Control of the steepness of a heating curve

Abstract

The invention relates to a method for controlling the steepness of a heating curve in a heating system (100) for heating one or more apartments, each with at least one radiator (203), comprising the following steps: measuring the differential pressure between a heating flow and a heating return, measuring the speed of a circulating pump (110) and measuring the valve position of a central control valve (140), and increasing the steepness of the heating curve if the valve position of the central control valve (140) remains the same, and the differential pressure between the heating flow and the heating return becomes smaller and the speed of the circulating pump (110) increases or remains the same, and the temperature difference between the heating flow and the heating return increases, and reducing the steepness of the heating curve if the valve position of the central control valve (140) remains the same,and the differential pressure between the heating flow and the heating return increases and the speed of the circulation pump (110) decreases or remains the same, the difference in temperature between the heating flow and the heating return decreases.

Description

[0001] The invention relates to a method for controlling the steepness of a heating curve in a heating system for heating one or more apartments with at least one radiator each.

[0002] In the context of the energy crisis and increasing demands for rapid decarbonization of the real estate portfolio, the energy optimization of heating systems in properties is gaining importance. Heating systems can be optimized using digital solutions, thereby reducing the energy consumption of the heating system and also CO 2-Emissions from the heating system can be reduced. An efficient method used to optimise heating systems is to reduce the gradient of the heating curve using corrected outside temperature values, whereby the outside temperature correction is fed into the heating control system as a value that has been changed compared to the actual outside temperature. As a result, both any excess heat energy in the heating system and the interior temperature of the rooms to be heated are reduced. This leads to a situation that creates a conflict of objectives between energy conservation and the comfort of the building's occupants. Resolving this conflict of objectives promises maximum energy savings while maintaining the thermal comfort of the occupants. This conflict of objectives can be resolved if the low temperature limit orthe minimum heat requirement of a property, which depends on several factors, such as the subjective comfort temperature of the occupants or the weather conditions, can be determined as quickly and precisely as possible. The minimum heat requirement of a property is defined as the heat energy added to the living spaces in a property being sufficient to exactly meet the lower limit of the comfort temperature of all occupants. Since the lower limit of the comfort temperature is not a constant value, but fluctuates depending on the outside temperature, the minimum heat requirement also fluctuates in relation to the outside temperature. The heat energy supplied to the living spaces is controlled by an existing control technology using a heating curve, which maps a relationship between the flow temperature and the outside temperature.In most cases, the stored heating curve does not cover the minimum heat requirement of a property, but usually causes either an oversupply or an undersupply of heat to the property. If the lower limit of the comfortable temperature for one or more residents of a property in question is undercut, the residents tend to adjust one or more thermostats on the radiators in the living rooms. This means that conventional thermostats are suddenly adjusted to a higher level (e.g., from level 3 to level 4) or to the highest level (e.g., level 5), or the set target temperature of programmable / smart thermostats is increased. As a result, the volume flow in the corresponding radiator and in the riser pipe that supplies the radiator increases. This occurs while the circulation pump setting remains the same.If an apartment building is equipped with several heating circuits, the volume flow increases in each riser pipe that supplies the radiators.

[0003] In order to avoid a central control system having to measure the individual valve positions of the radiators in the individual living rooms, which would on the one hand require very complex cabling and on the other hand could cause data protection problems, the heat demand of the property, including the individual heat requirements of the property's residents, should be derived from parameters that can be detected on the central heating system.

[0004] The object of the invention is to provide a control concept which makes it possible to precisely define the minimum heat requirement and to precisely adapt the heat energy added to the living spaces of a property to the heat requirements of the residents.

[0005] The object of the invention is achieved by a method having the steps of claim 1. Further advantageous embodiments are specified in the subclaims to claim 1. A heating control system for carrying out the method is specified in claim 5. Further advantageous embodiments are specified in the subclaims to claim 5. Starting from a heating system which has at least one central heat exchanger for heating a heating fluid in the radiators, and which has at least one circulating pump to pump the heating fluid to the radiators against the action of a central control valve from the heat exchanger to the radiators (heating flow), wherein the heating fluid flows through the radiator, leaves the radiator and flows via a line (heating return) back to the at least one central heat exchanger,and wherein a heating controller regulates the temperature of the heating flow and the target value of the temperature of the heating flow is specified by the heating curve, which represents a temperature of the heating flow as a function of a measured outside temperature, the following control strategy is provided: measuring the differential pressure between the heating flow and the heating return, measuring the speed of the pump and measuring the valve position of the central control valve, and increasing the steepness of the heating curve if the valve position of the central control valve remains the same, and the differential pressure between the heating flow and the heating return becomes smaller and the speed of the pump increases, and the temperature difference between the heating flow and the heating return increases and reducing the steepness of the heating curve if the valve position of the central control valve remains the same,and the differential pressure between the heating flow and the heating return increases and the speed of the pump decreases, the difference in temperature between the heating flow and the heating return decreases.

[0006] This control strategy is based on the assumption that if the valve position of a central control valve used to regulate the flow temperature remains constant, the heating system is in a steady state. It is possible that the differential pressure between the flow and return lines may change. The differential temperature between the flow and return lines may also change, as may the pump speed. However, if no change in the valve position of the central control valve is detected, which is caused by an existing control device in the heating system, then the steepness of the heating curve will increase if the differential pressure between the flow and return lines decreases while the pump speed increases or remains constant and the temperature difference between the flow and return lines increases.Conversely, if the differential pressure between the flow and return lines increases while the pump speed decreases or remains constant, and the temperature difference between the flow and return lines decreases, the steepness of the heating curve decreases. In fact, a heating control system also changes the position of the central control valve when the heating system is stationary, provided the steepness of the heating curve has not been changed. Manual intervention in the entire heating system by an occupant by operating a heating valve on a radiator in a living space results in the differential pressure between the flow and return lines changing almost immediately, even if the position of the central control valve remains constant. The speed of the circulation pump can also change, particularly with larger manual interventions.Within a few seconds of manual user intervention, the temperature differential between the flow and return lines also changes. A little later, the heating controller intervenes, changing the position of the central control valve to adjust the heat demand in the heating system based on the existing heating curve. The previously described parameter detection serves to centrally record and detect manual user interventions in the heating system and prevent detection of user interventions on individual radiators.

[0007] The control strategy thus makes it possible to adapt the heat demand of the property based on the heat requirement for the individual comfort temperature by adjusting the steepness of the current heating curve. To increase or decrease the steepness of an existing heating system, it is alternatively possible to change the outside temperature supplied to the heating system as a detector signal. This makes it possible to reduce the actual outside temperature using an alternative temperature signal to achieve the same effect as if the steepness of the heating curve were increased in the internal control of the heating system. Conversely, it is possible to increase the actual outside temperature using an alternative temperature signal to achieve the same effect as if the steepness of the heating curve were decreased in the internal control of the heating system.

[0008] The invention is explained in more detail with reference to the following figures. It shows: Fig. 1 a sketch of a central heating system with modules necessary for the control method presented here, Fig. 2 a process diagram illustrating the process according to the invention.

[0009] In Fig. Figure 1 shows a diagram of a central heating system 100 with modules necessary for the control method presented here. The heating system 100 supplies individual radiators 203 of a heating circuit 200. For this purpose, a heating fluid is piped to the radiators 203 via a piping system for a flow 102. In this circuit, these radiators 203 are manually and individually controlled via heating valves 204, which are connected in the flow 102 of the heating system 100. In the heating system 100, a central control valve 140 is located in the flow 102 to limit the volume flow of the heating fluid in the heating circuit 200. The volume flow of the heating fluid in the heating line 200 is generated by a circulation pump 110 in the flow 101 and pumps the heating fluid from the heat exchanger 120, which heats the heating fluid from the return 101, into the flow 102.Depending on the type of heating, the heat exchanger 120 transfers heat from a gas flame, oil flame, or heat pump, which are present in a primary circuit 105 (not described in detail here), into the heating fluid. The lower the volume flow of the heating fluid through the heat exchanger 120, the more heat is transferred into the heating fluid. Thus, an existing heating controller 131 can limit the volume flow of the heating fluid by adjusting the central control valve 140 and thus adjust the temperature of the heating fluid in the flow line 102. A heating control system 130 present here is connected to a differential pressure gauge 150, via which the heating control system 130 can measure the differential pressure between the return line 101 and the flow line 102. The differential pressure is preferably measured in the ascending and descending line 103 of the flow line 102 and the return line 101.Furthermore, the heating control system 130 is connected to two thermometers 160 and 161, via which the temperature difference between the flow 102 and the return 101 can be measured in the heating control system 130. The temperature difference between the flow 102 and the return 101 is also preferably measured in the ascending and descending pipes 103 of the flow 102 and the return 101. Finally, the heating control system 130 is connected to the circulation pump 110 in order to detect the speed of the circulation pump 110. At this point, it should be noted that the heating control system 130 is to be distinguished from an existing heating controller 131 in the heating system 100. The heating controller 131 controls the heating system 100 according to a heating curve. The steepness of the heating curve is varied by the heating control system 130.This can be done indirectly via a changed outside temperature, which the heating control system 130 transmits to the heating controller 131 or - and if the heating controller 131 allows it due to its design - the central heating control system 130 parametrically changes the steepness of the heating curve stored internally in the heating controller 131 by transferring a parameter.

[0010] The method is now designed in such a way that, with a constant position of the central control valve 140, with a falling differential pressure from the differential manometer 150, an increasing differential temperature between the two thermometers 160 and 161 and an increasing or constant speed of the circulating pump 110, the steepness of the heating curve is increased and, conversely, with a constant position of the central control valve 140, with an increasing differential pressure from the differential manometer 150, a falling differential temperature between the two thermometers 160 and 161 and a falling or constant pump speed, the steepness of the heating curve is reduced.

[0011] In Fig.Figure 2 shows a process diagram illustrating the method according to the invention. Starting from start 1, the valve position of the central control valve 140 is measured in a loop in decision step 2. If the position of the central control valve 140 changes, i.e., does not remain the same, then the diagram runs from decision step 2 to the right and returns to start 1. If the position of the central control valve 140 does not change, i.e., remains the same, then in decision step 3, the differential pressure between the supply line 102 and the return line 101 is measured, the pump speed of the circulation pump 110, and the differential temperature between the supply line 102 and the return line 101 are measured using thermometers 160 and 161. The order in which these parameters are measured is irrelevant. The method is now based on a decision diagram: If the differential pressure remains constant in decision step 3, the path in the diagram runs from decision step 3 back to start 1 to the right. If the differential pressure in the diagram is greater in decision step 3, the path in the diagram runs downwards from decision step 3 to decision step 5. If the differential pressure in decision step 3 is smaller, the path in the diagram runs to the left to decision step 4.

[0012] If the differential pressure increases in decision step 3, the next decision is made in decision step 5 based on the pump speed: If the pump speed is higher in decision step 5, the path in the diagram runs from decision step 5 to the left back to start 1, and if the pump speed in decision step 5 is lower or equal to, the path in the diagram continues downwards to decision step 7. If the pump speed decreases or remains the same in decision step 5, the next decision in decision step 7 is made based on the differential temperature between the flow 102 and the return 101: If the differential temperature has remained the same in decision step 7, the path in the diagram runs from decision step 7 to the right back to start 1.If the differential temperature has decreased in decision step 7, the path in the diagram runs downwards from 7 and results in a reduction in the steepness of the heating curve in step 9. If, on the other hand, the differential pressure has increased in decision step 7, the path in the diagram runs to the left back to start 1.

[0013] If the differential pressure in decision step 3 decreases, the next decision is made based on the pump speed in decision step 4: If the pump speed in decision step 4 is greater than or equal to, the path in the diagram from decision step 4 runs downwards and if the pump speed in decision step 4 is lower, the path in the diagram from decision step 4 runs to the left back to start 1.

[0014] If the pump speed has increased or remained the same in decision step 4, the next decision in decision step 6 is made based on the temperature difference between the flow 102 and the return 101. If the temperature difference has decreased in decision step 6, the path in the diagram runs from 6 to the left back to start 1. If the temperature difference has remained the same in decision step 6, the path in the diagram runs from decision step 6 to the right back to start 1. If, on the other hand, the temperature difference has increased in decision step 6, the path in the diagram runs downwards from decision step 6 and results in an increase in the steepness of the heating curve in step 8.

[0015] Before the control process returns to the start after adjusting the slope of the heating curve, the system waits in step 10 until all parameters have stabilized again. This avoids unwanted control oscillations of the entire heating system, which can occur under unfavorable conditions, for example, due to multiple user interventions.

[0016] This diagram, which follows one of several possible sequential decision paths, serves as an illustration. In fact, the four parameters—valve position, differential pressure, differential temperature, and circulation pump speed—can also be measured in parallel, and a parallel decision can be made to increase the steepness of the heating curve, decrease the steepness of the heating curve, or omit control intervention. LIST OF REFERENCE SYMBOLS 1 start 2 Decision step 3 Decision step 4 Decision step 5 Decision step 6 Decision step 7 Decision step 8 Step 9 Step 100 heating system 101 Return 102 Lead-up 103 cable harness 105 Primary circuit 110 Circulation pump 120 heat exchangers 130 Heating control system 131 heating controllers (stock) 140 central control valve 150 differential pressure gauges 160 thermometers 161 thermometers 200 heating lines 203 radiators 204 heating valve

Claims

[1] Method for controlling the steepness of a heating curve in a heating system (100) for heating one or more apartments with at least one radiator (203) each, wherein the heating system (100) has at least one central heat exchanger (120) for heating a heating fluid in the heating bodies (203), and wherein the heating system (100) has at least one circulation pump (110) for pumping the heating fluid to the radiators (203) from the heat exchanger (120) to the radiators (203) against the action of a central control valve (140) (heating flow), wherein the heating fluid flows through the heating elements (203), leaves the heating elements (203) and flows back to the at least one central heat exchanger (120) via a line (heating return), wherein a heating controller (131) regulates the temperature of the heating flow and the target value of the temperature of the heating flow is predetermined by the heating curve, which represents a temperature of the heating flow as a function of a measured outside temperature, comprising the following steps - Measuring the differential pressure between the heating flow and the heating return, - Measure the speed of the circulation pump (110) and - Measuring the valve position of the central control valve (140), and - Increasing the steepness of the heating curve when - the valve position of the central control valve (140) remains the same, and - the differential pressure between the heating flow and the heating return becomes smaller and - the speed of the circulation pump (110) increases or remains the same, and - the difference in temperature between the heating flow and return increases and - Reducing the steepness of the heating curve when - the valve position of the central control valve (140) remains the same, and - the differential pressure between the heating flow and the heating return becomes larger and - the speed of the circulation pump (110) drops or remains the same, - the temperature difference between the heating flow and the heating return falls. [2] Method according to claim 1, characterized by that the steepness of the heating curve is passed as a parameter to a heating controller (131) as an existing controller. [3] Method according to claim 1, characterized by that the steepness of the heating curve is transferred indirectly via a calibrated outside temperature to a heating controller (131) as an existing controller as a parameter. [4] Method according to one of claims 1 to 3, characterized bythat the pressure difference between the flow and return is measured via a differential manometer (150) in the ascending and descending pipe string (103) of the flow (102) and return (101). [5] Method according to one of claims 1 to 4, characterized by that the central control valve (140) is arranged in the flow line. [6] Heating control system (130) for carrying out the method according to claims 1 to 5, comprising - a differential pressure gauge (150), - a tachometer for a circulation pump (110), - a consumer for the position of a central control valve (140), - one electronic thermometer each for measuring the temperature in a heating flow and in a heating after-flow, wherein the differential pressure gauge (150), the speed meter for the circulation pump (110), the sensor for the position of a central control valve (140) and the electronic thermometers are each connected to an input of the heating control system (130), and wherein a parameter output of the heating control system (130) is connected to a heating controller (131) as an inventory controller, characterized by , that the heating control system (130) transfers the steepness of the heating curve as a parameter to the heating controller (131) as the existing controller. [7] Heating control system according to claim 6, characterized by that the heating control system (130) electronically transmits the parameter to the heating controller (131) in the form of a numerical coefficient. [8] Heating control system according to claim 7, characterized by that the heating control system (130) transfers the parameter to the heating controller (131) in the form of a calibrated outside temperature. [9] Heating control system according to claims 6 to 8 in the form of an additional controller as a retrofit controller, which can be connected to a heating controller (131) as an existing controller.

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