An arrangement for domestic heating and a method for controlling an arrangement

Abstract

An arrangement (100) comprising a heat pump (130); a buffer tank (140), a switchable conduit system (150) configured to fluidly connect the heat pump (130) to a radiator circuit (160) or to the buffer tank (140), a tap water heat exchange circuit (170) comprising a circulation pump (172), one or more first sensors (240, 250, 260) configured to obtain first data; one or more second sensors (210, 220, 230) configured to obtain second data; and one or more control units (190) configured to execute, when the heat pump (130) is fluidly connected to the radiator circuit (160): a determination function configured to determine a data relationship between the first data and the second data; and a comparison function configured to compare the data relationship with a comparison criterion, and upon the comparison not fulfilling the comparison criterion: control the circulation pump (172) such that the temperature of the heat buffer fluid within the second portion (140b) is decreased. The disclosure further relates to a method (500) for controlling an arrangement (100).

Description

[0001] AN ARRANGEMENT FOR DOMESTIC HEATING AND A METHOD FOR CONTROLLING AN ARRANGEMENT

[0002] Technical field

[0003] The present disclosure relates to an arrangement for domestic heating. The present disclosure further relates to a method for controlling an arrangement.

[0004] Background art

[0005] Nearly all large, developed cities in the world have at least two types of energy grids incorporated in their infrastructures; one grid for providing electrical energy and one grid for providing space heating and hot tap water preparation. Today a common grid used for providing space heating and hot tap water preparation is a gas grid providing a burnable gas, typically a fossil fuel gas. The gas provided by the gas grid is locally burned for providing space heating and hot tap water. In order to reduce the carbon dioxide emissions there are plans to replace such gas grid with more “green” energy efficient energy systems.

[0006] One such energy efficient energy system is cold thermal grids. Cold thermal grids are an evolution of district heating and district cooling systems, where combined district heating and district cooling system with aid of using heat pumps for heating and cooling can provide both cooling, heating and tap water preparation to buildings.

[0007] In order to succeed with the replacement of gas grids, where the respective gas burner is replaced by a heat pump, the heat pumps used need to be smaller, less costly, easier to control and with lower technical complexity, e.g., with fewer and / or less complex sensors for measuring the space heat and tap water energy consumption than presently used heat pumps.

[0008] Thus, the conventional heating and / or cooling systems are associated with several drawbacks. There is thus a need in the art for an improvement in this area. Summary

[0009] It is an object to mitigate, alleviate or eliminate one or more of the above-identified deficiencies in the art and disadvantages singly or in any combination and solve at least the above mentioned problem.

[0010] It is an object of the disclosure to provide an efficient arrangement for domestic heating.

[0011] Another object of the disclosure is to provide a flexible arrangement for domestic heating.

[0012] Another object of the disclosure is to provide time-efficient arrangement for domestic heating.

[0013] Another object of the disclosure is to provide a cost-efficient arrangement for domestic heating.

[0014] It is also an object to provide an efficient and flexible method for controlling an apparatus.

[0015] According to a first aspect, there is provided an arrangement for domestic heating comprising: a heat pump; a buffer tank configured to store a heat buffer fluid, and having a first portion and a second portion, wherein the first portion and the second portion are spaced from each other within the buffer tank; a switchable conduit system configured to fluidly connect the heat pump to a radiator circuit while preventing fluid communication with the buffer tank, or to fluidly connect the heat pump to the buffer tank while preventing fluid communication with the radiator circuit, wherein fluid exiting the heat pump is provided to the first portion of the buffer tank and fluid entering into the heat pump is retrieved from the second portion of the buffer tank; a tap water heat exchange circuit comprising a heat exchanger and a circulation pump, said tap water heat exchange circuit being arranged to retrieve heat buffer fluid from the first portion of the buffer tank to a first side of the heat exchanger and to return the retrieved heat buffer fluid to the second portion of the buffer tank, wherein a second side of the heat exchanger is arranged to be connected to a tap water circuit; one or more first sensors being configured to obtain first data which pertains at least to a heat pump inlet fluid temperature of fluid entering the heat pump from the switchable conduit system; one or more second sensors being configured to obtain second data which pertains at least to a heat buffer fluid temperature of heat buffer fluid within the second portion of the buffer tank; and one or more control units configured to execute, when the heat pump is fluidly connected to the radiator circuit: a determination function configured to determine a data relationship between the first data and the second data; and a comparison function configured to compare the data relationship with a comparison criterion, and upon the comparison not fulfilling the comparison criterion: control the circulation pump such that the temperature of the heat buffer fluid within the second portion of the buffer tank is decreased. The heat pump may be introduced in a housing or a zone, e.g., in a controlled space of a building. The arrangement may be configured to cover, i.e. , being able to heat and / or provide tap water to, an area. The area may be the whole, or a part of, the building. The arrangement may be configured to provide heating and / or tap water to the building, or a part of the building. The heat pump may comprise a refrigerant circulation path which includes a first heat exchanger unit, a compressor, a second heat exchanger unit and an expander which may be connected to one another in a sequence. In this context, the arrangement is arranged as both a radiator system (for floor heating and / or radiators) and a tap water system depending on if the heat pump is fluidly connected to the radiator circuit or to the buffer tank.

[0016] The temperature of the fluid retrieved from the switchable conduit system to the heat pump (i.e., the temperature of the fluid entering the heat pump from the switchable circuit system) may depend on the type of heating system, i.e., if the radiator circuit or the tap water circuit that is operating. Thus, the temperature of the fluid retrieved from the switchable conduit system may vary depending on the type of heating system. By way of example, the data relationship may be a difference between the first data and the second data, and the comparison criterion may be a maximum tolerable difference between the first data and the second data. This implies that the comparison criterion may be fulfilled if the data relationship exceeds the comparison criterion. Alternatively, the data relationship may be a ratio between the first data and the second data, and the comparison criterion may be a minimum (or maximum) tolerable ratio between the first data and the second data. This implies that the comparison criterion may be fulfilled if the data relationship exceeds (or falls below) the comparison criterion. As readily appreciated by the person skilled in the art, there are many alternative conceivable data relationships and comparison criterions which may be used within the scope of the claims.

[0017] Depending on which heating system the heat pump is fluidly connected to, i.e. , the current use of hot tap water or the radiator circuit, there may be scenarios where the temperature of the fluid retrieved from the switchable conduit system may be too high for the heat pump to work in an efficient way, i.e., if the comparison between the data relationship and the comparison criterion does not fulfill the comparison criterion. This may occur if a user activates the tap water circuit, i.e., starts using tap water, when the heat pump is fluidly connected to the radiator circuit. In this case, the data relationship may not fulfill the comparison criterion and the circulation pump may be controlled as introduced above. In this scenario, if the heat pump may switch to be fluidly connected to the buffer tank in order to generate heat to the buffer tank, this may give risk for temperature reduction in the compressor of the heat pump and heat gas which may be present in the refrigerant circulation path may become fluid. This may further cause the heat pump to start operating backwards. The disclosed arrangement is advantageous as it allows for avoiding the heat pump to go backwards by being able to control the temperature of the heat buffer fluid before being supplied to the heat pump, i.e., before the heat pump switch to be fluidly connected to the buffer tank. The disclosed arrangement is further advantageous as it allows for controlling the circulation pump such that the temperature of the heat buffer fluid in the second portion of the buffer tank is decreased before being supplied to the heat pump. As long as the comparison criterion is not fulfilled, the heat pump is fluidly connected to the radiator circuit and the heat pump is arranged to generate heat to the radiator circuit although the tap water circuit has been activated by a user. This is advantageous as it allows for an efficient heat pump as well as a reduced risk of destroying the compressor comprised in the heat pump.

[0018] This is further advantageous as the need of adding more complex solutions to the technical problem, such as the provision of a compressor heater in the heat pump, which is a solution known in the art, is avoided. Thus, the complexity of the arrangement is reduced compared to conventional solutions. This is yet further advantageous as it avoids restricting direct access to hot tap water thus improving the “Quality of Service” for a user, i.e. the user will be able to get a lot of hot tap water quickly.

[0019] In this context, the first and second portions of the buffer tank may be referred to first and second sub-volume of the buffer tank which are spaced from each other. It should be noted that the first and second portions are portions of the same volume of the buffer tank, but the heat buffer fluid comprised in the different portions may have different properties, e.g., different temperature, different density, or the like. It is conceivable that the spaced apart first and second portions are upheld by their mere distance from each other. For example, a buffer tank having a relatively long elongated extension in the horizontal dimension could have a first portion in the first end of the elongated extension and a second portion at the second end of the elongated extension. However, preferably the first and second portions are upheld by natural layering as will be detailed later. It should be noted that the smaller the property differences may be, the less distinct may the layering be.

[0020] By the term “fluidly connect” is here meant that the switchable conduit system is configured to connect the heat pump to the radiator circuit or to the buffer tank such that a fluid communication between the heat pump and the radiator circuit or the buffer tank is formed. It should be noted that the switchable conduit system may at all-time be physically connected to both the radiator circuit and the buffer tank but may only be fluidly connected, i.e., has fluid communication with, one of the radiator circuit and the buffer tank. Thereby, the heat pump may be arranged to supply heat pump fluid from the heat pump, i.e. , fluid exiting the heat pump, to either the radiator circuit or to the buffer tank. Preferably, the arrangement comprises one or more valves arranged to direct the heat pump fluid to either the radiator circuit or the buffer tank. When the heat pump is fluidly connected to the radiator system, the arrangement is arranged to transfer heat to radiator systems within buildings or the like. When the heat pump is fluidly connected to the radiator circuit, fluid exiting the heat pump may be provided to an inlet port of the radiator circuit and fluid entering into the heat pump from the radiator circuit may be retrieved from an outlet port of the radiator circuit. When the heat pump is fluidly connected to the buffer tank, the arrangement is arranged to transfer heat to the buffer tank which in turn may transfer heat to the tap water circuit. Thus, the arrangement is arranged to transfer heat to either the radiator circuit or to the tap water circuit. When the heat pump is fluidly connected to the buffer tank, fluid exiting the heat pump is provided to the first portion of the buffer tank and fluid entering into the heat pump from the buffer tank is retrieved from the second portion of the buffer tank. Preferably, the fluid exiting the heat pump into the first portion may have different properties than the fluid entering into the heat pump from the second portion because of the arrangement of the buffer tank which comprises the first and second portions as discussed above.

[0021] In this context, the circulation pump may be arranged either downstream or upstream the heat exchanger such that a circulation path may be formed between the first portion of the buffer tank, the heat exchanger, the circulation pump and the second portion of the buffer tank. The heat exchanger may comprise a first side inlet, a first side outlet, a second side inlet and a second side outlet. The first side inlet may be arranged to receive heat buffer fluid from the first portion of the buffer tank. The second side inlet may be configured to receive return tap water from the tap water circuit. In the heat exchanger, the heat buffer fluid from the first portion and the return tap water from the tap water circuit are configured to exchange thermal energy between each other such that a temperature of the return tap water may be increased, and a temperature of the heat buffer fluid may be decreased. Thereafter, the heat buffer fluid may be supplied to the buffer tank via the first side outlet and the return tap water may be supplied to the tap water circuit via the second side outlet. The circulation pump may be arranged to control a flow of the heat buffer fluid which is supplied in the tap water heat exchanger circuit.

[0022] The term “obtain first data” is here meant that the one or more first sensors are configured to transmit the first data which pertains at least to the heat pump inlet fluid temperature of the fluid entering the heat pump. The term “obtain second data” is here meant that the one or more second sensors are configured to transmit the second data which pertains at least to the heat buffer fluid of the fluid within the second portion of the buffer tank. The first and second data may be transmitted from the respective sensor to a secondary device which may be able to convert the data such that the data may be usable by the control unit. It is also conceivable that the control unit receives the first and second data directly from the sensors and, if a conversion is required, performs the conversion on its own.

[0023] In this context, the first data may pertain to at least the heat pump inlet fluid temperature of the fluid entering the heat pump from the radiator circuit or of the fluid entering the heat pump from the second portion of the buffer tank. If the heat pump is fluidly connected to the radiator circuit, the first data pertains at least to the temperature of the fluid entering the heat pump from the radiator circuit. If the heat pump is fluidly connected to the second portion of the buffer tank, the first data pertains at least to the temperature of the fluid entering the heat pump from the second portion of the buffer tank. In this context, the second data pertains to at least the heat buffer fluid temperature of the heat buffer fluid in the second portion of the buffer tank.

[0024] By the term “one or more control units” is here meant that the control unit(s) may be configured to execute the determination function and / or the comparison function together. Preferably, the arrangement comprises one control unit which is configured to execute the determination function and the comparison function. By the term “control unit” is here meant any device or unit configured to control an operation of the arrangement. Each control unit may be e.g., a microprocessor or a central processing unit, CPU. The control unit may be configured to control the power and enablement of the arrangement. The control unit is preferably configured to control the circulation pump as introduced above. The control unit may be wired or wirelessly connected to the one or more first sensors and / or the one or more second sensors. The control unit may be wired or wirelessly connected to the circulation pump.

[0025] The control unit may be configured to receive the first data. The control unit may be configured to receive the second data. The control unit may be configured to store the first data. The control unit may be configured to store the second data. The control unit may be configured to receive the comparison criterion. The control unit may be configured to store the comparison criterion. The control unit may be configured to execute a comparison criterion determination function configured to determine the comparison criterion based on current heat pump operation point in terms of temperatures or pressures in the heat pump.

[0026] The control unit may be configured to receive data on a regular basis, i.e. , every second or millisecond, such that the control unit has access to latest data obtained by the sensors of the arrangement.

[0027] The determination function is advantageous as it enables the data relationship between the first data and the second data to be determined in a way such that it may be able to be compared with the comparison criterion.

[0028] The comparison function is advantageous as it enables the comparison between the relationship data and the comparison criterion to be performed. In this context, the comparison criterion may pertain to a maximum data tolerance between the first data and the second data that may be tolerated by the heat pump. The comparison criterion may be a maximum temperature tolerance between the heat pump inlet fluid temperature and the heat buffer fluid within the second portion of the buffer tank. The comparison criterion may be in the range of + / -20 degrees Celsius of the data relationship, preferably in the range of + / -15 degrees Celsius of the data relationship, more preferably + / -10 degrees Celsius of the data relationship and even more preferably +Z-5 degrees Celsius of the data relationship. Thus, upon the first data comprises a heat pump inlet fluid temperature of X degrees, the comparison criterion may be fulfilled if the second data comprises a heat buffer fluid of + / -20 degrees Celsius of the data relationship. By way of examples, in the easiest performance, the comparison criterion may be based on the heat pump inlet fluid temperature of the fluid entering the heat pump and the data relationship may be the difference in temperature between the heat pump inlet fluid temperature and the heat buffer fluid within the second portion of the buffer tank. Thereby, the comparison criterion may be in the range of + / -20 degrees Celsius of the heat pump inlet fluid temperature, i.e. , if the heat pump inlet fluid temperature is 20 degrees Celsius, the comparison criterion is fulfilled if the data relationship is in the range of 0 to 40 degrees Celsius.

[0029] The arrangement is advantageous as it allows to, when the comparison between the data relationship and the comparison criterion does not fulfill the comparison criterion, control the circulation pump such that the heat buffer fluid temperature in the second portion of the buffer tank is decreased. This is advantageous as it preferably decreases the data tolerance between the first data and the second data in order to be lower than the maximum data tolerance between the first and second data tolerated by the heat pump.

[0030] As readily appreciated by the person skilled in the art, controlling the circulation pump such that the heat buffer fluid temperature in the second portion of the buffer tank is decreased may be achieved by adjusting the flow speed of the pump. This is because the water which is returned to the buffer tank in the second portion while heat exchanging to the tap water will be considerably colder than the initial water temperature in the second portion. If the comparison criterion is not fulfilled, the circulation pump may be configured to decrease the flow such that the fluid supplied in the tap water heat exchanger circuit may be supplied with a lower flow speed such that the heat exchanger may be configured to transfer more thermal energy from the heat buffer fluid to the return tap water such that the fluid leaving the first side outlet to the circulation pump, and thereafter to the buffer tank, has a decreased temperature to fulfill the criterion. Once the criterion is fulfilled, the circulation pump may be configured to increase the flow rate again, preferably to a flow rate for optimal operation of the heat exchanger.

[0031] It should be noted that as long as the comparison criterion is not fulfilled, the heat pump is fluidly connected to the radiator circuit and the circulation pump being controlled to decrease the second data. This is advantageous as the heat pump is prevented from retrieving fluid having a temperature which is above a tolerance of the heat pump.

[0032] The control unit may be configured to, upon the comparison fulfilling the comparison criterion, switch the switchable conduit system to fluidly connect the heat pump to the buffer tank while preventing fluid communication with the radiator circuit.

[0033] This is advantageous as it allows for the heat pump to be fluidly connected to the buffer tank when the comparison criterion is fulfilled. This is further advantageous as it allows for fluidly connecting the heat pump and the buffer tank when the relationship data between the first data and the second data is within a range which is tolerated by the heat pump. The heat pump is capable of retrieving the heat buffer fluid as provided by the second portion of the buffer tank. This is further advantageous as it allows for the heat pump to be an efficient heat pump, operating in an efficient way.

[0034] At least one of the one or more first sensors may be comprised in the heat pump.

[0035] This is advantageous as it allows to obtain the first data pertaining to at least the heat pump inlet fluid temperature in an easy and accurate way.

[0036] The one or more first sensors should be interpreted broadly to encompass any sensors capable of providing the first data pertaining to the heat pump inlet fluid temperature of the fluid entering the heat pump. The one or more first sensors may be in physical contact with the fluid, such as a thermometer, thermocouple, thermistor etc. However, the one or more first sensors may alternatively be based on remote sensing, such as e.g., spectrally resolved IR imaging or the like. Irrespective of which technique is chosen, the first data will relate to the temperature of the heat pump inlet fluid and thereby be useful to be part of determining the data relationship with the second data in the first aspect of the disclosure. It should be noted that other sensors capable of providing temperature-based data may be used as well.

[0037] The at least one of the one or more first sensors may be arranged at an inlet conduit / pipe through which said fluid from the switchable conduit system enters the heat pump. Another sensor of the one or more first sensors may be arranged in the refrigerant circulation path, downstream the second heat exchanger. Another sensor of the one or more first sensors may be arranged in the refrigerant circulation path, upstream the second heat exchanger. This implies that the first data may be based on sensor data from only one first sensor. The first data may alternatively be based on sensor data from more than one first sensor. For the latter alternative, the sensor data may pertain to more than one temperature. Upon that is the case, the first data may be a function of a plurality of first sub data, wherein each first sub data pertains to a specific temperature of the heat pump. By providing two or more first sensors to provide the first data, the arrangement will be more redundant. If one of the sensors malfunctions, or starts to deviate from its specified behavior, it may still be possible to operate the arrangement without putting the heat pump in an increased risk of being exposed to intolerably high temperature shifts.

[0038] At least one of the one or more second sensors may be comprised in the buffer tank.

[0039] This is advantageous as it allows to obtain second data pertaining to at least the heat buffer temperature in an easy and accurate way.

[0040] The one or more second sensors should be interpreted broadly to encompass any sensors capable of providing the second data pertaining at least to the heat buffer fluid temperature of heat buffer fluid within the second portion of the buffer tank. The one or more second sensors may be in physical contact with the fluid, such as a thermometer, thermocouple, thermistor etc. However, the one or more second sensors may alternatively be based on remote sensing, such as e.g., spectrally resolved IR imaging or the like. Irrespective of which technique is chosen, the second data will relate to the temperature of the heat buffer fluid and thereby be useful to be part of determining the data relationship with the first data in the first aspect of the disclosure. It should be noted that other sensors capable of providing temperature-based data may be used as well.

[0041] The at least one of the one or more second sensors may be arranged at an inlet through which heat buffer fluid having passed the first side of the heat exchanger is returned to the second portion of the buffer tank. Alternatively, the at least one of the one or more second sensors may be arranged within the buffer tank. The at least one of the one or more second sensors may be arranged within the second portion of the buffer tank.

[0042] The one or more second sensors may further comprise a sensor configured to determine tap water data which pertains to an outgoing hot tap water temperature of tap water leaving the second side of the heat exchanger and / or a sensor configured to determine a temperature of heat buffer fluid leaving the first side of the heat exchanger.

[0043] The one or more second sensors may additionally or alternatively comprise a sensor configured to determine tap water data which pertains to an ingoing hot tap water temperature of tap water entering the second side of the heat exchanger. The one or more second sensors may additionally or alternatively comprise a sensor configured to determine a temperature of heat buffer fluid entering the first side of the heat exchanger. A sensor of the one or more second sensors may be arranged in the circulation pump. If the arrangement comprises more than one second sensor, the second data may be a function of a plurality of second sub data, wherein each second sub data pertains to a specific temperature as previously introduced. By providing two or more second sensors to provide the second data, the arrangement will be more redundant. If one of the sensors malfunctions, or starts to deviate from its specified behavior, it may still be possible to operate the arrangement without putting the heat pump in an increased risk of being exposed to intolerably high temperature shifts.

[0044] The first portion may be defined in an uppermost part of the buffer tank and the second portion is defined in a lowermost part of the buffer tank.

[0045] This arrangement may depend on the properties as introduced and discussed above. If the arrangement is configured to transfer heat to the tap water circuit, and if the heat pump is fluidly connected to the buffer tank, the heat buffer fluid within the first portion may have a temperature between 55- 75 degree Celsius and the heat buffer fluid within the second portion may have a temperature between 10-50 degree Celsius. Since the water density varies with temperature, a natural layering will occur in the vertical direction of the buffer tank. By providing the high-temperature water at the upper part (i.e. providing the first portion at the uppermost part of the tank) and providing the low-temperature water to the lower part (i.e. providing the second portion at the lowermost part of the tank) the natural layering will strive to maintain the separation between the first and second portions also over time. This is advantageous as it may ensure that the warmer heat buffer fluid, provided in the first portion, will be supplied to the heat exchanger (which is connected to the first portion) and that the cooler heat buffer fluid, provided in the second portion, will be supplied to the heat pump (which may be connected to the second portion).

[0046] The arrangement may be a modular arrangement and may comprise a plurality of heat pump modules wherein one of the heat pump modules comprises said heat pump. By the term “modular arrangement” is here meant an arrangement which comprises a plurality of heat pump modules which are separate from and independently of each other. Thus, the plurality of heat pump modules may be introduced in a housing or a zone, e.g., in a controlled space in which the plurality of heat pump modules is arranged, without the need of being attached, e.g., fastened, or mounted, to each other. The arrangement may be configured to cover, i.e., being able to heat and / or provide tap water to, an area. The area may be the whole, or a part of, the building. Each heat pump module of the plurality of heat pump modules may be detachable from its position in the arrangement. The term “detachable” is here meant that at least one heat pump module of the plurality of heat pump modules are removably arranged in the arrangement. Put differently, at least one heat pump module of the plurality of heat pump modules is arranged in the arrangement in a way such that it is possible to remove and / or replace the heat pump module.

[0047] This is advantageous as it allows to use the arrangement as a scalable solution which may also be applied to a modular arrangement. If the arrangement is the modular arrangement, the first data may pertain to at least the heat pump inlet fluid temperature of the fluid entering the heat pump module which comprises said heat pump. In other modular embodiments comprising a plurality of heat pump modules, the arrangement comprises one or more first sensors for each heat pump module of the plurality of heat pump modules, said one or more first sensors being configured to obtain first data which pertains at least to a heat pump inlet fluid temperature of fluid entering the associated heat pump module from the switchable conduit system. The one or more control units may further be configured to execute the determination function to determine a data relationship between the first data of each heat pump module and the second data. Thus, a plurality of data relationships will be obtained, one for each heat pump module. The comparison function may then be configured to compare the data relationship of each heat pump module with the comparison criterion. Each heat pump module may have an associated comparison criterion, wherein the comparison criterion pertains to a maximum data tolerance between the first data and the second data that may be tolerated by that heat pump module. The comparison criterion which pertains to lowest maximum data tolerance which may be tolerated by a heat pump module of the arrangement may be defined as a common comparison criterion for the arrangement. Thus, the heat pump module having the lowest maximum data tolerance may determine the comparison criterion for the whole arrangement. The comparison criterion may thus be determined individually for each heat pump module. Thus, different heat pump modules may be associated with different comparison criterions. However, the arrangement may only be associated with one common comparison criterion. In some embodiments, the controlling of the circulation pump such that the temperature of the heat buffer fluid within the second portion of the buffer tank is decreased will be performed upon determining that at least one comparison of said plurality of comparisons is not fulfilling the comparison criterion associated with that heat pump module. For other embodiments, the controlling of the circulation pump such that the temperature of the heat buffer fluid within the second portion of the buffer tank is decreased will be performed upon determining that each comparison of said plurality of comparisons is not fulfilling the comparison criterion associated with that heat pump module.

[0048] This is advantageous as it allows for a flexible arrangement to be provided in which the plurality of heat pump modules may be operated in an efficient way.

[0049] The determination function may be configured to determine the data relationship based on a difference between first data and the second data.

[0050] This is advantageous as it allows for an easy and efficient way of determining the data relationship. If the arrangement comprises more than one first sensor and more than one second sensor, the difference may be determined between each data point of a function of data points.

[0051] The determination function may be configured to determine the data relationship based on a ratio between first data and the second data.

[0052] This is advantageous as it allows for an alternative way of determining the data relationship compared to determining a difference between the first and second data. If the arrangement comprises more than one first sensor and more than one second sensor, the ratio may be determined between each data point of a function of data points.

[0053] The determination function may be configured to determine the data relationship based on both the difference between the first and second data and the ratio between the first and second data. This may provide for determining the data relationship in an accurate way.

[0054] It should be understood that the above are examples only, and that any determination function which is capable of providing a data relationship between the first data and the second data is equally applicable for the arrangement of the present disclosure.

[0055] The one or more control units may be further configured to retrieve heat pump characteristics from the heat pump and determine the comparison criterion based at least on said heat pump characteristics.

[0056] By “heat pump characteristics” are herein meant properties of the heat pump in general, such as the type and operating range of the compressor, evaporator, refrigerant, pipe dimensions, etc. It is conceivable that different heat pumps have different tolerance for a shift in inlet fluid temperature, and therefore should be associated with different comparison criterions. Some heat pumps may operate without problem for a temperature increase of 20 degrees, while other heat pumps may not.

[0057] If the arrangement is a modular arrangement which comprises a plurality of heat pump modules, each heat pump of the plurality of heat pump module may have an individual comparison criterion, i.e. , each heat pump may have an individual maximum data tolerance in order to operate in an efficient way.

[0058] The comparison criterion may be based on the heat pump characteristics and the first data. For example, the comparison criteria may be a function of heat pump characteristics and the inlet temperature of the heat pump. This is advantageous as it allows for an accurate comparison criterion and thereby also an accurate comparison to be performed.

[0059] The heat pump characteristics may include data pertaining to one or more from the list of: the compressor type, the compressor construction, refrigerant properties, a refrigerant temperature, a refrigerant pressure, and the heat pump inlet fluid temperature.

[0060] According to a second aspect of the disclosure, these and other objects are also achieved in full or at least in part, by a method for controlling an arrangement which comprises: a heat pump; a buffer tank configured to store a heat buffer fluid, and having a first portion and a second portion, wherein the first portion and the second portion are spaced from each other within the buffer tank; a switchable conduit system configured to fluidly connect the heat pump to a radiator circuit while preventing fluid communication with the buffer tank, or to fluidly connect the heat pump to the buffer tank while preventing fluid communication with the radiator circuit, wherein fluid exiting the heat pump are provided to the first portion of the buffer tank and fluid entering into the heat pump is retrieved from the second portion of the buffer tank; a tap water heat exchange circuit comprising a heat exchanger and a circulation pump, said tap water heat exchange circuit being arranged to retrieve heat buffer fluid from the first portion of the buffer tank to a first side of the heat exchanger and to return the retrieved heat buffer fluid to the second portion of the buffer tank, wherein the second side of the heat exchanger is arranged to be connected to a tap water circuit; the method comprising: receiving, from one or more first sensors of the arrangement, first data which pertains at least to a first temperature of a fluid entering a heat pump from a switchable conduit system; receiving, from one or more second sensors of the arrangement, second data which pertains at least to a second temperature of heat buffer fluid within a second portion of a buffer tank; determining a data relationship between the first data and the second data; and comparing the data relationship to a comparison criterion; wherein, upon the comparison does not fulfill the comparison criterion, controlling the circulation pump such that the temperature of the heat buffer fluid within the second portion is decreased.

[0061] Upon the comparison may fulfill the comparison criterion, the method may further comprise switching the switchable conduit system to fluidly connect the heat pump to the buffer tank while preventing fluid communication with the radiator circuit.

[0062] The step of determining a data relationship between the first data and the second data may comprise determining a difference between the first data and the second data.

[0063] The step of determining a data relationship between the first data and the second data may comprise determining a ratio between the first data and the second data.

[0064] The method may further comprise controlling the arrangement, wherein the arrangement is a modular arrangement and comprises a plurality of heat pump modules wherein one of the plurality of heat pump modules comprises said heat pump. The method may comprise controlling a modular arrangement which comprises a plurality of heat pump modules. The method may further comprise determining the comparison criterion based on at least heat pump characteristics. By “heat pump characteristics” is herein meant properties of the heat pump in general, such as the type and operating range of the compressor, evaporator, refrigerant, pipe dimensions, etc. It is conceivable that different heat pumps have different tolerance for a shift in inlet fluid temperature, and therefore should be associated with different comparison criterions. Some heat pumps may operate without problem for a temperature increase of 20 degrees, while other heat pumps may not.

[0065] Effects and features of the second aspect are largely analogous to those described above in connection with the first aspect. Embodiments mentioned in relation to the first aspect are largely compatible with the second aspect. It is further noted that the inventive concepts relate to all possible combinations of features unless explicitly stated otherwise. A further scope of applicability of the present invention will become apparent from the detailed description given below. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the scope of the invention will become apparent to those skilled in the art from this detailed description.

[0066] Hence, it is to be understood that this invention is not limited to the particular component parts of the device described or steps of the methods described as such device and method may vary. It is also to be understood that the terminology used herein is for purpose of describing particular embodiments only and is not intended to be limiting. It must be noted that, as used in the specification and the appended claim, the articles "a", "an", "the", and "said" are intended to mean that there are one or more of the elements unless the context clearly dictates otherwise. Thus, for example, reference to "a unit" or "the unit" may include several devices, and the like. Furthermore, the words "comprising", "including", "containing" and similar wordings does not exclude other elements or steps.

[0067] The disclosure may also in short be said to relate to an arrangement comprising a heat pump; a buffer tank, a switchable conduit system configured to fluidly connect the heat pump to a radiator circuit or to the buffer tank, a tap water heat exchange circuit comprising a circulation pump, one or more first sensors configured to obtain first data; one or more second sensors configured to obtain second data; and one or more control units configured to execute, when the heat pump is fluidly connected to the radiator circuit: a determination function configured to determine a data relationship between the first data and the second data; and a comparison function configured to compare the data relationship with a comparison criterion, and upon the comparison not fulfilling the comparison criterion: control the circulation pump such that the temperature of the heat buffer fluid within the second portion is decreased.

[0068] Brief description of the drawings

[0069] The disclosure will by way of example be described in more detail with reference to the appended schematic drawings, which shows a presently preferred embodiment of the invention.

[0070] Figure 1 illustrates an arrangement for domestic heating.

[0071] Figure 2 illustrates a modular arrangement for domestic heating.

[0072] Figure 3 illustrates the arrangement as depicted in figure 1 in a simplified manner in which a heat pump is fluidly connected to a radiator circuit.

[0073] Figure 4 illustrates the arrangement as depicted in figure 1 in a simplified manner in which a heat pump is fluidly connected to a buffer tank.

[0074] Figure 5 is a flowchart illustrating a method for controlling an arrangement.

[0075] Detailed description

[0076] The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which currently preferred embodiments of the invention are shown. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided for thoroughness and completeness, and to fully convey the scope of the invention to the skilled addressee. Like reference characters refer to like elements throughout.

[0077] With reference to figure 1 , an arrangement 100 for domestic heating is illustrated by way of example. The arrangement 100 comprises a heat pump 130, a buffer tank 140, a switchable conduit system 150 and a tap water heat exchanger circuit 170. The arrangement 100 is configured to transfer heat to a radiator circuit 160 or to a tap water circuit 180. The arrangement 100 is using the same heat pump 130 for the radiator circuit 160 (i.e. , floor heating / radiator systems) and for generating hot tap water to the tap water circuit 180.

[0078] The heat pump 130 comprises first inlet and outlet ports 131 a, 131 b and second inlet and outlet ports 132a, 132b. The first inlet and outlet ports 131a, 131 b are connected to a cold fluid grid 111. The heat pump 130 is connected to a cold fluid side 101 via the cold fluid grid 111. The cold fluid grid 111 is configured to supply a cold fluid from the cold fluid side 101 to the arrangement 100, and especially to the heat pump 130. The cold fluid grid 111 is further configured to return the cold fluid from the arrangement 100, or especially from the heat pump 130, to the cold fluid side 101 . The fluid may be colder when being returned to the cold fluid side 101 than when being supplied from the cold fluid side 101 . The cold fluid side 101 may be an evolution of district heating and cooling system with aid of using heat pumps for heating and cooling and may provide both heating and tap water preparations to buildings. The cold fluid side 101 may be coupled to a downhole heat exchanger, or borehole heat exchanger.

[0079] The second inlet and outlet ports 132a, 132b are connected to a hot fluid grid 112. The heat pump 130 is physically connected to the radiator circuit 160 and the buffer tank 140 via the hot fluid grid 112. The switchable conduit system 150 is configured to fluidly connect the heat pump 130 to the radiator circuit 160 (as illustrated in figure 3) or to fluidly connect the heat pump 130 to the buffer tank 140 (as illustrated in figure 4). Thus, it should be noted that the heat pump 130 is physically connected to the radiator circuit 160 and the buffer tank 140 at the same time. It should however be noted that the heat pump 130 is fluidly connected to either the radiator circuit 160 or the buffer tank 140. When the heat pump 130 is fluidly connected to the radiator circuit 160, it is preventing fluid communication with the buffer tank 140. When the heat pump 130 is fluidly connected to the buffer tank 140, it is preventing fluid communication with the radiator circuit 160. The hot fluid grid 112 is configured to supply a hot fluid from the heat pump 130 to the radiator circuit 160 or the buffer tank 140. The hot fluid grid 112 is further configured to return the hot fluid from the radiator circuit 160 or the buffer tank 140 to the heat pump 130. The hot fluid being returned from the radiator circuit 160 or the buffer tank 140 is entering the heat pump 130 from the switchable conduit system 150. The hot fluid is herein after referred to as “fluid”.

[0080] The heat pump 130 further comprises a refrigerant circulation loop 134. The refrigerant recirculation loop 134 comprises a first heat exchanger unit 135 and a second heat exchanger unit 137 as well as a compressor 136 and an expander 138. The first heat exchanger unit 135 is fluidly connected to the first inlet and outlet ports 131a, 131 b. The second heat exchanger unit 137 is fluidly connected to the second inlet and outlet ports 132b, 132a. The refrigerant circulation loop 134 preferably circulates a refrigerant through the first heat exchanger unit 135, the compressor 136, the second heat exchanger unit 137 and the expander 138. The refrigerant and the cold fluid are configured to exchange thermal energy between each other in the first heat exchanger unit 135 such that a temperature of the refrigerant increases and a temperature of the cold fluid decreases. The cold fluid is returned to the cold fluid side 101. The refrigerant is circulated from the first heat exchanger unit 135 to the compressor 136 which is configured to increase the temperature and pressure of the refrigerant even further before supplying the refrigerant to the second heat exchanger unit 137. The refrigerant and the hot fluid are configured to exchange thermal energy between each other in the second heat exchanger unit 137 such that a temperature of the refrigerant decreases and a temperature of the hot fluid increases. The hot fluid is supplied to the radiator circuit 160 or to the buffer tank 140. The refrigerant is circulated from the second heat exchanger unit 137 to the expander 138 which is configured to control an amount of refrigerant released into the first heat exchanger unit 135. The buffer tank 140 is configured to store a heat buffer fluid. The buffer tank 140 comprises a first portion 140a and a second portion 140b, wherein the first and second portions 140a, 140b are spaced from each other. The first portion 140a is defined in an uppermost part of the buffer tank 140 and the second portion 140b is defined in a lowermost part of the buffer tank 140. As further depicted in Fig. 1 , the first and second portions 140a, 140b are spaced from each other by a third portion 140c. Although not illustrated, the buffer tank 140 may comprise further portions arranged between the first and second portions 140a, 140b. The buffer tank 140 comprises a first portion inlet 141 a configured to receive fluid exiting the heat pump 130 and being supplied to the buffer tank 140, when the heat pump 130 is fluidly connected to the buffer tank 140. Thus, when the heat pump 130 is fluidly connected to the buffer tank 140, fluid exiting the heat pump 130 is provided to the first portion 140a of the buffer tank 140 via the first portion inlet 141 a. The buffer tank 140 comprises a second portion outlet 142b configured to return fluid from the buffer tank 140 to the heat pump 130, when the heat pump 130 is fluidly connected to the buffer tank 140. Thus, when the heat pump 130 is fluidly connected to the buffer tank 140, fluid entering the heat pump 130 is retrieved from the second portion 140b of the buffer tank 140 via the second portion outlet 142b.

[0081] The buffer tank 140 further comprises a first portion outlet 141 b and a second portion inlet 142a, both being connected to the tap water heat exchange circuit 170. The tap water heat exchange circuit 170 comprises a heat exchanger 171 and a circulation pump 172. The tap water heat exchange circuit 170 is arranged to retrieve heat buffer fluid from the first portion 140a of the buffer tank 140, via the first side outlet 141 b, to a first side 171 a of the heat exchanger 171. The tap water heat exchanger circuit 170 is further configured to return the retrieved heat buffer fluid from the first side 171 a of the heat exchanger 171 to the second portion 140b of the buffer tank 140, via the second portion inlet 142a. As depicted in figure 1 , the tap water heat exchanger circuit 170 is configured to return the retrieved heat buffer fluid from the first side 171a of the heat exchanger 171 to the buffer tank 140 via the circulation pump 172. A second side 171 b of the heat exchanger 171 is connected to the tap water circuit 180. The tap water circuit 180 is connected to the second side 171 b of the heat exchanger 171 via a domestic hot water supply line DHW and a cold water supply line CW. The domestic hot water supply line DHW is arranged for supply hot tap water from the tap water heat exchange circuit 170 to the tap water circuit 180. The cold water supply line CW is arranged for return tap water from the tap water circuit 180 to the tap water heat exchange circuit 170. A hot water circulation supply line HWC is connected to the cold water supply line CW. The hot water circulation supply line HWC is arranged for maintaining a constantly circulating base flow of hot tap water from the tap water circuit such that hot tap water is always available once the tap water circuit is activated.

[0082] As said, the switchable conduit system 150 is configured to fluidly connect the heat pump 130 to the radiator circuit 160 or to fluidly connect the heat pump 130 to the buffer tank 140.

[0083] As depicted in figure 1 , the switchable conduit system 150 comprises two valves 151a, 151 b arranged to fluidly connect the heat pump 130 to either the radiator circuit 160 or to the buffer tank 140. The valves 151a, 151 b are arranged for controlling the fluid flow retrieved from the heat pump 130 to the switchable conduit system 150 and for controlling the fluid flow entering the heat pump 130 from the switchable conduit system 150.

[0084] The valve 151a is arranged for directing the fluid flow retrieved from the heat pump 130 to either the radiator circuit 160 or to the buffer tank 180. The valve 151 b is arranged for directing the fluid flow entering the heat pump 130 from either the radiator circuit 160 or the buffer tank 140.

[0085] As best illustrated in figure 3, the heat pump 130 is fluidly connected to the radiator circuit 160. The fluid flow retrieved from the heat pump 130 is directed to the radiator circuit 160 via an inlet port 161a of the radiator circuit 160 and fluid flow entering the heat pump 130 from the radiator circuit 160 is exiting the radiator circuit 160 via an outlet port 161 b of the radiator circuit 160.

[0086] With reference to figure 3, the arrangement 100 is depicted in a simplified manner in which only some parts of the arrangement 100 is included. It should however be noted that the arrangement 100 depicted in figure 3 comprises the same features and components as the arrangement 100 depicted in figure 1 . These figures are included for increasing understanding of the disclosure as well as to get an overview of the arrangement in a simplified way.

[0087] As best illustrated in figure 4, the heat pump 130 is fluidly connected to the buffer tank 140. The fluid flow retrieved from the heat pump 130 is directed to the first portion 140a of the buffer tank 140 via the first portion inlet 141a and fluid flow entering the heat pump 130 from the buffer tank 140 is exiting the second portion 140b via the second portion outlet 142b.

[0088] With reference to figure 4, the arrangement 100 is depicted in a simplified manner in which only some parts of the arrangement 100 is included. It should however be noted that the arrangement 100 depicted in figure 4 comprises the same features and components as the arrangement 100 depicted in figure 1 . These figures are included for increasing understanding of the disclosure as well as to get an overview of the arrangement in a simplified way.

[0089] Referring back to figure 1 , the arrangement 100 further comprises one or more first sensors 240, 250, 260. As depicted in figure 1 , the heat pump 130 further comprises three first sensors 240, 250, 260. The sensor 240 is arranged in an inlet supply line 133 of the heat pump 130 and is configured to obtain first data which pertains at least to a heat pump inlet fluid temperature of the fluid entering the heat pump 130 from either the radiator circuit 160 or from the buffer tank 140. Thus, the sensor 240 is configured to obtain the first data which pertains at least to a heat pump inlet fluid temperature of the fluid entering the heat pump 130 from the switchable conduit system 150. The sensor 250 is arranged upstream the second heat exchanger unit 137 in the heat pump 130. The sensor 260 is arranged downstream the second heat exchanger unit 137 in the heat pump 130.

[0090] The arrangement 100 further comprises one or more second sensors 210, 220, 230. As depicted in figure 1 , the buffer tank 140 comprises a second sensor 210 configured to obtain second data which pertains at least to a heat buffer fluid temperature of heat buffer fluid within the second portion 140b of the buffer tank 140. As further depicted in figure 1 , the tap water heat exchanger circuit 170 comprises a second sensor 220. The second sensor 220 is arranged downstream the heat exchanger 171 and is arranged to determine a temperature of heat buffer fluid leaving the first side 171a of the heat exchanger 171 . As yet further depicted in figure 1 , the arrangement 100 comprises a second sensor 230 arranged downstream the second side 171 b of the heat exchanger 171 . The second sensor 230 is configured to determine tap water data which pertains to an outgoing hot tap water temperature of tap water leaving the second side 171 b of the heat exchanger 171 to the tap water circuit 180.

[0091] The arrangement 100 further comprises one or more control units 190. As depicted in figure 1 , the arrangement 100 comprises one control unit 190. Although the control unit 190 is illustrated as being remote from the components of the arrangement 100, the control unit 190 may be comprised in any of the components which are comprised in the arrangement 100. The control unit 190 is configured to control an operation of the arrangement 100. The control unit 190 may be wired, or wireless connected to the one or more first sensors 240, 250, 260 and / or to the one or more second sensors 210, 220, 230. The control unit 190 may be wired, or wireless connected to any of the components comprised in the arrangement 100.

[0092] The control unit 190 may be configured to determine a data relationship between the first data and the second data. The control unit 190 may be configured to determine the data relationship by executing a determination function when the heat pump 130 is fluidly connected to the radiator circuit 160.

[0093] The control unit 190 may be configured to compare the data relationship with a comparison criterion. The control unit 190 may be configured to compare the data relationship with the comparison criterion by executing a comparison function when the heat pump 130 is fluidly connected to the radiator circuit 160.

[0094] With reference to figure 2, a modular arrangement 200 for domestic heating is illustrated by way of example. The modular arrangement 200 comprises the same features as illustrated and discussed in connected with figure 1 apart from the heat pump 130. Instead, the modular arrangement 200 comprises two heat pump modules 130a, 130b. Each heat pump module 130a, 130b comprises the same features as the heat pump 130 illustrated and discussed in connection with figure 1 . Although not illustrated, the modular arrangement 200 may comprise more than two heat pump modules 130a, 130b. Each heat pump module 130a, 130b of the plurality of heat pump modules 130a, 130b may be detachable from its position in the modular arrangement 200. The term “detachable” is here meant that at least one heat pump module 130a, 130b of the plurality of heat pump modules 130a, 130b are removably arranged in the modular arrangement 200. Put differently, at least one heat pump module 130a, 130b of the plurality of heat pump modules 130a, 130b is arranged in the modular arrangement 200 in a way such that it is possible to remove and / or replace the heat pump module 130a, 130b.

[0095] Each of the heat pump module 130a, 130b is connected to the radiator circuit 160 and the buffer tank 140. The switchable conduit system 150 is configured to fluidly connect each of the heat pump module 130a, 130b to either the radiator circuit 160 or to the buffer tank 140. Thus, the heat pump modules 130a, 130b are either fluidly connected to the radiator circuit 160 or to the buffer tank 140.

[0096] With reference to figure 5, a flowchart illustrating a method 500 for controlling an arrangement 100, 200 is shown by way of example. The arrangement 100 corresponds to the arrangement 100, 200 as depicted in figures 1 to 4.

[0097] The method 500 comprises receiving S502, from one or more first sensors 240, 250, 260 of the arrangement 100, 200, first data which pertains at least to a first temperature of a fluid entering a heat pump 130 from a switchable conduit system 150.

[0098] Thereafter, the method 500 comprises receiving S504, from one or more second sensors 210, 220, 230 of the arrangement 100, 200, second data which pertains at least to a second temperature of heat buffer fluid within the second portion 140b of the buffer tank 140.

[0099] Thereafter, the method 500 comprises determining S506 a data relationship between the first data and the second data. Optionally, the step of determining S506 the data relationship between the first data and the second data comprises determining a difference between the first data and the second data.

[0100] Optionally, the step of determining S506 the data relationship between the first data and the second data comprises determining a ratio between the first data and the second data.

[0101] In a next step, the method 500 comprises comparing S508 the data relationship with a comparison criterion. Upon the comparison does not fulfill the comparison criterion, the method 500 further comprises controlling S510 the circulation pump 172 such that the temperature of the heat buffer fluid within the second portion 140b of the buffer tank 140 is decreased.

[0102] The method 500 may be repeated until the comparison criterion is fulfilled.

[0103] Upon the comparison fulfills the comparison criterion, the method 500 further comprises switching S511 the switchable conduit system 150 to fluidly connect the heat pump 130 to the buffer tank 140 while preventing fluid communication with the radiator circuit 160.

[0104] If the arrangement is the modular arrangement 200 as introduced in connection with Fig. 2, the first data may pertain to at least the heat pump inlet fluid temperature of the fluid entering the heat pump module 130a, 130b which comprises said heat pump 130. In other modular embodiments comprising a plurality of heat pump modules 130a, 130b, the arrangement 200 comprises one or more first sensors 240, 250, 260 for each heat pump module 130a, 130b of the plurality of heat pump modules 130a, 130b, said one or more first sensors 240, 250, 260 being configured to obtain first data which pertains at least to a heat pump inlet fluid temperature of fluid entering the associated heat pump module 130a, 130b from the switchable conduit system 150. For modular arrangements such as the arrangement 200, the method 500 may be configured to determine S506 the data relationship between the first data of each heat pump module and the second data. Thus, a plurality of data relationships may be obtained, one for each heat pump module 130a, 130b. Thereafter, the method 500 may be configured to compare S508 the data relationship of each heat pump module 130a, 130b with a comparison criterion. Each heat pump module 130a, 130b may have an associated comparison criterion, wherein the comparison criterion pertains to a maximum data tolerance between the first data and the second data that may be tolerated by that heat pump module 130a, 130b. This implies that the tolerance for a sudden change in temperature may be different for different heat pump modules. The comparison criterion which pertains to lowest maximum data tolerance which may be tolerated by a heat pump module 130a, 130b of the arrangement 200 may be defined as a common comparison criterion for the arrangement 200. Thus, the heat pump module 130a, 130b having the lowest maximum data tolerance may determine the comparison criterion for the whole arrangement 200. The comparison criterion may thus be determined individually for each heat pump module 130a, 130b. Thus, different heat pump modules 130a, 130b may be associated with different comparison criterions. However, the arrangement 200 may be associated with one common comparison criterion only, being the comparison criterion which pertains to the lowest maximum data tolerance.

[0105] Thus, it should be noted that the disclosed method 500 is equally valid for the arrangement 100 as introduced in connection with Fig. 1 as for the modular arrangement 200 as introduced in connection with Fig. 2.

[0106] Even though illustrated and described in a certain order, other orders may also be used.

[0107] The person skilled in the art realizes that the present invention by no means is limited to the preferred embodiments described above. On the contrary, many modifications and variations are possible within the scope of the appended claims. Additionally, variations to the disclosed embodiments may be understood and effected by the skilled person in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims.

Claims

CLAIMS1. An arrangement (100) for domestic heating comprising: a heat pump (130); a buffer tank (140) configured to store a heat buffer fluid, and having a first portion (140a) and a second portion (140b), wherein the first portion (140a) and the second portion (140b) are spaced from each other within the buffer tank (140); a switchable conduit system (150) configured to fluidly connect the heat pump (130) to a radiator circuit (160) while preventing fluid communication with the buffer tank (140), or to fluidly connect the heat pump (130) to the buffer tank (140) while preventing fluid communication with the radiator circuit (160), wherein fluid exiting the heat pump (130) is provided to the first portion (140a) of the buffer tank and fluid entering into the heat pump (130) is retrieved from the second portion (140b) of the buffer tank (140); a tap water heat exchange circuit (170) comprising a heat exchanger (171 ) and a circulation pump (172), said tap water heat exchange circuit (170) being arranged to retrieve heat buffer fluid from the first portion (140a) of the buffer tank (140) to a first side (171 a) of the heat exchanger (171 ) and to return the retrieved heat buffer fluid to the second portion (140b) of the buffer tank (140), wherein a second side (171 b) of the heat exchanger (171 ) is arranged to be connected to a tap water circuit (180); one or more first sensors (240, 250, 260) being configured to obtain first data which pertains at least to a heat pump inlet fluid temperature of fluid entering the heat pump (130) from the switchable conduit system (150); one or more second sensors (210, 220, 230) being configured to obtain second data which pertains at least to a heat buffer fluid temperature of heat buffer fluid within the second portion (140b) of the buffer tank (140); and one or more control units (190) configured to execute, when the heat pump (130) is fluidly connected to the radiator circuit (160): a determination function configured to determine a data relationship between the first data and the second data; anda comparison function configured to compare the data relationship with a comparison criterion, and upon the comparison not fulfilling the comparison criterion: control the circulation pump (172) such that the temperature of the heat buffer fluid within the second portion (140b) of the buffer tank (140) is decreased.

2. The arrangement (100) according to claim 1 , wherein the one or more control units (190) are configured to, upon the comparison fulfilling the comparison criterion, switch the switchable conduit system (150) to fluidly connect the heat pump (130) to the buffer tank (140) while preventing fluid communication with the radiator circuit (160).

3. The arrangement (100) according to claim 1 or 2, wherein at least one of the one or more first sensors (240, 250, 260) is comprised in the heat pump (130).

4. The arrangement (100) according to any one of the preceding claims, wherein at least one of the one or more second sensors (210, 220, 230) is comprised in the buffer tank (140).

5. The arrangement (100) according to any one of the preceding claims, wherein the one or more second sensors (210, 220, 230) further comprise a sensor (230) configured to determine tap water data which pertains to an outgoing hot tap water temperature of tap water leaving the second side (171 b) of the heat exchanger (171 ) and / or a sensor (220) configured to determine a temperature of heat buffer fluid leaving the first side (171a) of the heat exchanger (171 ).

6. The arrangement (100) according to any one of the preceding claims, wherein the first portion (140a) of the buffer tank (140) is defined in an uppermost part of the buffer tank (140) and the second portion (140b) of the buffer tank (140) is defined in a lowermost part of the buffer tank (140).

7. The arrangement (100) according to any one of the preceding claims, wherein the arrangement (100) is a modular arrangement (200) and comprises a plurality of heat pump modules (130a, 130b) wherein one of the plurality of heat pump modules (130a, 130b) comprises said heat pump (130).

8. The arrangement (100) according to any one of claims 1 to 7, wherein the determination function is configured to determine the data relationship based on a difference between first data and the second data.

9. The arrangement (100) according to any one of claims 1 to 7, wherein the determination function is configured to determine the data relationship based on a ratio between first data and the second data.

10. The arrangement (100) according to any one of the preceding claims, wherein the one or more control units (190) are further configured to retrieve heat pump characteristics from the heat pump (130) and determine the comparison criterion based at least on said heat pump characteristics.11 . The arrangement (100) according to any one of the preceding claims, wherein the heat pump characteristics include data pertaining to one or more from the list of: the compressor power, a refrigerant temperature, a refrigerant pressure, and the heat pump inlet fluid temperature.

12. A method (500) for controlling an arrangement (100) which comprises: a heat pump (130); a buffer tank (140) configured to store a heat buffer fluid, and having a first portion (140a) and a second portion (140b), wherein the first portion (140a) and the second portion (140b) are spaced from each other within the buffer tank (140); a switchable conduit system (150) configured to fluidly connect the heat pump (130) to a radiator circuit (160) while preventing fluid communication with the buffer tank (140), or to fluidly connect the heat pump(130) to the buffer tank (140) while preventing fluid communication with the radiator circuit (160), wherein fluid exiting the heat pump (130) are provided to the first portion (140a) of the buffer tank (140) and fluid entering into the heat pump (130) is retrieved from the second portion (140b) of the buffer tank (140); a tap water heat exchange circuit (170) comprising a heat exchanger (171 ) and a circulation pump (172), said tap water heat exchange circuit (170) being arranged to retrieve heat buffer fluid from the first portion (140a) of the buffer tank (140) to a first side (171a) of the heat exchanger (171 ) and to return the retrieved heat buffer fluid to the second portion (140b) of the buffer tank (140), wherein the second side (171 b) of the heat exchanger (171 ) is arranged to be connected to a tap water circuit (180); the method (500) comprising: receiving (S502), from one or more first sensors (240, 250, 260) of the arrangement (100), first data which pertains at least to a first temperature of a fluid entering a heat pump (130) from a switchable conduit system (150); receiving (S504), from one or more second sensors (210, 220, 230) of the arrangement (100), second data which pertains at least to a second temperature of heat buffer fluid within the second portion (140b) of the buffer tank (140); determining (S506) a data relationship between the first data and the second data; and comparing (S508) the data relationship to a comparison criterion; wherein, upon the comparison does not fulfill the comparison criterion, controlling (S510) the circulation pump (172) such that the temperature of the heat buffer fluid within the second portion (140b) of the buffer tank (140) is decreased.

13. The method (500) according to claim 12, wherein, upon the comparison fulfills the comparison criterion, the method (500) further comprises switching (S511 ) the switchable conduit system (150) to fluidly connect the heat pump (130) to the buffer tank (140) while preventing fluid communication with the radiator circuit (160).

14. The method (500) according to claim 12 or 13, wherein the step of determining (S506) the data relationship between the first data and the second data comprises determining a difference between the first data and the second data.

15. The method (500) according to claim 12 or 13, wherein the step of determining (S506) the data relationship between the first data and the second data comprises determining a ratio between the first data and the second data.

Images