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

Abstract

A method for operating a heating appliance (1) comprising a heat exchanger (11) for hot water preparation integrated between a flow (12) and a return (13) of a heating circuit (28) is proposed, comprising at least the following steps: a) operating the heating appliance (1), wherein the heating circuit (28) is closed via the heat exchanger (11) for hot water preparation, b) recording a temperature curve (21) of a heat transfer medium circulating in the heating circuit (28) during the heating of the heat exchanger (11), c) determining a slope (25) of the temperature curve (21) recorded in step a), d) determining an offset (27) of the output of the pumping device (2) taking into account the slope (25) determined in step c) and a given reference relationship (23, 24), e) operating the heating appliance (1) with the offset (27) of the output of the pumping device determined in step d). (2)The invention serves in particular to automatically adapt the settings of a heating device (1) to a connected exhaust system (6).

Description

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

[0002] Heating appliances that generate heat by burning fuel typically have an exhaust system to remove the combustion products. Depending on the building's structure, these exhaust systems can vary in length, resulting in different flow resistances and corresponding pressure drops or losses. During initial installation, the heating appliance should be adjusted to the specific exhaust system. The heating system installer can adjust the appliance to the length of the exhaust system. This adjustment involves increasing the output of the heating appliance's air delivery system, which supplies a fuel-air mixture to the burner. Manual adjustment by an installer carries the risk of incorrect settings or unintentional omissions.

[0003] There are also known methods for automatically adapting a heating appliance to a connected exhaust system. This can involve using an additional sensor installed in the heating appliance, such as a pressure sensor and / or a mass flow sensor. However, the additional sensor has the disadvantage of causing more effort during installation and / or maintenance, as well as potentially additional costs for the user and / or an increased risk of errors, breakdowns, etc.

[0004] Finally, particles produced during combustion, such as soot, can clog an exhaust system, reducing the cross-sectional area through which the exhaust can flow and increasing flow resistance. This can also be countered to a certain extent by adjusting the heating appliance or increasing the output of its conveying system.

[0005] German patent DE 10 2020 110 482 A1 describes a method for adjusting the control system of a heating appliance, whereby the heating appliance is initially operated with a specific initial drive power of the conveying system (e.g., based on experience from a reference system), then a current actual heating output is determined (e.g., via sensor-based energy measurement), and then, if necessary, the operation is adjusted to achieve a target heating output. This method has already proven effective, but for some heating appliances, such as those equipped with very complex exhaust systems, it may not be able to reliably determine the current actual heating output, which may lead to increased control effort.

[0006] EP 3 081 861 A1 describes a burner device with blockage detection. It proposes detecting a blockage in a fluid path, such as an exhaust system, by means of a drop in at least one operating parameter. These operating parameters can include, in particular, a pulse-width modulated control signal from the pump and / or an ionization current. The method does not allow for the adaptation of a heating appliance to an exhaust system.

[0007] In practice, adjusting a heating device repeatedly leads to problems, firstly due to human error during manual adjustment and secondly, in the case of at least partially automated implementation, the effort required and the lack of reliability of the additional sensor are disadvantageous.

[0008] Based on this, the object of the invention is to propose a method for operating a heating appliance that at least partially overcomes the problems of the prior art described above. In particular, adapting a heating appliance to the exhaust system should be particularly easy.

[0009] Furthermore, the invention should not significantly increase the complexity of a heating device and / or require only minor structural modifications to a heating device and / or enable simple integration into an existing production process. In particular, it should allow adaptation to an exhaust system, for example during the installation of a new heating system, without the use of additional sensors.

[0010] These problems are solved by the features of the independent claims. 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.

[0011] This involves a method for operating a heating appliance that includes a burner and a conveying device that supplies a mixture of fuel and combustion air to the burner, as well as a heat exchanger located downstream of the burner in an exhaust gas path and by means of which heat can be transferred from an exhaust gas stream of the burner to a heat transfer medium of a heating circuit, and a heat exchanger for domestic hot water preparation, which is integrated or arranged between a flow and a return of the heating circuit and is configured to transfer a heat flow from the heat transfer medium of the heating circuit to a mass flow of potable or process water. The method comprises at least the following steps: a) Operating the heating appliance, with the heating circuit closed via the heat exchanger for hot water preparation, b) Recording a temperature curve of the heat transfer medium circulating in the heating circuit during the heating of the heat exchanger, c) Determining a rise in the temperature curve recorded in step b), d) Determining an offset in the output of the pumping device, taking into account the rise determined in step c) and a given reference relationship, e) Operating the heating appliance with a pumping device output that includes the offset determined in step d).

[0012] Steps a), b), c), d), and e) are typically performed at least once in the specified order during a regular procedure. This can be done, in particular, after the installation of a heating appliance and / or an exhaust system. Specifically, steps a) through e) can be performed at regular intervals, for example, each time the heating appliance starts heating water. This proposed procedure also allows for continuous monitoring of the exhaust system, combined with adjustments to the heating appliance settings to compensate for any blockages in the exhaust system.

[0013] The invention serves in particular to automatically adapt the settings or operating mode of a heating appliance to a connected exhaust system. The method can be carried out especially after the installation of a new heating system or exhaust system. Furthermore, the method can be performed at regular intervals on an existing heating system to adjust the heating appliance to a clogged or cleaned exhaust system.

[0014] The heating appliance in question is, in particular, a gas-fired and / or oil-fired heating appliance. In other words, this refers specifically to a heating appliance designed to burn one or more fuels, such as natural gas, hydrogen, and / or heating oil, with the addition of combustion air to provide heating energy or hot water for a building. For example, the heating appliance could be a so-called condensing gas boiler. The heating appliance typically has at least one burner and a delivery system that supplies a mixture of fuel (gas) and combustion air (through a mixture channel within the heating appliance) to the burner. Often, a fuel gas (natural gas, hydrogen, or a mixture thereof) is added to a mass flow of combustion air via a gas valve. The exhaust gas produced by combustion can then be routed through an (internal) exhaust pipe of the heating appliance to a building's exhaust system.

[0015] The heating unit is connected to a heating circuit via a flow and a return pipe, in which a heat transfer medium (especially water) is circulated by a circulation pump. Heat from the exhaust gas stream is transferred to the heat transfer medium in the heating circuit via a heat exchanger located downstream of the burner in the flue gas path and made available for use.

[0016] The heating unit features a heat exchanger for domestic hot water preparation, which transfers heat from a heat transfer medium in the heating circuit to a mass flow of potable or service water. The heat exchanger is located within the heating unit between the flow and return lines of the heating circuit. A three-way valve can be configured to either close the heating circuit for domestic hot water preparation via the heat exchanger or to connect consumers located in the heating circuit to the flow and return lines for heating operation. Domestic hot water preparation typically requires a high heat flow; therefore, the entire heating circuit is often routed through the heat exchanger for domestic hot water preparation.

[0017] The invention is based on the idea of ​​recording the temperature of the heat transfer medium in the heating circuit during the heating phase of hot water preparation, or its temporal profile, and determining the (current) pressure loss of the exhaust system based on the temperature profile. For example, if the heating rate of the heat transfer medium is (too) low at the beginning of hot water preparation, it can be concluded that there is a (too) high pressure loss in the exhaust system, which reduces the effective heating output of the heating appliance.

[0018] According to step a), the heating appliance is operated with the heating circuit closed via the heat exchanger for domestic hot water preparation. In other words, the heating circuit is closed (for the first time) via the heat exchanger for domestic hot water preparation, and the heat transfer medium heated in the heat exchanger by the burner begins to heat the heat exchanger and the potable or process water contained within it. Specifically, no heated potable or process water is drawn during the implementation of the procedure proposed here, so that the heat transfer medium of the heating circuit can heat the heat exchanger for domestic hot water preparation and a defined quantity of potable or process water contained within it.

[0019] According to an alternative design, the heat exchanger for hot water preparation can also be subjected to a mass flow of potable or process water during the execution of the procedure proposed here. To ensure comparability of the results, the mass flow rate could advantageously also be recorded, for example by means of a flow sensor.

[0020] As per step b), a temperature curve of the heat transfer medium circulating in the heating circuit can be recorded. The temperature curve (the change in temperature over time) reflects the heating of the heat exchanger and the domestic hot water (or the mass flow of domestic hot water) it contains. The temperature curve can be recorded, in particular, by a temperature sensor installed in the heating circuit for hot water preparation. The temperature sensor could, for example, be an NTC resistor (also known as a thermistor or NTC thermistor).

[0021] For this purpose, the temperature sensor can, for example, be positioned downstream of the heat exchanger in the direction of circulation within the heating circuit. Advantageously, the heating device already includes a suitable temperature sensor, so that no structural modifications are necessary to carry out step a).

[0022] According to an advantageous embodiment, the temperature curve can be recorded for a period of heating from a starting temperature, for example room temperature or approximately 25 °C, to a temperature of more than 60 °C, 70 °C, or 80 °C. The recording of the temperature curve can begin, in particular, with the ignition or ignition of the flame in the burner (where the three-way valve should be in a hot water preparation position, allowing the heat transfer medium to circulate (completely) through the heat exchanger for hot water preparation), since the heat input for the heating process to be recorded begins at this point.

[0023] In this context, it should be noted that for the implementation of the procedure proposed here, it is helpful if the heat exchanger used for hot water preparation has a temperature below a minimum. This minimum temperature can be 50°C, 40°C, or preferably 30°C. If the procedure is carried out twice in immediate succession, the second run will often only record a temperature curve for a small temperature range of the heating process in step b), as the heat exchanger has not yet cooled sufficiently. This limited temperature range can lead to a higher susceptibility to errors in the execution of step c).

[0024] According to step c), the increase in the temperature curve determined in step b) can now be determined. Since the heating of the heating circuit at the beginning of hot water preparation is largely linear with respect to time, a linear regression of the temperature profile is performed according to an advantageous embodiment, and the increase in the curve determined by the linear regression is calculated.

[0025] According to step d), an offset in the output of the delivery system (for the entire modulation range of the heating appliance) can be determined by taking into account the increase determined in step c) and a given relationship. The offset in the output of the delivery system here refers to an offset of the (current) output of the delivery system towards a predetermined (target) output of the delivery system, which is helpful or necessary for the safe operation of the heating appliance, the maintenance of an expected heat output, and / or the regular formation of a flame in the burner, in accordance with the pressure loss caused by the exhaust system.

[0026] According to an advantageous embodiment, in step d), a pressure loss can first be determined using a first reference relationship. A reference relationship can be a dependency, a (mathematical) function, or the like. A reference relationship can be defined by a curve, function, or otherwise. The first reference relationship can assign a pressure loss (of the exhaust system) to each increase (determined in step c). Subsequently, using the determined pressure loss and a second reference relationship, an offset in the output of the conveying device can be determined that corresponds to the determined pressure loss.The offset in the heating appliance's output (often given as the output of the heating appliance's fan) to be determined using the second reference relationship is an operating parameter that allows the heating appliance to be adapted to the pressure loss determined using the first reference relationship, thus ensuring safe operation. The first and / or second reference relationship can be determined through investigations and stored digitally on the memory of a computer executing the procedure proposed here. For the implementation of the procedure proposed here, the first and second reference relationships can also be combined into a single relationship / function for determining the offset in the heating appliance's output based on the slope determined in step c).In particular, one or more reference relationships can be determined in advance through (laboratory) tests on at least one reference heating appliance operated with varying pressure losses (of the exhaust system). In this process, tests can be carried out on several reference heating appliances, and reference relationships can be determined or established by averaging the results.

[0027] According to another preferred embodiment, the conveying device can be a blower. In this case, the performance of the conveying device is considered to be the rotational speed of the blower.

[0028] According to an advantageous embodiment, in step f), in the event of a critical (high) pressure drop, information can be sent as a message and / or made available via a network. A critical pressure drop can manifest itself in a particularly slow heating of the heat transfer medium at the beginning of hot water preparation and thus be reflected by a low rise in the temperature curve. A high pressure drop can indicate a blocked flue gas path and make safe operation of the heating appliance more difficult. Therefore, information about a critical pressure drop can advantageously be sent as a message, for example, via a mobile network or a network such as the internet, or such information can be made available via a network (such as the internet), which can then be accessed, for example, via a computer program (app) on a mobile device.In an advantageous way, for example, a service company could be informed about the critical pressure loss and schedule and carry out a maintenance appointment.

[0029] Another aspect is addressed by proposing a computer program comprising commands that cause a computer to perform a procedure described here.

[0030] Another aspect proposed is a control unit for a heating appliance with a temperature sensor for recording the temperature curve of the heat transfer fluid circulating in the heating circuit, configured to carry out a procedure presented here. For this purpose, the control unit can, for example, include or be equipped with a processor. In this context, the processor can, for example, execute the procedure stored in the control unit's memory.

[0031] Another aspect is the proposed heating appliance comprising a burner, a conveying device that supplies a mixture of fuel and combustion air to the burner, a heat exchanger located downstream of the burner in an exhaust gas path and through which heat can be transferred from the burner's exhaust gas stream to a heat transfer medium in a heating circuit, a heat exchanger for domestic hot water preparation integrated between the flow and return lines of a heating circuit and configured to transfer a heat flow from the heating circuit's heat transfer medium to a mass flow of potable or process water, and a control and regulation device presented here. The heating appliance can, in particular, be a gas-fired heating appliance with a gas burner and a conveying device that can supply a mixture of combustion gas and combustion air to the gas burner.

[0032] The details, features, and advantageous configurations discussed in connection with the process can also occur in the computer program, control unit, and heating device presented here, and vice versa. In this respect, full reference is made to the explanations provided therein for a more detailed characterization of the features.

[0033] This document presents a method for operating a heating appliance, a computer program, a control and regulation device, and a heating appliance, which at least partially solve the problems described with reference to the prior art. In particular, the method and the heating appliance contribute to simplifying the installation of a heating appliance and / or an exhaust system and reducing its susceptibility to errors. Furthermore, it advantageously allows for the detection of a clogging exhaust system, thus improving the operational reliability of a heating appliance or heating system.

[0034] Furthermore, the invention can be implemented particularly easily, for example by installing a computer program on a control and regulating device of a heating appliance.

[0035] 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 sequence of a procedure proposed here, Fig. 2 : a heating device suggested here, and Fig. 3 bis 5 : Parameter profiles that can occur when carrying out a procedure proposed here.

[0036] Fig. 1 Figure 1 shows an exemplary and schematic representation of the sequence of a procedure proposed here. The procedure serves to adapt the settings of a heating appliance 1 to the characteristics of an exhaust system 6, in particular to adapt the output of a conveying device 2 to the pressure loss 26 caused by the exhaust system 6. The sequence of steps a), b), c), d) and e), represented by blocks 110, 120, 130, 140 and 150, can occur during a regular procedure.

[0037] Fig. 2 Figure 1 shows an exemplary and schematic representation of a proposed heating appliance 1, which can be designed as a gas-fired heating appliance. The heating appliance 1 can have a combustion air supply 4, to which combustion gas can be added via a gas valve 5. The resulting combustion mixture can be fed via a mixture channel 16, in which a conveying device 2 can be arranged, to a burner 3 located in a combustion chamber 8. The conveying device 2 can be designed as a blower, and the airflow to be conveyed can be controlled by the speed of the blower. Combustion products can be conveyed from the combustion chamber 8 to an exhaust system 6 via an exhaust pipe 9 (located within the heating appliance 1).

[0038] A heat exchanger 20 can be configured to transfer heat generated by the flame of the burner 3 to a heat transfer medium circulated in a heating circuit 28 with a circulation direction 19 by a circulation pump 29. The heating circuit 28 can comprise a flow 12 and a return 13, and the heating circuit 28 can be closed off for domestic hot water preparation via a heat exchanger 11 by means of a three-way valve 17. The heat transfer medium in the heating circuit 28 can then circulate from the heat exchanger 20 via the circulation pump 29, the three-way valve 17, the heat exchanger 11, and back to the heat exchanger 20. The heat exchanger 11 can also include a hot water outlet 15 and a cold water inlet 14. In the heating circuit 28, a temperature sensor 18 can be arranged to detect the temperature of the heat transfer medium circulating in the heating circuit 28, for example between the circulation pump 29 and the three-way valve 17.

[0039] The heating device 1 can also include a control unit 7, which is electrically connected to an ionization electrode 10 that can be arranged below the burner 3 for monitoring a flame in the combustion chamber 8. Furthermore, the control unit 7 can be electrically connected to the gas valve 5, the conveying device 2, the three-way valve 17, and the temperature sensor 18.

[0040] In block 110, according to step a), the heating device 1 is operated, whereby the heating circuit 28 is closed via the heat exchanger 11 for hot water preparation, whereby the heat transfer medium in the heating circuit 28 can then circulate from the heat exchanger 20 via the circulation pump 29, the three-way valve 17, the heat exchanger 11 and back to the heat exchanger 20.

[0041] In block 120, according to step b), a temperature curve 21 of a heat transfer medium circulating in the heating circuit 28 can be recorded during the heating of the heat exchanger 11 (and the potable or process water contained therein). The temperature curve 21 can be recorded as a discrete set of points.

[0042] Fig. 3 Figure 1 shows an exemplary and schematic diagram depicting a temperature curve 21 recorded in step b). The diagram illustrates the relationship between the temperature T (given in °C [degrees Celsius]) recorded by the temperature sensor in the heating circuit and the time (given in s [seconds]). The slope of the curve depends on the heat transfer from combustion to the heating circuit. This means, in particular, that a shallower slope indicates reduced heat transfer, especially a greater pressure drop across the exhaust gas path or exhaust system.

[0043] In block 130, according to step c), a slope 25 of the temperature curve 21 recorded in step b) (block 120) is determined. For this purpose, a linear regression 22 of the temperature curve 21 recorded in step b) can be carried out. Subsequently, a slope 25 of the linear function determined by the linear regression 22 can be determined.

[0044] In block 140, according to step d), an offset 27 of the conveying device 2 of the heating device 1 is determined. The offset 27 can be determined using a reference relationship between the (determined) offset 27, the (current) power of the conveying device 2 and the rise 25 of the temperature curve 21.

[0045] Fig. 4 Figure 23 shows a first reference relationship between a rise 25 of a temperature curve 21 during the heating of the heat exchanger 11 and a pressure drop f (given in Pa [Pascal]). Based on the first reference relationship 23, a pressure loss 26 in the exhaust system 6 can be assigned to the rise 25 determined in step c) (Block 130).

[0046] Fig. 5 Figure 24 shows a second reference relationship between a pressure drop 26 in the exhaust system 6 and a shift 27 in the output of the conveying device 2 (given in rpm [revolutions per minute]). Now, based on the determined pressure loss 26 in the exhaust system 6, a shift 27 in the output of the conveying device 2 can be determined.

[0047] In block 150, according to step e), the heating device 1 can now be operated with a power output of the conveying device 2 that includes the offset 27 determined in step d).

[0048] The method proposed here can be carried out, in particular, on the control unit 7 of the heating device 1. Advantageously, heating devices 1, according to the prior art, usually have a control unit 7 which has an electrical connection to all important sensors of the heating device 1, so that all data necessary for carrying out the method proposed here can be easily acquired.

[0049] This presents a new method for adjusting the heat output of the heating system without integrating a new sensor into the system or the heating unit, but rather by using only the existing sensors. The heat output can be set as a function of the pressure in the flue gas path, without the need for an additional sensor. This adjustment is made primarily using information from the (measured) flow temperature during the heating phase of the boiler's hydraulic circuit. The development of the temperature signal over time during the process reveals the pressure drop in the flue gas path. The longer the flue gas path, the smaller the temperature signal gradient. If the flue gas pressure drop is high, the heating output is reduced, meaning the water flow temperature takes longer to reach a reference value, such as 80°C.A linear regression can be performed over the entire range with the gas valve open and a flame present. Based on this, the exhaust pressure drop can be estimated by determining the slope of the temperature signal over time. Using this, an offset fan speed can be adjusted to the target fan speed according to the slope / pressure drop calculation. The power output is thus automatically adjusted based on the offset fan speed, independent of (specifically determined) lengths of the exhaust path and / or the (specifically determined) pressure drop within it.

[0050] 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. Reference symbol list

[0051] 1 Heating unit 2 Conveyor 3 Burner 4 Combustion air supply 5 Gas valve 6 Exhaust system 7 Control unit 8 Combustion chamber 9 Exhaust pipe 10 Ionization electrode 11 Heat exchanger 12 Flow 13 Return 14 Cold water inlet 15 Hot water outlet 16 Mixing channel 17 Three-way valve 18 Temperature sensor 19 Circulation direction 20 Heat exchanger 21 Temperature curve 22 Linear regression 23 First relationship 24 Second relationship 25 Rise 26 Pressure loss 27 Offset 28 Heating circuit 29 Circulating pump

Claims

1. Method for operating a heating appliance (1) comprising a burner (3) and a conveyor device (2) which conveys a mixture of fuel and combustion air to the burner (3), as well as a heat exchanger (20) which is located downstream of the burner (3) in an exhaust gas path and by means of which heat can be transferred from an exhaust gas flow of the burner (3) to a heat transfer medium of a heating circuit (28), as well as a heat exchanger (11) for hot water preparation connected between a flow pipe (12) and a return pipe (13) of the heating circuit (28) and designed to transfer a heat flow from the heat transfer medium of the heating circuit (28) to a mass flow of drinking or service water , comprising at least the following steps: a) operating the heating appliance (1), wherein the heating circuit (28) is closed via the heat exchanger (11) for hot water preparation, b) recording a temperature curve (21) of the heat transfer medium circulating in the heating circuit (28) during the heating of the heat exchanger (11), c) determining an increase (25) in the temperature curve (21) recorded in step b), d) Determining an offset (27) in the output of the conveyor device (2) taking into account the increase (25) determined in step c) and a given reference relationship (23, 24), e) operating the heating appliance (1) with a power of the conveyor device (2) that incorporates the offset (27) determined in step d).

2. Method according to claim 1, wherein in step c) the increase (25) is determined by means of linear regression (22).

3. Method according to one of the preceding claims, wherein in step d) the given reference relationship (23, 24) in a first reference relationship (23) with the rise (25) to determine a pressure loss (26) and, on the basis of the pressure loss (26), to determine an offset (27) of the output of the conveyor (2) on the basis of a second reference relationship (24).

4. Method according to one of the preceding claims, wherein the conveyor device (2) is a blower and the speed of the blower is considered to be its performance.

5. Method according to one of the preceding claims, wherein in step f), in the event of a critical pressure loss (26), information is sent as a message and / or made available via a network.

6. Control and regulation device (7) with a temperature sensor (18) for detecting a temperature curve of a heat transfer medium circulating in a heating circuit (28), designed to carry out a method according to one of claims 1 to 5.

7. Heating appliance (1) comprising a burner (3), a conveyor device (2) which conveys a mixture of fuel and combustion air to the burner (3), and a heat exchanger (20) which is located downstream of the burner (3) in an exhaust gas path and by means of which heat can be transferred from an exhaust gas flow of the burner (3) to a heat transfer medium of a heating circuit (28), and a heat exchanger (11) for hot water preparation connected between a flow pipe (12) and a return pipe (13) of the heating circuit (28) and designed to transfer heat from the heat transfer medium of the heating circuit (28) to a mass flow of drinking water or service water, and a control and regulating device (7) according to claim 6.

8. Computer program comprising commands that cause a control and regulation device (7) according to claim 6 to execute a method according to one of claims 1 to 5.

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