Heat pump and radiator system contol method

Abstract

A method for controlling a heat pump and a radiator system includes retrieving a duty cycle length from each of a set of digital thermostats in the radiator system, determining a longest duty cycle of the set of digital thermostats, and adjusting a target temperature for the fluid output from the heat pump based on the longest duty cycle This method optimizes the operation of the heat pump and radiator system, ensuring efficient heating and minimizing flow variations within the system.

Description

[0001] HEAT PUMP AND RADIATOR SYSTEM CONTOL METHOD

[0002] Field

[0003] The technology relates to the field of heating, ventilation, and air conditioning (HVAC) systems, specifically focusing on heat pump arrangements and radiator systems for residential and commercial buildings. The technology aims to improve the efficiency and performance of these systems by optimizing the control and distribution of heat throughout the building.

[0004] Background

[0005] Heating systems play a crucial role in maintaining thermal comfort in residential and commercial buildings. A common control method for heating systems is degree-minute control or curve control. Degree-minute control is based on utilizing a predefined supply temperature curve for the heating system as a function of the outdoor temperature, a setpoint or often called a reference or target temperature. This target temperature is compared with the actual supply temperature to the heating system at a determined time interval, and then, time interval by time interval, a comparison is made between the actual value and the setpoint. The objective is to create a control signal that starts and stops the heat pump's compressor in thermal comfort operation.

[0006] Heat pumps are often connected to a system of radiators to distribute heat throughout a building. The radiator systems are equipped with digital thermostat valves, which attempt to control the indoor temperature comfort in each room within a narrow temperature range. These digital thermostat valves control the room temperature by fully opening for a short period and then closing for a longer period, which creates significant flow variations in the radiator system.

[0007] Heat pumps are sensitive to frequent cycling on and off, and therefore, it is desirable to wait as long as possible before starting the heat pump to achieve as long operating times as possible before it stops. The combination of the heat pump's longer operating times for optimal function combined with the on-off behavior of digital thermostat valves leads to large flow variations in the radiator system, which causes the degree-minute control not to work optimally. This results in a poorer heating system with lower efficiency.

[0008] In addition, the frequent cycling of the heat pump can reduce its operational efficiency and potentially shorten its lifespan. The mismatch between the heat pump operation and thermostat valve control can further exacerbate the inefficiency of the heating system.

[0009] Therefore, there is a need for a more efficient control methods that can better manage the flow variations caused by the on-off behavior of digital thermostat valves and coordinate the heat pump cycling with the thermostat valve operation to optimize the heating system's efficiency and performance.

[0010] Summary

[0011] According to a first aspect of the disclosure, a method for controlling a heat pump and a radiator system is provided. This method involves retrieving a duty cycle length from each of a set of digital thermostats in the radiator system, determining the longest duty cycle of the set of digital thermostats, and adjusting a target temperature for the fluid output from the heat pump based on the longest duty cycle. This approach allows for more efficient control of the heat pump and radiator system, optimizing energy usage and ensuring a consistent temperature throughout the system.

[0012] Optionally in some examples, the method further involves comparing the longest duty cycle to a first threshold, and if the longest duty cycle is shorter than the first threshold, decreasing the target temperature for the fluid output from the heat pump. This feature allows for further optimization of the heat pump's operation, reducing energy consumption when the heating demand is low.

[0013] Optionally in some examples, the method may also involve comparing the longest duty cycle to a second threshold, and if the longest duty cycle is longer than the second threshold, increasing the target temperature for the fluid output from the heat pump. This feature ensures that the heat pump can meet higher heating demands, providing a comfortable temperature in all rooms of the house. Optionally in some examples, the method may also involve adjusting offsets for the digital thermostats not having the longest duty cycle to minimize flow variation within the radiator system. This feature helps to maintain a more consistent flow of heat throughout the entire time cycle, optimizing the heat pump's operation and reducing flow variations in the radiator system.

[0014] Optionally in some examples, the method may also involve determining if the temperature of the fluid output from the heat pump has reached a lowest target temperature, and shunting heat from an accumulator tank to the radiator system if the lowest target temperature has been reached. This feature ensures efficient heating when heating demand is low and thereby reduce the need for short on-cycles for the heat pump.

[0015] Optionally in some examples, adjusting a target temperature for the fluid output from the heat pump may involve adjusting a target temperature signal for the heat pump. This feature provides a more precise control of the heat pump's operation, ensuring optimal energy usage and a consistent temperature throughout the system.

[0016] According to a second aspect of the disclosure, a heat pump arrangement and radiator system is provided. This system comprises a heat pump, an accumulator tank, a controller, and a plurality of radiators, each equipped with a digital thermostat. The controller is configured to retrieve a duty cycle length from each digital thermostat of the plurality of radiators, determine a longest duty cycle of the set of digital thermostats, and adjust a target temperature for the fluid output from the heat pump based on the longest duty cycle. This system provides an efficient and effective solution for controlling the temperature in a house or apartment, ensuring a comfortable environment while optimizing energy usage.

[0017] Optionally in some examples, the controller is further configured to compare the longest duty cycle to a first threshold, and if the longest duty cycle is shorter than the first threshold, decrease the target temperature for the fluid output from the heat pump. This feature allows for further optimization of the system's operation, reducing energy consumption when the heating demand is low.

[0018] Optionally in some examples, the controller may also be configured to compare the longest duty cycle to a second threshold, and if the longest duty cycle is longer than the second threshold, increase the target temperature for the fluid output from the heat pump. This feature ensures that the system can meet higher heating demands, providing a comfortable temperature in all rooms of the house or apartment.

[0019] Optionally in some examples, the controller may also be configured to adjust offsets for the digital thermostats not having the longest duty cycle to minimize flow variation within the radiator system. This feature helps to maintain a more consistent flow of heat throughout the entire time cycle, optimizing the system's operation and reducing flow variations in the radiator system.

[0020] Optionally in some examples, the controller may also be configured to determine if the temperature of the fluid output from the heat pump has reached a lowest target temperature, and shunt heat from the accumulator tank to the radiator system if the lowest target temperature has been reached. This feature ensures efficient heating when heating demand is low and thereby reduce the need for short on-cycles for the heat pump.

[0021] Optionally in some examples, adjusting a target temperature for the fluid output from the heat pump may involve the controller adjusting a target temperature signal for the heat pump. This feature provides a more precise control of the system's operation, ensuring optimal energy usage and a consistent temperature throughout the system. This approach allows for more efficient control of the heat pump and radiator system, optimizing energy usage and ensuring a consistent temperature throughout the system.

[0022] Brief Description of the Drawings

[0023] Examples are described in more detail below with reference to the appended drawings. Figure 1 is a schematic representation of a heat pump and radiator system according to an embodiment of the method.

[0024] Figure 2 is a flowchart illustrating the steps of the method for controlling the heat pump and radiator system.

[0025] Figure 3 is a graphical representation of the duty cycle information retrieved from the digital thermostats and offset adjustments made for minimizing the flow variations.

[0026] Figure 4 is a schematic representation of the three-way valves and their fluid connection to the heat pump, accumulator tank, and radiator system when shunting heat from the accumulator tank to the radiator system.

[0027] Detailed

[0028] The detailed description set forth below provides information and examples of the disclosed technology with sufficient detail to enable those skilled in the art to practice the disclosure.

[0029] Figure 1 shows a schematic representation of a heat pump and radiator system according to an embodiment of the method. The heat pump arrangement 100 includes a heat pump 105 that may comprise of one or more modular heat pumps 105a, 105b. The heat pump 105 may be an air to fluid, or fluid to fluid heat pump. The fluid may be tap water, distilled water, or treated water. The heat pump 105 is connected to a heat source 170 on an input side and powered by an electric grid 195. A pump 132 and an accumulator tank 110 is connected via a first connection 141 , a second connection 142, and a third connection 143 to the output side of the heat pump 105. Furthermore, the output side of the heat pump 105, which transfer hot fluid in the conduit system is also connected to a space heating system 180 comprising a plurality of radiators 1000, 1100, 1200, optionally each equipped with a digital thermostat 155a, 155b, 155c. An external heat exchanger 120 has a first side connected to the accumulator tank 110 and a pump 130 and a second side connected to a hot tap water system 190. The controller 125 is connected to the heat pump 105, and optionally to the digital thermostats, 155a, 155b, 155c. The heat pump 105 provides heat to the radiator system 180 and the accumulator tank 110 and the two three-way valves 135 and 140 control the flow of the heated fluid depending on heating needs. The accumulator tank 110 provides hot tap water and may also store excess heat. The radiator system 180 distributes heat throughout a house or an apartment. The system also includes a direct electric heater 115, for generating for instance excess heat, powered by the electric grid 195, and located within the accumulator tank 110, and optionally a temperature sensor 150 that provides outdoor temperature information to the controller 125. Furthermore, in the heat pump 105, not shown in the figure, there is a temperature sensor measuring the temperature of the fluid output from the heat pump 105 and that information is fed to the controller 125.

[0030] Figure 2 is a flowchart illustrating the steps of the method for controlling the heat pump and radiator system. The method begins with step S1 , where the controller 125 retrieves a duty cycle length from each of a set of digital thermostats 155a, 155b, 155c in the radiator system 180. In step S2, the controller 125 determines the longest duty cycle of the set of digital thermostats. In step S3, the controller 125 adjusts a target temperature for the fluid output from the heat pump 105 based on the longest duty cycle. Step S3 may further comprise the details of the Steps S4 and S5. In step S4, the controller 125 compares the longest duty cycle to a first threshold, and if the longest duty cycle is shorter than the first threshold, the controller 125 decreases the target temperature for the fluid output from the heat pump 105. In step S5, the controller 125 compares the longest duty cycle to a second threshold, and if the longest duty cycle is longer than the second threshold, the controller 125 increases the target temperature for the fluid output from the heat pump 105. Optionally in a step S6, the controller 125 adjusts offsets for the digital thermostats 155a, 155b, 155c not having the longest duty cycle to minimize flow variation within the radiator system 180, and the method may then return to step S1. In an optional step S7, the controller 125 determines if the temperature of the fluid output from the heat pump 105 has reached a lowest target temperature. Optionally, in a step S8, the controller 125 shunts heat from the accumulator tank 110 to the radiator system 180 if the lowest target temperature has been reached and the method may then return to step S1 .

[0031] Figure 3 is a graphical representation of the duty cycle information retrieved from the digital thermostats and offset adjustments made for minimizing the flow variations according to one example. The graphs A shows the duty cycle lengths of the three digital thermostats 155a, 155b, 155c over a period of time, the time cycle period. The duty cycle length is represented on the y-axis and the time is represented on the x- axis. The graphs A shows that the duty cycle length varies for each digital thermostat, where the digital thermostat 155a for radiator 1000 has a duty cycle of 50%, while the digital thermostats 155a, 155b for radiators 1100 and 1200 has a duty cycle of 25%. The target temperature is decreased, until the first radiator’s 1000 thermostat 155a reports a duty cycle of 100%, see graphs B. Then the thermostats for radiator 1100, 1200 reports a duty cycle of 50%. As can be seen in graphs B, during the first halve of the time cycle period all radiators require heat, while during the second half only radiator 1000 requires heat. This will cause a large variation of the hot fluid flow in the radiator system requiring the heat pump to significantly vary the heat pump power during the time cycle period. Now, as can be seen in graphs C, the controller, configures the duty cycle offset (i.e. the start of the on-time of the thermostat in the time cycle period) for the digital thermostats 155b, 155c for radiator 1100 and 1200 respectively such that radiator 1100 requires heat during the first half cycle period, while radiator 1200 is configured to require heat in the second half of the cycle period. By this duty cycle offset configuration of the thermostat 155b the heat required in the radiator system is the same during the entire time cycle period, i.e. minimizing the flow variations, giving a low varying heat pump power.

[0032] Figure 4 is a schematic representation of the three-way valves 135 and 140 and their fluid connection to the heat pump 105, accumulator tank 110, and radiator system 180 when shunting heat from the accumulator tank 110 to the radiator system 180. The three-way valve 135 is connected to the return flow of the output from the heat pumps 105, the accumulator tank 110, and the return flow from the radiator system 180. The three-way valve 140 is connected to the forward flow of the output from the heat pumps 105, the accumulator tank 110, and the forward flow to the radiator system 180. The controller 125 controls the position of the three-way valves 135 and 140 based on the operational mode of the heating arrangement and the heating needs of the space heating system. When there is a low heating demand in the radiator system, when there is no need for continuous heat pump operation to fulfill space heating demand which in some examples may happen when the temperature of the fluid output from the heat pump 105 has reached a lowest target temperature, the controller 125 shunts heat from the accumulator tank 110 to the radiator system 180. This is done by adjusting the position of the three-way valves 135 and 140 to direct the flow of hot fluid 165a, 165b, 165c from the accumulator tank 110 to the radiator system 180. The valve 140 may be adjusted (shunted) such that the fluid flows 165a, 165b corresponds to the heating need for the radiator system 180.

[0033] 1 . Component Details

[0034] The disclosure comprises several components that work together to control a heat pump and radiator system. These components include digital thermostats, a controller, and a heat pump. Each of these components plays a unique role in the operation of the system and contributes to the overall efficiency and effectiveness of the heat pump and radiator system.

[0035] 1.1. Method For Controlling Heat Pump and Radiator System

[0036] The method for controlling the heat pump and radiator system involves several steps that are executed by the controller 125. These steps include retrieving a duty cycle length from each of a set of digital thermostats, determining the longest duty cycle of the set of digital thermostats, and adjusting a target temperature for the fluid output from the heat pump. The method is designed to optimize the operation of the heat pump and radiator system, ensuring that the system operates efficiently and effectively to meet the heating needs of the space.

[0037] 1.1.1. Retrieve A Duty Cycle Length from Each of a Set of Digital Thermostats

[0038] In one implementation, the controller 125 retrieves a duty cycle length from each of a set of digital thermostats. The duty cycle length is a measure of the time during which a digital thermostat is in an active or "on" state during a time period, that is typically measured in percentage. The controller 125 retrieves this information from each digital thermostat in the system, providing the controller with valuable information about the operational state of each thermostat and the heating demand in each room or zone of the space. 1 .1 .1 .1 . Digital Thermostats

[0039] The digital thermostats 155a, 155b, 155c are a set of devices that control the operation of the radiators in the system. Each digital thermostat is equipped with a valve that opens and closes to control the flow of hot fluid through the radiator. The digital thermostats provide operational state information to the controller 125, indicating the duty cycle of the respective radiator valves. This information allows the controller 125 to determine the heating demand in each room or zone of the space. In one example, the digital thermostats 155a, 155b, 155c may be wired, for instance using ethernet or USB cables, connected to the controller 125. In another example, the digital thermostats 155a, 155b, 155c may be wireless, for instance using WiFi, Bluetooth, or 4G, 5G connected to the controller 125.

[0040] 1.1.2. Determine a Longest Duty Cycle of The Set of Digital Thermostats

[0041] In some configurations, the controller 125 determines the longest duty cycle of the set of digital thermostats. The longest duty cycle is the longest period during which a digital thermostat is in an active or "on" state. By determining the longest duty cycle, the controller 125 can identify the room or zone with the highest heating demand.

[0042] 1.1.2.1. Controller

[0043] The controller 125 is a device that controls the operation of the heat pump and radiator system. The controller 125 retrieves duty cycle information from the digital thermostats, determines the longest duty cycle, and adjusts the target temperature for the fluid output from the heat pump based on this information. The controller 125 plays a role in optimizing the operation of the heat pump and radiator system, ensuring that the system operates efficiently and effectively to meet the heating needs of the space.

[0044] 1.1.3. Adjust A Target Temperature for The Fluid Output from The Heat Pump

[0045] In some examples, the controller 125 adjusts a target temperature for the fluid output from the heat pump based on the longest duty cycle of the digital thermostats. The target temperature is the desired temperature of the fluid output from the heat pump. By adjusting the target temperature based on the longest duty cycle, the controller 125 can ensure that the heat pump operates at an optimal level to meet the heating demand in the room or zone with the highest demand.

[0046] In some implementations, the controller 125 compares the longest duty cycle to a first threshold. If the longest duty cycle is shorter than the first threshold, the controller 125 decreases the target temperature for the fluid output from the heat pump 105. This adjustment helps to ensure that the heat pump 105 provides the right amount of heat to the radiator system.

[0047] In some configurations, the controller 125 compares the longest duty cycle to a second threshold. If the longest duty cycle is longer than the second threshold, the controller 125 increases the target temperature for the fluid output from the heat pump 105. This adjustment helps to ensure that the heat pump 105 provides enough heat to meet the heating demand in the room or zone with the longest duty cycle. The second threshold may in some examples be higher than the first threshold.

[0048] 1.1.3.1. Heat Pump

[0049] The heat pump 105 is a device that provides heat to the radiator system and the accumulator tank. The heat pump 105 operates based on a target temperature signal from the controller 125. For instance, when the longest duty cycle is shorter than the first threshold, the controller 125 decreases the heat pump 105 target temperature and when the longest duty cycle is longer than the second threshold, the controller 125 increases the heat pump 105 target temperature. The heat pump 105 is adversely affected by frequent cycling on and off, so the controller 125 adjusts the target temperature to optimize the operation of the heat pump and reduce the frequency of cycling. The heat pump 105 plays a role in ensuring that the radiator system and accumulator tank receive the heat they need to meet the heating needs of the space. 1.1.4. Adjust The Digital Thermostats Offsets for The Thermostats Not Having the Longest Duty Cycle

[0050] In some examples, the controller 125 adjusts the offsets for the digital thermostats that do not have the longest duty cycle. The offset is the time when a duty cycle starts for a digital thermostat. By adjusting the offsets, the controller 125 can minimize flow variation within the radiator system, ensuring a more consistent flow of heat throughout the entire duty cycle.

[0051] 1.1.4.1. Controller

[0052] The controller 125, as previously described, controls the operation of the heat pump and radiator system. In this step, the controller 125 adjusts the time when each radiator's digital thermostat valve starts its duty cycle. This adjustment helps to maintain a more consistent flow of heat throughout the entire duty cycle, optimizing the heat pump's operation and reducing flow variations in the radiator system.

[0053] 1.1.5. Determine If the Temperature of The Fluid Output from The Heat Pump Has Reached a Lowest Target Temperature

[0054] In some configurations, the controller 125 determines if the temperature of the fluid output from the heat pump 105 has reached a lowest target temperature. Indicating the heating demand for the radiator system 180 is low. If the temperature of the fluid output from the heat pump 105 has reached the lowest target temperature, the controller 125 may shunt heat from the accumulator tank to the radiator system, and the heat pump may be turned off The determination of lowest target temperature reached as well as the optionally disabling of the heat pump and rely on excess heat from the accumulator tank 110, ensures efficient heating when heating demand is low and thereby reduces the need for short on-cycles for the heat pump.

[0055] 1.1.5.1. Controller The controller 125, as previously described, controls the operation of the heat pump and radiator system. In this step, the controller 125 monitors the temperature of the fluid output from the heat pump 105. If the temperature has reached the lowest target temperature, the controller 125 may shunt heat from the accumulator tank to the radiator system and may turn off the heat pump. This adjustment reduces the need for short on-cycles for the heat pump 105 in low heat load scenarios and that the radiator system receives the heat it needs to meet the heating needs of the space.

[0056] 1 .1 .5.2. Shunt Heat from The Accumulator Tank to The Radiator System

[0057] In some examples, if the temperature of the fluid output from the heat pump 105 has reached the lowest target temperature, the controller 125 shunts heat from the accumulator tank to the radiator system. This process involves directing the flow of hot fluid from the accumulator tank to the radiator system, ensuring that the system continues to receive the heat it needs even when the heat pump 105 has been turned off.

[0058] 1.1.5.2.1. Accumulator Tank

[0059] The accumulator tank 110 is a component of the heat pump and radiator system that may store excess heat. The accumulator tank 110 can provide this stored heat to the radiator system when needed, without the heat pump need to be enabled, acting as a thermal battery. When the temperature of the fluid output from the heat pump 105 has reached the lowest target temperature, the controller 125 shunts heat from the accumulator tank 110 to the radiator system. This ensures that the heating system continues to operate efficiently even under varying electricity availability and heating needs.

[0060] 1 .2. Heat Pump Arrangement

[0061] The heat pump arrangement 100 is a system that includes a heat pump 105, an accumulator tank 110, a controller 125, and a plurality of radiators, each equipped with a digital thermostat. The heat pump arrangement 100 is designed to provide heat to a space, such as a house or an apartment, in an efficient and effective manner.

[0062] 1.2.1. Heat Pump

[0063] The heat pump 105 is a component of the heat pump arrangement 100 that provides heat to the radiator system and the accumulator tank. The heat pump 105 operates based on a target temperature signal from the controller 125. The heat pump 105 is adversely affected by frequent cycling on and off, so the controller 125 adjusts the target temperature to optimize the operation of the heat pump and reduce the frequency of cycling.

[0064] 1.2.2. Radiator System

[0065] The radiator system 180 is a component of the heat pump arrangement 100 that distributes heat throughout the space. The radiator system 180 may include a plurality of radiators, each equipped with a digital thermostat. The digital thermostats control the operation of the radiators, opening and closing valves to control the flow of hot fluid through the radiators.

[0066] 1.2.3. Accumulator Tank

[0067] The accumulator tank 110 is a component of the heat pump arrangement 100 that stores excess heat and provides hot tap water. The accumulator tank 110 acts as a thermal battery, storing excess heat for later use in the radiator system or to heat tap water for domestic use. The accumulator tank 110 plays a role in ensuring that the heating system continues to operate efficiently even under varying heating needs.

[0068] 1.2.4. Controller

[0069] The controller 125 is a component of the heat pump arrangement 100 that controls the operation of the heat pump and radiator system using target temperature signals. The controller 125 retrieves duty cycle information from the digital thermostats, determines the longest duty cycle, and adjusts the target temperature for the fluid output from the heat pump based on this information. The controller 125 may also adjusts the offsets for the digital thermostats that do not have the longest duty cycle, and monitors the temperature of the fluid output from the heat pump. The controller 125 plays a role in optimizing the operation of the heat pump and radiator system, ensuring that the system operates efficiently and effectively to meet the heating needs of the space.

[0070] 1.2.5. Direct Electric Heater

[0071] The direct electric heater 115 is a component of the heat pump arrangement 100 that is located within the accumulator tank 110. The direct electric heater 115 generates heat, which can be used to heat the water in the accumulator tank 110. This heat can be stored for later use in the radiator system or to heat tap water for domestic use. The direct electric heater 115 is powered by the electric grid 195 and can be used to generate excess heat when there is surplus electricity available. This ensures that the heating system continues to operate efficiently even during periods of electricity deficiency or low heating demand.

[0072] 1 .2.6. Three-Way Valve

[0073] The three-way valve 135 is a component of the heat pump arrangement 100 that controls the flow of heat to the accumulator tank or to the space heating system based on the heating needs. The three-way valve 135 is connected to the return flow of the output from the heat pumps 105, the accumulator tank 110, and the return flow from the radiator system 180. The controller 125 controls the position of the three-way valve 135 based on the operational mode of the heating arrangement and the heating needs of the space heating system.

[0074] 1 .2.7. Three-Way Valve

[0075] The three-way valve 140 is another component of the heat pump arrangement 100 that controls the flow of heat from the accumulator tank 110 based on the operational mode of the heating arrangement and the heating needs of the space heating system. The three-way valve 140 is connected to the forward flow of the output from the heat pumps 105, the accumulator tank 110, and the forward flow to the radiator system 180. The controller 125 controls the position of the three-way valve 140 to direct the flow of hot fluid from the accumulator tank 110 to the radiator system 180 when needed.

[0076] 2. Method For Controlling Heat Pump and Radiator System Method Details

[0077] The method for controlling the heat pump and radiator system involves several steps that are executed by the controller 125. These steps include retrieving a duty cycle length from each of a set of digital thermostats, determining the longest duty cycle of the set of digital thermostats, and adjusting a target temperature for the fluid output from the heat pump. The method is designed to optimize the operation of the heat pump and radiator system, ensuring that the system operates efficiently and effectively to meet the heating needs of the space.

[0078] 2.1. Retrieving Duty Cycle Length from Digital Thermostats

[0079] In one implementation, the controller 125 retrieves a duty cycle length from each of a set of digital thermostats. The duty cycle length is a measure of the time during which a digital thermostat is in an active or "on" state during a time period. The controller 125 retrieves this information from each digital thermostat in the system, providing the controller with valuable information about the operational state of each thermostat and the heating demand in each room or zone of the space.

[0080] 2.1.1. Role and Function of Digital Thermostats

[0081] The digital thermostats are a set of devices that control the operation of the radiators in the system. Each digital thermostat is equipped with a valve that opens and closes to control the flow of hot fluid through the radiator. The digital thermostats provide operational state information to the controller 125, indicating the duty cycle of the respective radiator valves. This information allows the controller 125 to determine the heating demand in each room or zone of the space. 2.2. Determining the Longest Duty Cycle

[0082] In some configurations, the controller 125 determines the longest duty cycle of the set of digital thermostats. The longest duty cycle is the longest period during which a digital thermostat is in an active or "on" state. By determining the longest duty cycle, the controller 125 can identify the room or zone with the highest heating demand.

[0083] 2.2.1. Role and Function of Controller in Determining Duty Cycle

[0084] The controller 125 is a device that controls the operation of the heat pump and radiator system. The controller 125 retrieves duty cycle information from the digital thermostats, determines the longest duty cycle, and adjusts the target temperature for the fluid output from the heat pump based on this information. The controller 125 plays a role in optimizing the operation of the heat pump and radiator system, ensuring that the system operates efficiently and effectively to meet the heating needs of the space.

[0085] 2.3. Adjusting Target Temperature for Fluid Output

[0086] In some examples, the controller 125 adjusts a target temperature for the fluid output from the heat pump based on the longest duty cycle of the digital thermostats. The target temperature is the desired temperature of the fluid output from the heat pump. For instance, when the longest duty cycle is shorter than the first threshold, the controller 125 decreases the heat pump 105 target temperature and when the longest duty cycle is longer than the second threshold, the controller 125 increases the heat pump 105 target temperature. By adjusting the target temperature based on the longest duty cycle, the controller 125 can ensure that the heat pump operates at an optimal level to meet the heating demand in the room or zone with the highest demand.

[0087] 2.3.1. Role and Function of Heat Pump in Temperature Adjustment

[0088] The heat pump 105 is a device that provides heat to the radiator system and the accumulator tank. The heat pump 105 operates based on a target temperature that may be a target temperature signal from the controller 125. The heat pump 105 is adversely affected by frequent cycling on and off, so the controller 125 adjusts the target temperature to optimize the operation of the heat pump and reduce the frequency of cycling. The heat pump 105 plays a role in ensuring that the radiator system and accumulator tank receive the heat they need to meet the heating needs of the space.

[0089] 2.4. Adjusting Digital Thermostats Offsets

[0090] In some examples, the controller 125 adjusts the offsets for the digital thermostats that do not have the longest duty cycle. The offset is the time when a duty cycle starts for a digital thermostat. By adjusting the offsets, the controller 125 can minimize flow variation within the radiator system, ensuring a more consistent flow of heat throughout the entire duty cycle.

[0091] 2.4.1 . Role and Function of Controller in Adjusting Thermostat Offsets

[0092] The controller 125, as previously described, controls the operation of the heat pump and radiator system. In this step, the controller 125 adjusts the time when each radiator's digital thermostat valve starts its duty cycle. This adjustment helps to maintain a more consistent flow of heat throughout the entire duty cycle, optimizing the heat pump's operation and reducing flow variations in the radiator system.

[0093] 2.5. Determining Lowest Target Temperature

[0094] In some configurations, the controller 125 determines if the temperature of the fluid output from the heat pump 105 has reached a lowest target temperature. If the temperature of the fluid output from the heat pump 105 has reached the lowest target temperature, the controller 125 may shunt heat from the accumulator tank to the radiator system, and the Heat pump may be turned off. The determination of lowest target temperature reached as well as disabling of the heat pump and rely on excess heat from the accumulator tank 110, ensures efficient heating when heating demand is low and thereby reduces the need for short on-cycles for the heat pump. 2.5.1 . Role and Function of Controller in Temperature Monitoring

[0095] The controller 125, as previously described, controls the operation of the heat pump and radiator system. In this step, the controller 125 monitors the temperature of the fluid output from the heat pump 105. If the temperature has reached the lowest target temperature, the controller 125 may shunt heat from the accumulator tank to the radiator system and may turn off the heat pump 105. This ensures efficient heating when heating demand is low and thereby reduces the need for short on-cycles for the heat pump, and that the radiator system receives the heat it needs to meet the heating needs of the space.

[0096] 2.5.2. Shunting Heat from Accumulator Tank to Radiator System

[0097] In some examples, if the temperature of the fluid output from the heat pump 105 has reached the lowest target temperature, the controller 125 shunts heat from the accumulator tank to the radiator system. This process involves directing the flow of hot fluid from the accumulator tank to the radiator system, ensuring that the system continues to receive the heat it needs even when the heat pump 105 has been turned off.

[0098] 2.5.2.1. Role and Function of Accumulator Tank in Heat Shunting

[0099] The accumulator tank 110 is a component of the heat pump and radiator system that stores excess heat. The accumulator tank 110 can provide this stored heat to the radiator system when needed, acting as a thermal battery. When the temperature of the fluid output from the heat pump 105 has reached the lowest target temperature, the controller 125 shunts heat from the accumulator tank 110 to the radiator system. This ensures that the heating system continues to operate efficiently even under varying electricity availability and heating needs.

[0100] 3. Description of Examples of the Disclosure The disclosure provides several examples of the method for controlling the heat pump and radiator system. These examples illustrate how the method can be implemented in practice and provide a detailed description of the processes involved in retrieving duty cycle information, determining the longest duty cycle, adjusting the target temperature for the fluid output from the heat pump, and adjusting the offsets for the digital thermostats.

[0101] 3.1. Example of Duty Cycle Retrieval and Determination

[0102] In one example, the controller 125 retrieves a duty cycle length from each of a set of digital thermostats. The duty cycle length is a measure of the time during which a digital thermostat is in an active or "on" state during a given time period and is typically measured in percentage. For instance, if the duty cycle is 0%, 50%, 100%, and the time period, or time cycle period is 30 minutes, the thermostat is active 0, 15, respective 30 minutes in the 30-minute period. This means that during 0, 15, 30 minutes, the heat if fed through the radiator which is controlled by the digital thermostat, and during 30, 15, 0 minutes the heat bypass the radiator. The controller 125 retrieves this information from each digital thermostat in the system, providing the controller with valuable information about the operational state of each thermostat and the heating demand in each room or zone of the space. The controller 125 then determines the longest duty cycle of the set of digital thermostats, identifying the room or zone with the highest heating demand. For instance, the controller determines that the longest duty cycle may be 50% for one radiator, while the duty cycles for, say the two other radiators in the system may be 25%.

[0103] 3.2. Example of Temperature and Offset Adjustments

[0104] In another example, the controller 125 adjusts a target temperature for the fluid output from the heat pump based on the longest duty cycle of the digital thermostats. The target temperature is the desired temperature of the fluid output from the heat pump. The target temperature may be between 25-70 degrees Celsius, depending on the space heating type (wall radiators, or floor radiators) as well as the insulation in the walls of the house or apartment. For well insulated buildings it may be in the range of 30-45 degrees Celsius, while in old buildings not well insulated the target temperature may be 50-65 degrees Celsius. Hence, also the lowest target temperature may vary depending on the radiator system as well as building insulation. It may be 25 or 30 degrees Celsius in modem insulated buildings while it may be 30-40 degrees Celsius in older buildings. Furthermore, when the longest duty cycle is shorter than the first threshold, the controller 125 decreases the heat pump 105 target temperature and when the longest duty cycle is longer than the second threshold, the controller 125 increases the heat pump 105 target temperature. The threshold first threshold may be 100 % however, may in some examples be 95-102 %. The second threshold may be 100%, however may in some examples be between 105-115%. If the radiator reports a duty cycle over 100% to the controller 125, that means that there is a need for more heat in the fluid output from the heat pump to fulfill the heating need for the radiator associated to the thermostat indicating duty cycle of over 100%. By adjusting the target temperature based on the longest duty cycle, the controller 125 can ensure that the heat pump operates at an optimal level to meet the heating demand in the room or zone with the highest demand.

[0105] The controller 125 also adjusts the offsets for the digital thermostats that do not have the longest duty cycle, minimizing flow variation within the radiator system and ensuring a more consistent flow of heat throughout the entire time cycle period. The controller may use a mathematical algorithm for determining how to adjust the offset for the digital thermostats that do not have the longest duty cycle. Furthermore, minimizing the flow variation over a time cycle period may be based on minimizing a variation metric, that for instance may be minimizing the variance or standard deviations, or the maximum deviation between max and min of the fluid flow needed during the time cycle period by using algorithms and minimizing the flow variations based on a variation metric, ensures an optimized heat pump operation.

[0106] 4. Potential Applications

[0107] The method for controlling a heat pump and radiator system has potential applications in a variety of settings. These include residential heating systems, where the method can be used to optimize the operation of the heating system to meet the heating needs of a house or one or more apartments in a building, and commercial heating systems, where the method can be used to efficiently heat large spaces.

[0108] List of examples

[0109] Example 1 : A method for controlling a heat pump and a radiator system, including retrieving a duty cycle length from each of a set of digital thermostats in the radiator system, determining a longest duty cycle of the set of digital thermostats, and adjusting a target temperature for the fluid output from the heat pump based on the longest duty cycle.

[0110] Example 2: The method of example 1 , further comprising comparing the longest duty cycle to a first threshold, and if the longest duty cycle is shorter than the first threshold, decreasing the target temperature for the fluid output from the heat pump.

[0111] Example 3: The method of example 1 or 2, further comprising comparing the longest duty cycle to a second threshold, and if the longest duty cycle is longer than the second threshold, increasing the target temperature for the fluid output from the heat pump.

[0112] Example 4: The method of any one of examples 1 to 3, further comprising adjusting offsets for the digital thermostats not having the longest duty cycle to minimize flow variation within the radiator system.

[0113] Example 5: The method of any one of examples 1 to 4, further comprising determining if the temperature of the fluid output from the heat pump has reached a lowest target temperature, and shunting heat from an accumulator tank to the radiator system if the lowest target temperature has been reached.

[0114] Example 6: The method of any preceding example, wherein adjusting a target temperature for the fluid output from the heat pump comprises adjusting a target temperature signal for the heat pump. Example 7: A heat pump arrangement and radiator system comprising a heat pump, an accumulator tank, a controller, and a plurality of radiators, each equipped with a digital thermostat, wherein the controller is configured to retrieve a duty cycle length from each digital thermostat of the plurality of radiators, determine a longest duty cycle of the set of digital thermostats, and adjust a target temperature for the fluid output from the heat pump based on the longest duty cycle.

[0115] Example 8: The heat pump arrangement and radiator system of example 7, wherein the controller is further configured to compare the longest duty cycle to a first threshold, and if the longest duty cycle is shorter than the first threshold, decrease the target temperature for the fluid output from the heat pump.

[0116] Example 9: The heat pump arrangement and radiator system of example 7 or 8, wherein the controller is further configured to compare the longest duty cycle to a second threshold, and if the longest duty cycle is longer than the second threshold, increase the target temperature for the fluid output from the heat pump.

[0117] Example 10: The heat pump arrangement and radiator system of any one of examples 7 to 9, wherein the controller is further configured to adjust offsets for the digital thermostats not having the longest duty cycle to minimize flow variation within the radiator system.

[0118] Example 11 : The heat pump arrangement and radiator system of any one of examples 7 to 10, wherein the controller is further configured to determine if the temperature of the fluid output from the heat pump has reached a lowest target temperature, and shunt heat from the accumulator tank to the radiator system if the lowest target temperature has been reached.

[0119] Example 12: The heat pump arrangement and radiator system of any of examples 7 to 11 , wherein adjusting a target temperature for the fluid output from the heat pump comprises adjusting a target temperature signal for the heat pump. Example 13: A method for controlling a heat pump and a radiator system by controlling the target temperature for the fluid output from the heat pump comprising determining if the temperature of the fluid output from the heat pump has reached a lowest target temperature, and shunting heat from an accumulator tank to the radiator system if the lowest target temperature has been reached.

[0120] Example 14: The method of example 13 wherein the heat pump is turned off.

[0121] Example 15: A heat pump arrangement and radiator system comprising a heat pump, an accumulator tank, a controller, and a plurality of radiators, wherein the controller is configured to controlling the target temperature for the fluid output from the heat pump and further configured to determine if the temperature of the fluid output from the heat pump has reached a lowest target temperature, and shunt heat from the accumulator tank to the radiator system if the lowest target temperature has been reached.

[0122] Example 16: The heat pump arrangement and radiator system of example 15 wherein the heat pump is turned off.

[0123] The terminology used herein is for the purpose of describing particular aspects only and is not intended to be limiting of the disclosure. As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. It will be further understood that the terms "comprises," "comprising," "includes," and / or "including" when used herein specify the presence of stated features, integers, actions, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, actions, steps, operations, elements, components, and / or groups thereof.

[0124] It will be understood that, although the terms first, second, etc., may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element without departing from the scope of the present disclosure.

[0125] Relative terms such as "below" or "above" or "upper" or "lower" or "horizontal" or "vertical" may be used herein to describe a relationship of one element to another element as illustrated in the Figures. It will be understood that these terms and those discussed above are intended to encompass different orientations of the device in addition to the orientation depicted in the Figures. It will be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element, or intervening elements may be present. In contrast, when an element is referred to as being "directly connected" or "directly coupled" to another element, there are no intervening elements present.

[0126] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms used herein should be interpreted as having a meaning consistent with their meaning in the context of this specification and the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0127] It is to be understood that the present disclosure is not limited to the aspects described above and illustrated in the drawings; rather, the skilled person will recognize that many changes and modifications may be made within the scope of the present disclosure and appended claims. In the drawings and specification, there have been disclosed aspects for purposes of illustration only and not for purposes of limitation, the scope of the disclosure being set forth in the following claims.

Claims

Claims1 . A method for controlling a heat pump (105) and a radiator system (180), the method comprising: retrieving a duty cycle length from each of a set of digital thermostats (155a, 155b, 155c) in the radiator system (180) [S1 ]; determining a longest duty cycle of the set of digital thermostats [S2]; and adjusting a target temperature for a fluid output from the heat pump (105) based on the longest duty cycle [S3],2. The method according to claim 1 , further comprising: comparing the longest duty cycle to a first threshold, and if the longest duty cycle is shorter than a first threshold, decreasing the target temperature for the fluid output from the heat pump (105) [S4].

3. The method according to claim 1 or 2, further comprising: comparing the longest duty cycle to a second threshold, and if the longest duty cycle is longer than the second threshold, increasing the target temperature for the fluid output from the heat pump (105) [S5],4. The method according to any one of claims 1 to 3, further comprising: adjusting offsets for the digital thermostats (155a, 155b, 155c) not having the longest duty cycle to minimize flow variation within the radiator system (180) [S6],5. The method according to any one of claims 1 to 4, further comprising: determining if the temperature of the fluid output from the heat pump (105) has reached a lowest target temperature [S7]; and shunting heat from an accumulator tank (110) to the radiator system (180) if the lowest target temperature has been reached [S8],6. The method according to any preceding claim, wherein adjusting a target temperature for the fluid output from the heat pump (105) comprises adjusting a target temperature signal for the heat pump (105).

7. A heat pump arrangement (100) and radiator system (180) comprising: a heat pump (105); an accumulator tank (110); a controller (125), and a plurality of radiators (1000, 1100, 1200), each equipped with a digital thermostat (155a, 155b, 155c), wherein the controller (125) is configured to: retrieve a duty cycle length from each digital thermostat (155a, 155b, 155c) of the plurality of radiators, determine a longest duty cycle of the set of digital thermostats, and adjust a target temperature for a fluid output from the heat pump (105) based on the longest duty cycle.

8. The heat pump arrangement (100) and radiator system (180) according to claim 7, wherein the controller (125) is further configured to compare the longest duty cycle to a first threshold, and if the longest duty cycle is shorter than the first threshold, decrease the target temperature for the fluid output from the heat pump (105).

9. The heat pump arrangement (100) and radiator system (180) according to claim 7 or 8, wherein the controller (125) is further configured to compare the longest duty cycle to a second threshold, and if the longest duty cycle is longer than the second threshold, increase the target temperature for the fluid output from the heat pump (105).

10. The heat pump arrangement (100) and radiator system (180) according to any one of claims 7 to 9, wherein the controller (125) is further configured to adjust offsets for the digital thermostats (155a, 155b, 155c) not having the longest duty cycle to minimize flow variation within the radiator system (180).11 . The heat pump arrangement (100) and radiator system (180) according to any one of claims 7 to 10, wherein the controller (125) is further configured to determine if the temperature of the fluid output from the heat pump (105) has reached a lowest target temperature, and shunt heat from the accumulator tank (110) to the radiator system (180) if the lowest target temperature has been reached.

12. The heat pump arrangement (100) and radiator system (180) according to any of claims 7 to 11 , wherein adjusting a target temperature for the fluid output from heat pump (105) comprises adjusting a target temperature signal for the heat pump (105).

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