Method for adjusting an overflow valve for a heating system

Abstract

Method for adjusting a bypass valve (1) in a heating system (2), wherein the heating system (2) has a heat generator circuit (17), two parallel heating circuits (3, 4) and a controllable first pump (5) for adjusting a total volume flow rate Qs (6) to the two heating circuits (3, 4); wherein the second heating circuit (4) is fluidically connected to the first pump (5) via the bypass valve (1) and wherein the total volume flow rate Qs (6) pumped by the first pump (5) and flowing through the heat generator circuit (17) is measured.

Description

[0001] The invention relates to a method for adjusting an overflow valve in a heating system, in particular in a heating system for a building.

[0002] Heating systems (also referred to as heating, ventilation, and / or air conditioning systems) are often used to control comfort within a building. Such systems typically include an HVAC (heating, ventilation, and / or air conditioning) control that operates one or more HVAC components (heat pump, gas or oil heater, air conditioner, ventilation unit, etc.) of the system to influence and / or control one or more environmental conditions (temperature, humidity, water temperature, etc.) within the building.

[0003] In this case, we consider heating systems with multiple parallel heating circuits (with different temperature levels). These are thermally coupled to a heat generator circuit, with heat being transferred between the heat generator circuit and the heating circuits.

[0004] Various designs of such heating systems with a single heat generator circuit and multiple heating circuits are known. Firstly, there are heating systems with hydraulic decoupling, in which, for example, a hydraulic separator (between the heat generator circuit and the heating circuits) and a pump for adjusting a flow rate are provided for the heat generator circuit and each heating circuit. Secondly, there are heating systems without hydraulic decoupling, in which only one pump is used for the heat generator circuit and the single heating circuit.

[0005] Heating systems with hydraulic decoupling do not require hydraulic balancing via individual pump operating points because the respective volume flow for each circuit (heating circuit and heat generator circuit) can be controlled independently of the other circuits.

[0006] Heating systems without hydraulic decoupling require, for example, an overflow valve, whereby at least two volume flow sensors must be present to determine the volume flow distribution between the heating circuits, because both heating circuits influence each other.

[0007] Heating systems without hydraulic decoupling are also known, in which only one volume flow sensor is used, which then results in a system that is underdetermined in terms of measurement technology.

[0008] This problem of metrological indeterminacy is already being solved today as follows. In the system without hydraulic decoupling, the overflow valve must be adjusted to ensure appropriate heat distribution between the two heating circuits. Because only one volume flow sensor is used in the heat generator circuit, a specific setting specification for the overflow valve is necessary. Currently, the overflow valve is adjusted manually using installation instructions and by reading a pump performance diagram. Using this setting method, the installer must specify a PWM (pulse width modulation) on the pump and set a specific volume flow through trial and error. The PWM control signal provides the pump controller with the information about the pump speed at which it should operate. Using the now known combination of volume flow and PWM, the pressure loss is determined and adjusted on the overflow valve.The PWM of the pump must then be increased until the desired total volume flow is reached (see Vaillant installation and maintenance instructions, 0020318683_01).

[0009] For the installer, adjusting the overflow valve based on a pump diagram is time-consuming and, with the tools available, usually relatively inaccurate. There is no feedback on the precise distribution of the flow rates (and thus the heat distribution) in the heating system. Thus, there is no direct confirmation that the overflow valve is correctly adjusted.

[0010] The object of the invention is therefore to at least partially alleviate or solve the problems described with reference to the prior art. In particular, an alternative method for adjusting an overflow valve in a heating system is to be proposed. The method is intended to be simpler to implement and more accurate, thereby enabling, in particular, the adjustment of the overflow valve in a heating system with indeterminate measurement technology.

[0011] These objects are achieved by the features of the independent patent claim. It should be noted that the features listed in the dependent patent claims can be combined with one another in any technologically expedient manner and define further embodiments of the invention. Furthermore, the features listed in the patent claims are further specified and explained in the description, with further preferred embodiments of the invention being presented.

[0012] A method for adjusting an overflow valve in a heating system contributes to this, wherein the heating system has at least one heat generator circuit, two parallel heating circuits, and a controllable pump for adjusting a total volume flow Qs to the two heating circuits; wherein the second heating circuit is fluidly connected to the first pump via an overflow valve, and wherein a total volume flow Qs conveyed by the first pump and flowing through the heat generator circuit is measured. The method comprises at least the following steps: a) Determining a relationship between a control of the first pump and the total volume flow Qs flowing through the heat generator circuit using the equation Qs = ax PWM + b by operating the first pump with the overflow valve closed; with a and b as constant parameters and with PWM as the control signal of the first pump; b) Setting a required value for the first partial volume flow Q 1 flowing through the first heating circuit; c) Determining a control signal required to adjust the first partial volume flow using the equation PWM Soll = (Qs - b) / a; where the parameters a and b were determined in step a) and Qs is specified; d) Determining a value of a (necessary) residual head H Rest , where H Rest = H Pump , HK1 - H verlust,seriell ; where H Pump, HK1 are known as the characteristic of the first pump and H verlust,seriell as the property of the heat generator circuit;e) Setting the value (of the required residual head previously determined in step d)) H Rest on the overflow valve. ;

[0013] The above (non-exhaustive) division of the process steps into a) to e) is primarily intended to serve as a distinction and does not enforce any order and / or dependency. The frequency of the process steps, e.g. during setup and / or operation of the heating system, can also vary. It is also possible for process steps to overlap one another at least partially. Most preferably, process steps a) and b) take place before step c). In particular, steps d) and e) take place after steps a) to c). In particular, step e) takes place after step d). In particular, steps a) to e) are carried out in the order listed.

[0014] The heating system comprises, in particular, a first heating circuit connected to a heat generator circuit, in which the first pump is arranged. The first heating circuit is provided, for example, for heating radiators in a building. The second heating circuit is assigned, for example, to an underfloor heating system. The second heating circuit or its flow is connected to the first heating circuit or the heat generator circuit (or their course) via an overflow valve. The overflow valve generates a freely adjustable pressure loss via a valve disk that is, for example, spring-loaded, and can thus be used as an adjustment device for the hydraulic balancing of the heating circuits. As soon as a differential pressure applied to the overflow valve exceeds a set value (this value is, after step e), the residual delivery head H residual ), the overflow valve opens and thus connects the second heating circuit to the first heating circuit or the heat generator circuit. In the heat generator circuit (ieA volume flow sensor is arranged (in particular upstream of the first pump) by means of which the total volume flow delivered by the first pump can be or is determined at any time.

[0015] Before the overflow valve opens, the total total volume flow Qs flows through the first heating circuit. It has been found that, in this state of the heating system, there is a sufficiently good approximation of a linear relationship between the PWM control signal of the first pump and the volume flow in the heat generator circuit or first heating circuit, which can then be described by the equation Qs = ax PWM + b. This linear relationship changes as soon as the overflow valve opens. The opening point (time) of the overflow valve can be detected by the change in this characteristic (i.e., when the linear relationship no longer exists).

[0016] To determine the opening point of the overflow valve, the linear equation is first determined according to step a) of the method, where Qs and the respectively set control signal (PWM) are known, so that the parameters a and b can already be determined from two operating points of the first pump (i.e. different PWM, where the overflow valve is closed).

[0017] In particular, it can be taken into account that the pressure losses of the second heating circuit are (significantly) lower than those of the first heating circuit.

[0018] It is known that as soon as the overflow valve opens, the first partial volume flow flowing through the first heating circuit remains essentially constant, even with increasing pump power. This means, in particular, that as soon as the overflow valve opens, the portion of the total volume flow that exceeds the total volume flow present at the opening point flows through the second heating circuit as the second partial volume flow.

[0019] In step b), a first partial volume flow (or its value) is defined that is to flow through the first heating circuit.

[0020] Within the scope of step c) and on the basis of the equation Qs = ax PWM + b as well as the known values ​​for Q s and a as well as b, the control signal PWM required for the first partial volume flow and to be set at the first pump can now be determined, namely by the equation PWM setpoint = (Qs - b) / a.

[0021] In step d), a value for the residual head H residual is determined, where H residual = H pump, HK1 - H loss, serial . Here, H pump, HK1 is known as the characteristic of the first pump and H loss, serial as the property of the heat generator circuit (hydraulic components within the device, essentially: condenser, controllable pump, volume flow sensor). The pump characteristic (i.e. head as a function of the volume flow delivered by the first pump at a certain speed / PWM) is always known, as it can be clearly determined by measurement. This relationship can be mapped into a software function using a polynomial approach (the volume flow corresponds to the total volume flow and is known from step b), whereby the required speed or control signal is then also known from step c).The difference between the head of the first pump H Pump, HK1 and the pressure losses of all serial hydraulic components in the heat generator circuit H loss, serial (these are always known for the respective device) results in the so-called residual head H Residual. The residual head indicates the usable head of the device at the interface between the device and the building's heating circuits. The residual head must be set so that the first heating circuit has exactly the head required to deliver the required flow rate in the first heating circuit.

[0022] In particular, the above-mentioned volume flow used to determine the residual head corresponds to the first partial volume flow determined in step b) and required for the first heating circuit. In particular, if the overflow valve opens upon increasing the total volume flow, the first partial volume flow then flowing through the first heating circuit remains constant, with the excess portion of the total volume flow then flowing as the second partial volume flow through the second heating circuit via the opened overflow valve.

[0023] Using the equations mentioned above, the residual head H Resid can now be determined, at which the first partial flow required for the first heating circuit, or its defined value, is reached. If this residual head value is set on the mechanical overflow valve, the head there is limited to the required value, and the defined value of the first partial flow in the first heating circuit is always reached when the overflow valve opens. Any flow rate that is pumped through the heat generator circuit in addition to this flow rate value is pumped into the second heating circuit.

[0024] This procedure enables precise adjustment of the overflow valve to achieve a desired volume flow distribution (division of the total volume flow into the first partial volume flow and the second partial volume flow).

[0025] In particular, when the overflow valve is closed, Qs = Q 1 ; where at the time of opening or when the overflow valve is opened, Qs = Q 1 , OP ; where when the overflow valve is open, Q 2 = QS - Q 1, OP ; where Q 2 is the second partial volume flow flowing through the second heating circuit.

[0026] As already mentioned above, it can be taken into account in particular that the pressure losses of the second heating circuit are (significantly) lower than those of the first heating circuit.

[0027] As soon as the overflow valve opens, the first partial volume flow Q 1 flowing through the first heating circuit remains essentially constant even with increasing pump power, i.e., it continues to correspond to Q 1 , OP to a sufficiently good approximation. This means, in particular, that as soon as the overflow valve opens, the portion of the total volume flow that exceeds the total volume flow present at the opening point flows through the second heating circuit as the second partial volume flow.

[0028] In particular, the total volume flow is recorded by a volume flow sensor.

[0029] In particular, the total volume flow flows through a condenser of a heat pump. In the condenser, a refrigerant used to operate the heat pump is liquefied again, with the heat released being used to heat the fluid flowing through the heat generator circuit or the heating circuits.

[0030] Furthermore, a heating system is proposed which has at least one component for heating, ventilating or air-conditioning a room volume and a control device, wherein the control device has means which are suitably equipped, configured and / or programmed to carry out the described method or carry out the method.

[0031] Furthermore, a control device for the described heating system is proposed, wherein the control device has means that are suitably equipped, configured and / or programmed to carry out the described method or carry out the method.

[0032] The means comprise, for example, a processor and a memory in which instructions to be executed by the processor are stored, as well as data lines or transmission devices that enable the transmission of instructions, measured values, data or the like between the means and the control unit and the heating system or component (and, for example, the volume flow sensors, valves, etc. provided in the heating system).

[0033] The "means" may in particular comprise one or more of the following components: controller(s), microcontroller, data memory, data connection, display devices (such as a display), counter or timer, at least one further sensor, an energy source, etc.

[0034] A computer program is further proposed, comprising instructions which, when the computer program is executed by a computer, cause the computer to carry out the described method or the steps of the described method.

[0035] Furthermore, a computer-readable storage medium is proposed, comprising instructions which, when executed by a computer, cause the computer to carry out the described method or the steps of the described method.

[0036] The statements regarding the method are particularly transferable to the heating, ventilation and / or air conditioning system or the component, the control unit and / or the computer-implemented method (i.e. the computer program and the computer-readable storage medium) and vice versa.

[0037] As a precaution, it should be noted that the numerals used here ("first", "second", ...) primarily serve (only) to distinguish between several similar objects, quantities, or processes, and therefore do not necessarily specify any interdependence and / or sequence of these objects, quantities, or processes. Should a dependence and / or sequence be required, this is explicitly stated here or will be obvious to the person skilled in the art upon studying the specifically described embodiment. To the extent that a component can occur multiple times ("at least one"), the description of one of these components may apply equally to all or part of the majority of these components, but this is not mandatory.

[0038] The proposed method is intended, in particular, to enable simpler and more precise adjustment of the overflow valve or its opening depending on the differential pressure across the overflow valve in a heating system with indeterminate measurement capabilities. In particular, this can eliminate the need for sensors (at least one flow sensor), hydraulic separators, or additional pumps.

[0039] The invention and the technical environment are explained in more detail below with reference to the accompanying figures. It should be noted that the invention is not intended to be limited by the exemplary embodiments cited. In particular, unless explicitly stated otherwise, it is also possible to extract partial aspects of the facts explained in the figures and combine them with other components and findings from the present description. In particular, it should be noted that the figures, and in particular the proportions shown, are only schematic. They show: Figure 1: a heating system; and Figure 2: a diagram.

[0040] Fig. 1 shows a heating system 2. Fig. 2 shows a diagram. The horizontal axis shows the control signal PWM 7 (in [%]) of the first pump. The vertical axis shows the volume flow 6 (in [liters per hour]). Fig. 1and 2 are described together below.

[0041] The heating system 2 comprises a first heating circuit 3 connected to a heat generator circuit 17, in which the first pump 5 is arranged. The first heating circuit 3 is intended, for example, for heating radiators in a building and thus for heating a room volume 14. The second heating circuit 4 is assigned, for example, to an underfloor heating system for heating a (different) room volume 14. The second heating circuit 4 or its flow is connected to the first heating circuit 3 or the heat generator circuit 17 (or their course) via an overflow valve 1. The overflow valve 1 generates a freely adjustable pressure loss via a valve disk, e.g., spring-biased, and can thus be used as an adjustment device for the hydraulic balancing of the heating circuits 3, 4.As soon as a differential pressure applied to the overflow valve 1 exceeds a set value (this value is the residual delivery head H residual after step e), the overflow valve 1 opens and thus connects the second heating circuit 4 to the first heating circuit 3 or the heat generator circuit 17. In the heat generator circuit 17 (in this case upstream of the first pump 5) there is a volume flow sensor 10, by means of which the total volume flow 6 delivered by the first pump 5 can be or is determined at any time. The heating system 2 comprises a control unit 15 which has means 16 (e.g. the overflow valve 1, the volume flow sensor 10 and the first pump 5 which can be controlled via control signals 7) for carrying out the described method.

[0042] Before the overflow valve 1 opens, the entire total volume flow Qs 6 flows through the first heating circuit 3. It has been found that in this state of the heating system 2, a linear relationship exists between the control signal PWM 7 (in [%] of the first pump 5 and the volume flow in the heat generator circuit 17 or first heating circuit 3, which can then be described by the equation Qs = ax PWM + b (see also Fig. 2, in which the linear relationship that exists until the overflow valve 1 opens is shown for a control signal 7 from 0 to approximately 62%). This linear relationship changes as soon as the overflow valve 1 opens (see Fig. 2, with a control signal 7 of approximately 62%), the overflow valve 1 opens). The opening (time) point 18 of the overflow valve 1 can be detected from the change in this characteristic (i.e. when the linear relationship no longer exists).

[0043] To determine the opening point 18 of the overflow valve 1, the linear equation is first determined according to step a) of the method, wherein Qs 6 and the respectively set control signal 7 (PWM) are known, so that the parameters a and b can already be determined from two operating points of the first pump 5 (i.e. different PWM 7, wherein the overflow valve 1 is closed).

[0044] In particular, it can be taken into account that the pressure losses of the second heating circuit 4 are (significantly) lower than those of the first heating circuit 3.

[0045] It is known that as soon as the overflow valve 1 opens, the first partial volume flow Q 1 8 flowing through the first heating circuit 3 remains essentially constant even with increasing pump power (see Fig. 2, between the values ​​62% and 100% of the control signal 7). This means, in particular, that as soon as the overflow valve 1 opens, the portion of the total volume flow Qs 6 that exceeds the total volume flow Qs 6 present at the opening point 18 flows through the second heating circuit 4 as the second partial volume flow Q 2 9.

[0046] In step b), a first partial volume flow Q 1 8 (or its value) is defined, which is to flow through the first heating circuit 3.

[0047] Within the scope of step c) and on the basis of the equation Qs = ax PWM + b as well as the known values ​​for Q s 6 and a and b, the control signal PWM 7 required for the first partial volume flow Q 1 8 and to be set at the first pump 5 can now be determined, namely by the equation PWM Soll = (Qs - b) / a.

[0048] In step d), a value for a residual delivery head H residual is determined, where H residual = H pump, HK1 - H loss, serial . H pump, HK1 is known as the characteristic of the first pump 5 and H loss, serial as the property of the heat generator circuit 17. The pump characteristic (i.e. delivery head as a function of the volume flow delivered by the first pump 5 at a specific speed) is always known, since it can be determined unambiguously by measurement. This relationship can be mapped using a polynomial approach in a software function (e.g. in the control unit 15) (the volume flow corresponds to the total volume flow Qs 6 and is known from step b), whereby the required speed is then also known from the pump characteristic).The difference between the delivery head of the first pump 5 H Pump, HK1 and the pressure losses of all serial hydraulic components 13 in the heating system 2 H loss,seriell (these are always known for the respective heating system 2) results in the so-called residual delivery head H Rest .

[0049] In particular, the above-mentioned volume flow used to determine the residual delivery head corresponds to the first partial volume flow Q 1 8 determined according to step b) and required for the first heating circuit 3. In particular, if the overflow valve 1 opens when the total volume flow Q s 6 increases, the first partial volume flow Q 1 8 then flowing through the first heating circuit 3 remains constant beyond that, with the excess part of the total volume flow Q s 6 then flowing as the second partial volume flow Q 2 9 via the opened overflow valve 1 through the second heating circuit 4.

[0050] Using the equations mentioned above, the residual delivery head H Rest can now be determined at which the first partial volume flow Q 1 8 required for the first heating circuit 3, or its defined value, is reached. If this value of the residual delivery head is set on the mechanical overflow valve 1, the defined value of the first partial volume flow Q 1 8 in the first heating circuit 3 is always reached when the overflow valve 1 opens. Any volume flow that is delivered through the heat generator circuit 17 in addition to this value of the volume flow is delivered as a second partial volume flow Q 2 9 into the second heating circuit 4.

[0051] This procedure enables precise adjustment of the overflow valve 1 to achieve a desired volume flow distribution (division of the total volume flow Q s 6 into the first partial volume flow Q 1 8 and the second partial volume flow Q 2 9).

[0052] When the overflow valve 1 is closed, Qs = Q 1 ; where at the time of opening (opening point 18) or when the overflow valve 1 is opened, Qs = Q 1, OP ; where when the overflow valve 1 is open, Q 2 = Qs - Q 1, OP ; where Q 2 9 is the second partial volume flow 9 flowing through the second heating circuit 4.

[0053] As already mentioned above, it can be taken into account in particular that the pressure losses of the second heating circuit 4 are (significantly) lower than those of the first heating circuit 3.

[0054] As soon as the overflow valve 1 opens, the first partial volume flow Q 1 8 flowing through the first heating circuit 3 remains essentially constant even with increasing pump power, i.e., it continues to correspond to Q 1, OP (see Fig. 2, curve 8 between the values ​​62% and 100% of the control signal 7). This means that as soon as the overflow valve 1 opens, the portion of the total volume flow Q s 6 that exceeds the total volume flow Q s 6 present at the opening point 18 flows as the second partial volume flow Q 2 9 through the second heating circuit 4.

[0055] The total volume flow Q s 6 is recorded by a volume flow sensor 10.

[0056] The total volume flow Q s 6 flows through a condenser 11 of a heat pump 12. In the condenser 11, a refrigerant used to operate the heat pump 12 is liquefied again, the heat released being used to heat the liquid flowing through the heat generator circuit 17 or the heating circuits 3, 4. List of reference symbols

[0057] 1Overflow valve 2Heating system (or heating, ventilation and / or air conditioning system) 3First heating circuit 4Second heating circuit 5First pump 6Total volume flow Qs 7Control signal 8First partial volume flow Q 1 9Second partial volume flow Q 2 10Volume flow sensor 11Condenser 12Heat pump 13Component 14Room volume 15Control unit 16Medium 17Heat generator circuit 18Opening point

Claims

1. A method for adjusting an overflow valve (1) in a heating system (2), wherein the heating system (2) has a heat generator circuit (17), two parallel heating circuits (3, 4) and a controllable first pump (5) for adjusting a total volume flow Qs (6) to the two heating circuits (3, 4); wherein the second heating circuit (4) is fluidically connected to the first pump (5) via the overflow valve (1), and wherein the total volume flow Qs (6) conveyed by the first pump (5) and flowing through the heat generator circuit (17) is measured, characterized in thatthe method comprises at least the following steps: a) determining a relationship between a control of the first pump (5) and the total volume flow Qs (6) flowing through the heat generator circuit using the equation Qs = ax PWM + b by operating the first pump (5), wherein the overflow valve (1) is closed; with a and b as constant parameters and with PWM as the control signal (7) of the first pump (5); b) setting a required value for the first partial volume flow Q1 (8) flowing through the first heating circuit (3); c) determining a control signal (7) required to adjust the first partial volume flow (8) using the equation PWM Soll = (Qs - b) / a; where the parameters a and b were determined in step a) and Qs (6) is specified; d) Determining the value of the residual head H Rest , where H Rest = H Pumpe, HK1 - H verlust,se-riell ; where H Pumpe, HK1 as characteristic of the first pump (5) and H verlust,seriellare known as a property of the heat generator circuit (17); e) setting the value H Rest on the overflow valve (1).

2. Method according to claim 1, characterized in that when the overflow valve (1) is closed, Qs = Q1; where at the time of opening of the overflow valve (1), Qs = Q 1, OP ; where when the overflow valve (1) is open, Q2 = Qs - Q 1, OP ; where Q2 is the second partial volume flow (9) flowing through the second heating circuit (4).

3. Method according to claim 1 or 2, characterized in that the total volume flow Qs (6) is detected by a volume flow sensor (10).

4. Method according to one of claims 1 to 3, characterized in that the total volume flow Qs (6) flows through a condenser (11) of a heat pump (12).

5. Heating system (2), comprising at least one component (13) for heating, ventilating or air-conditioning a room volume (14) and a control device (15), wherein the control device (15) has means (16) which are suitably configured for carrying out the method according to one of the preceding claims.

6. Control device (15) for a heating system (2) according to claim 5, wherein the control device (15) comprises means (16) suitably configured to carry out the method according to one of the preceding claims.

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