Method for operating a heating device, heating device and computer program

Abstract

A method is proposed for operating a heating device (1) which has at least one combustion chamber (2) with a burner (3) for burning a supplied gas mixture (4) and a heatable temperature sensor (5) for determining a temperature of a flame (6) of the gas mixture (7) burned by the burner (3) with a temperature-dependent resistance;wherein a relative increase in a power parameter is used for combustion control, and the relative increase in the power parameter is determined based on a first power parameter value (28) and a second power parameter value (30), wherein the second power parameter value (30) is detected while an electrical power of the temperature sensor (5) is being controlled to a predetermined electrical power, and the first power parameter value (28) is detected before switching on (21) or after switching off (22) the electrical power of the temperature sensor (5) to the predetermined power. In addition, a heater (1) and a computer program (33) are proposed. The method enables particularly precise and long-term stable combustion control of the heater (1). In addition, a heater (1) and a computer program (33) are proposed.;

Description

[0001] The invention relates to a method for operating a heater, a heater and a computer program.

[0002] A large number of heating devices are known which burn a mixture of a fuel, in particular a gas or hydrogen, and ambient air in a combustion chamber in order to generate heat to supply a building or to provide hot water.

[0003] Gas-fired heaters fueled by fossil fuels often utilize the ionization effect, which can be measured based on freely available charge carriers in the flame and at least one electrode in the flame. The measured ionization current then acts as a control variable to adjust the composition of the gas mixture in the heater. The central physical relationship underlying these systems is a change in the electrical flame resistance depending on the composition of the respective gas mixture.

[0004] Furthermore, DE 10 2004 055 716 C5 and DE 10 2004 063 992 B4 also disclose methods that use temperature measurement in the combustion chamber ("flame temperature") to regulate or control the gas-air mixture. Both methods involve calibration procedures designed to compensate for tolerances and aging effects. For this purpose, a reference condition, e.g., at a lambda value of 1 or the point of flame lift (from the burner), is often approached and compared with the underlying operating point of the heater.

[0005] The otherwise very robust option of flame monitoring by detecting the ionization current of the flame is not applicable, or only to a very limited extent, for hydrogen combustion because a hydrogen flame releases too few charge carriers. Therefore, other sensors are used for flame monitoring and combustion control during hydrogen combustion, such as optical sensors (e.g., UV (ultraviolet) sensors) for detecting the UV radiation emitted by the flame or temperature sensors for detecting the flame temperature. The disadvantage of such sensors is generally sensor drift, which can occur with age. Last but not least, with temperature sensors or optical sensors, there is the problem of potential interference from contamination.

[0006] Common temperature sensors used for mixture control, for example, have a temperature-dependent resistance that is measured (e.g., PTC resistors - "positive temperature coefficient" resistors, or HSI - "hot surface igniter"). The resistance of the temperature sensor is subject to the aforementioned aging effects, such as those resulting from oxidation or contamination. Such a drift in the resistance leads over time to incorrect temperature measurements and thus to errors in the control of the gas mixture composition. The same applies to component variation in the sensors, but also in other components of the heater, which can also result in a deviation in the regulated lambda value. Especially when controlling the gas mixture during hydrogen combustion, this can lead to an increased risk of backfiring or to an increased concentration of unburned hydrogen in the exhaust gas.

[0007] Furthermore, the reference state at a lambda value of 1 (stoichiometric combustion) is problematic for pure hydrogen combustion, as this poses an increased risk of backfiring. Flame liftoff is not clearly visible in hydrogen, so this state cannot be used as a reference either.

[0008] DE 10 2022 123 899 A1 describes a method for determining the combustion air ratio of a heater using a flame temperature sensor. An operating point of the heater is detected, the flame temperature sensor is then heated, and the supplied mass flow of combustion air is increased until the flame temperature sensor has cooled to the temperature before heating. The disadvantage of this method is that it is time-consuming and cannot detect or compensate for sensor drift of the flame temperature sensor.

[0009] Based on this, the object of the invention is to propose a method for operating a heater, a heater, and a computer program that at least partially overcome the described problems of the prior art. In particular, the invention is intended to enable combustion control or control of the composition of a gas-air mixture (hereinafter also referred to as the gas mixture) that ensures, at all permissible operating points (i.e., those occurring during normal operation), that the composition of the gas mixture intended for the respective operating point can be adjusted or regulated as precisely as possible.

[0010] These objects are achieved by the features of the independent patent claim. Further advantageous embodiments of the solution proposed here are specified in the dependent patent claims. It is pointed out 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 specified in the patent claims are further specified and explained in the description, with further preferred embodiments of the invention being presented.

[0011] A method for operating a heater contributes to this. The heater has at least one combustion chamber with a burner for combusting a gas mixture supplied (to the burner or the combustion chamber), and a temperature sensor with a temperature-dependent electrical resistance for determining a temperature of a flame of the gas mixture combusted by the burner. A relative increase in a power parameter is used for combustion control, wherein the relative increase in the power parameter is determined based on a first power parameter value and a second power parameter value. For this purpose, the second power parameter value is detected while controlling an electrical power of the temperature sensor to a predetermined power, and the first power parameter value is detected before the start or after the end of controlling the electrical power of the temperature sensor to the predetermined power.

[0012] The method is used to control the combustion of the heater, in particular to adjust the gas mixture or its composition. Thus, a combustion air ratio (also referred to as lambda or air ratio) can be derived or determined from the relative increase in the power parameter, which can be used to control combustion. Therefore, the method can be performed continuously during operation of the heater. In particular, a proposed method can be carried out fully automatically on a control unit of the heater.

[0013] Advantageously, any sensor drift that may occur in the temperature sensor has no influence on the relative increase in the performance parameter. In this respect, the method can enable particularly long-term stable combustion control of the heater.

[0014] The electrical output of the temperature sensor can be regulated to the specified output using a suitable controller, such as a PI controller. In other words, a voltage is applied to the temperature sensor, causing a current to flow. The controller can regulate the electrical output, which corresponds to the product as voltage and current, to the specified output. The specified output can be selected to cause a relevant temperature rise above a limit value. For a heater, this can vary depending on the temperature sensor used. For example, a suitable output can range from 2 watts to 20 watts. If necessary, a suitable output that enables precise combustion control can be determined through laboratory tests.Before the start or after the end of the regulation of the temperature sensor's electrical power, this refers to periods in which the temperature sensor's power regulation is inactive. In particular, the temperature sensor cannot be energized before and after the start and end of the regulation, so the temperature sensor is not heated. During the regulation of the temperature sensor's power, the power regulation is active, meaning that the temperature sensor's electrical power is regulated, thus heating it.

[0015] The heater can in particular comprise at least one combustion chamber as a heat generator, in particular a gas condensing boiler. The heat generator releases thermal energy through the combustion of a fuel and can transfer this to a heating circuit via at least one heat exchanger, wherein consumers of the heating circuit can be connected to the heater via a flow and a return. The exhaust gases produced during combustion can be fed to an exhaust system via an exhaust duct of the heater. In the heater, a circulation pump in the heating circuit can be configured to circulate a heat transfer medium (heating water), wherein heat transfer medium heated via a heating flow can be fed to consumers, such as convectors or surface heating systems, and returned to the heat generator or the at least one heat exchanger via a heating return.

[0016] For this purpose, the heater can have a conveying device, in particular a fan, which can supply a mixture of combustion air and fuel (e.g., hydrogen) to a burner of the heater via a mixture channel. The conveying device can comprise a power control, in particular a speed controller. The speed controller can usually provide a speed signal of the fan. The heater can, for example, have an electronic gas-air system in which, based on a signal from a flame monitor, conclusions can be drawn about the flame(s) and the combustion air ratio (also referred to as lambda or air ratio), thus enabling control of the combustion air ratio or the composition of the gas mixture.

[0017] The burner can, for example, comprise at least one flat perforated plate or a cylindrical perforated plate arranged between a burner cavity and the combustion chamber. The burner cavity can be connected to the mixture channel in such a way that the gas mixture can flow from the mixture channel through the burner cavity, exit the perforated plate, and be combusted there. An ignition device can also be arranged in the region of the perforated plate, designed to ignite a mass flow of the gas mixture exiting through the perforated plate.

[0018] The heater can be designed, in particular, to burn hydrogen as a fuel or a mixture containing hydrogen. The fuel mixture can have a hydrogen content of at least 55%, at least 80%, or at least 90%.

[0019] The heater has a flame monitor. The flame temperature can be detected using a suitably positioned temperature sensor, in particular a PTC (positive temperature coefficient thermistor) resistor or sensor or a hot-surface igniter (HSI). A method proposed here can be implemented, in particular, using a temperature sensor of the flame monitor. A signal from the flame monitor or temperature sensor can indicate the presence of a flame and allow for inference about the combustion air ratio during combustion, thus enabling control of the composition of the gas mixture.

[0020] In particular, the heater comprises a control unit that is designed to at least regulate the composition of the gas mixture supplied to the combustion chamber or to regulate the combustion of the gas mixture based on the relative increase in the power parameter. In particular, the control unit is also designed to carry out the described method.

[0021] According to one embodiment, the first performance parameter value and / or the second performance parameter value can be detected in a steady-state state of the performance parameter. A steady-state state is characterized by a parameter to be detected that does not oscillate or does not oscillate within a predetermined tolerance range, and thus only moves within predetermined tolerances within a predetermined period of time. In other words, the performance parameter is largely stationary during detection. This may be particularly relevant when detecting the second performance parameter value, since a settling or stabilization of the temperature sensor's power control should be waited for before detection occurs.However, a transient response may also occur when the first power parameter value is recorded after the electrical power of the temperature sensor has been adjusted to the specified power or as a result of a modulation process of the heater prior to the execution of a process.

[0022] According to one embodiment, the relative increase in the performance parameter can be determined by dividing the second performance parameter value by the first performance parameter value. This can be done automatically on the control unit of the heater.

[0023] According to a continuation, the relative increase of the performance parameter can be determined as follows: rAL = LP 1 LP 2 − 1 This corresponds to rAL the relative increase of the performance parameter, LP1 the first performance parameter value, and LP" the second performance parameter value.

[0024] According to one embodiment, combustion control can be carried out at least based on the relative increase in the performance parameter, a detected air mass flow or a detected speed of the conveying device, and predefined reference data. For clarification, a detected air mass flow and / or a detected speed of a conveying device of the heater can thus be used to determine a combustion parameter for combustion control. The detected air mass flow and the detected speed of the conveying device thus indicate two possible parameters that allow a conclusion to be drawn about the mass flow of combustion air flowing through the heater. The reference data can establish a relationship between the determined relative increase in the performance parameter and a combustion parameter, in particular the combustion air ratio.In particular, the reference data can establish a relationship between a combustion parameter to be determined (combustion air ratio) and the relative increase in the performance parameter in conjunction with the air mass flow recorded at the time the first and / or second performance parameter value is recorded or the speed of the conveying device recorded at the time the first and / or second performance parameter value is recorded. For this purpose, the reference data can be determined in advance in laboratory tests on a reference heater and stored, for example, in a memory of the heater's control unit. The inclusion of a recorded speed or a recorded air mass flow, since the relative increase in the performance parameter, particularly with a resistance value of the temperature sensor as a performance parameter, can depend on the occurring air mass flow.This relationship can also be taken into account by the reference data.

[0025] According to one embodiment, the performance parameter can be a detected electrical resistance of the temperature sensor. During the detection of the first performance parameter value and the second performance parameter value, the supplied air mass flow and the gas valve position are kept constant. In other words, the operating point of the heater is kept constant.

[0026] According to one embodiment, the first performance parameter value and the second performance parameter value can be a detected rotational speed of a conveying device of the heater or a detected supplied air mass flow. During the implementation of the method (i.e., during the detection of the first and second performance parameter values), a gas valve position is kept constant, and a resistance value of the temperature sensor is controlled using the air mass flow or the rotational speed as the actuator. For clarification, a sequence of events for this embodiment is described below as an example. The gas valve position, i.e., an opening position of the gas valve, is kept constant, and the resistance of the temperature sensor is controlled using the detected air mass flow or the detected rotational speed as the actuator. In other words, the detected air mass flow or the detected rotational speed is adjusted such that the resistance of the temperature sensor is kept constant.In this state, the first power parameter value and the second power parameter value can now be recorded, with the second power parameter value being recorded while regulating the electrical power of the temperature sensor to a predetermined power level. The first power parameter value corresponds to a recorded speed or a recorded air mass flow before or after the start or completion of regulating the electrical power of the temperature sensor to the predetermined power level, and the second power parameter value corresponds to the recorded speed and the recorded air mass flow while regulating the electrical power of the temperature sensor to the predetermined power level.

[0027] According to one embodiment, the performance parameter value can be a detected gas valve position of the heater. During the implementation of the method (i.e., during the detection of the first and second performance parameter values), a detected speed of a conveyor device of the heater or a detected supplied air mass flow is kept constant, and a resistance value of the temperature sensor is controlled using the gas valve position as an actuator. This embodiment can be understood as the inversion of the previously described embodiment. For clarification, a sequence of events for this embodiment is described below as an example. The air mass flow flowing through the heater or a speed of the conveyor device is kept constant, and the resistance of the temperature sensor is controlled using the detected gas valve position as an actuator.In other words, the detected gas valve position is adjusted such that the resistance of the temperature sensor is kept constant. In this state, the first power parameter value and the second power parameter value can now be detected, with the second power parameter value being detected while regulating the electrical power of the temperature sensor to a predetermined power. The first power parameter value corresponds to a detected gas valve position before the start or after the end of regulating the electrical power of the temperature sensor to the predetermined power, and the second power parameter value corresponds to the detected gas valve position during regulating the electrical power of the temperature sensor to the predetermined power.

[0028] In this context, it should be noted that the detected air mass flow can be the signal from a mass or volume flow sensor or a signal from a differential pressure sensor. Other options for detecting air mass flow, for example, using a temperature sensor, are also expressly included. The speed of the conveying device can be measured or recorded. Fans often provide a speed signal, or this is accessible to a combustion control system anyway. The speed signal can also be a control signal from a speed controller, which is often implemented as a PWM (pulse-width modulated) signal.

[0029] According to one embodiment, the first performance parameter value can be recorded before the electrical power of the temperature sensor is regulated to the specified power, and a third performance parameter value can be recorded after the electrical power of the temperature sensor is regulated to the specified power. In other words, a performance parameter value is recorded before, during, and after the electrical power of the temperature sensor is regulated to the specified power. This embodiment advantageously enables compensation for a drift in the operating point of the heater during the implementation of the method, for example, caused by a temperature change of the gas valve.

[0030] According to a further embodiment, in order to determine the relative increase in the performance parameter, the mean value of the first performance parameter value and the third performance parameter value can be formed and the relative increase in the performance parameter can be determined by the quotient of the second performance parameter value divided by the formed mean value.

[0031] A heating device is further proposed, comprising a conveying device for a gas mixture, a combustion chamber with a burner for burning the supplied gas mixture, a temperature sensor for determining a temperature of a flame of the gas mixture burned by the burner and a control unit which is designed at least for regulating the composition of the gas mixture supplied to the combustion chamber or for regulating the combustion of the gas mixture on the basis of the temperature measured by the temperature sensor and is suitable for carrying out the described method.

[0032] The electrically heatable temperature sensor has, in particular, a temperature-dependent electrical resistance. The combusted gas mixture has a lambda value / combustion air ratio. The temperature sensor has, in particular, an electrical voltage-resistance curve dependent on the lambda value.

[0033] In particular, at least one data processing system is provided which has means which are suitably equipped, configured or programmed to carry out the described method or which carry out the method.

[0034] In particular, the heating device comprises a data processing system, e.g., a control unit, which has means for executing the steps of the described method and / or has means that are suitably equipped, configured, or programmed to execute the steps of the method or that execute the method.

[0035] The means include, 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 elements mentioned.

[0036] 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.

[0037] Furthermore, a computer program is proposed, comprising instructions which cause the described heating device to carry out the described method or 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.

[0038] 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.

[0039] The statements regarding the method are particularly transferable to the heating device, the data processing system and / or the computer-implemented method (i.e. the computer program and the computer-readable storage medium) and vice versa.

[0040] The use of indefinite articles ("a," "an," "one," and "another"), particularly in the patent claims and the description reproducing them, is to be understood as such and not as a numeral. Terms or components introduced accordingly are therefore to be understood as being present at least once and, in particular, as being able to be present multiple times.

[0041] 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.

[0042] The details, features, and advantageous embodiments discussed in connection with the method may also be present in the computer program and / or the heating device presented here, and vice versa. In this respect, reference is made in full to the explanations therein for a more detailed characterization of the features.

[0043] 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: Fig. 1 : a heater proposed here, and Fig. 2, Fig 3 und Fig. 4 : Parameter curves that can occur when carrying out a procedure proposed here.

[0044] Fig. 1 shows a heater 1 that can include a burner 3 arranged in a combustion chamber 2. A heat exchanger 18 can be arranged on the combustion chamber 2, which heat exchanger transfers the heat generated during combustion to a heat transfer medium. Combustion air can be sucked in by a conveying device 9, in particular designed as a fan, via a combustion air supply 8, in which a flow sensor 12 can be arranged. The conveying device 9 can be connected to a speed controller 10, which can regulate a speed n of the conveying device 9 by means of a pulse width modulated (PWM) signal. A gas valve 13 can add fuel gas from a gas supply 14 to the sucked-in air mass flow of combustion air and can comprise a safety valve and a gas control valve for controlling the mass flow of fuel gas to be added.The generated gas mixture 4 of fuel gas and combustion air can flow via a mixture channel 11 to the burner 3 and combust there, forming a flame 6. The burner 3 can have a cylindrical shape, whereby the gas mixture 4 can flow from the mixture channel 11 into the burner 3. After combustion, the combusted gas mixture 7 can be fed to an exhaust system 16 via an exhaust channel 15 of the heater 1.

[0045] A control unit 17 can be configured to regulate the heater 1. For this purpose, it can be electrically connected, for example, to the speed controller 10, the conveyor device 9, the gas valve 13, a temperature sensor 5 arranged in the combustion chamber 2, and a network 19 (Internet). The control unit 17 can be configured to carry out the method proposed here and, for example, have a computer program 33 configured to carry out a method proposed here. The control unit 17 can be capable of regulating the composition of the gas mixture 4 supplied to the combustion chamber 2 and / or regulating the combustion of the gas mixture 4 based on the temperature measured by the temperature sensor 5.

[0046] The temperature sensor 5 of the heater 1 has a temperature-dependent resistance RT and is electrically heated. Fig. 2 shows a first curve 20 of the resistance RT of the temperature sensor 5 as a power parameter over time t, which can be established when carrying out a method proposed here. The heater 1 is operated with a lean gas mixture 4 while the first curve 20 is being recorded, for example with a combustion air ratio of 1.4. First, the power control of the temperature sensor 5 is switched on 21 to a predetermined power, as a result of which the resistance RT increases. The power of the temperature sensor 5 can be controlled, for example, with a PI controller to a power of 5 watts. After the resistance RT has stabilized, the second power parameter value 30 can be recorded in a period 23. The power control is then switched off 22.As a result, the resistance RT drops and oscillates, resulting in a period 24 after the oscillation for recording the first power parameter value 28. It is expressly pointed out that the first power parameter value 28 can also be recorded before the power control is switched on 21. A relative increase in the resistance RT as a power parameter can be determined by forming a quotient of the second power parameter value 30 divided by the first power parameter value 28. In the . Fig. 2 an absolute increase of 31 of the first trend of 20 is recorded.

[0047] Fig. 3 shows a second curve 25, which was recorded analogously to the first curve 20, but during the combustion of a rich gas mixture 4, for example with a combustion air ratio of 1.1. Here, too, an absolute increase 32 of the second curve 25 is recorded. The absolute increase 31, 32, and thus also the relative increase, is visible for a lean gas mixture 4 according to Fig. 2 significantly higher than with a rich gas mixture 4 according to Fig. 3 . In this respect, the relative increase in the performance parameter can allow a conclusion to be drawn about the current combustion air ratio of the supplied gas mixture 4 and can thus be used for combustion control of the heater 1.

[0048] Fig. 4shows a curve of the resistance RT as a power parameter as a third curve 26 in the event of a drift of the operating point 27, which can be caused, for example, by heating of the gas valve 13. A drift of the operating point 27 of the heater 1 can be compensated by detecting a first power parameter value 28 before switching on 21 the power control and a third power parameter value 29 after switching off 22 the power control. Before determining the relative increase in the power parameter, an average of the first power parameter value 28 and the third power parameter value 29 can be calculated, which at least partially compensates for the drift of the operating point. List of reference symbols

[0049] 1 Heater 2 Combustion chamber 3 Burner 4 Gas mixture 5 Temperature sensor 6 Flame 7 Combusted gas mixture 8 Combustion air supply 9 Conveyor system 10 Speed ​​control 11 Mixture duct 12 Flow sensor 13 Gas valve 14 Gas supply 15 Exhaust duct 16 Exhaust system 17 Control unit 18 Heat exchanger 19 Network 20 First curve 21 Switching on power control 22 Switching off power control 23 Period for recording first power parameter value 24 Period for recording second power parameter value 25 Second curve 26 Third curve 27 Drift operating point 28 First power parameter value 29 Third power parameter value 30 Second power parameter value 31 Absolute increase, first curve 32 Absolute increase, second curve 33 Computer program

Claims

1. Method for operating a heating device (1) which has at least one combustion chamber (2) with a burner (3) for burning a supplied gas mixture (4) and an electrically heatable temperature sensor (5) for determining a temperature of a flame (6) of the gas mixture (7) burned by the burner (3) with a temperature-dependent electrical resistance;wherein a relative increase in a power parameter is used for combustion control, and the relative increase in the power parameter is determined on the basis of a first power parameter value (28) and a second power parameter value (30), wherein the second power parameter value (30) is detected during regulation of an electrical power of the temperature sensor (5) to a predetermined electrical power, and the first power parameter value (28) is detected before switching on (21) or after switching off (22) the regulation of the electrical power of the temperature sensor (5) to the predetermined power.; 2. The method according to claim 1, wherein the first performance parameter value (28) and / or the second performance parameter value (30) is detected in a steady state of the performance parameter.

3. Method according to one of the preceding claims, wherein the relative increase in the performance parameter is determined by the quotient of the second performance parameter value (30) and the first performance parameter value (28).

4. Method according to one of the preceding claims, wherein the combustion control is carried out at least on the basis of the relative increase in the performance parameter, on the basis of a detected air mass flow or on the basis of a detected speed of the conveying device (9) and on the basis of predetermined reference data.

5. Method according to one of the preceding claims, wherein the performance parameter is a detected electrical resistance of the temperature sensor (5) and during the detection of the first performance parameter value (28) and the second performance parameter value (30) the supplied air mass flow and the gas valve position are kept constant.

6. The method according to any one of claims 1 to 4, wherein the first performance parameter value (28) and the second performance parameter value (30) is a detected rotational speed of a conveying device (9) of the heater (1) or a detected supplied air mass flow, and during the execution of the method, a gas valve position is kept constant and a resistance value of the temperature sensor (5) is controlled with the air mass flow or the rotational speed of the conveying device (9) as an actuator.

7. Method according to one of claims 1 to 4, wherein the performance parameter value is a detected gas valve position of the heater (1) and during the execution of the method a detected speed of a conveyor device (9) of the heater (1) or a detected supplied air mass flow is kept constant and a resistance value of the temperature sensor (5) is controlled by means of the gas valve position as an actuator.

8. Method according to one of the preceding claims, wherein the first power parameter value (28) is detected before regulating the electrical power of the temperature sensor (5) to the predetermined power, and a third power parameter value (29) is detected after regulating the electrical power of the temperature sensor (5) to the predetermined power.

9. The method according to claim 8, wherein the relative increase in the performance parameter is determined by forming the mean value of the first performance parameter value (28) and the third performance parameter value (29), and the relative increase in the performance parameter is determined by the quotient of the second performance parameter value (30) and the formed mean value.

10. Heating device (1) comprising a conveying device (9) for a gas mixture (4), a combustion chamber (2) with a burner (3) for burning the supplied gas mixture (4), a temperature sensor (5) for determining a temperature of a flame (6) of the gas mixture (7) burned by the burner (3), a control unit (17) which is designed to regulate the combustion of the gas mixture (4) based on at least one relative increase in a performance parameter, and means for carrying out a method according to one of claims 1 to 9.

11. A computer program (33) comprising instructions causing a heating device (1) according to claim 10 to carry out a method according to any one of claims 1 to 9.

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