Method for operating a hybrid combination heater and hybrid combination heater

Abstract

The invention relates to a method for operating a hybrid combination heating appliance (200) for tempering a heating water flow (1) and a domestic hot water flow (2). A heat generator (206) and / or a heat pump heat exchanger (202) connected in series with it in a heating water circuit (208) temper the heating water flow (1), wherein the heat pump heat exchanger (202) can be connected to a heat pump (300) on the secondary side. The heating water flow (1) flows into a connectable, building-side section of a heating water circuit (400) or into a hydraulically parallel bypass (214) of the hybrid combination heating appliance (200) with a domestic hot water heat exchanger (216), wherein a valve device (220) directs the heating water flow (1) into the heating water circuit (400) or into the bypass (214).It is proposed that a control unit (204) detects a risk of icing at the heat pump heat exchanger (202) and / or at another heat exchanger (308) of the heat pump (300) and switches the valve assembly (220) depending on the detected risk of icing so that the heating water flow (1), in particular coming from the heat generator (206), flows through the bypass (214) and the heat pump heat exchanger (202). The heating water flow (1) is in particular greater than or equal to a predefinable minimum flow rate.

Description

State of the art

[0001] A hybrid combination heater for tempering a heating water flow and a drinking water flow and a method for operating the hybrid combination heater are known from the prior art, wherein the heater comprises a heat generator and a heat pump heat exchanger connectable on the secondary side to a heat pump, connection means for connecting to a heating water circuit, a bypass with a drinking water heat exchanger, and a valve device for directing the heating water flow into the heating water circuit or into the bypass.

[0002] It is an object of the invention to provide an improved hybrid combination heater and an improved method for operating it. Disclosure of the invention

[0003] The invention is based on a method for operating a hybrid combination heating device for controlling the temperature of a heating water flow and a drinking water flow. A heat generator and / or a heat pump heat exchanger connected in series with it in a heating water line control the temperature of the heating water flow, wherein the heat pump heat exchanger can be connected to a heat pump on the secondary side. The heating water flow flows into a connectable, building-side section of a heating water circuit or into a bypass of the hybrid combination heating device with a drinking water heat exchanger arranged hydraulically parallel to the heating water circuit. A valve device directs the heating water flow into the heating water circuit or into the bypass.

[0004] It is proposed that a control unit detects a risk of icing on the heat pump heat exchanger and / or on another heat exchanger of the heat pump and, depending on the detected risk of icing, switches the valve device so that the heating water flow, particularly coming from the heat generator, flows through the bypass and the heat pump heat exchanger. In this case, the heating water flow is, in particular, greater than or equal to a predeterminable minimum volume flow.

[0005] By means of the configuration according to the invention, the operation of the hybrid combination heater can be adapted to a detected risk of icing of the heat pump heat exchanger and / or the additional heat exchanger of the heat pump, as can occur, for example, during operation of the heat pump in defrost mode. By directing the heating water flow through the bypass, and consequently ensuring that the heat pump heat exchanger is reliably supplied with heating water, in particular with a heating water flow greater than or equal to a predeterminable minimum volume flow, the valve device enables or ensures sufficient heat provision at the heat pump heat exchanger. This can counteract icing of the heat pump heat exchanger and / or the additional heat exchanger of the heat pump.

[0006] In particular, if the hybrid combination heater is operated in heating mode (the valve device is in a first switching position and the heat generator and / or the heat pump are operating in heating mode) and the heat pump then switches to defrost mode, the control unit can detect whether there is a risk of icing on the heat pump heat exchanger and / or on the heat pump's other heat exchanger. If there is a risk of icing, the control unit reacts to compensate for the heat extraction from the heat pump heat exchanger while the heat pump is operating in defrost mode and to prevent icing. If there is a risk of icing, the valve device switches to a second switching position so that the heating water flow flows through the bypass and the heat pump heat exchanger.

[0007] By means of the design according to the invention, drinking water can also advantageously be heated in parallel with operation in defrost mode.

[0008] The heat generator can generate heat and thus temper a heating water flow, in particular a heating water flow flowing through the heat generator. In particular, the heat generator has a heating mode for generating heat. A heating water pump (circulation pump) can pump the heating water flow. In this context, a heat generator is understood to mean, in particular, a fuel-fired heat generator. Alternatively, the heat generator can also be an electric heat generator. Tempering here is understood to mean, in particular, heating or cooling.

[0009] A combination heater is understood here in particular to be a heater with a heat generator that can regulate the temperature of a hot water flow and a drinking water flow. A hybrid combination heater is understood here in particular to be a combination heater that can be connected to a heat pump. In addition to the heat generator, the hybrid combination heater comprises a heat pump heat exchanger through which the hot water flow flows on the primary side and can regulate its temperature. On the secondary side, a heat transfer medium, in particular a refrigerant, of a heat pump can flow through the heat pump heat exchanger. The heat transfer medium flows through a heat transfer medium circuit that connects the heat pump heat exchanger to the heat pump in a fluid-conducting manner. If the heat transfer medium is a refrigerant, the heat transfer medium circuit is formed by a refrigerant circuit.The hybrid combination heater can be operated in a bivalent alternative and / or bivalent parallel mode. A hybrid heating system is understood here to mean a system with a hybrid combination heater and a heat pump.

[0010] The heating water flow pumped by a heating water pump can circulate through a heating water circuit from the heater into a building and back into the heater. The heating water circuit comprises a section formed in the heater and a section of the heating water circuit formed in the building. If reference is made to only one heating water circuit in the following, this specifically refers to the section of the heating water circuit formed in the building. A heating water line is understood here in particular to be the section of the heating water circuit formed in the heater. The heat generator and the heat pump heat exchanger are arranged in the heating water line, connected in series by pipe sections that conduct the heating water. In particular, the heat pump heat exchanger is arranged upstream of the heat generator in a flow direction of the heating water flow.The heating water pump is in particular part of the hydraulic combination heater and / or is controlled by the control unit of the hydraulic combination heater.

[0011] The heating water line of the heater has a flow section for connection to a flow line and a return section for connection to a return line of the building-side section of the heating water circuit. The heating water flow tempered in the heat generator can, for example, be directed through the flow section into the flow line, then through the return line into the return section back to the heat generator. The building can be heated using heating elements, particularly radiators and / or underfloor heating elements, in the building-side section of the heating water circuit.

[0012] A heating water bypass with a drinking water heat exchanger is arranged in the heating device between the flow section and the return section and - with respect to the heat generator - hydraulically parallel to the connectable building-side section of the heating water circuit. This bypass can be switched in particular by means of a valve device. As an alternative to flowing through the building-side section of the heating water circuit and depending on the switching position of the valve device, the tempered heating water flow can also be passed through the bypass and a primary side of the drinking water heat exchanger. The drinking water flow can be passed through a secondary side of the drinking water heat exchanger and thus tempered. For this purpose, the drinking water heat exchanger can be fluidly connected to a drinking water source by means of an inlet line and to a drinking water tap by means of an outlet line. The drinking water heat exchanger is arranged in the bypass.The bypass and the drinking water heat exchanger are both part of the combi boiler and are located within the combi boiler. A switchable bypass refers in particular to a bypass through which the flow can be varied using a switchable valve device, either for flow to the building-side section of the heating water circuit or to the drinking water heat exchanger. "Switching the bypass" refers to either shutting off the bypass to allow flow through the building-side section of the heating water circuit or switching on the bypass to allow flow through the drinking water heat exchanger.

[0013] A valve device is understood here in particular to mean a fluid-conducting device with at least two switching positions for changing the flow of heating water. The valve device is arranged on the supply section and / or return section and / or on the bypass. In particular, the valve device is arranged on a fluid-conducting branch from the supply section into the bypass or on a fluid-conducting branch from the return section into the bypass. The valve device can in particular have a three-way changeover valve. Alternatively, the valve device can have two two-way valves. By means of the valve device, the heating water flow can be directed into the building-side section of the heating water circuit in a first switching position or into the bypass in a second switching position.The valve device can, for example, switch depending on a heating demand and / or a domestic hot water demand and / or depending on a detected risk of icing. In particular, a control unit can send a switching signal to the valve device and thus switch the valve device.

[0014] The heat pump heat exchanger can be connected on its secondary side to a heat pump, in particular to a heat transfer medium circuit, in particular to the refrigerant circuit, of the heat pump. In particular, the heat pump heat exchanger can be designed as a condenser of the heat pump. In particular, the additional heat exchanger of the heat pump can be designed as an evaporator of the heat pump.

[0015] The building-side section of the heating water circuit may include additional pipe sections, valves, particularly radiator valves, and radiators for the flow of heating water through which the building is heated. Users of the building can use the valves to adjust the flow and heat output of the radiators depending on their personal heat sensitivity. Continuous flow of heating water through the building-side section of the heating water circuit cannot be assumed to be guaranteed in the structural and / or control engineering design of the hybrid combination boiler. In particular, the design must consider the possibility that the valves in the building-side section of the heating water circuit may be closed, preventing or insufficient flow of heating water. This can be particularly the case when using electrically controlled valves.It must also be considered that the building-side section of the heating water circuit is a heating water circuit without an additional bypass for the flow of heating water from the supply line to the return line. In particular, the building-side section of the heating water circuit may be closed to the flow of heating water, at least temporarily. If the valve device is in the first switching position, the flow of heating water through the heat pump heat exchanger cannot be reliably guaranteed.

[0016] By means of the design according to the invention, a sufficient flow of heating water through the heat pump heat exchanger is ensured during operation in defrost mode - even without the need for an open valve in the building-side section of the heating water circuit or a building-side bypass for the overflow of heating water from the flow line into the return line.

[0017] Icing and / or the risk of icing can occur during operation of the hybrid combination heater and / or the heat pump under certain operating conditions. A risk of icing is understood here in particular to mean impending icing, potentially imminent icing, or icing anticipated, particularly by the control unit. Alternatively or additionally, a risk of icing can also be understood to mean icing that has already occurred. Icing can be averted, particularly if the risk of icing is recognized, through countermeasures or protective measures.

[0018] When the heat pump connectable to the hybrid combination heater is operating in heating mode, heat flows from the additional heat exchanger (in particular the heat pump's evaporator) to the heat pump's heat exchanger (in particular the heat pump's condenser); the additional heat exchanger becomes cold in the process. Depending on the operating point or operating mode of the heat pump connectable to the heater, the heat pump heat exchanger and / or the additional heat exchanger of the heat pump are at risk of icing up. For example, the additional heat exchanger (in particular the evaporator, e.g., an air / refrigerant heat exchanger) can ice up in the heat pump's heating mode. When the additional heat exchanger ices up, a coating of frost or ice forms on the additional heat exchanger, which impairs its function and / or reduces the efficiency of heat transfer.In a defrost mode, which is different from the heating mode, for defrosting the additional heat exchanger of the heat pump, the frost or ice deposit is defrosted by supplying heat to the additional heat exchanger. The defrost mode can be implemented, in particular, using reversible heat pump operation. In defrost mode, heat is extracted from the heat pump heat exchanger by the heat transfer medium, in particular the refrigerant, of the heat pump, and the heat flows from the heat pump heat exchanger to the additional heat exchanger; in the process, the heat pump heat exchanger becomes cold. If the temperature of the heating water in the heat pump heat exchanger is close to freezing or falls below freezing, particularly in defrost mode of heat pump operation, the heat pump heat exchanger is at risk of freezing.If, particularly during defrosting during heat pump operation, there is no flow of heating water through the heat pump heat exchanger, the heat pump heat exchanger is at risk of freezing. Icing can cause damage to the heat pump heat exchanger, and in the worst case, heat transfer medium can leak out. This type of icing, particularly icing of the heating water and / or the heat transfer medium in the heat pump heat exchanger, can be reliably prevented with the invention.

[0019] The fact that the valve device switches depending on a detected risk of icing can be understood in particular to mean that the valve device switches when a risk of icing is detected. In particular, the valve device switches from the first switching position to the second switching position depending on a detected risk of icing. If the valve device is already in the second switching position, it remains in the second switching position. If the valve device is in the second switching position, flow through the heat pump heat exchanger is ensured. If the heating water flow flows through the bypass and the heat pump heat exchanger, the heat pump heat exchanger can reliably receive heat from the heating water flow for operation of the heat pump in defrost mode, thus counteracting icing of the heat pump heat exchanger.If at least a minimum volume flow of heating water flows through the bypass and the heat pump heat exchanger, the heat pump heat exchanger can reliably receive sufficient heat for the heat pump to operate in defrost mode, preventing the heat pump heat exchanger from freezing. In particular, the valve device remains in the second switching position until the heat pump's defrost mode is terminated.

[0020] The combination heater has a control unit configured to operate the combination heater in such a way that a risk of icing on the heat pump heat exchanger and / or on another heat exchanger of the heat pump is detected, and that the valve device switches depending on a detected risk of icing so that the heating water flow flows through the bypass and the heat pump heat exchanger, in particular for operation of the heat pump in defrost mode, wherein the heating water flow is in particular greater than or equal to a predeterminable minimum volume flow. "Configured" should be understood to mean that the control unit has the appropriate hardware with inputs and outputs, logic circuits, memory, and the appropriate software required for such control. The control unit is therefore customized in this respect.

[0021] The heat required to prevent icing and / or defrost can come from the heating water circulating through the hybrid combination heater. Alternatively, the required heat can come from the heating water circulating through the building-side section of the heating circuit.

[0022] In a preferred embodiment, the control unit detects the risk of icing based on a defrost signal about an impending, starting or ongoing operation of the connectable heat pump in defrost mode.

[0023] The defrost signal contains information about the upcoming, incipient, or ongoing operation of the connectable heat pump in defrost mode. For example, the control unit reads the defrost signal coming from the heat pump. In particular, the control unit has a data interface configured for this purpose to establish a signal-conducting connection with the heat pump.

[0024] In a further preferred embodiment, a heat exchanger device comprising the heat pump heat exchanger outputs a signal or a value of a heat exchanger parameter of the heat exchanger device via at least one first data interface. The control unit detects the risk of icing based on the signal or value of the heat exchanger parameter.

[0025] For example, the control unit reads the information coming from the heat exchanger device. In particular, the control unit has a data interface configured for this purpose for establishing a signal-conducting connection with the heat exchanger device. In particular, the heat exchanger device has a sensor that generates a signal, based on which the signal or value of the heat exchanger parameter is determined. The heat exchanger parameter allows a conclusion to be drawn about a condition of the heat pump heat exchanger, in particular a condition describing a risk of icing.

[0026] In a preferred embodiment, a heating water temperature at the heat pump heat exchanger is measured using at least one temperature sensor on the heating water side. The heating water temperature sensor is the sensor on the heat exchanger device. The control unit detects the risk of icing based on the heating water temperature, particularly when the heating water temperature falls below a predefined first minimum value. The first minimum value can, for example, be in the range of 2 °C to 10 °C.

[0027] In a further preferred embodiment, a heating water temperature spread at the heat pump heat exchanger is determined by means of at least one (preferably two) heating water-side temperature sensor. The at least one heating water-side temperature sensor is the sensor on the heat exchanger device. The control unit detects the risk of icing based on the heating water temperature spread, particularly when a predeterminable maximum value of the heating water temperature spread is exceeded.

[0028] In a further preferred embodiment, a temperature of the heat transfer medium, in particular a refrigerant temperature, is measured by means of at least one temperature sensor or pressure sensor arranged on the secondary side or heat pump side of the heat pump heat exchanger. The at least one secondary-side temperature sensor or pressure sensor is the sensor on the heat exchanger device. The control unit detects the risk of icing based on the temperature of the heat transfer medium, in particular when the temperature of the heat transfer medium falls below a predeterminable second minimum value. The second minimum value can, for example, be in the range of 2 degrees Celsius to 8 degrees Celsius. If the heat transfer medium is a refrigerant that circulates between the heat pump and the heat pump heat exchanger, the temperature of this heat transfer medium can, for example, be in the range of -8 degrees Celsius to 2 degrees Celsius.

[0029] In a further preferred embodiment, a heating water pump conveys the heating water flow in the hybrid combination heater, with the heating water pump outputting a value of a pump parameter via at least one second data interface. The control unit detects the risk of icing based on the value of the pump parameter, particularly when the value falls below a predeterminable third minimum value of the pump parameter.

[0030] The heating water pump comprises, in particular, a pump impeller for conveying the heating water flow and a motor for driving the pump impeller. The pump parameter can be, for example, a parameter representing the conveyed heating water flow and / or a rotational frequency (speed) of a pump impeller or a pressure differential across the heating water pump and / or a current intensity or electrical power consumption of the heating water pump motor. The control unit determines a value of the heating water flow based in particular on the pump parameter. The third minimum value is measured in particular according to the defrosting power provided when the connectable heat pump is operating in defrost mode or from the heat extraction during operation of the heat pump in defrost mode.The third minimum value can, for example, be in the range of 5 liters per minute to 20 liters per minute for hybrid heating systems used in the home.

[0031] From the value of the pump parameter, which represents the size of the heating water flow, the control unit can detect whether the heat pump heat exchanger is flowing with sufficient heating water to compensate for the heat extraction during operation of the heat pump in defrost mode with sufficient heat provision and to prevent icing.

[0032] In particular, if the hybrid combination heater is operating in heating mode (the valve device is in a first switching position and the heat generator and / or the heat pump are operating in heating mode) and the heat pump switches to defrost mode, the control unit can use the pump parameter value to determine whether sufficient heating water is flowing through the heat pump heat exchanger to compensate for the heat extraction during heat pump operation in defrost mode with sufficient heat provision and to prevent icing. If the pump parameter value is less than the third minimum value, the valve device switches to a second switching position so that the heating water flows through the bypass and the heat pump heat exchanger.

[0033] Alternatively or additionally, a separate mass flow sensor could be used to determine the size of the heating water flow.

[0034] In a further preferred embodiment, the control unit operates the heat generator in a heating mode depending on a detected risk of icing, in particular when a risk of icing is detected. This increases the temperature of the heating water flowing through the heat generator, the bypass, and the heat pump heat exchanger.

[0035] By switching the heat generator to heating mode and heating the heating water flow, the heat pump heat exchanger is reliably supplied with warm heating water. This ensures sufficient heat supply to the heat pump heat exchanger. This reliably prevents icing of the heat pump heat exchanger and / or the heat pump's other heat exchangers.

[0036] A further preferred embodiment relates to an initial situation in which a risk of icing is detected and / or the valve device switches to the second switching position depending on the detected risk of icing, in particular is already in the second switching position, so that the heating water flow flows through the bypass and the heat pump heat exchanger, in particular for operation of the heat pump in defrost mode. If domestic hot water preparation or domestic hot water tapping then begins and / or is added, a target temperature value underlying the domestic hot water preparation is reduced compared to a standard target temperature value.

[0037] This ensures that the setpoint temperature used for domestic hot water preparation is reduced while the heat pump is operating in defrost mode. This ensures that sufficient heat is available at the heat pump heat exchanger for defrost mode, even when domestic hot water is being prepared.

[0038] Otherwise, if no risk of icing is detected, in particular if the heat pump is not operating in defrost mode, and domestic hot water preparation or domestic hot water tapping begins, the standard setpoint temperature value is used as the basis for domestic hot water preparation.

[0039] If the need to defrost the heat pump is detected during domestic hot water preparation or dispensing, the defrost mode is reset for the duration of the domestic hot water preparation. To this end, the hybrid combination heater communicates with the heat pump and exchanges corresponding information. The setpoint temperature value underlying the domestic hot water preparation then remains unchanged compared to the standard setpoint temperature value. The hybrid combination heater, in particular the control unit, is designed to output a corresponding reset signal to reset the defrost mode to the connectable heat pump, in particular to a control unit controlling the heat pump. As soon as domestic hot water preparation ends, the heat pump can also switch to defrost mode, which is signaled to the heat pump by the control unit, in particular by canceling the reset signal.

[0040] During domestic hot water preparation or domestic hot water tapping, a domestic hot water temperature T (the actual temperature of the domestic hot water) of the prepared domestic hot water is determined and approximated or adjusted to the target temperature value or standard target temperature value. The domestic hot water temperature T of the prepared domestic hot water can, in particular, be measured or calculated, in particular based on directly measured values ​​or derived from values ​​measured in the drinking water stream or heating water stream.

[0041] In a preferred embodiment, a variable of the tempered drinking water flow is measured. At least in a subsection of the drinking water flow, the setpoint temperature used for domestic hot water preparation, in particular by the control unit, is reduced depending on the size of the drinking water flow. In particular, in said subsection of the drinking water flow, the setpoint temperature is progressively reduced as the size of the drinking water flow increases.

[0042] This ensures that the target temperature value used for domestic hot water preparation is only reduced by so much that the hybrid combination heater heats the domestic hot water stream with the greatest possible comfort, i.e. as close as possible to the standard target temperature value, even when the heat pump is operating in defrost mode.

[0043] In a further preferred embodiment, the target temperature value on which the domestic hot water preparation is based is determined, in particular taken or calculated, from a value table stored in the control unit or according to a formula stored in the control unit.

[0044] The invention also relates to a method for operating a hybrid heating system for controlling the temperature of a heating water flow and a drinking water flow. A heat generator and / or a heat pump heat exchanger connected in series with it in a heating water line control the temperature of the heating water flow. The heat pump heat exchanger is connected on the secondary side to a heat pump, in particular to a heat exchanger medium circuit, in particular to a refrigerant circuit, of a heat pump. The heating water flow flows into a heating water circuit or into a bypass arranged hydraulically parallel to the heating water circuit, in particular a switchable bypass with a drinking water heat exchanger. A switchable valve device directs the heating water flow into the heating water circuit or into the bypass, in particular depending on the switching position and / or depending on a heating heat demand and / or a domestic hot water demand.It is proposed that a control unit executes a method as described above.

[0045] The invention also relates to a hybrid combination heating device for controlling the temperature of a heating water flow and a drinking water flow, comprising a heat generator and a heat pump heat exchanger connected in series therewith in a heating water line of the heating device. The heat pump heat exchanger can be connected on the secondary side to a heat pump, in particular to a heat exchanger medium circuit, in particular a refrigerant circuit, of a heat pump. The heating water line has a flow section for connection to a flow line and a return section for connection to a return line of a heating water circuit (not included in the heating device). A bypass, in particular a switchable bypass, with a drinking water heat exchanger is arranged in the heating device between the flow section and the return section, in particular hydraulically parallel to the heating water circuit.A valve device arranged on the flow section or return section is configured and arranged to direct the heating water flow from the heating water line into the heating water circuit or into the bypass. Furthermore, the hybrid combination heater comprises a control unit configured to execute a method as described above.

[0046] In a preferred embodiment, the control unit is configured to detect a risk of icing on the heat pump heat exchanger and / or on another heat exchanger of the heat pump and to switch the valve device depending on a detected risk of icing so that the heating water flow flows through the bypass and the heat pump heat exchanger, wherein the heating water flow is in particular greater than or equal to a predeterminable minimum volume flow.

[0047] In a further preferred embodiment, the control unit is configured to detect the risk of icing based on a defrost signal indicating an impending, incipient, or ongoing operation of the heat pump in defrost mode. In particular, the control unit is configured to switch the bypass to allow the heating water flow to flow through it depending on the defrost signal.

[0048] A further preferred embodiment comprises a heat exchanger device having the heat pump heat exchanger, wherein the heat exchanger device has at least one first data interface for outputting a value of a heat exchanger parameter of the heat exchanger device. The control unit is configured to detect the risk of icing based on the value of the heat exchanger parameter. For example, the heat exchanger device has sensors on the heating circuit side and / or the secondary side. In particular, the control unit is configured to switch the bypass to flow with the heating water depending on a risk of icing of the heat pump heat exchanger detected by the sensors, in particular when a risk of icing exists.

[0049] A preferred embodiment comprises at least one temperature sensor on the heating water side for measuring a heating water temperature at the heat pump heat exchanger. The control unit is configured to detect the risk of icing based on the heating water temperature, particularly when the heating water temperature falls below a predeterminable first minimum value. In particular, the control unit is configured to switch the bypass to flow with the heating water depending on the heating water temperature, particularly when the heating water temperature falls below a predeterminable first minimum value.

[0050] A further preferred embodiment comprises at least one temperature sensor on the heating water side for determining a heating water temperature spread at the heat pump heat exchanger. The control unit is configured to detect the risk of icing based on the heating water temperature spread, in particular when a predeterminable maximum value of the heating water temperature spread is exceeded. In particular, the control unit is configured to switch the bypass to flow with the heating water depending on the heating water temperature spread, in particular when a predeterminable maximum value of the heating water temperature spread is exceeded.

[0051] A further preferred embodiment comprises at least one secondary-side or heat pump-side temperature sensor for measuring a temperature of the heat transfer medium, in particular the refrigerant, of the heat pump at the heat pump heat exchanger. The control unit is configured to detect the risk of icing based on the temperature of the heat transfer medium, in particular when the temperature of the heat transfer medium falls below a predeterminable second minimum value. In particular, the control unit is configured to switch the bypass to allow the heating water to flow through it depending on the temperature of the heat transfer medium, in particular when the temperature falls below a predeterminable second minimum value.

[0052] The heat pump heat exchanger has two connections for the heat transfer medium for fluidly connecting the heat pump heat exchanger to a heat transfer medium circuit, in particular the refrigerant circuit, of the heat pump.

[0053] A further preferred embodiment comprises a heating water pump for conveying the heating water flow in the heater, in particular in the heating water line, wherein the heating water pump has at least one second data interface for outputting a value of a pump parameter of the heating water pump. The control unit is configured to detect the risk of icing based on the value of the pump parameter, in particular when a predeterminable third minimum value of the pump parameter is undershot. In particular, the control unit is configured to switch the bypass to allow the heating water flow to flow through it depending on the value of the pump parameter, in particular when a predeterminable third minimum value of the pump parameter is undershot.

[0054] In a further preferred embodiment, the control unit is configured to put the heat generator into operation in a heating mode depending on a detected risk of icing, in particular when a risk of icing is detected.

[0055] The invention also relates to a hybrid heating system for tempering a drinking water flow and a building or part of a building with a heating water flow.

[0056] It is proposed that the hybrid heating system comprise a hybrid combination heater as described above and a heat pump, in particular a split heat pump, with an outdoor unit and an indoor unit. The indoor unit is integrated into the hybrid combination heater and includes the heat pump heat exchanger. In particular, the indoor unit is formed by the heat pump heat exchanger or a heat exchanger device comprising the heat pump heat exchanger. In particular, the heat exchanger device corresponds to the indoor unit. Because the indoor unit is integrated into the hybrid combination heater, only one device needs to be installed in an installation room, which is significantly more space-saving and much easier for the installer. drawing

[0057] Further embodiments and advantages will become apparent from the following description of the drawings. The drawings illustrate two exemplary embodiments of the invention. The drawings, the description, and the claims contain numerous features in combination. Those skilled in the art will also conveniently consider the features individually and combine them into useful further combinations. The following schematically show: Fig. 1 a hybrid heating system with a hybrid combination heater and an air heat pump, Fig. 2 line diagrams of two temperature functions for the target temperature value used for domestic hot water preparation in defrost mode of the heat pump.

[0058] Fig. 1 shows a hybrid heating system 100 with a hybrid combination heater 200, a heat pump 300, here an air heat pump 300, and a heating water circuit 400, in particular a building-side section of a heating water circuit 400.

[0059] The hybrid heating system 100 is designed to control the temperature of a heating water stream 1 and a drinking water stream 2. The hybrid heating system 100 comprises a hybrid combination heater 200 and a heat pump 300, here a split heat pump 300, with an outdoor unit 302 and an indoor unit 304. The indoor unit 304 is integrated into the hybrid combination heater 200 and includes the heat pump heat exchanger 202. The outdoor unit 302 and the indoor unit 304 are fluidly connected to one another by means of a refrigerant circuit 316 in which a refrigerant stream 4 can circulate.

[0060] The arrows in the figure indicate the flow directions of heating water, drinking water, heat exchanger medium / refrigerant and air respectively.

[0061] The outdoor unit 302 here comprises a fan 306 for conveying an outside air flow 3, a further heat exchanger 308 (here an air / refrigerant heat exchanger 308) for evaporating the refrigerant flow 4 in a heating mode of the heat pump 300, a compressor 310 for compressing and conveying the refrigerant flow 4, an expansion device 312 for expanding the refrigerant flow 4, and a further control unit 314 for controlling the operation of the outdoor unit 302 and for exchanging data with the control unit 204 of the hybrid combination heater 200.

[0062] The hybrid combination heater 200 is configured to control the temperature of the heating water stream 1 and the drinking water stream 2. In this exemplary embodiment, the hybrid combination heater 200 comprises a fuel-fired heat generator 206 and the heat pump heat exchanger 202, which is connected on the secondary side to the refrigerant circuit 316 of the heat pump 300. The heat generator 206 and the heat pump heat exchanger 202 are connected in series in a heating water line 208 of the heater 200. The heating water line 208 has a flow section 210 for connection to a flow line 402 and a return section 212 for connection to a return line 404 of a building-side section of a heating water circuit 400. In the hybrid combination heater 200, between the flow section 210 and the return section 212, a bypass 214 with a drinking water heat exchanger 216 for the heating water flow 1 to flow through is arranged.The bypass 214 is hydraulically arranged parallel to the heating water circuit 400. The heating water flow 1 is pumped by the heating water pump 218. The hybrid combination heater 200 further comprises a valve device 220, here a three-way switching valve 220, for directing the heating water flow 1 from the heating water line 208 into the building-side section of the heating water circuit 400 or into the bypass 214. In the present exemplary embodiment, the valve device 220 is arranged at the connection between the return section 212 and the bypass 214. The valve device 220 can alternatively also be arranged at the connection between the flow section 210 and the bypass 214.The control unit 204 is configured to detect a risk of icing at the heat pump heat exchanger 202 and / or at the additional heat exchanger 308 of the heat pump 300 and, depending on the detected risk of icing, to switch the valve device 220 such that the heating water flow 1 flows through the bypass 214 and the heat pump heat exchanger 202. In this case, the heating water flow 1 is, in particular, greater than or equal to a predeterminable minimum volume flow. This effectively prevents icing of at least the heat pump heat exchanger 202.

[0063] The control unit 204 can detect a risk of icing on the heat pump heat exchanger 202 and / or on the further heat exchanger 308 of the heat pump 300 based on a defrost signal, on a measurement of at least one heating water temperature, a refrigerant temperature or a refrigerant pressure on the heat pump heat exchanger 202 or on a value of a pump parameter of the heating water pump 218.

[0064] The control unit 204 can prevent icing on the heat pump heat exchanger 202 and / or on the further heat exchanger 308 by means of a sufficiently large heating water flow and / or by means of a sufficiently warm heating water flow through the heat pump heat exchanger 202.

[0065] Depending on a detected risk of icing on the heat pump heat exchanger 202, the control unit 204 can operate the heat generator 206 in a heating mode.

[0066] Fig. 2 shows line diagrams of two functions for the course of the domestic hot water temperature T during operation of the heat pump in defrost mode over the domestic hot water flow V tempered in the domestic hot water heat exchanger 216.

[0067] Here, an underlying initial situation will be considered in which a risk of icing is detected at the heat pump heat exchanger 202 and / or the valve device 220 switches to the second switching position depending on the detected risk of icing, in particular is already in the second switching position, so that the heating water flow 1 flows through the bypass 214 and the heat pump heat exchanger 202 for operation of the heat pump 300 in defrost mode. In this defrost mode, defrosting power in the form of heat is extracted from the heat pump heat exchanger 202 and supplied to the further heat exchanger 308 of the heat pump 300. This initial situation is then supplemented by domestic hot water preparation or domestic hot water tapping.

[0068] In this exemplary embodiment, a standard setpoint temperature value TSS underlying the domestic hot water preparation is constantly 55 °C above the domestic hot water flow V. In contrast, a current setpoint temperature value TSV underlying the domestic hot water preparation is variable.

[0069] With a simple temperature control T(TSS) according to the standard setpoint temperature value TSS, the hybrid combi heater 200 can maintain the domestic hot water temperature T (that is the actual temperature of the domestic hot water) at the standard setpoint temperature value TSS at low and medium domestic hot water flow V between approx. 2 litres per minute and approx. 8 litres per minute (compare the horizontal dashed line in Fig. 2). At a higher drinking water flow V above approximately 8 liters per minute, the heating capacity of the hybrid combination heater 200, in particular of the heat generator 206, is no longer sufficient to maintain this relatively high domestic hot water temperature of 55 °C in addition to providing the defrosting capacity; the domestic hot water temperature drops sharply in the relatively small drinking water flow interval between approximately 8 liters per minute and approximately 10 liters per minute (compare the sharply declining dashed line in Fig. 2).

[0070] With a more complex temperature control T(TSV) with a variable setpoint temperature TSV, the setpoint temperature is gradually reduced starting from a low to medium drinking water flow V of approximately 5 liters per minute, depending on the drinking water flow V. This avoids a sudden drop in temperature as with the simple control T(TSS). For example, the control T(TSV) of the hybrid combi heater 200 maintains the domestic hot water temperature T at the standard setpoint temperature TSS at a low drinking water flow V of between approximately 2 liters per minute and approximately 5 liters per minute (compare the horizontal solid line in Fig. 2). Above approximately 5 liters per minute, the variable setpoint temperature TSV is progressively lowered compared to the standard setpoint temperature TSS depending on the drinking water flow V. The domestic hot water temperature T(TSV) of the prepared domestic hot water follows this variable setpoint temperature TSV (compare the slowly decreasing solid line in Fig. 2). The user will either barely notice this slowly decreasing domestic hot water temperature T(TSV) or will find it significantly more pleasant than the temperature drop with the simple control T(TSS).

[0071] In the above explanation, a constant cold drinking water temperature (inlet temperature) is assumed. If this temperature changes, the limit flow rate up to which hot drinking water can be drawn at the standard setpoint temperature TSS also changes with the simple control system T(TSS). The more complex control system T(TSV) smooths and reduces the impact of this disturbance on the hot drinking water temperature T.

Claims

[1] Method for operating a hybrid combination heating device (200) for tempering a heating water flow (1) and a drinking water flow (2), • wherein a heat generator (206) and / or a heat pump heat exchanger (202) connected in series therewith in a heating water line (208) temper the heating water flow (1), wherein the heat pump heat exchanger (202) is connectable on the secondary side to a heat pump (300), • wherein the heating water flow (1) flows into a heating water circuit (400) or into a bypass (214) arranged hydraulically parallel to the heating water circuit (400) with a drinking water heat exchanger (216), • wherein a valve device (220) directs the heating water flow (1) into the heating water circuit (400) or into the bypass (214), characterized by that a control unit (204) • detects a risk of icing on the heat pump heat exchanger (202) and / or on another heat exchanger (308) of the heat pump (300) and • the valve device (220) switches depending on a detected risk of icing so that the heating water flow (1) flows through the bypass (214) and the heat pump heat exchanger (202), wherein the heating water flow (1) is in particular greater than or equal to a predeterminable minimum volume flow. [2] Method according to claim 1, wherein the control unit (204) detects the risk of icing based on a defrost signal relating to an impending, beginning or ongoing operation of the connectable heat pump (300) in defrost mode. [3] Method according to one of the preceding claims, wherein a heat exchanger device having the heat pump heat exchanger (202) outputs a signal or a value of a heat exchanger parameter of the heat exchanger device via at least one first data interface, wherein the control unit detects the risk of icing on the basis of the signal or the value of the heat exchanger parameter. [4] Method according to one of the preceding claims, wherein a heating water temperature is measured at the heat pump heat exchanger (202) by means of at least one heating water-side temperature sensor, wherein the control unit (204) detects the risk of icing on the basis of the heating water temperature, in particular when the heating water temperature falls below a predeterminable first minimum value. [5] Method according to one of the preceding claims, wherein a heating water temperature spread at the heat pump heat exchanger (202) is determined by means of at least one heating water side temperature sensor, wherein the control unit (204) detects the risk of icing on the basis of the heating water temperature spread, in particular when a predeterminable maximum value of the heating water temperature spread is exceeded. [6] Method according to one of the preceding claims, wherein a refrigerant temperature at the heat pump heat exchanger (202) is measured or determined by means of at least one secondary-side temperature sensor or pressure sensor, wherein the control unit (202) detects the risk of icing on the basis of the refrigerant temperature, in particular when the refrigerant temperature falls below a predeterminable second minimum value. [7] Method according to one of the preceding claims, wherein a heating water pump (218) conveys the heating water flow (1) in the hybrid combination heater (200), wherein the heating water pump outputs a value of a pump parameter via at least one second data interface, wherein the control unit detects the risk of icing on the basis of the value of the pump parameter, in particular when a predeterminable third minimum value of the pump parameter is undershot. [8] Method according to one of the preceding claims, wherein the control unit (204) operates the heat generator (206) in a heating mode depending on a detected risk of icing. [9] Method according to one of the preceding claims, wherein, when the valve device (220) switches in dependence on a detected risk of icing so that the heating water flow (1) flows through the bypass (214) and the heat pump heat exchanger (202) for operation of the heat pump (300) in defrost mode, and domestic hot water preparation begins, then a setpoint temperature value (TSV) on which the domestic hot water preparation is based is reduced compared to a standard setpoint temperature value (TSS), wherein a domestic hot water temperature (T) of the domestic hot water preparation is determined and approximated or adjusted to the setpoint temperature value (TSV). [10] Method according to claim 9, wherein a drinking water flow (2) is measured and the setpoint temperature value (TSV) on which the drinking water preparation is based is reduced as a function of the drinking water flow (2), in particular the setpoint temperature value (TSV) is progressively reduced with increasing drinking water flow (2). [11] Method according to claim 9 or 10, wherein the target temperature value (TSV) on which the domestic hot water preparation is based is determined from a value table stored in the control unit (204) or according to a formula stored in the control unit (204). [12] Method for operating a hybrid heating system (100) for tempering a heating water flow (1) and a drinking water flow (2), • wherein a heat generator (206) and / or a heat pump heat exchanger (202) connected in series therewith in a heating water line (208) temper the heating water flow (1), wherein the heat pump heat exchanger (202) is connected on the secondary side to a heat pump (300), • wherein the heating water flow (1) flows into a heating water circuit (400) or into a bypass (214) arranged hydraulically parallel to the heating water circuit (400) with a drinking water heat exchanger (216), • wherein a valve device (220) directs the heating water flow (1) into the heating water circuit (400) or into the bypass (214), characterized by that a control device (204) carries out a method according to one of the preceding claims. [13] Hybrid combination heater (200) for tempering a heating water stream (1) and a drinking water stream (2) • with a heat generator (206) and a heat pump heat exchanger (202) connected in series therewith in a heating water line (208) of the heating device (200), wherein the heat pump heat exchanger (202) can be connected on the secondary side to a heat pump (300), • wherein the heating water line (208) comprises a flow section (210) for connection to a flow line (402) and a return section (212) for connection to a return line (404) of a heating water circuit (400), wherein in the heating device (200) between the flow section (210) and the return section (212) a bypass (214) with a drinking water heat exchanger (216) for flowing through with the heating water flow (1) is arranged, • with a valve device (220) for directing the heating water flow (1) into the heating water circuit (400) or into the bypass (214), and • with a control unit (204), characterized bythat the control device (204) is configured to carry out a method according to one of claims 1 to 11. [14] Hybrid heating system (100) for tempering a heating water flow (1) and a drinking water flow (2) • with a hybrid combination heater (200) according to claim 13 and • with a heat pump (300), in particular a split heat pump (300), with an outdoor unit (302) and an indoor unit (304), • wherein the indoor unit (304) is integrated in the hybrid combination heater (200) and comprises the heat pump heat exchanger (202), in particular is formed by the heat pump heat exchanger (202) or a heat exchanger device comprising the heat pump heat exchanger (202).

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