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

Abstract

A method for operating a heating device (1) is proposed, which has at least one combustion chamber (2) with a burner (3) for burning a supplied gas mixture (4) and a temperature sensor (5) for determining the temperature of a flame (6) of the gas mixture (7) burned by the burner (3), wherein the temperature sensor (5) has a temperature-dependent resistance (8); wherein the burned gas mixture (7) has a lambda value (9) and the temperature sensor (5) is electrically heatable and has a voltage-resistance curve (10) that depends on the lambda value (9). Furthermore, a heating device (1) and a computer program (19) are proposed.

Description

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

[0002] A variety of heating appliances are known that burn a mixture of a fuel, especially a gas or hydrogen, and ambient air in a combustion chamber to generate heat for supplying a building or for providing hot water.

[0003] Gas-fired heating appliances that use 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 heating appliance. 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, methods are also known from DE 10 2004 055 716 C5 and DE 10 2004 063 992 B4 which regulate or control the gas-air mixture by measuring the temperature in the combustion chamber ("flame temperature"). Both methods include calibration procedures to compensate for tolerances and aging effects. A reference state is often used for this purpose, e.g., at a lambda value of 1 or the point of flame lift-off.

[0005] (from the burner) and this was compared with the underlying operating point of the heating device.

[0006] Another heating device that uses a measured temperature for combustion control is described in DE 10 2021 108 014 A1.

[0007] EP 4 137 745 A1 discloses a method for operating a heating appliance with a burner and combustion chamber. A temperature sensor is provided for determining the temperature of a flame of the gas mixture combusted by the burner, wherein the temperature sensor has a temperature-dependent resistance. The temperature sensor is electrically heatable. The method comprises the steps: a) setting an operating point of the heating appliance at which the gas mixture supplied to the combustion chamber has a constant composition; b) setting a voltage across the temperature sensor to a first voltage value; c) measuring and determining a first resistance value of the temperature sensor.

[0008] The otherwise very robust method of flame monitoring by detecting the flame's ionization current is not applicable, or only applicable to a very limited extent, in the combustion of hydrogen, as a hydrogen flame releases too few charge carriers. Therefore, other sensors are used for flame monitoring and combustion control in hydrogen combustion, such as optical sensors (e.g., UV (ultraviolet) sensors) to detect the UV radiation emitted by the flame, or temperature sensors to detect the flame's temperature. A disadvantage of such sensors is that they typically exhibit sensor drift, which can occur due to age. Finally, temperature sensors and optical sensors are susceptible to interference from contamination.

[0009] Common temperature sensors used for mixture control have a temperature-dependent resistance that is measured (e.g., PTC resistors – positive temperature coefficient resistors, or HSI resistors – hot surface igniters). The resistance of the temperature sensor is subject to the aforementioned aging effects, such as those caused by oxidation or contamination. Over time, such resistance drift leads to inaccurate temperature measurements and consequently to errors in the control of the gas mixture composition. The same applies to component variations in the sensors, as well as in other components of the heating device, which can also result in deviations from the regulated lambda value. Specifically, when controlling the gas mixture during hydrogen combustion, this can lead to an increased risk of backfire or a higher concentration of unburned hydrogen in the exhaust gas.

[0010] Furthermore, using a lambda value as a reference condition during pure hydrogen combustion is problematic, as this poses an increased risk of backfire. Flame lift is not clearly visible with hydrogen, so this condition cannot be used as a reference either.

[0011] Based on this, the object of the invention is to propose a method for operating a heating device, a heating device, and a computer program that at least partially overcome the problems of the prior art described above. In particular, the invention is intended to enable the control of the composition of a gas-air mixture (hereinafter also referred to as a gas mixture) in such a way that, at all permissible operating points (i.e., those occurring during intended operation), the composition of the gas mixture intended for the respective operating point can be set or regulated as precisely as possible.

[0012] These problems are solved by the features of the independent claim. Further advantageous embodiments of the solution proposed here are specified in the dependent claims. It should be noted that the features listed in the dependent claims can be combined with one another in any technologically meaningful way and define further embodiments of the invention. Furthermore, the features specified in the claims are further specified and explained in the description, which also presents further preferred embodiments of the invention.

[0013] This involves a method for operating a heating device. The heating device has at least one combustion chamber with a burner for burning a gas mixture supplied to the burner (or combustion chamber) and a temperature sensor for determining the temperature of a flame of the gas mixture burned by the burner. The temperature sensor has a temperature-dependent resistance. The burned gas mixture has a lambda value. The temperature sensor is electrically heatable and exhibits a voltage-resistance curve that depends on the lambda value. The method comprises at least the following steps. a) Setting an operating point of the heating device at which the gas mixture supplied to the combustion chamber has a constant composition; b) Setting a voltage at the temperature sensor to a first voltage value; c) Measuring and determining a first resistance value of the temperature sensor; d) Changing the voltage at the temperature sensor to a second voltage value; e) Measuring and determining a second resistance value of the temperature sensor; f) Determining the slope of a voltage-resistance curve and determining the lambda value of the gas mixture.

[0014] The above (non-exhaustive) classification of the process steps into a) to f) is primarily intended for differentiation purposes and does not impose any sequence or dependency. The frequency of the process steps, e.g., during operation of the heating device, can also vary. It is also possible that process steps may overlap, at least partially. Process steps b) to e) preferably take place during step a). In particular, step f) takes place after steps a) to e). Specifically, steps a) to f) are carried out in the order listed.

[0015] The heating appliance can, in particular, include at least one combustion chamber as a heat generator, especially a gas condensing boiler. The heat generator releases thermal energy through the combustion of a fuel and can transfer this energy to a heating circuit via at least one heat exchanger. Consumers in the heating circuit can be connected to the heating appliance via a flow and a return line. The exhaust gases produced during combustion can be routed to an exhaust system via an exhaust duct in the heating appliance. A circulation pump can be installed in the heating circuit of the heating appliance to circulate a heat transfer medium (heating water). Heated heat transfer medium is supplied to consumers, such as convectors or underfloor heating systems, via a heating flow line and returned to the heat generator or the at least one heat exchanger via a heating return line.

[0016] For this purpose, the heating appliance may, in particular, include a conveying device, especially a blower, which can supply a mixture of combustion air and fuel (e.g., hydrogen) to a burner of the heating appliance via a mixture channel. The conveying device may include a power control, in particular a speed controller. The heating appliance may, for example, have an electronic gas-air mixture control system in which a signal from a flame monitoring system allows conclusions to be drawn about the flame(s) and the combustion air-fuel ratio (also known as lambda or air-fuel ratio), thus enabling control of the combustion air-fuel ratio or the composition of the gas mixture.

[0017] The burner can, for example, comprise at least one flat perforated plate or a perforated plate in the shape of a cylinder, which is 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 area of ​​the perforated plate, configured to ignite a mass flow of the gas mixture exiting through the perforated plate.

[0018] The heating appliance can be specifically designed for burning hydrogen as fuel or a mixture containing hydrogen. The fuel mixture can have a hydrogen content of at least 80% or at least 90%.

[0019] The heater features flame monitoring. The flame temperature can be detected by means of a suitably positioned temperature sensor, in particular a PTC (positive temperature coefficient thermistor) resistor or sensor, or a hot-surface igniter (HSI). A signal from the flame monitor or temperature sensor can indicate the presence of a flame and allow conclusions to be drawn about the combustion air-fuel ratio, thus enabling control of the gas mixture composition.

[0020] In particular, the heating device includes a control unit that is suitable for regulating at least the composition of the gas mixture supplied to the combustion chamber or for regulating the combustion of the gas mixture based on the temperature measured by the temperature sensor. In particular, the control unit is also suitable for carrying out the described procedure.

[0021] According to step a) of the procedure, an operating point of the heating device is set at which the gas mixture supplied to the combustion chamber (e.g. via the mixture channel) has a constant composition (and a constant mass flow).

[0022] According to step b), a voltage is applied to the temperature sensor to a first voltage value. The temperature sensor can be electrically heated or supplied with an electric current. A predetermined first voltage value or voltage potential is set via a current source connected to the temperature sensor.

[0023] According to step c), a first resistance value of the temperature sensor is measured and determined. This resistance value can be determined in a known manner based on the known parameters (first voltage value, current of the electric current flowing through the temperature sensor).

[0024] In step d), the voltage at the temperature sensor is changed (increased or decreased) to a second voltage value. The explanations for step b) apply accordingly.

[0025] According to step e), a second resistance value of the temperature sensor is measured and determined. This resistance value can also be determined in a known manner based on the known parameters (second voltage value, current of the electric current flowing through the temperature sensor).

[0026] According to step f), the slope of a voltage-resistance curve is determined and the lambda value of the gas mixture is determined.

[0027] The proposed method exploits the changing behavior of the temperature sensor depending on the lambda value. The temperature sensor exhibits a voltage-resistance curve that is dependent on the lambda value; that is, as the applied voltage increases, the resistance of the temperature sensor also increases, with the slope of the respective curve changing in particular depending on the lambda value.

[0028] In a further step (g), the lambda value determined in step (f) is used, at least for a first control process to regulate the composition of the gas mixture supplied to the combustion chamber, or for a second control process to regulate the combustion of the gas mixture. Specifically, the lambda value determined in step (f) is used for both control processes. These control processes are hereinafter also referred to as the control of the heating appliance.

[0029] The first control process includes, in particular, the control of the composition of the gas mixture. The second control process includes, in particular, the control of the combustion of the gas mixture, e.g., the mass flow rate of the gas mixture.

[0030] In particular, steps a) to g) are performed as a calibration process to calibrate the respective control system. Specifically, after the calibration process, the heating device is operated taking into account the last determined lambda value.

[0031] In particular, steps a) to g) are each carried out as a calibration process, with the heating device operating as intended between two such calibration processes, in which the combustion process of the gas mixture is regulated (exclusively) on the basis of a temperature of the flame measured by the temperature sensor and determined on the basis of the measurement.

[0032] In particular, during normal operation of the heating device, at least one control process is carried out on the basis of a temperature of the flame measured by the temperature sensor and determined on the basis of the measurement, whereby in step g) the temperature sensor is calibrated, i.e. its measurement result is changed by a correction value.

[0033] In particular, steps a) to g) are carried out as a calibration process to calibrate the temperature sensor, whereby after the calibration process the heating device uses the measurement results of the temperature sensor changed by the correction value for the respective control.

[0034] In particular, the heating device is controlled based on the measured and subsequently determined flame temperature. This control involves adjusting the gas mixture composition depending on the determined temperature. The measurement is performed by the temperature sensor, which is subject to aging processes. To compensate for these aging processes and their influence on the measurement result, it is proposed to calibrate the temperature sensor. This calibration specifically utilizes the fact that the temperature sensor can be subjected to an electrical current or voltage and that its voltage-resistance curve is dependent on the lambda value.

[0035] The gas mixture composition, which is set according to a specific temperature, is only a target value that can be verified through the temperature sensor calibration process. If a lambda value determined in step f) deviates from the supposedly set target value, this indicates aging, and the temperature sensor should be recalibrated. This means that the temperature measured by the sensor must be adjusted by a correction value to determine the correct (actual) flame temperature.

[0036] With such a calibrated temperature sensor, the actual temperature of the flame can at least be determined better, and thus the control of the composition of the gas mixture and therefore the lambda value can be carried out more precisely.

[0037] In particular, the temperature sensor includes a PTC resistor or an HSI.

[0038] In particular, the supplied gas mixture contains at least hydrogen.

[0039] In particular, the supplied gas mixture contains only ambient air and hydrogen.

[0040] The proposed procedure can be carried out at fixed or varying intervals. This allows for regular monitoring of the temperature sensor's aging process. In particular, the procedure can also be performed during normal operation of the heating device, as the current operating point does not need to be changed.

[0041] 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 the temperature of a flame of the gas mixture burned by the burner, and a control unit that is designed to regulate at least the composition of the gas mixture supplied to the combustion chamber or the combustion of the gas mixture based on the temperature measured by the temperature sensor and is suitable for carrying out the described procedure.

[0042] The temperature sensor exhibits a temperature-dependent resistance. The combusted gas mixture has a lambda value. The temperature sensor is electrically heatable and exhibits a voltage-resistance curve that depends on the lambda value.

[0043] In particular, at least one data processing system is provided which includes means that are appropriately equipped, configured or programmed to carry out the described procedure, or that execute the procedure.

[0044] In particular, the heating device includes a data processing system, e.g. a control unit, which has means for carrying out the steps of the described procedure and / or has means that are suitably equipped, configured or programmed to carry out the steps of the procedure or that carry out the procedure.

[0045] 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, measurements, data or the like between the aforementioned elements.

[0046] The "means" may include, in particular, one or more of the following components: control(s), microcontroller, data storage, data connection, display devices (such as a display), counter or timer, at least one other sensor, a power source, etc.

[0047] Furthermore, a computer program is proposed, comprising commands that cause the described heating device to perform the steps of the described procedure, or that, when the computer program is executed by a computer, cause it to perform the described procedure or the steps of the described procedure.

[0048] Furthermore, a computer-readable storage medium is proposed, comprising instructions which, when executed by a computer, cause it to perform the described procedure or the steps of the described procedure.

[0049] The explanations regarding the procedure are particularly applicable to the heating device, the data processing system and / or the computer-implemented procedure (i.e., the computer program and the computer-readable storage medium) and vice versa.

[0050] The use of indefinite articles ("a", "an", "a" and "one"), particularly in the patent claims and the description reproducing them, is to be understood as such and not as a numeral. Accordingly, terms or components introduced by these articles are to be understood as occurring at least once and, in particular, may also occur multiple times.

[0051] It should be noted as a precaution that the numerical terms used here ("first", "second", etc.) primarily serve (only) to distinguish between several similar objects, quantities, or processes, and thus do not necessarily dictate any dependency and / or sequence between these objects, quantities, or processes. Should a dependency and / or sequence be required, this is explicitly stated here, or it will be obvious to a person skilled in the art upon studying the specific configuration described. Where a component can occur multiple times ("at least one"), the description of one of these components may apply equally to all or some of the multiple components, but this is not mandatory.

[0052] The invention and its technical context 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 shown. In particular, unless explicitly stated otherwise, it is also possible to extract partial aspects of the situations described in the figures and combine them with other components and findings from the present description. It should be emphasized that the figures, and especially the depicted dimensions, are only schematic. They show: Fig. 1: a heating device, Fig. 2: diagram, and Fig. 3: a sequence of the process.

[0053] Fig. 1 A heating device shows 1. Fig. 2 shows a diagram. Fig. 3 shows a sequence of events. Fig. 1 and 2The following sections describe them together. The vertical axis of the diagram shows the resistance 8 in ohms. The horizontal axis shows the voltage 11. The voltage-resistance curves 10 shown illustrate the dependence of the resistance 8 of the temperature sensor 5 on the voltage 11 applied to the resistance 8.

[0054] The in Fig. 3 The execution of steps a) to g) as shown in blocks 30, 31, 32, 33, 34, 35 and 36 can be carried out at least once in the specified order during a regular operating procedure. This procedure ensures the safe operation of the heating device 1, particularly when it is operated with hydrogen or a hydrogen-containing mixture as fuel.

[0055] The heating device 1 can include a burner 3 arranged in a combustion chamber 2. Combustion air can be drawn in via a combustion air supply 20, in which a flow sensor 25 may be arranged, by a conveying device 17, in particular designed as a blower. The conveying device 17 can be connected to a speed controller 22, which can regulate the speed n of the conveying device 17 by means of a pulse-width modulated (PWM) signal. A gas valve 21 can add fuel gas from a gas supply 26 to the intake air mass flow and may include 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 to the burner 3 via a mixture channel 24. The burner 3 can have a cylindrical shape, with the gas mixture 4 flowing from the mixture channel 24 into the burner 3.The burned gas mixture 7 can be discharged to the outside via an exhaust system 23 of the heating appliance 1 after combustion.

[0056] A control unit 18 can be configured to control the heating device 1. For this purpose, the heating device 1 can be electrically connected, for example, to the speed controller 22, the conveying device 17, the gas valve 21, a temperature sensor 5 arranged in the combustion chamber, a network 28 (Internet), and a display device 27. The control unit 18 can be configured to carry out the procedure proposed here and may, for example, include the computer program 19. The control unit 18 can be designed to control the composition of the gas mixture 4 supplied to the combustion chamber 2 and / or to control the combustion of the gas mixture 4 based on the temperature measured by the temperature sensor 5, and thereby be suitable for carrying out the described procedure.

[0057] The temperature sensor 5 of the heating device 1 has a temperature-dependent resistance 8. The combusted gas mixture 7 has a lambda value 9. The temperature sensor 5 is electrically heatable and exhibits a voltage-resistance curve 10 that depends on the lambda value 9.

[0058] In step a) of the procedure, an operating point of the heating device 1 is set at which the gas mixture 4 supplied to the combustion chamber 2 (e.g. via the mixture channel 24) has a constant composition (and a constant mass flow rate) (see first block 30 in Fig. 3 ).

[0059] In step b), a voltage 11 is set at the temperature sensor 5 to a first voltage value 12 (see second block 31 in Fig. 3 The temperature sensor 5 can be electrically heated or supplied with an electric current. A predetermined first voltage value 12 or voltage potential is set via a current source 29 connected to the temperature sensor 5.

[0060] According to step c), a first resistance value 13 of the temperature sensor 5 is measured and determined (see third block 32 in Fig. 3 ). This first resistance value 13 can be determined in a known manner based on the known parameters (first voltage value 12, current of the electric current flowing through the temperature sensor 5) e.g. by the control unit 18.

[0061] In step d) the voltage 11 at the temperature sensor 5 is changed (increased or decreased) to a second voltage value 14 (see fourth block 33 in Fig. 3 The explanations for step b) apply accordingly.

[0062] In step e) a second resistance value 15 of the temperature sensor 5 is measured and determined (see fifth block 34 in Fig. 3 ). This resistance value 15 can also be determined in a known manner based on the known parameters (second voltage value 14, current of the electric current flowing through the temperature sensor 5).

[0063] According to step f), a slope 16 of a course of the stress-resistance curve 10 is determined and the lambda value 9 of the gas mixture 7 is determined (see sixth block 35 in Fig. 3 ).

[0064] The proposed method utilizes the changing behavior of the temperature sensor 5 depending on the lambda value 9. The temperature sensor 5 exhibits a voltage-resistance curve 10 that depends on the lambda value 9; that is, as the applied voltage 11 increases, the resistance 8 of the temperature sensor 5 also increases, with the slope 16 of the respective curve 10 changing in particular depending on the lambda value 9.

[0065] In a further step g), the lambda value 9 determined in step f) can be used for a first control process to control the composition of the gas mixture 4 supplied to the combustion chamber 2 and / or for a second control process to control the combustion of the gas mixture 4 (see seventh block 36 in Fig. 3 ). The lambda value 9 determined in step f) can be used for both control processes.

[0066] Steps a) to g) are performed as a calibration process to calibrate the respective control system. In particular, after the calibration process, the heating device 1 is operated taking into account the last determined lambda value 9.

[0067] Steps a) to g) are therefore each carried out as a calibration process, whereby between two such calibration processes the heating device 1 is operated as intended, in which the combustion process of the gas mixture 4 is regulated (exclusively) on the basis of a temperature of the flame 6 measured by the temperature sensor 5 and determined on the basis of this measurement.

[0068] In the intended operation of the heating device 1, at least one control process is carried out on the basis of a temperature of the flame 6 measured by the temperature sensor 5 and determined on the basis of the measurement, wherein in step g) the temperature sensor 5 is calibrated, i.e. its measurement result is changed by a correction value.

[0069] Steps a) to g) are performed as a calibration process to calibrate the temperature sensor 5, whereby the heating device 1 uses the measurement results of the temperature sensor 5, modified by the correction value, for the respective control after the calibration process.

[0070] The heating device 1 is controlled based on the measured and subsequently determined temperature of the flame 6. The control system adjusts the composition of the gas mixture 4 according to the determined temperature. The measurement is performed by the temperature sensor 5, which is subject to aging processes. To compensate for these aging processes and their influence on the measurement result, it is proposed to calibrate the temperature sensor 5. This calibration takes advantage of the fact that the temperature sensor 5 can be subjected to an electric current or voltage 11 and that its voltage-resistance curve 10 is dependent on the lambda value 9.

[0071] The composition of the gas mixture 4, which is set depending on the specific temperature, is only a target value of the composition that can be verified by the calibration process of the temperature sensor 5. If a lambda value 9 is determined in step f) that deviates from the supposedly set target value, aging is obviously present and the temperature sensor 5 should be recalibrated, i.e., the temperature measured by the temperature sensor 5 must be changed by a correction value in order to determine the correct (actual) temperature of the flame 6.

[0072] With the temperature sensor 5 calibrated in this way, the actual temperature of the flame 6 can at least be determined better, and thus the control of the composition of the gas mixture 4 and the lambda value 9 can be determined more precisely.

[0073] The temperature sensor 5 includes a PTC resistor or an HSI. Reference symbol list

[0074] 1 Heater 2 Combustion chamber 3 Burner 4 Supply gas mixture 5 Temperature sensor 6 Flame 7 Combusted gas mixture 8 Resistance 9 Lambda value 10 Curve 11 Voltage 12 First voltage value 13 First resistance value 14 Second voltage value 15 Second resistance value 16 Slope 17 Conveyor 18 Control unit 19 Computer program 20 Combustion air supply 21 Gas valve 22 Speed ​​controller 23 Exhaust system 24 Mixture channel 25 Flow sensor 26 Gas supply 27 Display unit 28 Network 29 Power source 30 First block 31 Second block 32 Third block 33 Fourth block 34 Fifth block 35 Sixth block 36 Seventh block

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 a temperature sensor (5) for determining a temperature of a flame (6) of the gas mixture (7) burned by the burner (3), wherein the temperature sensor (5) comprising a temperature-dependent resistor (8); wherein the combusted gas mixture (7) has a lambda value (9) and the temperature sensor (5) is electrically heatable and has a voltage-resistance curve (10) dependent on the lambda value (9); wherein the method comprises at least the following steps: a) setting an operating point of the heating device (1) at which the gas mixture (4) supplied to the combustion chamber (2) has a constant composition; b) setting a voltage (11) at the temperature sensor (5) to a first voltage value (12); c) measuring and determining a first resistance value (13) of the temperature sensor (5); d) Changing the voltage (11) at the temperature sensor (5) to a second voltage value (14); e) measuring and determining a second resistance value (15) of the temperature sensor (5); f) determining a slope (16) of a voltage-resistance curve (10) and determining the lambda value (9) of the gas mixture (7).

2. Method according to claim 1, wherein in a further step g) the lambda value (9) determined in step f) is used at least for a first control process for controlling the composition of the gas mixture (4) supplied to the combustion chamber (2) or for a second control process for controlling the combustion of the gas mixture (4).

3. Method according to claim 2, wherein steps a) to g) are carried out as a calibration process for calibrating the respective control; wherein the heating device (1) is operated after the calibration process, taking into account the last determined lambda value (9).

4. Method according to one of the preceding claims 2 and 3, wherein, during normal operation of the heating device (1), the at least one control process is carried out on the basis of a temperature of the flame (6) measured by the temperature sensor (5) and determined on the basis of the measurement, wherein step g) calibrates the temperature sensor (5), i.e. its measurement result is modified by a correction value.

5. Method according to claim 4, wherein steps a) to g) are carried out as a calibration process for calibrating the temperature sensor (5), wherein after the calibration process, the heating device (1) uses the measurement results of the temperature sensor (5) modified by the correction value for the respective control.

6. Method according to one of the preceding claims, wherein the temperature sensor (5) comprises a PTC resistor or an HSI.

7. Method according to one of the preceding claims, wherein the supplied gas mixture (4) contains at least hydrogen.

8. Method according to one of the preceding claims, wherein the gas mixture (4) to be supplied contains only ambient air and hydrogen.

9. Heating device (1) comprising a conveyor device (17) 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 the temperature of a flame (6) of the gas mixture burned by the burner (3) (7) burned by the burner (3), and a control unit (18) which is designed at least for controlling the composition of the gas mixture (4) supplied to the combustion chamber (2) or for controlling the combustion of the gas mixture (4) on the basis of the temperature measured by the temperature sensor (5) and is thereby suitable for carrying out a method according to one of claims 1 to 9.

10. Computer programme (19) comprising instructions that cause a heating device (1) according to claim 9 to perform the steps of a method according to one of claims 1 to 8.

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