Method for starting up a heating device, heating device and computer program product

Abstract

The invention relates to a method for commissioning a heating appliance (1). During commissioning, a conveying device (2) of the heating appliance (1) is brought up to a starting power and a mass flow of combustion air corresponding to the starting power is drawn in, to which a mass flow of fuel corresponding to a predetermined air ratio is added via a gas valve (5), and the resulting combustion mixture exits from a burner (3) into a combustion chamber (8) of the heating appliance (1) and is ignited there by an ignition device (15), whereby after the expiry of a safety period beginning with the opening of the gas valve (5), a flame must be detected by a flame monitoring device (12) of the heating appliance (1) so that the heating appliance (1) ends the commissioning and enters free modulation.The procedure includes at least the following steps: a) detecting a heat demand, b) determining at least a safety period duration and a starting power (27, 28) depending on the heat demand detected in step a), c) starting up the heating device (1) with the safety period duration and starting power (27, 28) determined in step b).

Description

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

[0002] A wide variety of fuel-burning heating appliances are known. These appliances burn a fuel and utilize the heat of combustion. Such heating appliances are frequently used to heat a building, providing both space heating and hot water. For this purpose, the heating appliance can be designed as a combination unit, heating both a heat transfer fluid in a heating circuit and domestic hot water. Typically, these heating appliances have a three-way valve that, depending on the heat demand, directs the heat transfer fluid heated by the appliance to a heating circuit or a heat exchanger. This heat exchanger is designed to transfer the heat to domestic hot water, thus providing hot water. Therefore, a distinction can be made between hot water operation (also known as DHW - Domestic Hot Water) and heating operation (also known as CH - Central Heating) when operating a heating appliance.

[0003] To start up such a heating appliance, the appliance's feed system is typically brought up to a predetermined starting power, drawing in a mass flow of combustion air through a combustion air supply. Once the starting power is reached, a mass flow of fuel can be added to the combustion air, and the resulting combustion mixture is fed to the appliance's burner. An ignition device can ignite the combustion mixture as it exits the burner into the appliance's combustion chamber. A safety period is then observed, and if, at the end of this period, the appliance's flame sensor detects a flame at the burner, the appliance can switch to free modulation, i.e., normal operation. The safety period thus represents the maximum opening time of the gas valve in the event of a failed start-up, for example, without flame ignition.The safety period limits the amount of unburned fuel that can escape during a failed start-up attempt. Start-up parameters, such as the heat output of the supplied combustion mixture or the length of the safety period, are selected to ensure a safe start-up process, particularly reliable flame formation and rapid flame stabilization, low noise levels, and the prevention of delayed ignition. A starting power output of the heating appliance is often selected to be approximately half its rated power (maximum heat output).

[0004] A disadvantage of starting up a heating appliance, particularly following a hot water demand, can be a delay that reduces user comfort, as the appliance typically operates at very high power or at its rated power to meet a hot water demand. Following ignition, which often starts at approximately half the rated power, a safety period must first elapse before the appliance can increase its output to or near its rated power to meet the hot water demand. Another disadvantage, especially when heating is required by a small consumer with a low capacity for the heating circuit's heat transfer fluid, is that the consumer may experience a delay in responding to the high heat flow immediately following the appliance's start-up.The heating unit may not be able to transmit half its rated power, or only a small portion thereof. As a result, the heating unit could switch off again due to the high return temperature. This undesirable effect also significantly reduces user comfort, as heating demands cannot be met.

[0005] DE 10 2022 125 189 A1 describes a method for commissioning a heating appliance in which the ignition power is adjusted to a detected power demand. However, this method is unable to solve the problems described above regarding a reduction in user comfort.

[0006] DE 10 2020 133 955 A1 also discloses a method for igniting a combustion process for a heating appliance operated with a hydrogen-containing fuel gas. In this method, an ignition time interval is selected that is shorter than the safety period. After the ignition time interval has elapsed, the ignition device is deactivated. This solution also fails to mitigate the problems described above.

[0007] The object of the present invention is to at least partially solve the problems described with reference to the prior art and, in particular, to propose a method for commissioning a heating device, a heating device and a computer program that enable safe and convenient commissioning of a heating device regardless of the heat requirement.

[0008] Furthermore, the invention should not significantly increase the complexity of a heating device, and retrofitting existing heating devices should also be possible.

[0009] 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 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.

[0010] This involves a method for commissioning a heating appliance. During commissioning, a feed mechanism of the heating appliance is brought up to a (predetermined or definable) starting power, thus drawing in a mass flow of combustion air corresponding to the starting power. A mass flow of fuel corresponding to a predetermined air-fuel ratio is added to this air. The resulting combustion mixture exits a burner located in a combustion chamber of the heating appliance and is ignited by an ignition device. After a (predetermined or definable) safety period, which begins with the opening of the gas valve, a flame must be detected by a flame monitoring system of the heating appliance so that the heating appliance can end the commissioning process and enter free modulation. The method includes at least the following further or more precise steps: a) Determining a heat demand, b) Defining a duration of the safety period and a starting power depending on the heat demand determined in step a), c) Commissioning the heating device with the duration of the safety period and the starting power determined in step b).

[0011] Steps a), b), and c) of the procedure can be performed at least once in the specified order during a regular operating procedure. The procedure can be performed at least once each time the heating appliance is commissioned. This procedure ensures a safe and convenient commissioning of the heating appliance.

[0012] The heating appliance is therefore a premixing or semi-premixing appliance designed for heating a building and providing heated domestic hot water or process water. The appliance draws in a mass flow of combustion air via a conveying device and adds a mass flow of fuel gas, corresponding to a predetermined combustion air ratio, through a gas valve. However, the appliance can also use oxidizers other than combustion air. The combustion mixture of fuel gas and combustion air can then be fed via a mixture channel to a burner located in a combustion chamber of the appliance. A burner cavity can be connected to a mixture channel, allowing the combustion mixture to flow into the burner cavity before exiting into a combustion chamber of the appliance and combusting there.The combustion chamber can be thermally coupled to at least one heat exchanger, which can transfer the heat generated during combustion to a heat transfer medium, such as heating water. This heat exchanger can be designed to cool the combustion gases to a temperature below the boiling point of water, thus utilizing the resulting condensation heat. Such a heating appliance can also be called a condensing boiler. The combustion gases can then be routed through a flue in the heating appliance to a building's exhaust system. The exhaust system can be a single- or multi-flue system. The heating appliance can, in particular, be a wall-mounted unit.

[0013] The heating appliance can operate at various points within a modulation or power range, thus operating at different output levels. To increase efficiency and service life, modern heating appliances often feature a wide modulation range, for example, from 3.7 kilowatts [kW] to 30 kW, or a modulation ratio (ratio of maximum to minimum output) of 1:8. The minimum output the heating appliance can deliver can be referred to as the minimum output, and the maximum output as the nominal output. A wide modulation range places high demands on the burner and the heating appliance due to the very different shapes and characteristics of the flame.

[0014] The heating appliance can be designed to burn liquid or gaseous fuels, such as heating oil, fossil fuels like natural gas or liquefied petroleum gas (LPG), or hydrogen. In particular, the heating appliance can be a gas-fired boiler, especially a condensing gas boiler.

[0015] The domestic hot water supply system of the heating appliance can include a heat exchanger that transfers heat from the heat transfer fluid in the heating circuit, heated by the heating appliance, to a mass flow of potable or domestic hot water. The heat exchanger for domestic hot water supply is usually located between a flow and a return pipe of the heating appliance. A three-way valve allows the mass flow of heat transfer fluid heated by the heating appliance to be directed either to the heat exchanger for domestic hot water supply and / or to the heating circuit. For domestic hot water supply, the heating appliance is often operated at or near its rated output. Therefore, for a comfortable supply of domestic hot water, the three-way valve is opened so that all of the heat transfer fluid heated by the heating appliance is directed to the heat exchanger for domestic hot water supply.Therefore, when the heating appliance is started up due to a hot water demand, the three-way valve is usually moved to a position that ensures that the entire heat transfer fluid heated by the heating appliance is used for hot water supply.

[0016] The ignition device can be any type of ignition system that ignites the combustion mixture in the combustion chamber during startup. Spark igniters are commonly used in heating appliances; these work by generating a spark between two electrodes, which ignites the combustion mixture. Glow igniters, also known as hot surface igniters, are another common type. These heat up to the ignition temperature of the combustion mixture based on their electrical resistance, thus igniting it. Pilot flames are also used; these are fueled by the heating appliance and are located near the burner, where they ignite the main flame.

[0017] When such a heating appliance is commissioned, a heat demand can be detected first, and in particular, a heat demand can be recorded. This allows for an assessment of which connected devices and / or heating circuits are requiring heat, for example, heat for a connected hot water circuit (e.g., for a shower, etc.) or for a connected heating circuit (e.g., with a radiator). Consequently, the heat demand can relate to either heating or hot water. The heat demand can, for example, be clearly detectable by sensors. The heat demand can be identified, for instance, by the (sensor-detected) opening of a thermostatic radiator valve as a consumer of a heating circuit connected to the heating appliance. This causes the heat transfer fluid of the heating circuit to flow through the consumer and cool down there, which the heating appliance can detect by a drop in the return temperature.A hot water demand can be identified by the (sensor-detected) opening of a hot water tap, which causes a mass flow of potable or process water in the heat exchanger of the hot water supply system, which can be detected by the heating appliance. As a result of the heat demand, the heating appliance can move the three-way valve to a position for heating operation or a position for hot water supply.

[0018] For commissioning, the conveying system is first brought up to a predetermined starting power. This starting power can be determined, for example, by the rotational speed of a conveying system designed as a blower. A mass flow of combustion air can be assigned to the blower's rotational speed or the starting power. Depending on the combustion air mass flow, which can be detected by a sensor and / or determined based on the rotational speed, a mass flow of fuel is added that corresponds to a predetermined combustion air-fuel ratio. The starting power of the conveying system thus determines the heat output of the heating unit during commissioning.

[0019] The invention proposes to define parameters of the ignition operation of the heating device, namely the safety period and a starting power, depending on the type or origin of the heat requirement.

[0020] According to step a), the heat demand can be detected. This detection can be carried out by the heating unit's control and monitoring device, possibly in conjunction with suitable sensors. The heating unit is usually switched off during step a).

[0021] According to step b), the duration of the safety period and the starting power can be determined based on the heat demand recorded in step a). The duration of the safety period and the starting power can be determined, in particular, depending on whether the heat demand is for heating or hot water. Alternatively or cumulatively, the safety period and the starting power can also be determined based on the magnitude of a heating demand. A characteristic curve or map can be used to define these parameters, establishing a relationship between the heat demand, the duration of the safety period, and the starting power. This characteristic curve or map can be determined beforehand using a reference heating device through testing.

[0022] According to step c), the heating appliance can be commissioned with the safety period duration and starting power specified in step b). Commissioning thus takes place with a safety period duration and starting power that are tailored to the heat demand. Therefore, the invention can, for example, significantly shorten the waiting time when hot water is required, without compromising the safety of the commissioning process.

[0023] According to one embodiment, in step b) the starting output for a hot water demand can be set in a range of 50% to 90% of the rated output of the heating appliance. In particular, the starting output for a hot water demand can be in a range of 60% to 80% of the rated output or in a range of 65% to 75%. The starting output can be set by the heating appliance or by the heating appliance's control unit based on the mass flow of combustion air supplied by the delivery system.

[0024] According to one embodiment, the safety period in step b) for a hot water demand can be set in a range of 2 seconds [s] to 6 s. In particular, the safety period for a hot water demand can be in a range of 3 s to 5 s. Here, the safety period refers to the time during the start-up of the heating appliance from the opening of the gas valve until modulation is enabled, at which point the heating appliance can freely move to a modulation point corresponding to the heat demand. Furthermore, the heating appliance can be configured so that, before modulation is enabled, and thus at the end of the safety period, the flame monitoring system of the heating appliance must detect a flame in order to enable modulation. If no flame is detected at the end of the safety period, the heating appliance could abort the start-up process.

[0025] According to one embodiment, in step b), the starting output for a heating demand can be set in a range of 95% to 255% or 150% to 200% of the minimum output of the heating appliance. In particular, the starting output for a heating demand can be in a range of 165% to 185% of the minimum output or in a range of 160% to 170%. Here, too, the starting output can be set by the heating appliance or by the heating appliance's control unit based on the mass flow of combustion air supplied by the conveying system.

[0026] According to one embodiment, the safety period in step b) for a heating demand can be set in a range of 3 s to 7 s. In particular, the safety period for a hot water demand can be in a range of 4 s to 6 s. Here, the safety period refers to the time during the commissioning of the heating appliance from the opening of the gas valve until modulation is enabled, at which point the heating appliance can freely move to a modulation point corresponding to the heat demand.

[0027] According to a further aspect, a heating appliance is proposed, comprising a conveying device, which may in particular be designed as a blower, a gas valve configured to add fuel gas from a gas supply to a mass flow of fuel gas, a burner arranged in a combustion chamber, an ignition device, a flame monitoring device, and a control and regulating device. The heating appliance may include further means adapted so that the heating appliance performs a method proposed herein. The heating appliance may in particular be configured for the combustion of a fuel gas.

[0028] The heating appliance includes a control unit that can be configured to carry out one of the procedures proposed here. For this purpose, the control unit can, for example, include and / or have a processor. In this context, the processor can, for example, execute the procedure stored in a memory (of the control unit). The control unit can, in particular, be electrically connected to the conveying system, the flame monitoring system, the gas valve, and the ignition system.Furthermore, data recorded or required during the implementation of a procedure proposed here can be stored on a memory of the control and regulating device, for example a heat demand recorded in step a) as well as characteristic curves or maps that establish a relationship between the recorded heat demand and an applicable starting power and an applicable safety period and can be used for the implementation of step b).

[0029] In addition, a computer program product is proposed that is designed to carry out the procedure presented here. In other words, this specifically concerns a computer program (product) comprising instructions that, when executed by a computer, cause it to perform the procedure proposed here. The computer program can, in particular, be executed on a control unit of the heating device.

[0030] The details, features, and advantageous configurations discussed in connection with the process may also occur in the heating device and computer program product 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.

[0031] This paper proposes a method for commissioning a heating appliance, a heating appliance itself, and a computer program that at least partially solve the problems described with reference to the state of the art. In particular, the method and the heating appliance enable a permanently safe, robust, and convenient ignition operation of the heating appliance, whereby the time required for ignition as well as the noise emissions occurring during ignition are reduced compared to the state of the art.

[0032] Furthermore, existing heating devices can easily be adapted to carry out the procedure proposed here, as no additional sensors or other components need to be retrofitted.

[0033] 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 method proposed here, Fig. 2: a heating device proposed here, and Fig. 3: parameter curves that can occur when carrying out a method proposed here.

[0034] Fig. 1 Figure 1 shows, in a schematic and exemplary manner, the sequence of a procedure proposed here. The execution of steps a), b), and c), depicted in blocks 110, 120, and 130, can be carried out at least once in the specified order during a regular procedure or when commissioning the heating appliance. In particular, steps a), b), and c) can be carried out at least once during each commissioning of the heating appliance. This procedure ensures a safe and convenient commissioning of a heating appliance.

[0035] Fig. 2 Figure 1 shows an exemplary and schematic representation of a proposed heating device 1. This device can draw in combustion air via a combustion air supply 4 through a conveying device 2 and add fuel gas from a gas supply 13 to the drawn-in mass flow of combustion air via a gas valve 5. The conveying device 2 can be designed, in particular, as a blower. The combustion mixture of fuel gas and combustion air can then be fed via a mixture channel 11 to a burner 3 arranged in a combustion chamber 8. The burner 3 can be connected to the mixture channel 11 such that the combustion mixture flows into a burner cavity, from which the burner 3 can exit into the combustion chamber 8 and combust. An ignition device 15 and a flame monitoring device 12 can also be arranged on the burner 3. The flame monitoring device 12 can, for example, include a UV sensor, i.e., a sensor for detecting ultraviolet radiation, or a glow plug.A first heat exchanger 6 can be arranged at the combustion chamber 8, which can transfer the heat generated during combustion to a heat transfer medium, for example heating water of a connected heating circuit 23.

[0036] The combustion products can be fed from the combustion chamber 8 to an exhaust pipe (exhaust system) 10 via an exhaust pipe 9. The heating appliance 1 can also have a control unit 7, which includes a memory on which a computer program 14 proposed here is stored. The control unit 7 can be connected to a network 16, for example to the Internet, and exchange data.

[0037] The heating unit 1 can be configured to provide heating heat to the heating circuit 23 as well as to provide domestic hot water, i.e., heated drinking or service water. For domestic hot water supply, the heating unit has a second heat exchanger 24, which can be arranged between a flow 19 and a return 20 of the heating circuit 23. The second heat exchanger 24 can include a cold water inlet 21, for example, connected to a supply network or a well, and a hot water outlet 22, which can be connected to draw-off points such as a shower or faucets. The second heat exchanger 24 can be connected to the flow 19 of the heating circuit 23 via a three-way valve 18. The three-way valve 18 can be connected to and controlled by the control unit 7. Thus, the control unit 7 can initiate flow through the second heat exchanger 24 and / or the heating circuit 23.In the return line 20 of the heating circuit 23, a circulation pump 17 can be arranged, which is designed to circulate the heat transfer medium in the heating circuit 23.

[0038] Fig. 3 The diagram shows exemplary parameter profiles that can occur when carrying out the procedure proposed here. It illustrates the combustion air ratio λ to be set by the heating unit 1 as a function of the heat output PQ. The heat output PQ of the heating unit 1 can be set within a range of a minimum output 25 and a nominal output 26. For the heating unit 1, the minimum output can be 3.7 kW and the nominal output 30 kW.

[0039] In block 110, a heat demand for the heating unit 1 can be detected according to step a). For this purpose, the control unit 7 can, for example, detect a mass flow of potable or service water flowing through the second heat exchanger 24, or recognize a temperature difference between the flow 19 and the return 20 greater than a predefined threshold value.

[0040] In block 120, according to step b), a safety period duration and a starting power output can be defined depending on the heat demand recorded in block 110 (step a)). This definition can be used, in particular, to differentiate between a hot water demand and a heating demand. For example, when performing step b) in block 120, a first starting power output 27 of 6.5 kW, i.e., 175% of the minimum power output 25 of the heating appliance 1, and a safety period duration of 5 seconds can be defined for a heating demand. For a hot water demand, a second starting power output 28 of 21 kW, i.e., 70% of the nominal power output of 20 kW, and a safety period duration of 4 seconds can be defined in step b) (block 120). These values ​​can significantly reduce the waiting time for hot water draw-off compared to a heating appliance 1 according to the state of the art.Advantageously, the heating unit 1 is started with a high starting power of approximately 70% of the nominal power, so that modulation to the nominal power as the operating point for hot water supply is reached more quickly and thus hot water at the desired temperature can be provided more quickly.

[0041] 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

[0042] 1 Heating unit 2 Conveyor 3 Burner 4 Combustion air supply 5 Gas valve 6 First heat exchanger 7 Control unit 8 Combustion chamber 9 Exhaust pipe 10 Exhaust system 11 Mixing channel 12 Flame monitoring 13 Gas supply 14 Computer program 15 Ignition device 16 Network 17 Circulating pump 18 Three-way valve 19 Flow 20 Return 21 Cold water inlet 22 Hot water outlet 23 Heating circuit 24 Second heat exchanger 25 Minimum output 26 Rated output 27 First start output 28 Second start output 110 Block 120 Block 130 Block

Claims

1. Method for starting up a heating appliance (1) with a conveying device (2), a combustion chamber (8) with a burner (3), a gas valve (5), an ignition device (15) and a flame monitoring device (12), wherein the conveying device (2) is brought up to a starting power, a mass flow of combustion air corresponding to the starting power is drawn in, to which a mass flow of fuel corresponding to a predetermined air ratio is added via the gas valve (5), and wherein the combustion mixture formed exits the combustion chamber (8) and is ignited there by the ignition device (15), wherein, after the expiry of a safety period beginning with the opening of the gas valve (5), a flame must be detected by a flame monitoring device (12) so that the heating appliance (1) ends the start-up and enters free modulation, wherein the method comprises at least the following further steps: a) detecting a heat demand,b) Determining the duration of the safety period and a starting power (27, 28) depending on the heat demand recorded in step a), c) Commissioning the heating appliance (1) with the duration of the safety period and the starting power (27, 28) determined in step b).

2. Method according to claim 1, wherein in step b) the duration of the safety period and the starting power (27, 28) are determined depending on whether the heat demand is a hot water demand or a heating demand.

3. Method according to claim 2, wherein the starting power (27, 28) in step b) is set for a heating demand in a range of 95 percent to 255 percent of the minimum power (25) of the heating device (1).

4. Method according to one of claims 2 or 3, wherein the starting power (27, 28) in step b) is set for a hot water demand in a range of 50 percent to 90 percent of the rated power (26) of the heating appliance (1).

5. Method according to any one of claims 2 to 4, wherein the safety period in step b) for a heating request is set in a range of 3 seconds to 7 seconds.

6. Method according to any one of claims 2 to 5, wherein the safety period in step b) for a hot water request is set in a range of 2 seconds to 6 seconds.

7. Heating device (1) comprising at least a conveying device (2), a gas valve (5), a burner (3) arranged in a combustion chamber (8), a flame monitoring device (12), an ignition device (15) and a control and regulating device (7), configured to carry out a method according to one of claims 1 to 6.

8. Heating appliance (1) according to claim 7, wherein the heating appliance (1) is a gas heating appliance and has condensing technology.

9. Computer program product (14) comprising commands that cause a heating device (1) according to claim 7 to execute a method according to claim 1.

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