Method for operating a flame-generating heating device of a heating system, computer program, storage medium, control device and heating device

Abstract

A proposed method for operating a heating appliance (2) of a heating system (1) comprises at least the following steps: a) determining a first lower power limit of the heating appliance (2) based on the flow rate of a heating circuit (3) of the heating system (1), b) determining a second lower power limit of the heating appliance (2) based on an ionization signal of the flame of the heating appliance (2), c) operating the heating appliance (2) in a power range above the higher value of the first or second power limit. The invention serves to operate a heating appliance (2) with an at least partially blocked exhaust gas path, in which the heating appliance (2) is operated with operating parameters that enable safe operation despite the partially blocked exhaust gas path. Likewise, the proposed method serves to detect a blockage of the exhaust gas path at which safe operation of the heating appliance is no longer possible.

Description

[0001] The invention relates to a method for operating a flame-generating heater of a heating system, in particular when a blocked exhaust system of the heater is detected, a computer program, a storage medium, a control and regulating device and a heater.

[0002] A blockage in the exhaust system of a heater can lead to unsafe operating conditions. Especially in heaters with a pneumatic gas-air system, if the exhaust system is at least partially blocked, the mixture composition of combustion air and fuel gas can drift into dangerous ranges.

[0003] For this purpose, GB 210 5888 A proposes installing a sensor in an exhaust system and measuring a pressure, which is then compared with a reference value. An increased pressure can indicate a blocked exhaust system.

[0004] WO 2012 / 53681 A1 proposes a system that measures both the exhaust system pressure and the speed of a heater fan. A change in the relationship between the two measured values may indicate an at least partially blocked exhaust system.

[0005] A disadvantage of the state-of-the-art solutions is the need for additional sensors, which, in addition to the costs and installation effort, also increases the complexity of the heating system.

[0006] DE 10 2015 206 810 A1 proposes detecting a blockage of at least one fluid path of the burner device based on a control signal from a fan of a burner device and / or an ionization current of a flame. However, this method is inaccurate because the operating state of the burner device is not taken into account. DE 10 2010 055 567 A1 discloses a method for operating a flame-generating heater of a heating system with a heating circuit. The method comprises the step of determining a power limit of the heater based on an ionization signal of the flame of the heater and the step of operating the heater in a power range above the value of the power limit.

[0007] Based on this, the object of the invention is to propose a method for detecting a blocked exhaust system or for operating a heater that at least partially overcomes the described problems of the prior art. In particular, the method should enable reliable detection of a blocked exhaust system without increasing the complexity of the heating system. Furthermore, if necessary, the heater's operating mode should also be (automatically) adjusted based on the detection of a (partially) blocked exhaust system.

[0008] In addition, the invention should be easy to implement and implement and, if possible, can be retrofitted to existing heating systems without any problems.

[0009] These objects are achieved by the features of the independent patent claims. Further advantageous embodiments of the solution proposed here are specified in the independent 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.

[0010] A method for operating a flame-generating heater of a heating system with a heating circuit contributes to this, comprising at least the following steps: a) Determining a first lower power limit of the heater based on the flow rate of the heating circuit, b) Determining a second lower power limit of the heater based on an ionization signal of the flame of the heater, c) Operating the heater in a power range above the larger value of the first power limit or the second power limit.

[0011] In a regular procedure, steps a), b), and c) are usually performed at least once in the specified order. In particular, steps a) to c) can be performed permanently or at regular (needs-based) intervals.

[0012] The invention serves to operate a heater with an at least partially blocked exhaust path, wherein the heater is operated with (predetermined) operating parameters that enable safe operation despite a partially blocked exhaust path. Likewise, or incidentally, the proposed method includes detecting an (undesirably large) blockage of the exhaust path, which would render safe operation of the heater impossible.

[0013] A partially blocked exhaust path is characterized by an (undesired) obstruction of the exhaust gas flow and thus an increase in the flow resistance of the exhaust path, for example due to its narrowing due to deposits on a wall of the exhaust path.

[0014] In principle, the method can be used with any heating device, but it appears particularly useful for gas-powered heaters. The invention can be used particularly advantageously with a heater with a pneumatic gas-air system.

[0015] The flame-generating heater can be configured, in particular, to combust one or more fossil fuels, such as natural gas or hydrogen, with the addition of combustion air, thus providing thermal energy, for example, for heating a building or supplying hot water. The heater typically comprises at least one burner and a device that conveys a mixture of fuel (gas) and combustion air through a mixture channel of the heater to the burner. The exhaust gas produced by the combustion can be conducted through an exhaust pipe of the heater, which can be part of a (higher-level) exhaust system, for example that of a building.

[0016] In particular, the heater may comprise a pneumatic gas-air combination, which is characterized in that a mass flow of combustion air is passed through a Venturi device (Venturi nozzle) and combustion gas can be added according to the resulting negative pressure.

[0017] The heating circuit comprises, in particular, a heating fluid that can be heated by the heater. The heating fluid can be supplied to one or more consumers (e.g., heat exchangers such as radiators, etc., and / or hot water dispensers such as showers, etc.) by means of a circulation pump. It is possible for the heating fluid to be reheated by the heater after heat has been released.

[0018] In step a), a first lower power limit of the heater is determined based on the flow rate of a heating circuit of the heating system. This means, in particular, that a (current and / or maximum) flow rate of the heating fluid in the heating circuit is measured. The flow rate can then, for example, be mathematically included in an evaluation that leads to a value of a first lower power limit of the heater. The first lower power limit is, in particular, a measure of the minimum power requirement of the heating circuit for the heater.

[0019] In step b), a second lower power limit of the heater is determined based on an ionization signal from the heater's flame. This means, in particular, that the (current) quality of the heating fluid's flame is determined using a measured ionization signal in the vicinity of the flame. This ionization signal can then, for example, be mathematically incorporated into an evaluation that leads to a value for a second lower power limit of the heater. The second lower power limit is, in particular, a measure of whether controllable or stable flame formation is present in the heater.

[0020] In step c), the (controlled or adjusted) operation of the heater takes place in a power range above the larger of the first power limit or the second power limit. Step c) can thus include comparing the first lower power limit determined in step a) with the second lower power limit determined in step b), and regulating and / or adjusting the operation of the heater so that it operates in a power range above the larger of the two power limits.

[0021] The first lower performance limit according to step a) can be determined based on the current flow rate of the heating circuit. The flow rate of the heating circuit is essentially determined by the current operation and / or the maximum operation of the heating circuit's circulation pump.

[0022] A first flow rate DP can be specified with a value that is calculated and provided by the circulation pump using internal routines. The (current) value for the flow rate DP provided by the circulation pump can, for example, be retrieved by a control and regulation device, which preferably also allows the method proposed here to be carried out. The circulation pump is, in particular, one whose performance is (automatically) regulated by means of a (current) differential pressure and / or a (current) temperature difference in the heating circuit. The differential pressure is the pressure difference between the heating fluid entering the circulation pump and that leaving it. The pressure in the heating circuit can thus drop when many consumers are active, which then results in an increase in the performance of the circulation pump.In the other case, the circulation pump reacts particularly to temperature differences between the temperature in the (hot, downstream of the heater) flow line and the temperature in the (colder, upstream of the heater) return line. For example, if the temperature difference is small, this is an indication that the pump output is currently too high, which leads to a reduction in the circulation pump's output. The output determined from such pump control can be used to determine the current flow rate.

[0023] Furthermore, a (second) maximum flow rate D max achievable by the circulation pump, which corresponds to a maximum power consumption or maximum operation, can be used. The maximum flow rate can be a heating circuit-specific and / or pump-specific parameter and can be set in particular when the flow resistance of the heating circuit is minimal. For circulation pumps that do not calculate the current flow rate DP using internal routines and / or for implausible values DP provided by the circulation pump, the maximum flow rate D max can be used and the current flow rate can be determined based on a (known) proportional relationship between the (current) speed of the circulation pump and its flow rate.

[0024] A (third) flow rate DT of the circulation pump can be determined by taking into account the flow and return temperatures as well as the heat energy provided by the burner. The following thermodynamic formula can be used as the basis for the calculation: P = η × Q = D T × c p × T Vor − T R ü ck These include: DT is the flow rate of the heating circuit T Before the flow temperature of the heating circuit T R ü ck the return temperature of the heating circuit cp the heat capacity of the heat carrier (e.g. water) Pthe heat emitted by the heater Qthe power absorbed by the heater n the efficiency of the heater (known function of T Before , T R ü ck and Q

[0025] Taking into account fluctuations and inertia of the system, the following equivalent formula can be used, especially when the flow and return temperatures and the absorbed power are not stabilized. P t = η × Q t ¯ = D T t × c p × T Vor t − T R ü ck t − Δ t − K × d dt × T Vor t + T R ü ck t with Δ t = V W D T t ¯ These include: VW the amount of heat transfer medium Δ contained in the heating circuit t the period in which the heat transfer medium flows through the heat exchanger Kthe heat capacity of the heat exchanger material X(t)time-dependent variables X ( t )Average values for the period during which the heat transfer medium flows through the heat exchanger.

[0026] Thus, three flow rates, DP, D max, and DT, can be determined. These can also be related to each other, resulting in a "superordinate" flow rate parameter, which can be considered here. Particularly in the case of an at least partially blocked exhaust system, the heat input into the heating fluid via the heater can no longer be maintained in the expected (constant) manner. This is evident in such a flow rate relationship and leads to the detection of a partially blocked exhaust system.

[0027] According to a preferred embodiment, the first lower power limit can be determined based on a minimum power of the heater. The minimum power of the heater can be regarded as the lowest power of the heater at which it can be operated with a stable flame. For example, the first lower power limit can result from the minimum power of the heater with a factor DT / D use. D Use can represent a calculation variable that is used to determine the first lower power limit. In particular, the determination of the first lower power limit can include and depend on a verification (described below) of the parameter DP determined by the circulation pump. The calculation variable D Use can be defined depending on the result of the verification of the parameter DP determined by the circulation pump.

[0028] For example, a lower performance limit can be determined based on the flow rates DP , D max and DT, including a verification of the parameter DP determined by the circulation pump as follows: 1.1 If no verification of the flow rate DP determined by the circulation pump has been carried out, the flow rate D Use can be defined as the minimum of D max or DP (+ tolerance) to determine the (first) lower capacity limit. 1.2 If a verification of the flow rate DP determined by the circulation pump has been carried out and this verification was successful, the flow rate D Use can be defined as DP (+ tolerance) to determine the (first) lower capacity limit. 1.3 If a verification of the flow rate DP determined by the circulation pump has been carried out and this verification was unsuccessful, the flow rate D Use can be defined as D max to determine the (first) lower capacity limit. 2. Once the flow rates have been determined or set accordingly, the flow rate DT , determined from the flow and return temperatures of the heating circuit, can be compared with D Use. 3.If DT >D Use is the result of the comparison according to 2., the (first) lower power limit can be determined from the minimum power of the heater using a factor of DT / D Use. 4. If the result of the comparison according to 2. is not DT >D Use, the minimum power of the heater can be defined as the (first) lower power limit.

[0029] The determination of the second lower power limit of the heater according to step b) is based on the ionization signal of the flame. An at least partially blocked exhaust path of the exhaust system can be detected from the ionization signal of the heater's flame, in particular by: a weakening of the ionization signal due to a reduction in the size of the flame and / or noise in the ionization signal because the control by means of the ionization signal enters an unstable range. However, the aforementioned characteristics of the flame ionization signal when the exhaust path is at least partially blocked can also occur for other reasons, such as a corroded ionization electrode or unstable combustion. To clearly identify an at least partially blocked exhaust path, other additional parameters and / or the flow rate in the heating circuit may be checked simultaneously.

[0030] According to an advantageous embodiment, a hybrid ionization signal can be determined that takes into account or assumes the two effects (attenuation and noise) of the ionization signal when the exhaust path is at least partially blocked. For this purpose, an attenuation of the ionization signal can be detected and cumulated with a filtered noise component of the ionization signal. Advantageously, the hybrid ionization signal can reliably detect an at least partial blockage of the exhaust path and, for example, distinguish it from a corroded electrode. Since unstable combustion can regularly occur with a worsening blockage of the exhaust path, it can be advantageous to adapt the filtering of the noise component of the ionization signal so that unstable combustion can still be detected.

[0031] A hybrid ionization signal can be determined, for example, as follows. The ionization signal is typically acquired periodically, for example, at intervals of 100 ms [milliseconds]. The ionization signal can, in particular, be a raw data signal, i.e., a largely unchanged signal from the ionization electrode. To eliminate noise in the (raw data) ionization signal, a current signal (new ion signal) and at least one (old) signal from a previous acquisition (old ion signal) can be linked: Ionsignal Hybrid = Ionsignal neu + Rauschen neu with Rauschen neu = Filter × Rauschen alt + Skalar × Ionsignal neu − Ionsignal alt Filter + 1 The parameters filter and Scalar The equation shown serves to amplify the ionization signal and to average the noise component of the ionization signal.

[0032] A second lower power limit can be determined based on the ionization signal and / or the hybrid ionization signal.

[0033] A characteristic feature of detecting a (partially) blocked exhaust path based on the flow rate of the heating circuit according to step a) is a largely proportional change in the signal relative to the rate or degree of blockage of the exhaust path. In other words, a continuously changing signal based on the flow rate can be determined proportional to the increasing blockage of the exhaust path. In contrast, a sudden increase in the (hybrid) ionization signal can be detected as soon as a threshold value for the blockage of the exhaust path is reached.

[0034] Thus, a first lower power limit can now be established based on the flow rate of the circulation pump, and a second power limit based on the ionization signal of the flame. Of these two lower power limits, the higher lower power limit can be selected as the lower power limit for the operation of the heater.

[0035] By operating the heater according to step c) with the higher of the two lower power limits, determined according to steps a) and b), it is ensured that the heater is not operated in a power range that could lead to unsafe operating conditions due to the blockage of the exhaust gas path.

[0036] According to an advantageous embodiment, according to step d), the heater can provide or transmit information about an at least partially blocked exhaust path. In particular, the heater can provide or transmit information about an at least partially blocked exhaust path if one of the two determined lower power limits reaches a limit value. The limit value can be a preset value, which can be stored, for example, in the memory of a control and regulation unit of the heater and represents a threshold value above which safe operation of the heater is no longer guaranteed.

[0037] According to a further advantageous embodiment, the heater can switch off alternatively or cumulatively when a predetermined limit value is reached with respect to one of the two lower power limits during step d). This advantageously prevents damage to the heater or accidents due to unsafe operating conditions.

[0038] According to a preferred embodiment, the signals of the sensors required to carry out a method proposed here can be verified at regular (temporal) intervals and / or as needed. These are, in particular, a temperature sensor for a flow temperature, a temperature sensor for the return temperature, and / or an ionization electrode.

[0039] For example, the temperature sensors in the return and flow of a heating circuit can be verified by using a three-way valve to connect the flow and return of the heating circuit via a heat exchanger for hot water supply, allowing the signals from the temperature sensors, located, for example, before and / or after a (main) heat exchanger, to be compared. A determined temperature difference between the two temperature sensors can be used to calibrate their signals, since only the temperature difference is used for the method proposed here. Verification of the flow rate DP, which is calculated by internal routines of the circulation pump, can be achieved by checking the signal of the internally determined flow rate DP at different speeds (rpm) of the circulation pump.Such verification can be carried out in particular when the heater is in standby mode or during boiler run-on.

[0040] According to a further aspect, a computer program is also proposed which is configured to (at least partially) carry out a method presented here. In other words, this relates in particular to a computer program (product) comprising instructions which, when executed by a computer, cause the computer to execute a method described here.

[0041] According to a further aspect, a machine-readable storage medium on which the computer program is stored is also proposed. The machine-readable storage medium is usually a computer-readable data carrier.

[0042] According to a further aspect, a control device for a heater is also proposed, configured to carry out a method presented here. The control device can, for example, have or be equipped with a processor for this purpose. In this context, the processor can, for example, execute the method stored in a memory (of the control device).

[0043] According to a further aspect, a heating device is also proposed, comprising a control and regulation device as proposed here. The heating device is, in particular, a gas heating device with a burner and a conveying device that can convey a mixture of fuel gas and combustion air to the burner. The heating device can, in particular, have a pneumatic gas-air connection.

[0044] The details, features, and advantageous embodiments discussed in connection with the method may also occur in the computer program, storage medium, control device, heater, and / or use 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.

[0045] Thus, a method for detecting a blocked exhaust system of a heating system, a computer program, a storage medium, a control device, and a heater are provided, which at least partially solve the problems described with reference to the prior art. In particular, the method, the computer program, the storage medium, the control device, and the heater at least contribute to enabling safe operation of a heater even with an at least partially blocked exhaust path. In particular, a method proposed here can detect a power range in which safe operation is possible despite the partial blockage of the exhaust path.

[0046] Furthermore, the invention is particularly easy to implement. For example, no additional sensor technology in a heater is required to carry out the method proposed here. This also makes it easy to implement it on existing heaters. For this, it is only necessary, for example, to store a computer program proposed here in a memory of the heater's control and regulation unit.

[0047] 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.

[0048] 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 sequence of a procedure proposed here, Fig. 2 : a heating system comprising a heating device as described here, Fig. 3 : a representation of parameter curves that can occur when carrying out a procedure presented here, Fig. 4: a representation of a raw data ionization signal and a hybrid ionization signal, and Fig. 5 : a representation of the hybrid ionization signal and the heater power.

[0049] Fig. 1 shows, by way of example and schematically, a sequence of a method proposed here. The method serves for the safe operation of a heater 2 when the exhaust path or exhaust system of the heater 2 is at least partially blocked. The sequence of steps a), b), and c) illustrated by blocks 110, 120, and 130 can occur during a regular operating sequence. In particular, however, steps a), b), and c) can be performed permanently or at regular (as needed) intervals.

[0050] In block 110, according to step a), a first lower power limit of the heater 2 is determined based on the flow rate of a heating circuit 3 of the heating system 1.

[0051] In block 120, according to step b), a second lower power limit of the heater 2 is determined based on an ionization signal of the flame of the heater 1.

[0052] In block 130, according to step c), the heater 1 is operated in a power range above the larger value of the first and second lower power limit.

[0053] Fig. 2shows, by way of example and schematically, a heating system 1 having a heating device 2 proposed here. The heating system 1 has a heating circuit 3, comprising a flow line 4, in which a circulation pump 18 can be arranged, and a return line 5. When the circulation pump 18 is in operation, a heat transfer medium or heating fluid can flow through the heating circuit 3 in a flow direction 7. To measure a flow and return temperature of the heating circuit 3, a temperature sensor can be arranged in the flow line 4 and in the return line 5, which can be electrically connected to a regulating and control device 8 of the heating device 2.

[0054] The heater 2 can comprise an air intake duct 12 through which combustion air can flow. A Venturi device (Venturi nozzle) can be arranged in the air intake duct 12, in which a negative pressure can be created, which can control a mass flow of fuel gas to be supplied via a gas supply 13. A conveying device 6 can be arranged in the adjoining mixture duct 14, which can feed the mixture of combustion air and fuel gas to a burner 9. The burner 9 can be arranged in a combustion chamber 15, which can comprise a heat exchanger 16, which is connected to the heating circuit 3 in such a way that the heat transfer medium can flow through it. An ionization electrode 17 can also be arranged on the burner 9, which can detect an ionization signal from a flame of the burner 9. The ionization electrode 17 can be electrically connected to the control and regulation unit 8.

[0055] The combustion products resulting from the combustion of the mixture of combustion air and fuel gas by the burner 9 in the combustion chamber 15 can be fed to an exhaust path, here designed as an exhaust duct 10, which leads from the combustion chamber 15 out of the heater 1. An exhaust system 11 is connected to the exhaust duct 10, which can, for example, direct the combustion products to a building's chimney. The exhaust duct 10 and the exhaust system 11 form the exhaust path.

[0056] A flow temperature sensor 36 can be arranged in the flow 4 and a return temperature sensor 37 in the return 5. A three-way valve 34 can be configured in a switching position to connect the flow 4 and return 5 via a hot water preparation heat exchanger 35. The heat transfer medium in the heating circuit 3 can transfer heat to a volume flow of domestic or drinking water via the hot water preparation heat exchanger 35 and thus provide hot water. This switching position of the three-way valve also enables a check of the flow temperature sensors 36 and return 37, since, particularly without a volume flow, the domestic or drinking water to be heated and the associated cooling of the heat transfer medium in the hot water preparation heat exchanger 35 must have essentially the same temperature.

[0057] Fig. 3This diagram shows exemplary and schematic parameter curves that can occur when implementing a method proposed here. The abscissa of the diagram represents the power Q of heater 2, and the ordinate axis represents the combustion air / combustion gas ratio η. The influence of various blockages in the exhaust path (exhaust duct 10 or exhaust system 11) is represented by curves 33.

[0058] The curves of a lower power limit based on the flow rate of the circulation pump 21, a lower power limit based on the ionization signal of the flame 23, and a lower power limit based on the maximum flow rate of the circulation pump 22 are shown. In a critical area 19, impure combustion can occur, accompanied by contamination of the exhaust duct 10 and exhaust system 11 and the environment.

[0059] Fig. 4shows, by way of example and schematically, a diagram with a raw data ionization signal 25 and a hybrid ionization signal 26 derived therefrom as a function of time t. It is clearly evident that the hybrid ionization signal 26 succeeds in averaging out the noise of the raw data ionization signal 25 and amplifying it. Impure combustion can occur in a critical region 19. A flame loss 27 can occur, particularly in a region between the critical region 20 and the lower power limit based on the ionization signal of the flame 23.

[0060] Fig. 5shows, by way of example and schematically, a hybrid ionization signal 26 and a power of the heater 2 over a time t. The heater 2 is operated with a lower power limit 30. A first limit 28 and a second limit 29 have been defined for the hybrid ionization signal 26. When the hybrid ionization signal 26 reaches the first limit 28, this indicates a destabilization of the flame 16. If the hybrid ionization signal 26 exceeds the first limit 28, the power of the heater can be temporarily increased for the time the limit is exceeded. When the hybrid ionization signal 26 reaches the second limit 29, this can indicate a critical state of the flame 16. In order to permanently avoid a loss of flame, i.e. also during further operation, the lower power limit 30 can, for example, be permanently increased by an offset 32. List of reference symbols

[0061] 1Heating system 2Heater 3Heating circuit 4Flow 5Return 6Feeding device 7Heating circuit flow direction 8Regulating and control unit 9Burner 10Exhaust duct 11Exhaust system 12Air intake duct 13Gas supply 14Mixing duct 15Combustion chamber 16Heat exchanger 17Ionization electrode 18Circulation pump 19Critical area 20Flame loss 21Lower performance limit based on circulation pump flow rate 22Lower performance limit based on the maximum circulation pump flow rate 23Lower performance limit based on the flame ionization signal 24Working area 25Raw data ionization signal 26Hybrid ionization signal 27Flame loss 28First limit 29Second limit 30Lower performance limit 31Heater power 32Offset 33Influence of various blockages of the flue gas path 34Three-way valve 35Heat exchanger for hot water preparation 36Temperature sensor for flow 37Temperature sensor for return

Claims

1. Method for operating a flame-forming heating device (2) of a heating system (1) with a heating circuit (3), comprising at least the following steps: a) determining a first lower power limit of the heating device (2) based on the flow rate of the heating circuit (3), b) determining a second lower power limit of the heating device (2) based on an ionisation signal of the flame of the heating device (2), c) operating the heating device (2) in a power range above the greater of the first power limit or the second power limit.

2. Method according to claim 1, wherein in a step d) the heating device (2) provides or sends an error message when at least one of the two lower power limits reaches a predetermined limit value.

3. Method according to claim 2, wherein in step d) the heating device (2) additionally switches off.

4. Method according to one of the preceding claims, wherein in a step e) a verification of the signals of an ionisation electrode (17) of the heating device (2) and / or at least one temperature sensor of a flow (4) or a return (5) of the heating circuit (3) is carried out.

5. Method according to one of the preceding claims, wherein the flow rate of the heating circuit (3) is determined by - a circulation pump (18) of the heating circuit (3), or - is determined at least on the basis of a temperature of the flow (4) and return (5) of the heating circuit (3), an inertia factor of a heat exchanger (16) of the heating device (2) and a power of the heating device (2).

6. Method according to one of the preceding claims, wherein in step b) a hybrid ionisation signal of the flame of the heating device (2) is used, wherein the hybrid signal takes into account a noise of the ionisation signal and a signal attenuation.

7. A computer programme which is arranged to carry out a method according to any of the preceding claims.

8. Machine-readable storage medium on which the computer program according to claim 7 is stored.

9. A regulating and control device (8) for a heating appliance (2), arranged for carrying out a method according to any one of claims 1 to 6.

10. Heating appliance (2), comprising a regulating and control device (8) according to claim 9.

11. Heating device (2) according to claim 10, comprising a pneumatic mixture control.

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