RETROFIT KIT FOR AN EXISTING CENTRAL HEATING SYSTEM, AND METHOD FOR RETROFITTING AN EXISTING CENTRAL HEATING SYSTEM USING A RETROFIT KIT

Description

The invention relates to a retrofit kit for an existing central heating system, having the features of the preamble of patent claim 1, and to a method for retrofitting an existing central heating system by means of a retrofit kit, having the features of the preamble of patent claim 14.

The central heating systems used nowadays and/or already known or already existing in buildings usually have a primary heat source, in particular a boiler and/or a combi boiler, which is able to be operated with the aid of fuels, a heat exchanger, preferably a heater or a radiator, for heating a building, and a domestic water storage tank. A heat medium fluid, in particular water, is able to be heated by means of the primary heat source. The heat medium fluid, which has in particular been previously heated, is able to be conveyed through or to the heat 13 exchanger by means of a heating pump. The heat medium fluid is able to be conveyed by means of a storage pump to the domestic water storage tank for the purpose of heating domestic water temporarily stored in the domestic water storage tank, in particular for the purpose of transmitting heat from the heat medium fluid to the domestic water through or adjacent to the domestic water storage tank. The primary heat source herein has a central heating open-loop control and/or closed-loop control apparatus for controlling the primary heat source in an open loop and/or closed loop.

In order to save fuels in the operation of the above-described central heating system, central heating systems of this type can also be enhanced with an electrically operable heat pump. Thus, a retrofit kit and/or a correspondingly enhanced central heating system can then have at least one electrically operable heat pump. The heat medium fluid is then likewise able to be heated with the aid of the heat pump. The heat medium fluid, for heating the latter, is then able to be conveyed to the heat pump in particular with the aid of a recirculating pump, or is conveyed through the heat pump in particular with the aid of the recirculating pump. Furthermore, the heat medium fluid is then also able to be conveyed through or to the primary heat source by means of the heating pump, in particular the recirculating pump, and/or the storage pump, wherein the heat medium fluid is also able to be correspondingly heated by the primary heat source.

DE 30 49 132 C2 shows an already known, here oil-fired, central heating system having a boiler as a primary heat source and a domestic water boiler which here is integrated therein. A line leads from the boiler to a connector of a four-way mixer valve (four-way cock). From a further connector of the four-way mixer valve, heat medium fluid, which is heated by means of the boiler, for example, is able to be supplied by means of a heating pump to the heat exchangers/radiators for heating a building. An additional line leads from the heaters back to the four-way mixer valve. This standard circuit of many central heating systems is now to be enhanced by a heat pump, for example of the air/water type. The heat pump, as part of a retrofit kit, is fluidically interposed in the central heating system so as to be in series with the boiler. The retrofit kit has a shut-off valve which is mechanically or electromagnetically activatable and by means of which, in the installed state, the heat pump is able to be bypassed. The heat pump can be easily and readily coupled to the existing central heating system. The four-way mixer valve already existing in the building can continue to be used. The retrofit kit furthermore has a recirculating pump by means of which, in the installed state, heat medium fluid is supplied to the heat pump.

The domestic water boilers which are disposed in boilers for heating domestic water usually have only a small storage volume, so that the heating of the domestic water in the operation of the central heating system has to take place rapidly, meaning at a high output. However, such a high output requires the operation of the boiler, in particular in addition to the heat pump, so that there is nevertheless a high requirement of fuels distributed throughout the year, which is disadvantageous and very cost-intensive.

DE 32 30 940 A1 shows a central heating system having a primary heat source embodied as a boiler, a heat pump and a domestic water storage tank for heating domestic water, wherein one pump and one heating circuit are assigned to each of these devices. A heat medium fluid is able to be supplied to the heat pump by way of a heat pump inflow line, also referred to as a return flow, from an underfloor heating, for example. A plurality of valves are provided so that different operating modes of the central heating system are able to be implemented by means of the boiler and the heat pump. The domestic water storage tank or the underfloor heating are in particular also able to be impinged solely with the heated heat medium fluid by means of the heat pump. Likewise, the domestic water storage tank or the underfloor heating are able to be impinged with the heated heat medium fluid solely by means of the boiler. Furthermore, it is also conceivable that the heat pump and the boiler are operated simultaneously in order to impinge the underfloor heating with correspondingly heated heat medium fluid by means of the heat pump and by means of the boiler, wherein the boiler in this instance is also impinged with the heat medium fluid heated by the heat pump, wherein the heat pump and the boiler are thus disposed fluidically in series by means of the valves. For reasons of economy, the heat pump is not operated at external temperatures below 5° C. 30 to 50% of the heat requirement can be generated by means of the heat pump. A ready-to-fit or ready-to-install coupling unit is thus provided as a hydraulic module in which all of the interconnections, or connections, for linking the boiler to the heat pump and the associated heating circuits are provided. The hydraulic module is either delivered conjointly with the boiler so as to be completely connected thereto and sitting directly on the rear side thereof, or the hydraulic module is delivered as an already completely installed hydraulic module which is then connected as an entity to the corresponding connectors of the boiler.

In that context, the heating of the domestic water in the domestic water storage tank is in particular not of an optimal design. Simultaneous heating of the domestic water by means of the heat pump and the boiler is thus not possible by means of the above-described valves and heating circuits. In particular, the domestic water is also heated at an early stage solely by the boiler while utilizing cost-intensive fuels, in particular because the heat pump is conceived for only 30-50% of the heat requirement, so that the fuel requirement increases throughout the year.

EP 2 322 880 B1 discloses a heat pump system for an apartment block having a plurality of residential units. Each residential unit has one heat pump. The heat pumps are supported by additional heating devices. These additional heating devices can be, for example, conventional natural gas-burning devices, specifically so-called combi boilers. The additional heating devices are thus embodied in particular as primary heat sources. The heat pumps herein can pre-heat a heat medium fluid which is then further heated in the additional heating devices disposed in series. The heat medium fluid is able to be supplied to a heat exchanger, in particular a radiator or a heater, for heating a residential unit by means of a heating circuit. The heat medium fluid is able to selectively bypass the heat exchanger by means of a provided overflow valve. As an alternative to being disposed in series, the additional heating devices could also be disposed in parallel with the heat pumps. Depending on the heating output required, the heat pump can also be operated in a monovalent manner (meaning without an additional heating device) or in a bivalent manner (meaning with an additional heating device). In monovalent operation, the residential unit is supplied with heat and with warm domestic water only by the heat pump by way of the heat exchanger/heaters. If the required heating output is higher than the maximum heating output of the heat pump, the heat pump is operated in a bivalent manner.

In this context, a distinction is made between a bivalent-alternative operation and a bivalent-parallel operation. In a bivalent-alternative operation, the heat pump solely covers the heat requirements of the residential unit up to a defined external temperature. Below this defined external temperature, the additional heating device solely covers the heat requirements. In the bivalent-parallel operation, the heat pump solely covers the required heating output up to a defined external temperature. Below this external temperature, the additional heating device is additionally switched on so that both heat generators (heat pump and additional heating device) then simultaneously supply the residential unit with heat. It applies here fundamentally that the lower the external temperature, the higher the proportion of the additional heating device in terms of the overall heat. When using an air/brine heat pump, the additional heating device solely supplies the residential unit with heat as from a defined minimum external temperature, because heat from the external air cannot be economically absorbed. The heat pump herein is simultaneously embodied as the connector console for the additional heating device so that a commercially available additional heating device can be fastened on top of the heat pump.

DE 26 13 967 A1 discloses an installation element/hydraulic module for a bivalent central heating system consisting of a heat pump and an additional heating (oil, gas or electric heating). The additional heating is thus in particular embodied as a primary heat source. A plurality of connectors for the heat pump, the additional heating and a domestic water storage tank are disposed in or on the hydraulic module. Furthermore, a plurality of valves are disposed in or on the hydraulic module, for example a multi-way switch-over valve for selectively impinging a heat exchanger for heating a building, or a further heat exchanger for heating the domestic water. Furthermore, the pipework of the components for the various heating circuits is disposed in or on the hydraulic module.

In the central heating systems known in the prior art, the heating of the domestic water in the domestic water storage tank is not yet of an optimal design when a primary heat source and/or an in particular retrofitted heat pump are provided for heating the domestic water. A large quantity of fuels is required throughout the year, as has already been described at the outset, because the primary heat source has to be operated over a long time in order to ensure that the actual domestic water temperature is actually above a specific critical temperature.

Additional issues arise in particular when a heat pump is to be retrofitted, and was not already taken into account as a constituent part during the basic design of the central heating system. In this instance, very complex modifications, for example, are required on a central heating open-loop and/or closed-loop control apparatus in order to then also be able to control the heat pump in an open loop or a closed loop by way of this central heating open-loop and/or closed-loop control apparatus. Furthermore, the open-loop and/or closed-loop control of the heat pump and of the primary heat source then have to be adapted to one another, in particular in the central heating open-loop and/or closed-loop control apparatus.

These are very complex jobs which have in particular to be carried out from scratch again when a heat pump is to be retrofitted to an existing central heating system, because the existing central heating systems often have comparatively large specific differences. Ultimately, conventional retrofitting an already existing central heating system is therefore problematic and also very labor-intensive and cost-intensive.

The invention is therefore based on the object of specifying a retrofit kit for an existing central heating system and/or a method for retrofitting an existing central heating system, or to design and/or refine such a retrofit kit and/or such a method in such a manner that a fuel consumption and the costs associated therewith are reduced, and/or an integration capability of the retrofit kit in terms of open-loop and/or closed-loop control into the existing central heating system is enabled in a simple and cost-effective manner, and/or retrofitting is enabled without great complexity in terms of labor and/or without high assembly costs.

In terms of the retrofit kit, this object on which the invention is based is first achieved by a retrofit kit for an existing central heating system, having the features of patent claim 1.

One aspect of the invention first lies fundamentally in the fact that the retrofit kit has a temperature probe and a heat pump open-loop and/or closed-loop control apparatus, wherein the temperature probe is connected, or connectable, in terms of control, signals and/or data to the heat pump open-loop and/or closed-loop control apparatus, wherein the heat pump is connected and/or connectable in terms of control to the heat pump open-loop and/or closed-loop control apparatus.

A further aspect of the invention lies in that the heat pump open-loop and/or closed-loop control apparatus is designed and/or embodied in such a way that the heat pump is able to be controlled in an open loop and/or closed loop as a function of an actual domestic water temperature measured by means of the temperature probe in a lower region of the domestic water storage tank, viewed vertically, or adjacent to that lower region of the domestic water storage tank, viewed vertically.

Owing to the fact that the retrofit kit now initially has a separate heat pump open-loop and/or closed-loop control apparatus for the heat pump, the central heating open-loop and/or closed-loop control apparatus does in particular not have to be adapted at all, or if so only to a very minor extent. In a preferred embodiment, the existing heat pump open-loop and/or closed-loop control apparatus, for example as a function of a specific heat pump, can be embodied in such a way that in particular heat pumps of an identical design and output can then also be retrofitted with identical heat pump open-loop and/or closed-loop control apparatuses on a very wide variety of existing central heating systems. This first of all simplifies the compiling of the components of the retrofit kit, and/or avoids having to adapt the heat pump open-loop and/or closed-loop control apparatus to specific heat pumps of different designs, but the latter is nevertheless also conceivable.

The savings in terms of fuels, and the simplified integration of the components into the existing central heating system in terms of control, is initially implemented with the aid of the above-mentioned temperature probe. In this instance, the desired temperature of the domestic water is able to be controlled in an open loop and/or closed loop in a particularly positive manner by means of the retrofitted or existing heat pump and the retrofitted heat pump open-loop and/or closed-loop control apparatus. Owing to the fact that the temperature probe is disposed, or will be then disposed, in the lower region of the domestic water storage tank, viewed vertically, or adjacent to that lower region of the domestic water storage tank, viewed vertically, the heat pump is then able to be actuated and/or controlled in a closed loop in a particularly rapid manner, in particular without a large temporal delay, when fresh and thus cold, or colder, (fresh) domestic water is then resupplied to the domestic water storage tank, in particular due to a retrieval of domestic water from the domestic water storage tank (for example for a domestic shower procedure), because the supplied “fresh” domestic water flows about the temperature probe before it mixes with the remainder of the domestic water still present in the domestic water storage tank. The lower region of the domestic water storage tank, viewed vertically, is preferably formed in a lower third, in particular in a lower quarter, of the overall height of the domestic water storage tank, or is correspondingly formed therein.

In the context of the term “domestic water storage tank”, it is to be briefly pointed out that this is in particular understood to mean a water tank in which the water is heated. Therefore, the “domestic water storage tank” can also be referred to as a “warm water storage tank”. The heated water is or can then be retrieved from the domestic water storage tank, for example for a domestic shower procedure or for a domestic cooking or dish washing procedure, whereby new fresh water is then resupplied to the domestic water storage tank in order for the latter to be topped up. Referring to this storage tank as the “domestic water storage tank” therefore does not mean that water which has already been used/utilized and/or contaminated is stored in this storage tank, but that the water stored and/or kept herein is destined for later “use”, for example for showering. Therefore, in particular, drinking water is stored, kept and heated in the domestic water storage tank. This has to be pointed out.

In a highly preferred embodiment of the retrofit kit, the temperature probe is able to be assembled, in particular by means of a T-fitting, in or on a part of a domestic water inflow line formed between an inflow valve and an inflow connector of the domestic water storage tank. Such a T-fitting is in particular also part of the retrofit kit in this instance.

Fresh domestic water is able to be supplied to the domestic water storage tank by way of the domestic water inflow line and the inflow connector by opening the inflow valve. Up to the inflow valve (when viewed proceeding from the domestic water storage tank), the domestic water inflow line is in functional terms to be assigned to the domestic water storage tank because temperatures of the domestic water which are comparable to those at the same height level within the domestic water storage tank arise here. Assembling the temperature probe on the domestic water inflow line is particularly simple, because the domestic water storage tank does not have to be modified in terms of its construction, and the temperature probe is nevertheless able to be assembled, in particular so as to have direct contact to the freshly supplied domestic water. In particular, a piece of the domestic water inflow line can also be cut out and replaced by a T-fitting, whereby the temperature probe in this instance is disposed in the branch of the T-fitting and preferably connected to the T-fitting by a closure cap. Alternatively, the T-fitting could also be interposed in the domestic water inflow line in such a manner that part of the domestic water inflow line is connected to the branch of the T-fitting in such a way that the temperature probe is still disposed on one of the two connectors of the T-fitting that are mutually parallel so as to close this connector, and the temperature probe in this instance preferably completely penetrates the T-fitting. By contrast, it is likewise conceivable and possible to dispose the temperature probe externally on or in a housing/shell region of the domestic water storage tank or of the domestic water inflow line.

Assembling a temperature probe which is to be correspondingly disposed externally on or in a housing/shell region of the domestic water storage tank, or on the domestic water inflow line, would be able to be performed in a particularly simple and rapid manner in this instance.

In a preferred embodiment of the retrofit kit, the above-mentioned temperature probe is embodied as a first temperature probe for determining a first actual domestic water temperature. A second temperature probe is disposed in a central or upper region of the domestic water storage tank, as viewed vertically, for measuring a second, preferably average, actual domestic water temperature. The second temperature probe is connected in terms of control, signals and/or data to the central heating open-loop and/or closed-loop control apparatus. The central heating open-loop and/or closed-loop control apparatus is designed and/or embodied in such a way that the primary heat source is able to be controlled in an open loop and/or closed loop as a function of the second actual domestic water temperature. In very general terms, it is also to be pointed out here that the term “connected in terms of control”, which is also used elsewhere hereunder, in particular may always comprise a connection in terms of signals and/or data.

The heat pump open-loop and/or closed-loop control apparatus is now designed and/or embodied in such a way that the heat pump is operable and/or activatable with the aid of the heat pump open-loop and/or closed-loop control apparatus for the purpose of heating the heat medium fluid when the first actual domestic water temperature measured, determined with the aid of the first temperature probe and/or calculated, in particular by the heat pump open-loop and/or closed-loop control apparatus, falls short of a first critical temperature.

The central heating open-loop and/or closed-loop control apparatus is designed and/or embodied in such a way that the primary heat source is operable and/or activatable with the aid of the central heating open-loop and/or closed-loop control apparatus for the purpose of heating the heat medium fluid when the second actual domestic water temperature measured, determined and/or calculated with the aid of the second temperature probe falls short of a second critical temperature.

In a highly preferred embodiment, the first and the second critical temperature are in particular chosen in such a manner that the primary heat source is operable and/or activatable with the aid of the central heating open-loop and/or closed-loop control apparatus for the purpose of heating the heat medium fluid only when a heat requirement of the domestic water storage tank exceeds an amount of heat that is able to be provided by means of the heat pump at a maximum output of the heat pump.

Therefore, no further complex and/or complicated modifications are required for controlling the central heating system, in particular the heating circuit for heating the domestic water. The central heating open-loop and/or closed-loop control apparatus and the heat pump open-loop and/or closed-loop control apparatus operate substantially independently of one another. In particular, the first critical temperature is entered at/into the heat pump open-loop and/or closed-loop control apparatus, or is already defined herein, and/or the input of the second critical temperature is correspondingly entered at/into the central heating open-loop and/or closed-loop control apparatus, or is already defined herein. In this way, the retrofit kit is able to be assembled in a particularly rapid manner, and easy to integrate in terms of open-loop and/or closed-loop control into the central heating system.

The central or upper region of the domestic water storage tank, as viewed vertically, is preferably formed in the upper two thirds, in particular in the upper half, of the overall height of the domestic water storage tank, or is correspondingly formed therein. Furthermore, optimal open-loop and/or closed-loop control of the entire central heating system with a view to a minimized requirement of fuels for the primary energy source is made possible by the skillful or specific disposal of the two temperature probes. The first temperature probe is disposed below the second temperature probe, as viewed substantially in the vertical direction, wherein, by virtue of temperature layering of the domestic water forming within the domestic water storage tank, a lower actual domestic water temperature is able to be determined by means of the first temperature probe than by means of the second temperature probe, but a variation of the temperature, in particular a temperature reduction, is in temporal terms able to be determined earlier by the first temperature probe than by the second temperature probe. This offers the basis for optimally actuating the heat pump, in particular to operate the latter in the preferred manner, and to activate and/or operate the primary heat source only when the output, or the quantity of heat, in particular for covering the requirement for heating the domestic water storage tank, provided by the heat pump no longer suffices, so that the requirement in terms of fuels for the primary heat source is able to be minimized, or at least reduced, in this way.

The above-described particularly rapid open-loop and/or closed-loop control capability of the heat pump therefore also means in particular that the heat pump is in temporal terms able to be activated and/or operated before the primary heat source when a corresponding heat requirement of the domestic water storage tank is determined by the first temperature probe specifically. This is because a further heat requirement of the domestic water storage tank is not determined by means of the second temperature probe until later in temporal terms. The first and the second critical temperature are in particular correspondingly chosen and/or set.

For example, the first critical temperature is lower than the second critical temperature. Alternatively, the second critical temperature could also be lower than the first critical temperature, whereby the second critical temperature in this instance is in particular 43° C., in particular is in the range from 41° C. to 45° C., whereby the first critical temperature in this instance is in particular 48° C., and is in particular in the range from 46° C. to 50° C.

The heat exchanger and the heat pump are preferably disposed and/or able to be disposed fluidically in series in terms of the primary heat source.

An output connector of the heat pump is preferably fluidically connected and/or connectable to an input connector of the primary heat source. As a result of the fluidic disposal in series mentioned, the entire heat medium fluid heated by means of the heat pump is in this instance also able to be supplied to the primary heat source during the operation of the assembled and/or existing heat pump. In this way, the fuel requirement of the primary heat source is able to be furthermore reduced, because the primary heat source does not have to be activated and/or operated at all, or only rarely, due to the heat medium fluid being supplied at a relatively high temperature. Therefore, a desired temperature of the heat medium fluid is in most instances already able to be implemented within or in the region of the primary heat source, specifically by heating the heat medium fluid by means of the heat pump, without the primary heat source having to be operated.

A heat exchanger inflow line is advantageously fluidically connected, or connectable, and/or correspondingly attached to the primary heat source, on the one hand, and to the heat exchanger, on the other hand, so as to supply the heat medium fluid to the heat exchanger through the heat exchanger inflow line by means of the heating pump, in particular wherein the heat exchanger inflow line is partially existent and is partially part of the retrofit kit, in particular part of a hydraulic module. A heat pump inflow line is fluidically connected, or connectable, and/or correspondingly attached to the heat exchanger, on the one hand, and to the heat pump, on the other hand, so as to supply the heat medium fluid to the heat pump through the heat pump inflow line, in particular wherein the heat pump inflow line is partially existent and is partially part of the retrofit kit, in particular part of the hydraulic module. A heat pump outflow line is fluidically connected, or connectable, and/or correspondingly attached to the heat pump, on the one hand, and to the primary heat source, on the other hand, so as to supply the heat medium fluid to the primary heat source through the heat pump outflow line, in particular wherein the heat pump outflow line is partially existent and is partially part of the retrofit kit, in particular part of a hydraulic module.

In this way, a particularly simple integration of the retrofit kit into the existing central heating system is made possible. For this purpose, various lines of the retrofit kit are prefabricated, in particular as required. Fluidically disposing the heat exchanger, the heat pump and the primary heat source in series by means of the lines mentioned is particularly easy to achieve. The lines mentioned herein are able to be formed with the aid of pipes and/or hoses and/or flow ducts formed in housings.

In a further embodiment of the retrofit kit, the retrofit kit has at least one valve with the aid of which the heat medium fluid is able to be directed and/or guided selectively from the primary heat source to the heat exchanger, or to the heat pump while bypassing the heat exchanger.

Depending on the valve position, in particular two different heating circuits are able to be generated by means of the correspondingly assembled valve in this instance. In a first heating circuit, a flow of the heat medium fluid from the primary heat source by way of the valve, by way of the heating pump, by way of the heat exchanger, by way of the heat pump, by way of the recirculating pump and back to the primary heat source is able to be implemented. In a second heating circuit, a flow of the heat medium fluid from the primary heat source by way of the valve, by way of the heat pump, by way of the recirculating pump and back to the primary heat source is able to be implemented. In a third heating circuit, a flow of the heat medium fluid from the primary heat source by way of the domestic water storage tank, by way of the storage pump and back to the primary heat source is furthermore able to be implemented. Provided in the primary heat source is preferably a distributor system for the heat medium fluid; in particular, flow ducts which are able to be correspondingly passed through by the heat medium fluid and to which the heating circuits are in each case connected and/or connectable are provided. The heat exchanger inflow line, and the heat pump outflow line, and a line leading to the domestic water storage tank and a line returning from the domestic water storage tank are connected, and/or connectable, to the primary heat source, in particular to such a distributor system, or are fluidically connected to the primary heat source, in particular to a boiler.

Furthermore preferably, the retrofit kit has two 3/2-way valves each having three connectors and each having two switching positions, specifically a first 3/2-way valve, which is disposable, or disposed, and/or interposed in the heat exchanger inflow line, and a second 3/2-way valve, which is disposable, or disposed, and/or interposed in the heat pump inflow line. The first 3/2-way valve is fluidically connectable to the primary heat source and fluidically connectable or correspondingly attached second 3/2-way valve. The second 3/2-way valve is fluidically connectable, or correspondingly attachable, to the heat exchanger, fluidically connectable or correspondingly attachable or attached to the heat pump, and fluidically connectable or correspondingly attached to the first 3/2-way valve.

By means of the first 3/2-way valve, in the connected state, a flow of the heat medium fluid is enabled selectively from the primary heat source to the heat exchanger or from the primary heat source to the second 3/2-way valve. By means of the second 3/2-way valve, in the connected state, a flow of the heat medium fluid is enabled selectively from the heat exchanger to the heat pump or from the first 3/2-way valve to the heat pump.

By means of these two 3/2-way valves, the above-described heating circuits are likewise able to be implemented. Furthermore, the two 3/2-way valves can be procured at low cost and are able to be easily controlled in an open loop and/or a closed loop. The two 3/2-way valves are preferably able to be switched from an initial position to a switched position by means of an electrical actuator, counter to a spring force applied by a mechanical spring, when the actuator is energized.

The two 3/2-way valves are then installed in such a way that the two 3/2-way valves do not have to be energized over a comparatively long period during the operation of the central heating system, so that energy is also correspondingly saved as a result.

Of the group of elements/components, specifically the heat exchanger inflow line at least in portions, the heat pump inflow line at least in portions, the heat pump outflow line at least in portions, the recirculating pump, the heat pump open-loop and/or closed-loop control apparatus and the valve, in particular the first 3/2-way valve and the second 3/2-way valve, at least two elements and/or components, in particular however the heat exchanger inflow line in portions, the heat pump inflow line in portions, the heat pump outflow line in portions, the first 3/2-way valve and the second 3/2-way valve, preferably all elements and/or components mentioned above, and respectively associated connectors are disposed and/or formed on a hydraulic module forming a common functional unit.

By means of such a hydraulic module, assembling the retrofit kit on the central heating system can be highly simplified. The otherwise customary assembly errors can in particular be avoided, because specific arrangements of elements and/or components in relation to one another are already predefined as a result of a specific shape and/or design of the hydraulic module. Advantageously, the hydraulic module is correspondingly pre-assembled, for example in a factory or at a heating installer, so that the assembly time on the premises of an end customer who operates the central heating system and wishes to retrofit it correspondingly can be significantly shortened.

In a further embodiment of the retrofit kit, the hydraulic module has a frame for connecting the hydraulic module to a building wall and/or the primary heat source.

In this instance, the hydraulic module, in particular the frame, is preferably adapted to the specific design of the primary heat source in such a way that the hydraulic module, in particular the frame, is easy to assemble on the primary heat source, or easy to assemble on a building wall.

In an advantageous embodiment of the retrofit kit, the part of the heat exchanger inflow line associated with the retrofit kit has a first connector for supplying the heat medium fluid to the hydraulic module, and a second connector for discharging the heat medium fluid from the hydraulic module. The part of the heat pump inflow line associated with the retrofit kit has a third connector for supplying the heat medium fluid to the hydraulic module, and a fourth connector for discharging the heat medium fluid from the hydraulic module. The part of the heat pump outflow line associated with the retrofit kit has a fifth connector for supplying the heat medium fluid to the hydraulic module, and a sixth connector for discharging the heat medium fluid from the hydraulic module. Preferably, the part of the heat exchanger inflow line associated with the retrofit kit, and/or the part of the heat pump inflow line associated with the retrofit kit, and/or the part of the heat pump outflow line associated with the retrofit kit, is in each case formed in the hydraulic module. The connectors herein are mutually aligned in such a way that it is possible for the latter to be easily and rapidly connected to the parts of the lines associated with the central heating system.

The object on which the invention is based is also achieved by a method for retrofitting an existing central heating system by means of the above-described retrofit kit, as claimed in patent claim 14.

In this respect, one aspect of the invention first lies substantially in that the—first—temperature probe is assembled and/or disposed in a lower region of the domestic water storage tank, as viewed vertically, or adjacent to that lower region of the domestic water storage tank, as viewed vertically. Therefore, the actual domestic water temperature of the domestic water in the lower region of the domestic water storage tank can be correspondingly determined with the aid of this first temperature probe.

In this way, the method for retrofitting is initially able to be carried out in a very assembly-friendly manner. The disposal of the temperature probe in the lower region of the domestic water storage tank, as viewed vertically, leads to the entire central heating system being able to be controlled in an open loop and/or a closed loop in a cost-effective, uncomplicated and in particular easy manner, as already described above to a certain extent. Furthermore, by virtue of this disposal of the temperature probe in the lower region of the domestic water storage tank, as viewed vertically, only minor adaptations and/or settings to the existing heat pump open-loop and/or closed-loop control apparatus, and to the existing central heating open-loop and/or closed-loop control apparatus are required, in particular no further adaptations and/or adjustments are required in order to be able to operate the central heating system in an optimal manner.

The first temperature probe is preferably then connected to the heat pump open-loop and/or closed-loop control apparatus in terms of control, signals and/or data.

Subsequently, the measured values determined by means of the first temperature probe and/or signals are able to be transmitted to the heat pump open-loop and/or closed-loop control apparatus. An actual domestic water temperature associated with the respective measured value/the respective signal herein is determined and/or calculated either by means of the correspondingly designed temperature probe per se or by means of the heat pump open-loop and/or closed-loop control apparatus. It is however also conceivable that the first temperature probe in the retrofit kit is already connected to the heat pump open-loop and/or closed-loop control apparatus in terms of control, signals and/or data, in particular by way of a signal line. It is also to be pointed out at this point that corresponding wireless connections between the components are likewise conceivable.

For the case where the heat pump is part of the existing central heating system, the heat pump is advantageously connected in terms of control to the heat pump open-loop and/or closed-loop control apparatus. Or for the case where the heat pump is part of the retrofit kit, the heat pump is connected in terms of control, or is already correspondingly connected, to the heat pump open-loop and/or closed-loop control apparatus.

In particular, the heat pump open-loop and/or closed-loop control apparatus could also be disposed on the hydraulic module. It is furthermore conceivable that the heat pump open-loop and/or closed-loop control apparatus is assembled separately, for example on a building wall. Alternatively, the heat pump and the heat pump open-loop and/or closed-loop control apparatus could also be embodied as a common functional unit.

In a further embodiment of the method, the storage pump is then connected in terms of control to the heat pump open-loop and/or closed-loop control apparatus. Under certain circumstances, an existing control connection between the storage pump and the central heating open-loop and/or closed-loop control apparatus is released and/or interrupted beforehand. Subsequently, the storage pump is then able to be controlled in an open loop and/or closed loop in particular by means of the heat pump open-loop and/or closed-loop control apparatus, so that in particular a mutually adapted operation between the heat pump and the storage pump is enabled. In particular, the heat pump and the storage pump can then also be simultaneously activated and/or operated, and simultaneously deactivated again. In particular, however, the above-described third heating circuit can then be correspondingly operated for the purpose of heating the domestic water; specifically, in particular a mutually adapted operation of the heat pump and the storage pump can be performed.

Furthermore preferably, the heating pump is connected in terms of control to the heat pump open-loop and/or closed-loop control apparatus. Under certain circumstances, an existing control connection between the heating pump and the central heating open-loop and/or closed-loop control apparatus is released and/or interrupted beforehand. Subsequently, the heating pump is able to be controlled in an open loop and/or closed loop by means of the heat pump open-loop and/or closed-loop control apparatus, so that a mutually adapted operation between the heat pump and the heating pump is in particular enabled in that case also. In particular, the heat pump and the heating pump can be simultaneously activated and/or operated, and simultaneously deactivated again. In particular, a correspondingly mutually adapted operation, in particular also an adapted operation of the respective heating circuits, is enabled.

In a further embodiment of the method, the valve is connected in terms of control to the heat pump open-loop and/or closed-loop control apparatus. In particular when the valve and the heat pump open-loop and/or closed-loop control apparatus are disposed on the hydraulic module, the control connection is already implemented beforehand in a factory or at a heating installer, so that this assembly step then does not have to be carried out on the premises of the end customer.

In a further highly preferred embodiment of the method, the first 3/2-way valve and the second 3/2-way valve are in each case connected in terms of control to the heat pump open-loop and/or closed-loop control apparatus. In particular when the first, the second 3/2-way valve and the heat pump open-loop and/or closed-loop control apparatus are disposed on the hydraulic module, the control connection is implemented beforehand in a factory or at a heating installer, so that this assembly step then does not have to be carried out on the premises of the end customer.

In a preferred embodiment of the method, an external temperature probe is assembled in an external region surrounding a building, wherein the external temperature probe is connected, or will be connected, in terms of control, signals and/or data to the heat pump open-loop and/or closed-loop control apparatus. In this way, the components which are connected in terms of control to the heat pump open-loop and/or closed-loop control apparatus can be controlled in an open loop and/or closed loop as a function of the respective external temperature.

It is fundamentally the case that more open-loop and/or closed-loop control tasks are then carried out by means of the heat pump open-loop and/or closed-loop control apparatus during the operation of the central heating system with the retrofit kit than by the central heating open-loop and/or closed-loop control apparatus, wherein by means of the heat pump open-loop and/or closed-loop control apparatus some open-loop and/or closed-loop control tasks are carried out which prior to the integration of the retrofit kit were carried out by means of the central heating open-loop and/or closed-loop control apparatus.

The first critical temperature, or a table and/or formula for determining the first critical temperature, is advantageously entered into the heat pump open-loop and/or closed-loop control apparatus, and/or is already stored in the latter. The second critical temperature, or a table and/or formula for determining the second critical temperature, is entered into the central heating open-loop and/or closed-loop control apparatus, and/or is already stored in the latter.

In particular, as a result of this input of specific respective critical temperatures, and as a result of the presence of desired critical temperatures, an adaptation of the open-loop and/or closed-loop control of the heat pump to the open-loop and/or closed-loop control of the primary heat source is then also achieved, or implemented.

In order to simplify the method, the first and/or the second critical temperature are in particular stored as constant values in the heat pump open-loop and/or closed-loop control apparatus and/or in the central heating open-loop and/or closed-loop control apparatus, so that the first and the second critical temperature are independent of the external temperature. In particular, the first critical temperature is stored in the heat pump open-loop and/or closed-loop control apparatus, and/or is set in the latter, wherein the second critical temperature is in particular stored in the central heating open-loop and/or closed-loop control apparatus, or is set in the latter.

In an advantageous embodiment of the method, the part of the heat exchanger inflow line associated with the retrofit kit is connected to the existing part of the heat exchanger inflow line by means of the first and the second connector of the hydraulic module. The part of the heat pump inflow line associated with the retrofit kit is connected to the existing part of the heat pump inflow line by means of the third and the fourth connector of the hydraulic module. The part of the heat pump outflow line associated with the retrofit kit is connected to the existing part of the heat pump outflow line by means of the fifth and the sixth connector of the hydraulic module. Subsequently, the heat medium fluid is able to be supplied to the heat exchanger by way of the heat exchanger inflow line. Furthermore, the heat medium fluid is then able to be supplied to the heat pump by way of the heat pump inflow line, and to the primary heat source by way of the heat pump outflow line. For example, parts of flange connections are used as connectors, and are connected, in particular screwed, to corresponding mating pieces which are disposed and/or disposable on the existing parts of the lines. Alternatively, the lines of the retrofit kit can be also connected to the existing parts of the line in another way, for example welded and/or soldered/brazed thereto.

There are now a multiplicity of possibilities to advantageously design and refine the retrofit kit for an existing central heating system and the method for retrofitting an existing central heating system by means of a retrofit kit. In this context, reference can first be made to the patent claims dependent on patent claim 1 and patent claim 14. A preferred design embodiment of the retrofit kit according to the invention for an existing central heating system, and of the method according to the invention for retrofitting an existing central heating system by means of a retrofit kit, will be explained or described in more detail hereunder by means of the drawing and the associated description. In the drawing:

FIG. 1a shows in a schematic illustration a hydraulic circuit diagram of a first exemplary embodiment of the retrofit kit for an existing central heating system, and the existing central heating system;

FIG. 1b shows in a schematic illustration a hydraulic circuit diagram of a second exemplary embodiment of the retrofit kit for an existing central heating system;

FIG. 1c shows in a schematic illustration a hydraulic circuit/connection diagram of a third exemplary embodiment of the retrofit kit for a further existing central heating system, and of this existing central heating system;

FIG. 2 shows in a schematically simplified illustration a hydraulic circuit diagram of the first, the second or the third exemplary embodiment of the retrofit kit having the existing central heating system, in the assembled state;

FIG. 3a shows in a schematic illustration a domestic water storage tank for use in the central heating system, in a lateral view;

FIG. 3b shows in a schematic illustration a domestic water storage tank for use in the central heating system in a lateral view, having temperature layering which has changed in comparison to FIG. 3a;

FIG. 4 shows in a schematic illustration a flow chart for a method for operating and/or controlling in an open loop and/or closed-loop a heat pump in the assembled state of the retrofit kit on the existing central heating system according to FIG. 2;

FIG. 5 shows in a schematic illustration a flow chart for a method for operating and/or controlling in an open loop and/or closed loop a primary heat source in the assembled state of the retrofit kit on the existing central heating system according to FIG. 2;

FIG. 6a shows in a schematic illustration a correlation between a first target heat medium fluid temperature, a first critical temperature, a second target heat medium fluid temperature or a second critical temperature and the external temperature, wherein the first critical temperature is lower than the second critical temperature; and

FIG. 6b shows in a schematic illustration a correlation between a first target heat medium fluid temperature, a first critical temperature, a second target heat medium fluid temperature or a second critical temperature and the external temperature, wherein the first critical temperature is higher than the second critical temperature.

FIG. 1a to FIG. 1c show in each case in a schematic illustration a hydraulic circuit diagram of a first to third exemplary embodiment of the retrofit kit 1 for an existing central heating system 2. FIG. 1a and FIG. 1c herein also show the existing central heating system 2.

The central heating system 2 has at least one primary heat source 3, in particular a boiler and/or a combi boiler, which is able to be operated with the aid of fuels, at least one heat exchanger 4, preferably a heater or a radiator for heating a building, and at least one domestic water storage tank 5. It is also to be pointed out here that the terms “primary heat source 3 able to be operated with fuels”, or “boiler”, comprise in particular an oil boiler which is able to be operated with oil, or a gas boiler which is able to be operated with gas.

A heat medium fluid 6, in particular water, which is able to be conveyed through the line system illustrated is able to be heated by means of the primary heat source 3. The heat medium fluid 6, which has in particular been previously heated, is able to be conveyed through the heat exchanger 4 by means of a heating pump 7. The heat medium fluid 6 is able to be conveyed to the domestic water storage tank 5 by means of a storage pump 8 for the purpose of heating domestic water 9 temporarily stored in the domestic water storage tank 5, in particular for the purpose of transferring heat from the heat medium fluid 6 to the domestic water 9 through or adjacent to the domestic water storage tank 5. The primary heat source 3 has a central heating open-loop and/or closed-loop control apparatus 10 for controlling the latter in an open loop and/or a closed loop.

The retrofit kit 1 and/or the existing central heating system 2 have/has at least one electrically operable heat pump 11, wherein the heat medium fluid 6 is able to be heated with the aid of the heat pump 11. The substantial components of a respective retrofit kit 1 are in each case illustrated so as to be bordered by chain-dotted lines in FIG. 1a to FIG. 1c. According to the first and the second exemplary embodiment of the retrofit kit 1 from FIG. 1a and FIG. 1b, the heat pump 11 is part of the respective retrofit kit 1. According to the third exemplary embodiment of the retrofit kit 1 from FIG. 1c, the heat pump 11 is already part of the existing central heating system 2.

For heating the heat medium fluid 6, the latter is able to be conveyed to the heat pump 11, or through the heat pump 11, in particular with the aid of a recirculating pump 12. By means of the heating pump 7, in particular the recirculating pump 12, and/or the storage pump 8, the heat medium fluid 6 is able to be conveyed to the primary heat source 3, or through the latter.

Such a recirculating pump 12 is according to FIG. 1a to FIG. 1c likewise embodied as part of the retrofit kit 1. Alternatively, it would also be conceivable, in particular when the heat pump 11 is already part of the existing central heating system 2, that the recirculating pump 12 in this instance is also part of the central heating system 2, but the latter is not illustrated here.

The retrofit kit 1 has a temperature probe 13.1 and a heat pump open-loop and/or closed-loop control apparatus 14, wherein the temperature probe 13.1 is connected, or connectable, in terms of control, signals and/or data to the heat pump open-loop and/or closed-loop control apparatus 14. The heat pump 11 is connected and/or connectable in terms of control to the heat pump open-loop and/or closed-loop control apparatus 14. According to FIG. 1b, the heat pump 11 in the retrofit kit 1 is already connected in terms of control to the heat pump open-loop and/or closed-loop control apparatus 14. According to FIG. 1a and FIG. 1c, the heat pump 11 is initially not yet connected in terms of control to the heat pump open-loop and/or closed-loop control apparatus 14.

The heat pump open-loop and/or closed-loop control apparatus 14 is designed and/or embodied in such a way that the heat pump 11 is able to be controlled in an open loop and/or a closed loop as a function of an actual domestic water temperature T_B1 which is measured by means of the temperature probe 13.1 in a lower region of the domestic water storage tank 5, as viewed vertically, or adjacent to that lower region of the domestic water storage tank 5, as viewed vertically. The disadvantages discussed at the outset are in particular avoided, and corresponding advantages achieved, as a result.

In the state of the retrofit kit 1 assembled with the existing central heating system 2, illustrated in FIG. 2, and in the schematic illustration of the domestic water storage tank 5 for use in the central heating system 1 of FIG. 3a and FIG. 3b, the position of the temperature probe 13.1 in the lower region of the domestic storage water tank 5, as viewed vertically, or adjacent to that lower region of the domestic water storage tank 5, as viewed vertically, is correspondingly shown or illustrated.

In the assembled state, the temperature probe 13.1 could penetrate a wall of the domestic water storage tank 5 in the lower region of the domestic water storage tank 5, as viewed vertically, in such a way that a measuring region of the temperature probe 13.1 within the domestic water storage tank 5 is disposed or positioned so as to be in direct contact with the domestic water 9 in the lower interior region of the domestic water storage tank 5.

According to FIG. 3a and FIG. 3b, the temperature probe 13.1 is able to be assembled, in particular by means of a T-fitting 15, in or on a part of a domestic water inflow line 18 formed between an inflow valve 16 and an inflow connector of the domestic water storage tank 5. Also according to FIG. 3a and FIG. 3b, the measuring region of the temperature probe 13.1, in the assembled state, is in direct contact with the domestic water 9, the latter being situated in the lower region of the domestic water storage tank 5. The T-fitting 15 according to FIG. 3a and FIG. 3b is interposed in the domestic water inflow line 18 in such a manner that a part of the domestic water inflow line 18 is connected to a branch of the T-fitting 15 in such a way that the temperature probe 13.1 is furthermore disposed on one of the two mutually parallel connectors of the T-fitting 15 and closes this connector by means of a closure cap. The temperature probe 13.1 preferably penetrates the T-fitting 15 completely and, according to FIG. 3a and FIG. 3b, is disposed by way of its measuring region within the domestic water storage tank 5, despite being disposed on the T-fitting 15. Alternatively, it would also be conceivable that the measuring region of the temperature probe 13.1 is disposed within the domestic water inflow line 18, in particular within the T-fitting 15.

Alternatively, it would also be conceivable that the temperature probe 13.1, in the assembled state, is disposed externally on the wall of the domestic water storage tank 5, in this instance in the lower region of the domestic water storage tank 5, or else is disposed externally on the domestic water inflow line 18, wherein in this instance a temperature gradient arising via the wall of the domestic water storage tank 5, or via a wall of the domestic water inflow line 18, in the determination of the actual domestic water temperature is preferably also taken into account when determining the actual domestic water temperature T_B1 by means of the heat pump open-loop and/or closed-loop control apparatus 14.

A check valve 16.r is integrated and/or disposed, or presently interposed, in the domestic water inflow line 18 so as to be fluidically adjacent to the inflow valve 16, so as to avoid a return flow of the domestic water 9 from the domestic water storage tank 5 into the domestic water inflow line 18 even in the event of an opened inflow valve 16.

The temperature probe 13.1 is presently embodied as a first temperature probe 13.1 for determining a first actual domestic water temperature T_B1. A second temperature probe 13.2 is disposed in a central or upper region of the domestic water storage tank 5, as viewed vertically, for the purpose of measuring a second, preferably average, actual domestic water temperature T_B2. The second temperature probe 13.2 is connected in terms of control, signals and/or data to the central heating open-loop and/or closed-loop control apparatus 10.

The central heating open-loop and/or closed-loop control apparatus 10 is designed and/or embodied in such a way that the primary heat source 3 is able to be controlled in an open loop and/or a closed loop as a function of the second actual domestic water temperature T_B2.

The heat pump open-loop and/or closed-loop control apparatus 14 is designed and/or embodied in such a way that the heat pump 11 is able to be operated and/or activated with the aid of the heat pump open-loop and/or closed-loop control apparatus 14 for the purpose of heating the heat medium fluid 6, in particular when the first actual domestic water temperature T_B1 measured, determined with the aid of the first temperature probe 13.1 and/or calculated, in particular by the heat pump open-loop and/or closed-loop control apparatus 14, falls short of a first critical temperature T_B1G. The heat pump 11 and/or the recirculating pump 12 are furthermore controlled in an open loop and/or a closed loop by means of the heat pump open-loop and/or closed-loop control apparatus 14, in particular additionally as a function of a first actual heat medium fluid temperature T_W1 forming at the outlet of the heat pump 11.

In particular, a first target heat medium fluid temperature T_{W1, Soll} which is then to be present at the outlet of the heat pump 11 is set for the heat pump 11. If the first actual heat medium fluid temperature T_W1 falls short of the desired or specified and/or set first target heat medium fluid temperature T_{W1, Soll} or exceeds the latter, the heat pump 11 is correspondingly controlled in an open loop and/or a closed loop in such a way that the first actual heat medium fluid temperature T_W1 then approaches the target heat medium fluid temperature T_{W1, Soll} again, in particular that the first actual heat medium fluid temperature T_W1 then corresponds to the first target heat medium fluid temperature T_{W1, Soll} at the outlet of the heat pump 11 again. Therefore, the heat pump 11 is in particular also controlled in an open loop and/or a closed loop as a function of a set and/or desired specified first target heat medium fluid temperature T_{W1, Soll}. In particular, the desired and/or specified target heat medium fluid temperature T_{W1, Soll} is set and/or calculated as a function of an in particular determined external temperature Ta and/or of a desired room temperature of a room to be heated by the heat exchanger 4, which will also be explained once again hereunder.

The central heating open-loop and/or closed-loop control apparatus 10 is designed and/or embodied in such a way that the primary heat source 3 is able to be operated and/or activated with the aid of the central heating open-loop and/or closed-loop control apparatus 10 for the purpose of heating the heat medium fluid 6 when the second actual domestic water temperature T_B2 measured, determined and/or calculated with the aid of the second temperature probe 13.2 falls short of a second critical temperature T_B2G. The primary heat source 3 is furthermore controlled in an open loop and/or a closed loop by means of the central heating open-loop and/or closed-loop control apparatus 10 as a function of a second actual heat medium fluid temperature T_W2 which forms within or in the region of the primary heat source 3. In particular, the primary heat source 3 is additionally controlled in an open loop and/or a closed loop as a function of a desired and/or set second target heat medium fluid temperature T_W2, Soll. In particular, a desired and/or specified second target heat medium fluid temperature T_W2, Soll for the region of the primary heat source 3 and/or the distributor system of the latter is set with the aid of the central heating open-loop and/or closed-loop control apparatus 10, wherein, when the second actual heat medium fluid temperature T_W2 falls below the desired and/or set second target heat medium fluid temperature T_W2, Soll, the primary heat source 3 is then actively operated in order to correspondingly reheat the heat medium fluid 6, in particular until the second actual heat medium fluid temperature T_W2 then corresponds to the desired second target heat medium fluid temperature T_W2, Soll.

The first and the second critical temperature T_B1G, T_B2G are in particular chosen in such a manner that the primary heat source 3 is able to be operated and/or activated with the aid of the central heating open-loop and/or closed-loop control apparatus 10 for the purpose of heating the heat medium fluid 6 only when a heat requirement of the domestic water storage tank 5 exceeds a heat quantity which is able to be provided by means of the heat pump 11 at the maximum output of the heat pump 11. In simple words, the heat pump 11 is in particular operated with priority as long as possible, thus operated with priority over the primary heat source 3.

For example, the first critical temperature T_B1G is lower than the second critical temperature T_B2G.

On the other hand, the second critical temperature T_B2G could also be lower than the first critical temperature T_B1G, whereby the second critical temperature T_B2G is in this instance in particular 43° C., in particular is in the range from 41° C. to 45° C., whereby the first critical temperature T_B1G is in this instance in particular 48° C., and is in particular in the range from 46° C. to 50° C.

The two temperature probes are referred to as the first and the second temperature probe only for the sake of unequivocal allocation. The reference pertaining to the first and the second temperature probe thus does not constitute any mutual correlation and is not to be considered limiting. Any other unequivocal reference to the two temperature probes would be conceivable.

The procedures for operating and/or open-loop controlling and/or closed-loop controlling the heat pump 11 with the aid of the retrofit kit 1 assembled on the central heating system 2 as per FIG. 2 are again highlighted in more detail by means of a schematic illustration of a flow chart according to FIG. 4.

First, it is continually verified whether the first actual domestic water temperature T_B1 is below the first critical temperature T_B1G. If this is the case, the method step V_WP1, specifically the corresponding operating/actuating and/or activating of the heat pump 11, is carried out. The heat pump 11 is then operated in particular until the first actual domestic water temperature T_B1 is again above the first critical temperature T_B1G. Alternatively, it is also conceivable that a first switch-off critical temperature T_B1G′ is provided, which is preferably 4° C. to 6° C. above the first critical temperature T_B1G, and the heat pump 11 in this instance is operated in particular until the first actual domestic water temperature T_B1 is above the first switch-off critical temperature T_B1G′. When the first actual domestic water temperature T_B1 thus exceeds the first critical temperature T_B1G or the first switch-off critical temperature T_B1G′, the method step V_WP2, specifically another operating mode and/or even the deactivation of the heat pump 11, is carried out. Subsequently, the method restarts by verifying whether the first actual domestic water temperature T_B1 is below the first critical temperature T_B1G. The previously described method steps are in particular carried out when domestic water is retrieved from the domestic water storage tank, for example for a shower procedure, and fresh “colder” domestic water is resupplied to the domestic water.

The third heating circuit, in particular the storage pump 8, is simultaneously activated for heating the domestic water.

The procedures for operating and/or for open-loop controlling and/or for closed-loop controlling the primary heat source 3 with the aid of the retrofit kit 1 assembled on the central heating system 2 as per FIG. 2 are again highlighted in more detail by means of a schematic illustration of a flow chart according to FIG. 5.

Here, it is first continually verified whether the second actual domestic water temperature T_B2 is below the second critical temperature T_B2G′. If this is the case, the method step V_PR1, specifically the operating and/or activating of the primary heat source 3, is carried out. The primary heat source 3 is then in particular operated until the second actual domestic water temperature T_B2 is above the second critical temperature T_B2G again. Alternatively, it is also conceivable that a second switch-off critical temperature T_B2G′ is provided, which is preferably 4° C. to 6° C. above the second critical temperature T_B2G, and the primary heat source 3 is 31 in this instance in particular operated until the second actual domestic water temperature T_B2 is above the second switch-off critical temperature T_B2G′. When the second actual domestic water temperature T_B2 thus exceeds the second critical temperature T_B2G or the second switch-off critical temperature T_B2G′, the method step V_PR2, specifically another operating mode and/or the deactivation of the primary heat source 3, is carried out. Subsequently, the method restarts by verifying whether the second actual domestic water temperature T_B2 is below the second critical temperature T_B2G. The previously described method steps are in particular carried out when domestic water is retrieved from the domestic water storage tank 5, for example for a shower procedure, and fresh “colder” domestic water is resupplied to the domestic water storage tank 5. The third heating circuit, in particular the storage pump 8, is simultaneously activated, or has been already activated, for heating the domestic water, because the method steps described in the context of FIG. 4 take place in particular temporally before the method steps described in the context of FIG. 5. In simple words, the correspondingly implemented control ensures that the heat pump 11 is preferably actuated or used before the primary heat source 3 for heating the domestic water 9.

However, the heat pump 11 can in particular also be, or is, always used, or correspondingly activated and/or actuated, with preference over the primary heat source 3 for heating the heat medium fluid 6 in a “normal heating operation” of the central heating system 2, thus when the domestic water 9 does not have to be heated and for example only the heat medium fluid 6 has to be heated for the purpose of operating the heat exchanger 4; this too is to be pointed out once again.

In the highly preferred embodiment of the retrofitted central heating system 2, it is now ensured in particular that the primary heat source 3 is operated and/or activated with the aid of the central heating open-loop and/or closed-loop control apparatus 10 for the purpose of heating the heat medium fluid 6 only when a heat requirement of the heat exchanger 4 and/or of the domestic water storage tank 5 exceeds a heat quantity which is able to be provided by means of the heat pump 11 at the maximum output of the heat pump 11. Such a heat requirement of the heat exchanger 4 is in particular also a function of a desired room temperature of a room to be heated by the heat exchanger 4. It is conceivable that such a desired room temperature is chosen by a user of the room to be heated, and is subsequently present in the heat pump open-loop and/or closed-loop control apparatus 14 for controlling the heat pump 11 in an open loop and/or a closed loop. It could also be said that the first target heat medium fluid temperature T_W1, Soll is then a function of the desired room temperature. When the heat pump 11 is controlled in an open loop and/or a closed loop by means of the desired room temperature, this is also referred to as a modulating operation of the heat pump 11.

During the operation of the domestic water storage tank 5, vertical layering of the temperature of the domestic water 9 occurs in the domestic water storage tank 5.

The first actual domestic water temperature T_B1 is measured in a lower first temperature layer, as viewed vertically. The second actual domestic water temperature T_B2 is measured in a central or upper second temperature layer, as viewed vertically. The first temperature layer is formed vertically below the second temperature layer. This temperature layering is illustrated in FIGS. 1a, 1c and 2, and in FIG. 3a by temperatures, chosen by way of example, between 30° in the first lowermost temperature layer, and 45° C. in the uppermost temperature layer.

This temperature layering, shown in FIG. 3a, between 30° C. in the first lowermost temperature layer and 45° C. in the uppermost temperature layer occurs in particular when the first critical temperature T_B1G is lower than the second critical temperature T_B2G, and in particular T_B1G=30° C. and T_B2G<40° C., in particular T_B2G is chosen to be between 35° C. and 38° C. in this instance.

When the second critical temperature T_B2G is lower than the first critical temperature T_B1G, in particular when the second critical temperature T_B2G is in particular 43° C., in particular is in the range from 41° C. to 45° C., and the first critical temperature T_B1G is in particular 48° C., and is in particular in the range from 46° C. to 50° C., in particular a temperature layering between 50° in the first lowermost temperature layer and 60° C. in the uppermost temperature layer occurs, which is shown in FIG. 3b.

The temperatures which are clearly illustrated in the individual layers in FIGS. 3a and 3b are in each case in particular an averaged temperature for the respective layer.

The first actual domestic water temperature T_B1 thus has in particular lower values than the second actual domestic water temperature T_B2 when the domestic water 11 rests over a specific time in the domestic water storage tank 5. The temperature layering can change when domestic water 9 is retrieved from the domestic water storage tank 5, in particular in the upper region of the latter, and/or “fresh” domestic water 9 is then resupplied to the domestic water storage tank 5, in particular in the lower region of the latter, wherein a corresponding respective temperature layering can in principle be maintained by means of a corresponding discharge and supply concept within the domestic water storage tank 5.

Owing to the fact that a temperature layering, which can be seen and is illustrated in FIGS. 1a, 1c, 2, 3a and 3b, is formed in the domestic water storage tank 5, it is initially ensured substantially that the first actual domestic water temperature T_B1 is below the second actual domestic water temperature T_B2. The domestic water 9, as is shown in particular also in FIGS. 2, 3a and 3b, is able to be supplied to the domestic water storage tank 5 in the region of the first lower temperature probe 13.1. If fresh domestic water 9, which is cold in comparison to the domestic water 9 present in the domestic water storage tank 5, is now supplied to the domestic water storage tank 5, the first actual domestic water temperature T_B1 will first drop, in temporal terms. The second actual domestic water temperature T_B2 will only drop later, in particular once the fresh cold domestic water 9, or the temperature of the latter, has spread to the second temperature probe 13.2.

When the relative values of the critical temperatures T_B1G, T_B2G have been correspondingly chosen, and when supplying cold domestic water 9, the first critical temperature T_B1G will always be undershot by the associated first actual domestic water temperature T_B1 before the second critical temperature T_B2G is undershot by the second actual domestic water temperature T_B2, so that the heat pump 11 is then fundamentally always operated/actuated and/or activated before the primary heat source 3. If the output of the heat pump 11 is then sufficient to cover the heat requirement of the domestic water storage tank 5, the second actual domestic water temperature T_B2 will not drop below the second critical temperature T_B2G, and the primary heat source 3 does not have to be activated and then not operated while combusting fuels. The values of the critical temperatures T_B1G, T_B2G herein are in particular chosen in such a way that these procedures take place as described, and the primary heat source 3 in the context of saving fuels and in the context of a comfortable temperature of the domestic water 9 retrieved from the domestic water storage tank 5, is activated neither too early nor too late.

The first critical temperature T_B1G is either below the second critical temperature T_B2G, as shown in FIG. 6a, or the first critical temperature T_B1G is above the second critical temperature T_B2G, as shown in FIG. 6b, whereby if T_B1G<T_B2G the temperature layering according to FIG. 3a occurs in particular, and whereby if T_B1G>T_B2G, or T_B2G<T_B1G, the temperature layering according to FIG. 3b occurs in particular. In the first case mentioned above, the first critical temperature T_B1G is set in particular to 30° C., and the second critical temperature T_B2G is set to <40° C., where T_B2G is in particular between 35° C. and 38° C. In the second case mentioned above, the first critical temperature T_B1G is set in particular in the range from 46° C. to 50° C., in particular to 48° C., and the second critical temperature T_B2G is set in the range from 41° C. to 45° C., in particular to 43° C., as has to some extent already been described and/or explained above. The second critical temperature T_B2G can then be set in particular 3° C. to 7° C., in particular 5° C., lower than the first critical temperature T_B1G.

For setting/initiating a particularly optimal open-loop temperature control and/or closed-loop temperature control for heating the domestic water 9 of the domestic water storage tank 5, the following steps are in particular carried out initially: in particular upon installation of the system and/or prior to operating the system, the domestic water storage tank 5 which is initially completely filled with “cold” domestic water 9 is first heated “only” by means of the primary heat source 3, or the domestic water 9 here is heated only with the aid of the heat medium fluid 6 heated by the primary heat source 3. In this phase, the heat pump 11 remains switched off. Only upon reaching the desired second actual domestic water temperature T_B2, thus once the desired second actual domestic water temperature T_B2 is determined by the second temperature probe 13.2, is the heat pump 11 switched on, or additionally switched on. At the point in time at which the desired warm water temperature of the domestic water 9, or the desired second actual domestic water temperature T_B2 at the second temperature probe 13.2, is reached or established, the current first actual domestic water temperature T_B1 prevalent at the first temperature probe 13.1 is measured. For controlling the heat pump 11 for the further operation of the system, the first target heat medium fluid temperature T_{W1, Soll} for controlling the heat pump 11 in an open loop and/or a closed loop is set to a value which is substantially 5° C. higher than the determined first actual domestic water temperature value T_B1 mentioned above. The second target heat medium fluid temperature T_W2, Soll is then set in particular to a value which is 7° C. to 9° C., preferably 8° C., lower than T_{W1, Soll}. Setting the system in such a manner prevents an unnecessary operation of the primary heat source 3, wherein the heat pump 11, as has already been described, is in particular sufficient in this instance to correspondingly heat the domestic water 9 present in the domestic water storage tank 5 without an operation of the primary heat source 3 being necessary for this purpose. The first and/or the second critical temperature T_B1G, or T_B2G, respectively, is then set in particular so as to be in each case 2° C. to 5° C. lower than the respective corresponding determined or desired first and second actual domestic water temperature T_B1, or T_B2, respectively, or is then correspondingly automatically calculated by the heat pump open-loop and/or closed-loop control apparatus 14.

The following is to be explained once again in particular with reference to FIG. 3b: It is however also conceivable that the second critical temperature T_B2G is set lower than the first critical temperature T_B1G. For example, T_B1G is set to 49° C., and T_B2G is set to 43° C. In particular, this then results substantially in a temperature layering as is illustrated in FIG. 3b. The domestic water storage tank 5 reaches in particular an outflow temperature in the uppermost layer of 60° C., as a result of which a protection in relation to bacteria and Legionella is implemented or provided in the first place. Furthermore, as a result of the layering to be seen in FIG. 3b, the utilizable heated water quantity of the domestic water 9 in the domestic water storage tank 5 is significantly increased (in comparison to FIG. 3a) at the same time, in particular because the domestic water 9 of the domestic water storage tank 5 is now substantially correspondingly heated as far as the lowermost layer, or the domestic water 9 situated there has been or is correspondingly heated or warmed up. However, because the utilizable heated water quantity in FIG. 3b is now increased, for example in comparison to FIG. 3a, the heat pump 11 can be operated by way of a specified blockage time even when the first actual domestic water temperature T_B1 falls short of the first critical temperature T_B1G. Or again in other words, the domestic water 9 of the domestic water storage tank 5 is heated again with the aid of the heat pump 11, which is then active, in particular only once a specified blockage time has elapsed. As a result, the required cycle time of the heat pump 11 is less; in particular, a setting of T_B2G<T_B1G also ensures that the primary heat source 3 contributes to heating the domestic water 9 in the domestic water storage tank 5 in particular only once the second actual domestic water temperature T_B2 falls short of the second critical temperature T_B2G, which is in particular only the case when a correspondingly large quantity of already heated domestic water 9 has been retrieved from the domestic water storage tank 5, for example by very many shower procedures having taken place or taking place simultaneously in an apartment block with multiple residences. Blockage times of 15 to 30 minutes can be considered as a specified blockage time for the heat pump 11.

The heating pump 7 is controlled in an open loop and/or a closed loop by means of the heat pump open-loop and/or closed-loop control apparatus 14 in particular as a function of an external temperature Ta measured by means of an external temperature probe 13.a. The heating pump 7 is in particular first operated and/or activated synchronously with the heat pump 11, wherein the storage pump 8 is switched off, in particular deactivated. The synchronous actuation is made possible in particular due to the fact that the heating pump 7 as well as the heat pump 11 are controlled in an open loop and/or a closed loop by means of the heat pump open-loop and/or closed-loop control apparatus 14.

The heating pump 7 is switched off, in particular deactivated, by means of the heat pump open-loop and/or closed-loop control apparatus 14 when the storage pump 8 is operated and/or activated by means of the heat pump open-loop and/or closed-loop control apparatus 14, in particular due to a retrieval of domestic water 9 from the domestic water storage tank 5. In this way, the domestic water 9 can be more rapidly reheated with the aid of the heat medium fluid 6 after a retrieval of domestic water 9 from the domestic water storage tank 5, and after and/or during the supply of fresh cold domestic water 9. Alternatively, the heating pump 7 and the storage pump 8 can also be operated simultaneously, wherein a correspondingly high output would however have to be provided in that case by means of the heat pump 11 and/or the primary heat source 3 in order to heat the domestic water 9 in the domestic water storage tank 5 in the same time. The simultaneous operation of the heating pump 7 and the storage pump 8 is also referred to as a “parallel” operation of the central heating system 2. The simultaneous heating of the building and of the domestic water 9 is enabled in the “parallel” operation.

In relation to the primary heat source 3, the heat exchanger 4 and the heat pump 11 are disposed, or able to be disposed, fluidically in particular in series according to FIG. 2, and/or disposed, or able to be disposed, in series according to FIG. 1a to FIG. 1c.

In this way, in the state of the retrofit kit 1 assembled on the central heating system 2, the heat medium fluid 6 preheated by means of the heat pump 11 is then able to be completely supplied to the primary heat source 3.

A heat exchanger inflow line L_{WT, zu} is fluidically connectable, or connected, and/or correspondingly attached, to the primary heat source 3, on the one hand, and to the heat exchanger 4, on the other hand, so as to supply the heat medium fluid 6 to the heat exchanger 4 through the heat exchanger inflow line L_{WT, zu} by means of the heating pump 7, in particular wherein the heat exchanger inflow line L_{WT, zu} is partially already present and is partially part of the retrofit kit 1, in particular part of the hydraulic module 21. A heat pump inflow line L_{WP, zu} is fluidically connectable, or connected, and/or correspondingly attached to the heat exchanger 4, on the one hand, and to the heat pump 11, on the other hand, so as to supply the heat medium fluid 6 to the heat pump 11 through the heat pump inflow line L_{WP, zu}, in particular wherein the heat pump inflow line L_{WP, zu} is partially already present and is partially part of the retrofit kit 1, in particular part of the hydraulic module 21. A heat pump outflow line L_{WP, ab} is fluidically connected, or connectable, and/or correspondingly attached, to the heat pump 11, on the one hand, and to the primary heat source 3, on the other hand, so as to supply the heat medium fluid 6 to the primary heat source 3 through the heat pump outflow line L_{WP, ab}, in particular wherein the heat pump outflow line L_{WP, ab} is partially already present and is partially part of the retrofit kit 1, in particular part of the hydraulic module 21.

In simple words, the retrofit kit 1 has at least corresponding pipelines and/or hoses by means of which the desired fluidic connections of the parts/components of the retrofit kit 1 and of the existing central heating system 2 are able to be generated or implemented. For this purpose, the retrofit kit 1 has in particular the hydraulic module 21 already mentioned.

Provided in the primary heat source 3 is preferably a distributor system (illustrated with dashed lines in FIGS. 1a, 1c and 2) for the heat medium fluid 6, thus flow ducts which are correspondingly able to be passed through by the heat medium fluid 6, to which the heating circuits are in each case connected. The heat exchanger inflow line L_{WP, zu} and the heat pump outflow line L_{WP, ab}, and a line which leads to the domestic water storage tank 5 and returns from the domestic water storage tank 5, which in each case direct or transport the heat medium fluid 6, are connected to the primary heat source 3, in particular to such a distributor system, or are fluidically connected to the primary heat source 3, in particular to a boiler.

Therefore, the primary heat source 3, in particular the distributor system, can be passed through by a flow of the heat medium fluid 6 so that the heat medium fluid 6 is heated, optionally also with the aid of the primary heat source 3, while flowing therethrough. The primary heat source 3, in particular the distributor system, can however also be passed through by a flow of the heat medium fluid 6 without the heat medium fluid 6 being heated by the primary heat source 3 while flowing through the latter, thus in particular without the primary heat source 3 being actively operated.

The retrofit kit 1 has at least one valve 19 with the aid of which the heat medium fluid 6 is able to be directed and/or guided selectively from the primary heat source to the heat exchanger 4, or to the heat pump 11 while bypassing the heat exchanger 4.

In FIG. 1a to FIG. 2, the valve 19 is illustrated by dashed lines as a single valve 19, because the latter is able to be used as an alternative to the combination of two 3/2-way valves 20.1, 20.2 also described hereunder.

As an alternative to the single valve 19, the retrofit kit 1 has two 3/2-way valves each having three connectors and each having two switching positions, specifically a first 3/2-way valve 20.1 which is in particular able to be disposed, or is correspondingly disposed and/or interposed, in the heat exchanger inflow line L_{WT, zu}, and a second 3/2-way valve 20.2 which is in particular able to be disposed, or is correspondingly disposed and/or interposed, in the heat pump inflow line L_{WP, zu}. The first 3/2-way valve is fluidically connectable, or connected and/or correspondingly connectable or connected to the primary heat source 3 and to the heat exchanger 4 and to the second 3/2-way valve 20.2. The second 3/2-way valve is fluidically connectable, or connected and/or correspondingly attachable or attached, to the heat exchanger 4, to the heat pump and to the first 3/2-way valve 20.1. By means of the first 3/2-way valve 20.1, in the connected state, a flow of the heat medium fluid 6 is enabled selectively from the primary heat source 3 to the heat exchanger 4 or to the second 3/2-way valve 20.2. By means of the second 3/2-way valve 20.2, in the connected state, a flow of the heat medium fluid 6 is enabled selectively from the heat exchanger 4 or from the first 3/2-way valve 20.1 to the heat pump 11.

These flow paths described, which are able to be implemented by means of the two 3/2-way valves 20.1, 20.2, can also be implemented by means of the one single valve 19, wherein this one valve 19 in this instance is in particular embodied as a 4/2-way valve having four connectors and two switching positions, wherein in the first switching position of the valve 19 in the case of an assembled retrofit kit, thus in the connected state, a flow of the heat medium fluid 6 from the primary heat source 3 by way of the heat exchanger 4 to the heat pump 11 is enabled, and wherein in a second switching position of the valve 19 in the case of an assembled retrofit kit a flow of the heat medium fluid 6 from the primary heat source 3 to the heat pump 11 while bypassing the heat exchanger 4 is enabled.

The above-mentioned valve 19, in particular the first and the second 3/2-way valve 20.1, 20.2, or a valve 19 which is designed as a 4/2-way valve as mentioned above, is also connected in terms of control in particular to the heat pump open-loop and/or closed-loop control apparatus 14, which is intended to be illustrated by a corresponding dashed line, in particular in FIG. 2. Once again in other words, the respective switching positions of the above-mentioned valve 19 are able to be implemented with the aid of the heat pump open-loop and/or closed-loop control apparatus 14.

Of the group of elements/components, specifically the heat exchanger inflow line L_{WT, zu} at least in portions, the heat pump inflow line L_{WP, zu} at least in portions, the heat pump outflow line L_{WP, ab} at least in portions, the recirculating pump 12, the heat pump open-loop and/or closed-loop control apparatus 14 and the valve 19, in particular the first 3/2-way valve 20.1 and the second 3/2-way valve 20.2, at least two elements and/or components, in particular the heat exchanger inflow line L_{WT, zu} in portions, the heat pump inflow line L_{WP, zu} in portions, the heat pump outflow line L_{WP, ab} in portions, the first 3/2-way valve 20.1 and the second 3/2-way valve 20.2, but preferably all elements and/or components and respectively associated connectors are disposed and/or formed on a hydraulic module 21 forming a common functional unit.

According to FIG. 1a and FIG. 1c, the heat pump open-loop and/or closed-loop control apparatus 14 is not connected to the hydraulic module 21. According to FIG. 1b, the heat pump open-loop and/or closed-loop control apparatus 14 is connected to the hydraulic module 21, or is integrated in the latter. For the sake of clarity, the heat pump open-loop and/or closed-loop control apparatus 14 in FIG. is illustrated next to the hydraulic module 21, but FIG. 2 illustrates the assembled state for all three exemplary embodiments according to FIG. 1a to FIG. 1c, so that the heat pump open-loop and/or closed-loop control apparatus 14 according to FIG. 2 could also be connected to the hydraulic module 21, this having to be pointed out.

The central heating system 2 is usually disposed within a building. The heat pump 11, in particular an air/water heat pump 11 embodied as a compact functional unit, can be disposed within a building as well as outside the building. If disposed within the building, the heat pump 11 upon assembly of the latter is connected to the external environment of the building by way of air slots. The hydraulic module 21 is preferably designed to be assembled adjacent to the central heating system 2 within the building, so that the flow paths to be implemented are able to be embodied in a particularly short manner, and the components/elements connected to the hydraulic module 21 are able to be protected in relation to weather influences by the building.

The hydraulic module 21 has in particular a frame 22 for connecting the hydraulic module 21 to a building wall and/or to the primary heat source 3. The frame 22 could be embodied as a welded construction, for example. However, the frame 22 could also be disposed on a floor of the building, or assembled thereon, respectively.

The part of the heat exchanger inflow line L_{WT, zu} associated with the retrofit kit 1 has a first connector 23.1 for supplying the heat medium fluid 6 to the hydraulic module 21, and a second connector 23.2 for discharging the heat medium fluid 6 from the hydraulic module 21. The part of the heat pump inflow line L_{WP, zu} associated with the retrofit kit 1 has a third connector 23.3 for supplying the heat medium fluid 6 to the hydraulic module 21, and a fourth connector 23.4 for discharging the heat medium fluid 6 from the hydraulic module 21. The part of the heat pump outflow line L_{WP, ab} associated with the retrofit kit 1 has a fifth connector 23.5 for supplying the heat medium fluid 6 to the hydraulic module 21, and a sixth connector 23.6 for discharging the heat medium fluid 6 from the hydraulic module 21.

The connectors 23.1 to 23.6 herein are in spatial terms disposed on the hydraulic module 21, or formed in the hydraulic module 21, in such a manner that particularly simple and rapid connecting to the parts of the corresponding lines associated with the central heating system 2 is enabled. Furthermore, the spatial arrangement of the connectors 23.1 to 23.6 and of the lines is correspondingly optimized in particular in terms of the short flow paths to be implemented, which are embodied with a low flow resistance.

A method for retrofitting an existing central heating system 2 by means of the above-described retrofit kit 1 is once again described in more detail hereunder:

The method for retrofitting is carried out in order to progress from the separated state of the retrofit kit 1 and the central heating system 2, illustrated in FIG. 1a to FIG. 1c, to the assembled state of the retrofit kit 1 and the central heating system 2, illustrated in FIG. 2.

The first temperature probe 13.1 is assembled and/or disposed in a lower region of the domestic water storage tank 5, as viewed vertically, or adjacent to that lower region of the domestic water storage tank 5, as viewed vertically.

The first temperature probe 13.1 is either assembled so that the measuring region of the first temperature probe 13.1 is in direct contact with the domestic water 9, or is assembled in or on a wall of the domestic water storage tank 5 or of the domestic water inflow line 18 in the lower region of the domestic water storage tank 5, as viewed vertically.

The first temperature probe 13.1 is connected in terms of control, signals and/or data to the heat pump open-loop and/or closed-loop control apparatus 14. For this purpose, a cable of the first temperature probe 13.1 is connected in terms of control, signals and/or data to the heat pump open-loop and/or closed-loop control apparatus 14 in particular by way of a plug connection. Alternatively, a wireless connection, for example by means of radio, in particular Bluetooth, would also be conceivable, this connection then being correspondingly set up.

If the heat pump 11 is part of the existing central heating system 2, the heat pump 11 is connected in terms of control to the heat pump open-loop and/or closed-loop control apparatus 14. Or if the heat pump 11 is part of the retrofit kit 1, the heat pump 11 is connected in terms of control to the heat pump open-loop and/or closed-loop control apparatus 14, or is already connected thereto.

The storage pump 8 is connected in terms of control to the heat pump open-loop and/or closed-loop control apparatus 14.

The heating pump 7 is connected in terms of control to the heat pump open-loop and/or closed-loop control apparatus 14.

If the valve 19 is provided, the valve 19 is connected in terms of control to the heat pump open-loop and/or closed-loop control apparatus 14.

As an alternative to the valve 19, the first 3/2-way valve 20.1 and the second 3/2-way valve 20.2 are in each case connected in terms of control to the heat pump open-loop and/or closed-loop control apparatus 14.

All these control connections are in each case generated by means of a cable and/or in each case wirelessly, in particular by radio.

An external temperature probe 13.a is assembled in an external region, wherein the external temperature probe 13.a is connected in terms of control, signals and/or data to the heat pump open-loop and/or closed-loop control apparatus 14, or will be connected thereto.

The external temperature probe 13.a herein is in particular adapted to the heat pump open-loop and/or closed-loop control apparatus 14 in such a way that a correct determination of the external temperature in the external environment of a building is then made possible.

The first critical temperature T_B1G, or a table and/or formula for determining the first critical temperature T_B1G, is entered into the heat pump open-loop and/or closed-loop control apparatus 14, and/or is already stored therein. The second critical temperature T_B2G, or a table and/or formula for determining the second critical temperature T_B2G, is entered into the central heating open-loop and/or closed-loop control apparatus 10, and/or is already stored therein. When using the formula, it is conceivable in particular that specific parameters pertaining to this formula are likewise entered.

The critical temperature T_B1G, or the table and/or the formula for determining the first critical temperature T_B1G, is entered on an operator panel of the heat pump open-loop and/or closed-loop control apparatus 14, for example. Alternatively, it would be conceivable to couple an input unit, preferably a computer, to the heat pump open-loop and/or closed-loop control apparatus 14, and to perform the input by means of this input unit. This applies in an analogous manner also to the second critical temperature T_B2G and to the central heating open-loop and/or closed-loop control apparatus 10. In the highly preferred embodiment, the heat pump open-loop and/or closed-loop control apparatus 14 is however embodied as a computer and/or has a corresponding microprocessor for implementing the respective calculations and/or desired control procedures. In an analogous manner, the central heating open-loop and/or closed-loop control apparatus 10 can also be designed as a computer, or have a microprocessor.

It is conceivable that a further external temperature probe is connected in terms of control, signals and/or data to the central heating open-loop and/or closed-loop control apparatus 10 in such a way that the external temperature Ta is also able to be determined by means of this further external temperature probe and the central heating open-loop and/or closed-loop control apparatus 10.

FIGS. 6a and 6b show, in a schematic illustration the first critical temperature T_B1G and the second critical temperature T_B2G in relation to the external temperature Ta, the way these are in each case entered or stored as a table or as a formula in the heat pump open-loop and/or closed-loop control apparatus 14, or the central heating open-loop and/or closed-loop control apparatus 10. In particular, FIGS. 6a and 6b likewise show the settings of the first and the second target heat medium fluid temperatures T_{W1, Soll} and T_W2, Soll as a function of a corresponding external temperature Ta, respectively.

According to FIG. 6a and FIG. 6b, the first and the second critical temperature T_B1G, T_B2G are illustrated as horizontal lines parallel to the X-axis of the external temperature Ta. Thus, the first and the second critical temperature T_B1G, T_B2G are present as constant values in the heat pump open-loop and/or closed-loop control apparatus 14, or in the central heating open-loop and/or closed-loop control apparatus 10, so that, for the sake of simplicity, the first and the second critical temperature T_B1G, T_B2G are independent of the external temperature Ta.

In terms of setting/initiating the target heat medium fluid temperature T_{W1, Soll} and T_W2, Soll, respectively, and the respective first and second critical temperatures T_B1G and T_B2G, respectively, reference may be made to the previous explanations.

However, it may additionally be pointed out here that a temperature difference between the first target heat medium fluid temperature T_{W1, Soll} and the second target heat medium fluid temperature T_W2, Soll is preferably 7° C. to 9° C., in particular 8° C., where T_W2, Soll<T_{W1, Soll}. Yet again in other words, the second target heat medium fluid temperature T_W2, Soll is set in particular at a value which is 7° C. to 9° C. lower than the first target heat medium fluid temperature T_{W1, Soll}. The second critical temperature T_B2G is in particular lower than the second target heat medium fluid temperature T_W2, Soll, preferably at least 2° C. to 5° C. lower, preferably 3° C. to 4° C. lower. In this way, effective heating of the domestic water 9 by means of the primary heat source 3 can in particular also be achieved.

The part of the heat exchanger inflow line L_{WT, zu} associated with the retrofit kit 1 is connected to the existing part of the heat exchanger inflow line L_{WT, zu} by means of the first and the second connector 23.1, 23.2. The part of the heat pump inflow line L_{WP, zu} associated with the retrofit kit 1 is connected to the existing part of the heat pump inflow line L_{WP, zu} by means of the third and the fourth connector 23.3, 23.4. The part of the heat pump outflow line L_{WP, ab} associated with the retrofit kit 1 is connected to the existing part of the heat pump outflow line L_{WP, ab} by means of the fifth and the sixth connector 23.5, 23.6. This can be performed in a simple manner with the aid of the correspondingly designed hydraulic module 21.

Finally it may be pointed out yet once more that the central heating open-loop and/or closed-loop control apparatus 10 and/or the heat pump open-loop and/or closed-loop control apparatus 14 can be embodied as computers, and/or have corresponding microprocessors for implementing the desired calculations and/or control procedures. The central heating open-loop and/or closed-loop control apparatus 10 and the heat pump open-loop and/or closed-loop control apparatus 14 are in particular preferably embodied separately from one another, so that they do not directly influence one another and the open-loop and/or closed-loop controls carried out by means of the central heating open-loop and/or closed-loop control apparatus 10 and those carried out by means of the heat pump open-loop and/or closed-loop control apparatus 14 are also independent of one another. In the process, controlling the heat pump 11 and the primary heat source 3 in an open loop and/or a closed loop is then performed independently of one another.

However, this means in particular that no parameters and/or measured values for controlling the primary heat source 3, such as a level of fuel supply, are then present in the heat pump open-loop and/or closed-loop control apparatus 14. On the other hand, there are in particular also no operating data and/or parameters of the heat pump 11 present in the central heating open-loop and/or closed-loop control apparatus 10. Controlling the primary heat source 3 takes place, in particular exclusively, with the aid of the central heating open-loop and/or closed-loop control apparatus 10, wherein controlling the heat pump 11 takes place, in particular exclusively, with the aid of the heat pump open-loop and/or closed-loop control apparatus 14. An in particular indirect correlation between the control of the heat pump 11 and the primary heat source 3 in an open loop and/or a closed loop is created in particular only as a result of the choice of the two critical temperatures T_B1G and T_B2G, relative to one another, and as a result of the specific disposal of the two temperature probes 13.1, 13.2 relative to one another. This is advantageous in particular when the heat pump open-loop and/or closed-loop control apparatus 14, including the heat pump 11, are integrated in an existing central heating system during retrofitting, because the central heating open-loop and/or closed-loop control apparatus 10 does not have to be modified in this instance. The heat pump open-loop and/or closed-loop control apparatus 14 is in particular connected to the central heating open-loop and/or closed-loop control apparatus 10 in particular only for the purpose of supplying energy to the heat pump open-loop and/or closed-loop control apparatus 14, which is in particular also symbolized by a dashed line, in particular in FIG. 2. Also conceivable is a connection of the heat pump open-loop and/or closed-loop control apparatus 14 to the electricity grid. Simple and cost-effective control of the system can be implemented as a result. The central heating open-loop and/or closed-loop control apparatus 10 and the heat pump open-loop and/or closed-loop control apparatus 14 can operate substantially independently of one another, or can control the central heating system 2, the latter being in particular retrofitted with the retrofit kit 1, in a substantially mutually independent manner. Therefore, a system which, for example, initially also has only one primary heat source 3, can be retrofitted in a simple and cost-effective manner with a heat pump 11 and the heat pump open-loop and/or closed-loop control apparatus 14; this may yet again be pointed out here.

After connecting/using the retrofit kit 1, all desired fluidic and/or control connections are implemented, and the correspondingly retrofitted central heating system 2 can then be controlled and/or operated, in particular as described above, in a simple manner with the above-explained advantages.

List of Reference Signs

1	Retrofit kit
2	Central heating system
3	Primary heat source
4	Heat exchanger
5	Domestic water storage tank
6	Heat medium fluid
7	Heating pump
8	Storage pump
9	Domestic water
10	Central heating open-loop and/or closed-loop control apparatus
11	Heat pump
12	Recirculating pump
13.1	First temperature probe
13.2	Second temperature probe
13.a	External temperature probe
14	Heat pump open-loop and/or closed-loop control apparatus
15	T-fitting
16	Inflow valve
16.r	Check valve
17	Inflow connector
18	Domestic water inflow line
19	Valve
20.1	First 3/2-way valve
20.2	Second 3/2-way valve
21	Hydraulic module
22	Frame
23.1	First connector
23.2	Second connector
23.3	Third connector
23.4	Fourth connector
23.5	Fifth connector
23.6	Sixth connector
TB1	First actual domestic water temperature
TB2	Second actual domestic water temperature
TB1G	First critical temperature
TB1G′	First switch-off critical temperature
TB2G	Second critical temperature
TB2G′	Second switch-off critical temperature
Ta	External temperature
TW1	First actual heat medium fluid temperature
TW2	Second actual heat medium fluid temperature
TW1, Soll	First target heat medium fluid temperature
TW2, Soll	Second target heat medium fluid temperature
LWT, zu	Heat exchanger inflow line
LWP, zu	Heat pump inflow line
LWP, ab	Heat pump outflow line
VWP1	Operating and/or activating the heat pump 3
VWP2	Deactivating the heat pump 3
VPR1	Operating and/or activating the primary heat source 2
VPR2	Deactivating the primary heat source 2