 35 of the electric backup heater 21 an opening 82 for a pres- sure relief valve 83 is provided. The same opening 82 could also be used to mount a temperature sensor (not shown) for determining the water temperature in the cavity 23. [107] As additional structural support for the distributor/collector units15 53, 55 and the water pumps 28, 32, the composite housing 35 of the elec- tric backup heater 21 comprises four ribs 80 which are arranged symmet- rically in pairs with respect to the center plane 49 of the electric backup heater 21. [108] Furthermore, as can be seen best in figure 5, the opening 23a of 20 the electric backup heater 21 through which the heating insert 36 can be inserted into the cavity 23 of the electric backup heater 21 and the openings 58a in the first and second distributor/collector unit 53, 55 through which the inserts 59 for configuring the distributor/collector units 53, 55 as three-way valves 27,31 as well as the impeller chambers 56a of 25 the pump housings 56 all face in the same direction so that all parts can be easily accessed for assembly and maintenance. [109] The integrated water circuit 14 as shown in figures 3 to 8 provides a particularly compact arrangement of an integrated water circuit 14 Patentanwälte Vollmann Hemmer Lindfeld GP 3692 WO, 12/12/2023 for a water pump 1 that is highly flexible in the number of external water circuits that can be supplied. Further, only a limited number of parts is required which makes assembly of the integrated water circuit 14 partic- ularly easy. Also, the entire structural support of the three-way valves 27, 5 31 and the water pumps 28, 32 is provided via the electric backup heater 21. In that regard it is noted that the water pumps 28, 32 and the distrib- utor/collector units 53, 55 are arranged symmetrically with regard to the center plane 49 of the electric backup heater 21. Also, they are ar- ranged at the same distance from a base plane 81 of the electric 10 backup heater 21 which extends perpendicular to the center plane 49 and in the embodiment shown in figures 3 to 8 parallel to the bottom cover 48 of the housing 15 of the integrated water circuit 14. [110] Operation of the integrated water circuit 14 shown in figures 3 to 8 and the electric backup heater 21 shown further in figures 9 to 12 has 15 already been described with reference to figure 2. [111] Figures 13 and 14 show a second exemplarily embodiment of an integrated water circuit 14. The integrated water circuit is based on the same electric backup heater 21 already discussed with regard to the first embodiment. Therefore, only those elements of the integrated water cir- 20 cuit 14 which are different from the first exemplary embodiment of an integrated water circuit 14 will be described in more detail. Throughout the following discussion of the further embodiments the same reference numerals will be used for the same elements. [112] Figure 13 shows an example of an integrated water circuit 14 25 which can be used to supply two external water circuits 2, 3, 4 with hot water from a heat pump 1. The main difference to the circuit 14 previ- ously discussed is that only one water pump 28 is provided and this single water pump is used to provide water for two external water circuits at the same time. Patentanwälte Vollmann Hemmer Lindfeld GP 3692 WO, 12/12/2023 [113] The two water circuits may, for example, be a first or a second external water circuit 2, 3 which may be underfloor heating circuit 5 or a conventional radiator circuit 6 and a third external water circuit 4 which is used for supplying domestic hot water 7. As can be seen in figure 14, 5 the resulting integrated water circuit 14 is largely identical to the first in- tegrated water circuit 14 previously discussed with the difference that there is no second distributor/collector unit, no second water pump and also no connecting element extending between the first and second dis- tributor/collector units. The corresponding outlets are sealed off with10 caps and a different return flow connector 85 is used for guiding the re- turn flow from the condenser 18 to the condenser connector 78 of the electric backup heater 21. Between the return flow connector 85 and the condenser connector 78 the temperature sensor 20 measuring the temperature of the water provided by the condenser 18 is integrated. 15 Note that in the embodiment in figure 14 also no supply connection to the condenser 18 is shown. [114] The integrated water circuit 14 in figure 14 thus does not make use of the second pump support 51 and the corresponding ribs 80. Never- theless, a particularly compact integrated water circuit is still provided 20 which apart from the single stud 70 and the ribs 80 does not comprise any support structures which are not also used for conducting water. Fur- thermore, the entire integrated water circuit 14 is supported on the bot- tom cover 48 of the housing 15 of the integrated water circuit 14 apart from the stud 70 entirely using the connectors of the electric backup 25 heater. [115] Finally, figures 15 and 16 show a third exemplarily embodiment of an integrated water circuit 14. Like the integrated water circuit 14 shown in figures 13 and 14, the integrated water circuit shown in figures 15 and 16 is used to drive only two external water circuits 2, 3, 4. However, this 30 integrated water circuit 14 uses two water pumps 28, 32, 28, 32 but can Patentanwälte Vollmann Hemmer Lindfeld GP 3692 WO, 12/12/2023 switch between using one pump or both at the same time. It is assumed that in most cases only the first pump 28, 32 is required for driving water through both external water circuits 2, 3, 4. The second pump 32, 54 is solely used as a booster pump. 5 [116] In the following only the differences as compared to the first ex- emplarily embodiment of an integrated water circuit 14 will be de- scribed. [117] The third exemplarily embodiment of an integrated water circuit 14 is also based on the same electric backup heater 21. The key differ-10 ence is that the second distributor/collector unit 55 is operated as a pas- sive distributor unit without any internal structure. A return flow connector for a first external water circuit 2, 3 which may, for example, be the un- derfloor heating circuit 5 or the radiator water circuit 6 is not connecting via the first pump support 50 to the first distributor/collector unit 53 but 15 instead connected to the second distributor/collector unit 55 from where it can flow via a bypass connector 89 to the first distributor/collector unit 53. Alternatively, the water can be drawn out of the second distribu- tor/collector unit 55 via the second water pump 32. The pressure outlet 74 of the latter is directly connected via a corresponding tube 88 to the 20 supply line 66 for the condenser 18 of the heat pump 1. Thus, by means of the second water pump 32 a flow of the external water circuit which is attached to the second distributor/collector unit 55 can be increased. Contrary to the first exemplary embodiment of an integrated water cir- cuit 14 shown in figures 3 to 8, the second pump support 51 is not used25 for providing water from the cavity 23 of the electric backup heater 21. [118] The third exemplarily embodiment is based on the same electric backup heater 21 as the other embodiments of an integrated water cir- cuit 14, 14 and also requires largely on the same parts. Again, the overall Patentanwälte Vollmann Hemmer Lindfeld GP 3692 WO, 12/12/2023 integrated water 14 circuit is very compact and requires only a few parts which makes assembly of the integrated circuit 14 very simple. Patentanwälte Vollmann Hemmer Lindfeld GP 3692 WO, 12/12/2023 Reference list 1 heat pump 2, 3, 4 external water circuit 5 underfloor heating circuit 5 6 radiator heating circuit 7 domestic hot water circuit 8 radiator 9 lines 10 warm water buffer 10 11 external heat exchanger unit 12 supply line 13 return flow line 14 integrated water circuit 15 housing of the integrated water circuit 15 16 expansion tank, expansion vessel 17 fan 18 condenser 19 refrigerant line 20 temperature sensor 20 21 electric backup heater 22 electric heating elements 23 cavity 23a opening towards cavity for receiving heating insert 24 temperature sensor 25 25, 26 flow direction 27 first three-way valve 28 first water pump 28a suction side inlet 29 first check valve 30 30 temperature sensor 31 second three-way valve 32 second water pump 32a suction side inlet 33 temperature sensor 35 34 second check valve 35 composite housing 36 heating insert/module 37 electric heating element 38 flange 40 39 bolts 40 power connector 41 first direct water connector 42 second direct water connector 43 fill/drain connector 45 44, 45, 46 couplings 47 brackets Patentanwälte Vollmann Hemmer Lindfeld GP 3692 WO, 12/12/2023 48 bottom cover of housing 15 49 center plane 50 first pump support 51 second pump support 5 52 conduit 52a temperature sensor 53 first distributor/collector unit 53a outflow 54 conduit 10 54a temperature sensor 55 second distributor/collector unit 55a outflow 56 pump housing of first/second water pump 56a impeller chamber 15 57 motor housing of first/second water pump 58 casing/housing of first/second distributor/collector unit 58a opening for receiving inserts 59 inserts 27, 31 three-way valves 20 62 first return flow connector 63 coupling 64 second return flow connector 64a coupling 65 pressure side connector of first water pump 25 65a tube 66 supply line for condenser 67 temperature sensor 68 connection 69 connection 30 70 shaft 71 coupling for underfloor heating 72 tubing 73 bypass connector 74 pressure side outlet of second water pump 35 75 tube 76 coupling 77 diverter 78 condenser connector 79 condenser return flow connector 40 80 ribs 81 base plane 82 opening 83 pressure relief valve 85 return flow connector 45 87 return flow connector 88 tubing 89 bypass connector Patentanwälte Vollmann Hemmer Lindfeld GP 3692 WO, 12/12/2023

Claims

Claims 1. An integrated water circuit (14) for a heat pump (1), the integrated water circuit (14) comprising an electric backup heater (1), a first water pump (28) for an external water circuit (2, 3, 4) and a first dis- 5 tributor/collector unit (53), wherein the electric backup heater (21) comprises a compo- site housing (35) defining a cavity (23) for heating water using at least one electric heating element (22) arranged in the cavity (23) and further comprising a condenser connector (78), a first direct 10 water connector (41) and a first pump support (50) which are all integrally formed with the composite housing (35), wherein the first direct water connector (41) is provided for supplying water from the cavity (23) to an external water circuit (2, 3, 4), wherein the condenser connector (78) is configured for con-15 necting the electric backup heater (21) to a return flow of a con- denser (18) of a heat pump (1), wherein the first water pump (28) is mounted via the distribu- tor/collector unit (53) to the first pump support (50) and an inlet of the first water pump (28) is in fluid connection with the first distribu-20 tor/collector unit (53). 2. Integrated water circuit (14) according to claim 1, wherein the in- tegrated water circuit (14) comprises a second water pump (32) for an external water circuit (2, 3, 4) and a second distributor/collector unit (55), 25 wherein the electric backup heater (21) comprises a second pump support (51) integrally formed with the composite housing (35) opposite the first pump support (50), wherein the second water pump (32) is mounted via the sec- ond distributor/collector unit (55) to the second pump support (51) atentanwälte Vollmann Hemmer Lindfeld GP 3692 WO, 12/12/2023 and an inlet of the second water pump (32) is in fluid connection with the second distributor/collector unit (55). 3. Integrated water circuit (14) according to claim 2, wherein the sec- ond water pump (32) is mounted via the second distributor/collec- 5 tor unit (55) to the second pump support (51) by forming a pump housing (56) of the second water pump (32) integrally with a hous- ing (58) of the second distributor/collector unit (55) and attaching the integrally formed housings (56, 58) to the second pump support (62). 10 4. Integrated water circuit (14) according to claim 2 or 3, wherein with respect to a center plane (49) of the composite housing (35), the first pump support (50) is formed opposite the second pump support (51), the first distributor/collector unit (53) is arranged opposite the second distributor/collector unit (55) and the first water pump (28)15 is arranged opposite the second water pump (32). 5. Integrated water circuit (14) according to claim 3, wherein the first distributor/collector unit (55) is arranged at the same distance and on a same side of a base plane (81) of the composite housing (35) as the second distributor/collector unit (55) and wherein the first wa- 20 ter pump (28) is arranged at the same distance and on a same side of the base plane (81) of the electric backup heater (21) as the water pump, wherein the base plane (81) extends perpendicular to the center plane (49). 6. Integrated water circuit (14) according to any of claims 2 to 5, 25 wherein the second pump support (51) forms a conduit establishing a fluid connection between the cavity (23) of the electric backup heater (21) and the second distributor/collector unit (55) so that an atentanwälte Vollmann Hemmer Lindfeld GP 3692 WO, 12/12/2023 inlet of the second water pump (32) is via the second distributor/col- lector unit (55) in fluid connection with the cavity (23) of the electric backup heater (21). 7. Integrated water circuit (14) according to any of claims 2 to 6, 5 wherein the first distributor/collector unit (53) is connected to the second distributor/collector unit (55) via a bypass connector (89), wherein the bypass connector (89) is formed as a single part and comprises a conduit for establishing a fluid connection between the first distributor/collector unit (53) and the second distributor/col-10 lector unit (55). 8. Integrated water circuit (14) according to any of claims 2 to 6, wherein the first distributor/collector unit (53) is structurally con- nected to the second distributor/collector unit (55) via a connect- ing element (73), wherein the connecting element (73) has a return 15 flow interface for a return flow of an external water circuit (2, 3, 4), wherein an external water circuit (2, 3, 4) connected to the return flow interface is in fluid communication with either the first or the second distributor/collector unit (51, 55) via the connecting ele- ment (73), and wherein no fluid connection between the first distrib- 20 utor/collector unit (53) and the second distributor/collector unit (55) is provided by the connecting element (73) wherein the connecting element (73) is preferably formed as a single piece. 9. Integrated water circuit (14) according to any of the preceding 25 claims, wherein the first pump support (50) further defines a return flow connector (85) for an external water circuit, wherein when a return flow of an external water circuit (2, 3, 4) is connected to the return flow connector (85) of the first pump support (50), the return flow of the external water circuit (2, 3, 4) is in fluid communication atentanwälte Vollmann Hemmer Lindfeld GP 3692 WO, 12/12/2023 via a conduit formed by the first pump support (50) with the first dis- tributor/collector unit (53) and the cavity (23) defined by the com- posite housing (35) is not in fluid communication with the first distrib- utor/collector unit (53) via the first pump support (50). 5 10. Integrated water circuit (14) according to any of the preceding claims, wherein the first and/or the second distributor/collector unit (53, 55) is a three-way valve, wherein the three-way valve can be operated in a diverter mode or a mixing mode. 11. Integrated water circuit according to any of the preceding claims, 10 wherein the integrated water circuit comprises an input condenser connector (78) for connecting at least an outlet of the first water pump to a condenser (18) of a heat pump (1). 12. Integrated water circuit according to any of the preceding claims, wherein the cavity (23) has a generally cylindrical shape. 15 13. Integrated water circuit according to any of the preceding claims, wherein the condenser connector (78) and the first direct water connector (41) extend in opposite directions away from the cavity (23) defined by the composite housing (35), wherein the condenser connector (78) and the first direct water connector (41) extend20 preferably in the center plane (49). 14. Integrated water circuit according to any of the preceding claims provided dependent on claims 8 and 13, wherein the return flow connector (85) extends away from the first pump support (50) in a direction extending parallel to the first direct water connector (41). atentanwälte Vollmann Hemmer Lindfeld GP 3692 WO, 12/12/2023 15. Integrated water circuit according to claim 14 or 15, wherein the first pump support (50) extends generally perpendicular to the cen- ter plane (49) away from the cavity (23) defined by the composite housing (35), 5 wherein the first pump support (50) is preferably formed so that a first water pump (28) mounted to the first pump support (50) is arranged on a side of the electric backup heater (21) towards which the condenser connector (78) extends. 16. Integrated water circuit according to any of the preceding claims, 10 wherein the electric backup heater (21) comprises a combined fill/drain connector (43) which is integrally formed with the compo- site housing (35), wherein the combined fill/drain connector (43) preferably extends parallel to the at least one direct water con- nector (41, 42) away from the cavity (23) defined by the composite15 housing (35). 17. Integrated water circuit (14) according to any of the preceding claims, wherein the first water pump (28) is mounted via the first dis- tributor/collector unit (53) to the first pump support (50) by forming a pump housing (56) of the first water pump (28) integrally with a 20 housing (58) of the first distributor/collector unit (53) and attaching the integrally formed housings (56, 58) to the first pump support (50). 18. Integrated water circuit (14) according to any of the preceding claims, wherein the integrated water circuit (14) is arranged in a housing (15) comprising a bottom cover (48), wherein the inte-25 grated water circuit (14) is supported by the first direct water con- nector (41) on the bottom cover (48). atentanwälte Vollmann Hemmer Lindfeld GP 3692 WO, 12/12/2023 19. Integrated water circuit (14) according to claims 16 and 18, wherein the integrated water circuit (14) is further supported by the com- bined fill/drain connector (43) on the bottom cover (48). atentanwälte Vollmann Hemmer Lindfeld GP 3692 WO, 12/12/2023