EP2682674B1 - Flame detector - Google Patents

Description

The invention relates to a flame detector for monitoring manually charged burners.

The subject matter of the invention is therefore a detector for monitoring the manual operation of a burner for wood or wood-like fuels.

All owners of wood-burning stoves know the problem: when you go to the stove to see if you need to add more fuel, you're either not there yet or, if you're lucky, you've come at just the right moment. It's really bad if you're late and have to heat up again. In the expectation that you will be late in the worst case, you tend to check more often and, in case of doubt, add fuel more or more often than would actually be sufficient for the correct, needs-based energy generation, which means that too much work is put into operation of the stove and consumes too much fuel. This leads to spending too much money and releasing more exhaust gases into the environment than is actually necessary. It is also uncomfortable because it is too warm in the house. You can then open a window and heat the environment, which is not exactly economical either.

Now there are ovens that try to solve the problem described by manual or thermostatic supply air regulation by the supply air and thus the heat output of the oven being throttled when the temperature of the oven reaches or exceeds the target temperature. This ensures that the performance of the combustion process is evened out and can be adapted to requirements by selecting the limit temperature. This works quite well for needs-based heating. However, it has the disadvantage that the Combustion process in the furnace becomes incomplete due to the restricted supply of oxygen and more CO and unburned aerosols appear in the exhaust gas, which leads to an energy-wise unfavorable yield of wood as fuel, because part of the fuel leaves the furnace unburned in the exhaust gas. In addition, the result is contamination of the furnace and the exhaust system with condensates from the aerosols. Furthermore, there is environmental pollution because the chimney is now smoking.

Better proposals therefore ensure complete combustion through sufficient air inflow and power control through the amount of fuel supplied.

Examples include pellet heating or wood chip heating. However, these are complex, automatic combustion processes that are more adapted to central heating in larger buildings or combined heat and power plants. In addition, these processes require uniform fuel suitable for automatic feeding, which as a rule cannot be produced in-house and must therefore be bought in and kept ready in storage bunkers. In their operating manual for their eco-plus model, the Harck company recommends placing 3 logs of wood in the combustion chamber after heating up and burning them down with a sufficient supply of combustion air for complete combustion until they are only embers in the combustion chamber and only then open add 3 more logs in the same way. This achieves complete combustion and clean operation, with an average heat output that is even throughout the day. This method is called interval method in the following.

The disadvantage of this method is that because of the size of the furnace, with a rated output adapted to the required output at 2-digit outside temperatures below freezing, especially during the Transitional period when too much power is still output with normal log size. Well-functioning combustion requires that several pieces of wood, ie at least two, preferably three, lie together and support each other in the combustion process by radiating heat, as every stove user knows from experience.

In order to achieve lower outputs, one could reduce the size of the logs, one then arrives at quantities of fuel which of course burn down more quickly and therefore have to be refilled more frequently, which is disadvantageous because of the increased workload. In addition, you only have the right log size at hand through additional work. Another disadvantage is that with this combustion process, the furnace and the exhaust gas lines never get really hot, so that condensates from the combustion gases are deposited on the walls and lead to contamination.

The state of the art today is that almost all stoves are equipped with a window in the door, so you don't have to open the stove door if you want to see how far the fuel has burned down, but then you have to be in the room is present to have a look from time to time. If you are busy with other activities in the house, it is necessary to interrupt them from time to time to look after the fire. The result is as described at the beginning.

Pellet or wood chip heating systems are equipped with optical or thermal monitoring devices for the fire, which monitor the combustion chamber in order to automatically take measures to adjust the fuel for the desired performance of the fire, or if no more fire is detected, to indicate a fault.

the DE102004028306 B4 describes a tiled stove or the like for the combustion of solid-like fuel that is fed manually. In order to prevent the fire from accidentally going out in the event of too long refueling pauses, it is proposed to additionally provide an evaporative burner arrangement with an ignition element. In order to be able to reliably control the operation of the evaporative burner arrangement even without manual interaction, various sensors can be present. For example, in the area of the combustion chamber there can be a flame monitor designed as a temperature sensor or the like, the signal from which indicates whether ignition has taken place in the combustion chamber or whether combustion is taking place.

the JP 2010 133677 A discloses a wood stove diagnostic system with an optical sensor, namely a camera, which evaluates the image of the flame.

When operating a wood-burning stove manually, the operator still has to rely on his estimate of how much he should extend the waiting times depending on the room temperature achieved, which, as described at the beginning, can easily lead to a the embers have cooled down so much that you have to heat them up again, although according to the heat requirement, you should have added more during the embers. So there is still a tendency to top up too early with the consequences described at the beginning. What is needed is a device that shows the user when fuel is to be added at the right time, which also has environmental and monetary advantages, because fuel is saved through the correct timing of adding fuel, together with a gain in comfort, because by correctly adding more fuel Prevent it from getting too warm or not warm enough in the fuel home is Labor savings in operating the burner is also desirable.

A flame detector is therefore sought in which a new ignition is to be avoided due to the amount of work involved and the waiting time is to be limited to such an extent that the remaining embers in the combustion chamber can ignite the fuel that has been added.

At the same time, a certain minimum amount of fuel is observed when adding fuel manually, an amount that is able to reach the target temperature for the greatest possible reduction of permanent deposits of condensates in the stove and also large enough to burn for a sufficiently long time, and thus makes an increased workload unnecessary. The regulation of the required mean heating power is achieved by different waiting times during the time. After the flames of the fuel still in the combustion chamber have gone out and there are embers in the combustion chamber, the fire can still be kept alive after the manually or automatically set waiting time has elapsed by adding fuel. Owners of wood-burning stoves know that, depending on the type of fuel, embers can sit in the combustion chamber for up to several hours before they cool down completely to ashes.

In the proposed method, the average output is achieved in that, during the course of the heating process, intervals of combustion with a flame and high heat emission alternate with waiting times in which the fuel is in the form of embers in the combustion chamber with less heat emission. The waiting time can be short or zero for a desired high heat output and very long for a desired low heat output, ie even so long that the embers in the combustion chamber have gone out and have to be reheated.

1. 1. über der Zeit kostante mittlere Wärmeabgabe erzeugen: Die Wartezeit ist dann konstant in den Intervallen.
2. 2. die Wärmeabgabe der Differenz zwischen Ist- und Solltemperatur des beheizten Raumes anpassen. Die angepasste Wartezeit, d.h. die maximale Dauer ist jedoch soweit begrenzt, dass nicht neu angeheizt werden muss.
3. 3. die Wärmeabgabe der Differenz zwischen Ist- und Solltemperatur des beheizten Raumes anpassen. Die angepasste Wartezeit, d.h. die maximale Dauer ist unbegrenzt, dass heißt es muss u.U. neu angeheizt werden.

In the proposed method, there are 3 options for structuring the waiting times, which alternatively depend on the desired result

1. 1. Generate constant average heat emission over time: The waiting time is then constant in the intervals.
2. 2. Adjust the heat output to the difference between the actual and target temperature of the heated room. However, the adjusted waiting time, ie the maximum duration, is limited to such an extent that it does not have to be reheated.
3. 3. Adjust the heat output to the difference between the actual and target temperature of the heated room. The adjusted waiting time, ie the maximum duration is unlimited, which means it may have to be reheated.

The proposed process is called the interval process below.

Table 1 shows the tabular procedure for the process.

A reference value serves as the signal threshold. This can be set in the controller. The currently measured signal from a sensor that monitors the burner is compared by the controller with this reference value, which serves as a signal threshold. If the sensor signal exceeds or falls below this signal threshold, this result generates a signal that generates an alarm and/or initiates actuators.

The object is achieved by a flame detector for monitoring manually charged burners in that it has an optical sensor with a controller which is designed to generate an alarm if there is a risk of fuel shortage and the flame detector is assigned to a burner and is arranged in visual contact with the combustion chamber, with a temperature sensor for detecting a room temperature, a temperature adjuster for setting a target temperature of a heated space, a comparator via which a temperature measured by the temperature sensor can be compared with the target temperature, and a 4 to 20 Hz bandpass, over which an output signal of the optical sensor is passed on, are provided, the flame detector being able to detect how long the fuel is still burning with a flame in an interval process, in order to insert a waiting time after the flame has gone out, the Duration depends on the room temperature reached and during which the embers are still in the combustion chamber and then, after this waiting time has expired, an alarm indicates that more fuel has to be added. The flame detector recognizes as soon as the fuel has been used up and gives an alarm in good time so that the fuel can be refilled.

Further advantageous configurations of the flame detector are described in dependent claims 2 to 5.

According to the invention, it is a flame detector that has been known per se from burner technology or fire protection technology for more than 40 years (e.g.: EP000002064491B1 ) which uses an optical sensor to detect the approx. 4 to 8 Hz flickering frequency of flames. However, the flame detector according to claim 1 is designed in functional modes in such a way that it depicts an advantageous handling of a stove with regard to the manual refilling of fuel as a cyclical interval process.

The flame detector is equipped with a device that has cyclically linked logic states for monitoring the illustrated, discontinuous, manual process steps of heating, burning and Adding fuel to a stove is beneficial. In the interval process, the device is able to recognize how long the fuel is still burning with the flame, to wait after the flame has gone out, the duration of which depends on the room temperature reached and during which the embers are still in the combustion chamber and then after they have expired an alarm during this waiting time to indicate that fuel needs to be refilled.

The flame detector thus supports the very advantageous, since labor and fuel-saving and therefore environmentally friendly interval method for stoves, in which the heat output delivered is controlled on the one hand by the choice of the fuel quantity when adding fuel discontinuously and on the other hand by the choice of the waiting time after the flames have gone out, i.e. by the choice the time in which the fuel gives off its heat as embers in the furnace can be influenced.

By being equipped with a height-adjustable stand, the device can be retrofitted in front of an existing stove with a window, and it can be tilted on the stand so that it can be tilted at a suitable distance and height in front of the stove's viewing window that the optical sensor has a good view of the burner. This stand is high enough for the optical sensor to be located above the combustion chamber door so as not to get in the way of opening this door. For this purpose, it is advantageous to design the stand with a swivel arm, the end of which the device is attached to, or the stand has wheels the furnace door has to be opened and closed to add fuel and the stand can be easily pulled back out of the swinging range of the door.

Another option is for the aforementioned optical sensor to be attached directly to the furnace door at the top with a hitch hung on the edge of the viewing pane so that it moves with the door, or subsequently attached to the wall of the stove above the door if there is space and the optical sensor has a good view of the burner from there.

Because of the radiant heat emitted by the oven, it must be ensured that the electronics of the device do not overheat. This can be achieved either with a heat-resistant electronics design or with a shielding plate in front of the device with a window for the sensor and/or a built-in fan that preferably only starts up when the inside of the housing has a temperature above a certain value, e.g. 60 °C over 60 has °C.

The temperature sensor for measuring the room temperature is advantageously arranged on the side of the housing facing away from the burner, where the fan also draws in the air for cooling the electronics.

The original equipment manufacturer from the factory of the stove naturally has even more options for arranging it inside the stove, but due to the heat sensitivity of electronics it is then necessary to ensure adequate cooling even when the stove is running at full capacity, but the sensor for the room temperature is advantageous outside to arrange the housing. Already existing burners can advantageously be retrofitted with devices according to the invention.

Figur 1:

eine perspektivische Ansicht eines Kaminofens mit erfindungsgemäßen Flammdetektor,

Figur 2:

die Gestaltung eines Ausführungsbeispiels des Gerätes,

Figur 3:

die Erweiterung des erfindungsgemäßen Gerätes durch einen Temperatursensor,

Figur 4:

das Schaltbild einer Schaltungsanordnung des erfindungsgemäßen Flammdetektors und

Figur 5:

das Schaltbild einer vereinfachten Schaltungsanordnung des erfindungsgemäßen Flammdetektors.

The invention is described by way of example in a preferred embodiment with reference to a drawing. The figures in the drawing show in detail:

Figure 1:

a perspective view of a fireplace with a flame detector according to the invention,

Figure 2:

the design of an exemplary embodiment of the device,

Figure 3:

the extension of the device according to the invention by a temperature sensor,

Figure 4:

the circuit diagram of a circuit arrangement of the flame detector according to the invention and

Figure 5:

the circuit diagram of a simplified circuit arrangement of the flame detector according to the invention.

The following describes how the electronic device advances the functions of the alarm functions depending on the state of the burner.

Before heating up, the device is switched on, although it is not immediately in the

goes into alarm mode, i.e. the absence of flames is acknowledged with an alarm, but goes into a waiting mode, it waits for flames to appear and initially only shows visually whether it detects flames or not.

If the continuous detection of flames is positive for more than 5 min, the device is automatically or manually switched to the operating state, i.e. mode, "Flame monitor".

When the fire has burned down, the flames will die out after some time, which the device will detect.

Depending on how high the room temperature is, ie how much you want to heat, the device then waits for an adjustable or determined by the temperature of the room to be heated waiting time, which determines the time after which you would like to be alarmed to add fuel. If you want to heat up a lot, ie the room temperature is still low, this time is very short, if you only want to heat up a little, this time will be an adjustable maximum, ie for example one hour or more, depending on how long you prefer Experience of the operator The fuel used in the special furnace keeps the embers. If you prefer to reheat before the embers go out in order to avoid reheating, then you have to go the more laborious route and reduce the output power if necessary by choosing smaller amounts of fuel for reheating. If you want to accept that the embers go out and you then have to heat up again, then the pause can be extended until the room temperature measured in the device in this operating mode falls below the desired setpoint temperature that can be set on the device.

On the one hand, this alarm is displayed optically on the device, or also acoustically, loud enough so that you can rush to other rooms in the house to add fuel.

If this sound bothers you, there is a further improved version with wireless transmission of the alarm to a receiver which, in the event of an alarm, emits an optical, acoustic or vibrating alarm when fuel needs to be refilled. When the alarm is acknowledged on the device or on the radio receiver, the device goes back into waiting mode and waits for flames to appear after adding fuel.

The waiting mode also fulfills the function that you can take your time before adding more wood or, if you want, you can let the fire go out without the device interfering with a new alarm.

The button for acknowledging the alarm is advantageously at the same time the button with which one can cycle through the function modes.

According to an example figure 1 The aim is to show how the device can be arranged on the stove:
On a stand 1, with a height adjustability 2 and with a sufficiently wide base 3, so that the entire arrangement does not tip over so easily, the device housing 4 sits with a window 5 on the front of the device, i.e. on the side facing the oven window 6, behind which the optical sensor 7 is attached. The device housing 4 can be tilted forwards and downwards in a fork 8 so that the optical sensor 7 has a good view of the burner 10 in the furnace. In order to quickly withdraw the device from the oven window 6 to open the oven door 6a, there are optional casters 9 on the feet. As already described, the temperature sensor 7a is attached to the back, that side of the device housing 4 which faces away from the burner 10 . There it is adequately protected from thermal radiation and gross incorrect measurements are avoided.

figure 2 shows as an example the design of the device when a constant average heat output is to be achieved, with a constant waiting time that can be set by the user.

The electronics 12 connected to the optical sensor 7 evaluate the output signal and forward the results to the optical display 13. This is advantageously implemented by a row of LEDs 18 and the acoustic alarm 14 on the side or rear of the device housing 4 , or via the antenna 15 for an alarm device connected remotely by means of radio technology.

A single button 16 is sufficient for switching on the device and operating the status modes. The device is switched on by pressing button 16 for the first time. After switching on, the device is in mode I "Waiting for flames", which is flame detection when heating up or post-heating.

It then either automatically switches to the next mode II after 5 minutes if the first flames are detected without interruption: "Flame monitoring" which is the detection of the absence of flames, or it is brought there manually by pressing button 16.

The transition to Mode III "Waiting" is usually almost always automatic when there is no flame in the fire, but can also be done with the help of the button, simply to be able to manually button the device through the various modes in sequence, to bring it into the correct mode appropriate to the respective status of the fire or to be able to test the functions.

During the waiting time, the glowing heat of the glowing, not yet fully burned fuel is used before new fuel is added. This adjustable time is also the manipulated variable with which the output of the burner can be controlled. After the waiting time has elapsed, the device goes into the next mode "Alarming". The alarm can also be acknowledged with button 16.

After acknowledging the alarm, the device is back in mode I: "Flame detection during heating up or post-heating".

The maximum waiting time that occurs after recognizing that there is no flame can be set with a rotary knob 17 either in steps or continuously between 5 minutes and 5 hours.

The minimum waiting time of 5 minutes is also necessary here so that the device does not go into alarm mode immediately if there is a brief absence of flames, such as during heating. If flames appear again after the waiting time has started, the waiting time starts again.

The modes are indicated visually with a row of LEDs 18 in the example shown. The device is switched off by pressing button 16 for more than 2 seconds.

A battery or rechargeable battery 19 supplies the electronics with power. When using the battery, it is also possible to connect a charger.

figure 3 shows the expansion of the device by a temperature sensor 7a and an adjustability 17a of the target temperature of the heated room. This makes it possible to make the waiting period after the flames have gone out dependent on the difference between the target and actual temperature. Setting option 17 is then used for the maximum waiting time, which is intended to prevent the pause from being extended to such an extent that heating has to be restarted.

If this limitation is not required, the rotary knob is simply turned to the right stop and thus switched off, in that this time setting is extended to such an extent that it no longer intervenes in the process.

The procedure is the same if you want to work with a constant pause. Then the temperature adjuster 17a is turned to the left stop and the setpoint temperature is adjusted so far down that it is already reached without heating and work is therefore only carried out with a constant pause, which is set with 17.

figure 4 shows the block diagram as an embodiment of the electronics without p-processor. A memory module 20 with a look-up table as status memory controls the sequence of the process steps with the transitions that are in some cases conditional. The inputs 20a of the memory module are the addresses under which the respective next status of the controller is stored as information and appears as a control signal at the outputs 20b and the optical Display 13 with the LED 18 of the respective mode or the acoustic Alarmgeber14 or via the transmitter controls the antenna 15.

A part of the output variables of the outputs 20b together with the input variables from the operation, the timers 30 and 30a for the waiting time after the flames have gone out or the respective 5 minutes until switching to the next mode as target information for the address where the information stands for the next status.

A pulse generator 31 as a clock generator ensures that the address is transferred to the memory with the rising edge of the pulse and the information is output with the falling edge. The waiting time after the absence of flames or the target temperature of the room can be adjusted from the outside by means of two rotary knobs 17 and 17a on the housing.

The optical sensor 7 is connected to the input of the bandpass filter 21 . The comparator 22 ensures that only signals of a specific magnitude are evaluated and that the memory module is driven with a digital signal. The temperature sensor 7a is connected to the preamplifier 21a and compared with the setpoint temperature via the comparator 22a.

A very simple and therefore not only inexpensive but also easy to use device version by operators who are not so technically experienced figure 5 The waiting time after the flames have gone out cannot be set, but uses the basic function of the interval method and only knows 3 modes: Mode I is fulfilled when the device is switched off. When heating up, you have to wait until flames clearly appear, only then is the device switched on and it is then already in Mode II "Flame monitoring", if there are no flames it then goes into Mode III "Waiting" and after 5 minutes in Mode IV "Flame absence alarm" ( figure 4 ).

It only has a green LED 24a, which is used as an indicator for the correct setting of the sensor preamplifier, and a red LED 28a, which indicates an alarm if there is no flame. To acknowledge and switch off the alarm, the device is simply switched back to the "Heating up or post-heating" (=OFF) status.

The following description serves to explain the electronic function.

The optical sensor 7, implemented here by a photoresistor, forwards its output signal, i.e. a signal with the flickering frequency of the flames of about 4 to 20 Hz via the 4 to 20 Hz bandpass filter 21 to the preamplifier 23, whose gain can be adjusted goes to the level detector 24. The upper edge of the bandpass has been extended to 20 Hz, since the flickering frequency increases when there is a heavy draft in the chimney. The amplification of the preamplifier is now set in such a way that the green LED 24a still flashes clearly in time with the flickering frequency when the flame size is the minimum that can be detected. This also ensures that the capacitor 26 of the timer 25 is always safely charged for the waiting time when flames appear and can only be slowly discharged via a high-impedance resistor 27 if the flickering signal does not occur, so that the voltage only drops after about 5 minutes at the capacitor has dropped so far that the alarm can be triggered by the alarm comparator 28 and the red LED 32 and the acoustic alarm device 33 go on.

To turn off the alarm, simply switch off the device with the ON-OFF switch 29. After adding fuel, the device is only switched on again when flames clearly appear, which is usually the case after a few seconds. You have to wait that long with the simple and inexpensive design of the device, which is quite reasonable.

Of course, the electronics can also be implemented with the help of a microprocessor for the convenient design of the device. Then operation and display correspond to the state of the art with a digital display and two buttons for switching on the device and the operation of the menu as + - buttons executable.

The range of functions of the device and the design of the device program corresponds to the process flow shown in Table 1. If a processor is selected as the electronics basis, there is also the option of channel selection for radio transmission of the alarm in the version with radio technology, either as is known with two step switches or via the digital user interface. Table 1 Process step / variant Process step des. Device function (modes) Condition for transition to the next state Conditions for process jumps 0 OUT Waiting for Pressing the acknowledgment button I Heating up / adding fuel Waiting for flames do flames last longer than approx. 5 minutes without an interruption of more than 5 seconds? if there are no flames after 10 minutes, the status control jumps to process step IV (alarm) OR Pressing the acknowledgment button OR Pressing the acknowledgment button longer than 2 seconds -> (OFF) II Heat monitor flames are there no flames for more than 5 minutes without a break? Pressing the acknowledgment button longer than 2 seconds -> process step 0 (OFF) OR Pressing the acknowledgment button III / 1 Use of the scorching heat Waiting Expiry of the set waiting time of approx. 60 minutes Pressing the acknowledgment button longer than 2 seconds -> (OFF) III / 2 Use the scorching heat and observe the room temperature Waiting Expiry of the set maximum waiting time of approx. 60 minutes Pressing the acknowledgment button longer than 2 seconds -> process step 0 (OFF) OR Drop in room temperature below the set target temp. OR Pressing the acknowledgment button III / 3 Observing the room temperature Waiting Drop in room temperature below the set target temperature Pressing the acknowledgment button longer than 2 seconds -> process step 0 (OFF) OR Pressing the acknowledgment button IV Refuel necessary Alert Switch off the alarm by pressing the acknowledgment button Pressing the acknowledgment button longer than 2 seconds -> process step 0 (OFF) OR 2 min alarm without acknowledgment I as above (cyclic) Heating up / adding fuel Waiting for flames do flames last longer than 5 minutes without an interruption of more than 5 seconds? if there are no flames after 10 minutes, the status control jumps to process step IV (alarm) OR Pressing the acknowledgment button OR Pressing the acknowledgment button longer than 2 seconds -> (OFF) Process step I is the same in terms of heating up and adding more fuel.

Reference List

1

stand

2

Height adjustability

3

base of the stand

4

device housing

5

Device case window

6

oven window

6a

oven door

7

optical sensor

7a

temperature sensor

8th

Fork can be tilted forwards and downwards

9

roll

10

burning point

11

oven

12

electronics

13

Optical display

14

acoustic alarm

15

antenna

16

button

17

Setting the waiting time

17 a

Setting the target temperature

18

LED for displaying the function modes

19

battery for power supply

20

memory chip

20a

Inputs of the memory chip

20b

Outputs of the memory chip

21

Bandpass 4 to 20 Hz

22

comparator

23

preamp

24

level detector

24a

green LED

25

timer

26

capacitor of the timer

27

resistance of the timer

28

alarm comparator

29

On-off switch

30

Timer for waiting time after flames go out

30a

5 min timer

31

pulser

32

red LED

33

acoustic alarm

Claims (5)

1. Flame detector comprising an optical sensor (7), for monitoring a manually fed burn site characterized in that
   the optical sensor 7 comprises a control unit which is developed to generate an alarm in the event of an imminent fuel shortage and which is assignable to a burn site (10) and disposable in the line of sight with the combustion chamber, wherein are provided a temperature sensor (7a) for acquiring a volume temperature, a temperature setter (17) for setting a nominal temperature of a heated volume, a comparator (22), across which a temperature measured by the temperature sensor (7a) can be compared with the nominal temperature, and a 4 to 20 HZ bandpass (21) across which an output signal of the optical sensor is transmitted, wherein the flame detector in an interval process is enabled to detect the length of time the fuel is still able to burn with a flame in order to set, after extinguishment of the flame, a waiting period the duration of which depends on the volume temperature reached and in which the embers are still within the combustion chamber and, after passage of this waiting period, to indicate by an alarm that fuel has to be added.
2. Flame detector as in claim 1, characterized in that it comprises a support (1) preferably a stand (1) rollable on the base, which stand (1) is in particular height adjustable between approximately 0.5 and 1.0 m, wherein preferably between the flame detector and its stand (1) a settable swivel device (8) is provided.
3. Flame detector as in claim 1 or 2, characterized in that it comprises a securement device, in particular a suspension device or a magnet, for securing the flame detector at the margin of the combustion chamber, in particular at the margin of a viewing window of a wood-burning fireplace insert.
4. Flame detector as in one of claims 1 to 3, characterized in that it comprises an alarm function and an acoustic (14) and/or optical display (13) is available for a first settable operating mode, in which waiting for flames takes place, and a second settable operating mode in which flames are monitored.
5. Flame detector as in one of claims 1 to 4, characterized in that an alarm is transmitted across a wireless operative connection, preferably a radio connection (15), to an external alarm generator which receives the alarm and subsequently outputs the alarm either visibly, audibly or haptically.

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