How does this igniter box work..... (1 Viewer)

[GaryGavlaar]

For some completeness to this thread, I eventually found this post on another forum. I'm still yet to receive my new igniter cable to see if I can get this working. However this description of how the single cable igniter works to sense a flame also i thought was decent.....

Firstly the spark generator is actually a reigniter rather than an igniter. This means it constantly checks the flame integrity and restarts the high voltage pulses to create sparks if the flame extinguishes for any reason. So in normal operation, should the flame be blown out it will be automatically be re-lit.



The way it achieves this is by exploiting the fact that the resistance through the ionised gases in a flame is significantly lower than through air. The reigniter unit measures the resistance between the probe tip and the "earth" terminal of the reigniter unit - doing this between the HV pulses.

This in turn means you need to pay attention to the following points to ensure the resistance measuring current path around the circuit is OK

1. Ensure probe tip is touching the outer part of the flame

2 Ensure the connection from the reigniter to the frame ( the chassis or earth connection) is good (not loose or corroded)

Then the low voltage circuit from the reigniter probe, the ionised flame gas, the brass flame tube, the fridge chassis, the reigniter earth connection should be complete and once a flame is lit current should flow and trigger the reigniter to stop HV pulses. Note that only about 5 mA flows in this measuring circuit - so connections have to be good.

 

[Orion]

‘Reignitor’ isn’t a term I’ve ever come across before, but apart from that pretty much as per post #23.

 

[GaryGavlaar]

New Igniter electrode and cable has made zero difference

Tried orientating the electrode in 3 possible positions which has made zero difference either.
.

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[GaryGavlaar]

Ok so, on to the switch.....

It has 3 pins/spades....

when i test continuity, the pin that the black wire from the igniter box is on, never has continuity to any of the other pins. When it's off there is no continuity between any pins, when it is on the two pins that the two blue wires are connected to are connected.

Does this sound right?

 

[ASW]

Ok so, on to the switch.....

It has 3 pins/spades....

when i test continuity, the pin that the black wire from the igniter box is on, never has continuity to any of the other pins. When it's off there is no continuity between any pins, when it is on the two pins that the two blue wires are connected to are connected.

Does this sound right?

View attachment 720166

Hi Gary, did you ever resolve this issue? I have the same fridge and the same problem. Did you get an ignitor cable?

 

[GaryGavlaar]

No....I got a new cable and it made no difference. I'm still none the wiser about what the problem is. I just have to turn the ignition off manually now.

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[tonyidle]

The copper cable on the far side is a thermocouple. When it detects heat ie aflame it tell the ignite to stop. If the flame goes out it will start the ignitor again. It has to be in the flame.

The flame rectifies the ac spark. The module detects the change and stops sparking. This circuitry require no extra connections or components and is independent of the flame failure device.

 

[Reallyretired]

As I understand it the flame itself should provide a path to earth, ionisation being the mechanism. The ignitor box could be at fault, or perhaps just a bad earth connection on the burner.

 

[Odd job]

The copper cable on the far side is a thermocouple. When it detects heat ie aflame it tell the ignite to stop. If the flame goes out it will start the ignitor again. It has to be in the flame.

That's not how it works, the thermocouple is separate it controls the gas not the spark. The ignition generator, depending on the model does not detect the flame and is controlled by a switch, although some ignition units do detect the flame and shut the spark off.
The first thing is to find out which ignition unit is fitted, if it's a manual then check the switch, if automatic then first check the cable and electrode for cracks and the electrode must be on the flame. Also the ignition unit must have the correct polarity.

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[ASW]

No....I got a new cable and it made no difference. I'm still none the wiser about what the problem is. I just have to turn the ignition off manually now.

How can you tell that the flame is alight? I can light mine with the fridge unit pulled out, the gland stays lit but the ignotor life yours continues to ignite. If I push the fridge back in to its hole, I'm wondering how I can ensure the flame has lit before turning off the ignitor switch, without having to remove the outside vent to check. It's gonna be extremely annoying.

 

[autorouter]

There are different ways of igniting the gas and shutting off the gas if the flame fails.

For a spark, one way is a piezoelectric sparker. When you give a quartz crystal a good solid whack (technical term) then it generates a sudden high voltage. A couple of electrodes on the crystal and a couple of very well insulated wires can carry the high voltage to where you want, and if there is a suitable gap it will produce a spark. That's the 'Press and Click' method, one spark per click.

The other way for a spark is to use an induction coil and an automatic switcher. When the current is interrupted, a spark is produced, similar to a spark for a petrol engine. If the button is pressed continuously, a constant stream of sparks is produced. Many gas hobs have a similar system.

To check if the flame is present, one way is a thermocouple. This produces a small voltage when it is hot, and the voltage is used to open/close an electrical solenoid valve which shuts off the gas supply. Obviously the thermocouple end must be in the flame to get hot, or it will never register the flame as present.

However there is another technology to sense the presence of a flame. A flame is a stream of ionised gas, and ionised gas conducts electricity. Ordinary air and non-burning gas are very good electrical insulators, and don't allow any current to flow. So if two electrodes in a flame suddenly start to allow a current to flow, then the control board knows there is a flame present. And if the current stops, it knows the flame has gone out. It can turn on the spark igniter. If after a suitable period of trying, there's still no current, it gives up, turns off the gas, and switches on the error light.

Actually, it is possible to incorporate the current sensing circuit in with the spark generating circuit, which is why there is only one wire to the gas flame, it produces the spark, and senses the flame too.

Anyway, the first thing to find out is which method is used in your particular gas appliance, now that you know the possibilities. In my fridge the ignition is by an 'igniter box' which has an induction coil inside, and the flame sensing is by electrical resistance not a thermocouple.

 

[GaryGavlaar]

How can you tell that the flame is alight? I can light mine with the fridge unit pulled out, the gland stays lit but the ignotor life yours continues to ignite. If I push the fridge back in to its hole, I'm wondering how I can ensure the flame has lit before turning off the ignitor switch, without having to remove the outside vent to check. It's gonna be extremely annoying.

Do you not have a flame window bottom left back inside your fridge?

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[mitzimad]

No thermo couple on most fridges under 20 years old all work on rectifcation most likely cause of not shutting off is a bad earth

 

[GaryGavlaar]

As I understand it the flame itself should provide a path to earth, ionisation being the mechanism. The ignitor box could be at fault, or perhaps just a bad earth connection on the burner.

I bought a new igniter box

 

[ASW]

Do you not have a flame window bottom left back inside your fridge?

No I don't unfortunately, my fridge (22yr old) is at the back of the unit, with the metal cover. So when the fridge is pushed back into place, the only way you can see the flame is to remove the outside vent and the metal plate. Or if the fridge was working correctly, the ignitor light would go out. Which in our case don't happen.

It got me thinking last night, the only way is to feel the outside top vent for heat. So I was thinking, if I place a permanent thermometer probe in the fridge flue exit by the outside vent and run the wire to the digital reading until to say the inside gas cupboard taps next to the fridge. Then when I light the flame, once the thermometer starts to increase I can safely turn off the continuous ignition switch from flicking knowing that the flame is lit by the thermometer reading. If for whatever reason the flame goes out, the gas is automatic cuts out anyway and the only way to allow gas through again is to physically push the button in on the fridge to reignite. It's the only option I can think of at present. If you do ever get yours sorted, please do let me know. Good luck

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[ASW]

No thermo couple on most fridges under 20 years old all work on rectifcation most likely cause of not shutting off is a bad eart

 

[ASW]

Bad earth to the thermocouple or the ignitor? Where is the earth taken from? The master mains to the fridge unit? Or would the earth be from the little screw that holds the burner in place? Thoughts

 

[GaryGavlaar]

No I don't unfortunately, my fridge (22yr old) is at the back of the unit, with the metal cover. So when the fridge is pushed back into place, the only way you can see the flame is to remove the outside vent and the metal plate. Or if the fridge was working correctly, the ignitor light would go out. Which in our case don't happen.

It got me thinking last night, the only way is to feel the outside top vent for heat. So I was thinking, if I place a permanent thermometer probe in the fridge flue exit by the outside vent and run the wire to the digital reading until to say the inside gas cupboard taps next to the fridge. Then when I light the flame, once the thermometer starts to increase I can safely turn off the continuous ignition switch from flicking knowing that the flame is lit by the thermometer reading. If for whatever reason the flame goes out, the gas is automatic cuts out anyway and the only way to allow gas through again is to physically push the button in on the fridge to reignite. It's the only option I can think of at present. If you do ever get yours sorted, please do let me know. Good luck

Mine too {age}.....are you sure you don't have a little round viewing window at the back of the fridge. I would think that would be a pretty standard feature with a gas fridge. You have to look at it from a pretty specific angle to see the flame and is obviously easier to see the darker it is.

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[GaryGavlaar]

Bad earth to the thermocouple or the ignitor? Where is the earth taken from? The master mains to the fridge unit? Or would the earth be from the little screw that holds the burner in place? Thoughts

This is where I got to before I gave up and just put up with turning the igniter on and off manually. I think I was checking the continuity of the cables going to the switch etc... I would need to revisit it all again.

Is there a better way to check for "bad earth's" other than continuity?

 

[ASW]

Mine too {age}.....are you sure you don't have a little round viewing window at the back of the fridge. I would think that would be a pretty standard feature with a gas fridge. You have to look at it from a pretty specific angle to see the flame and is obviously easier to see the darker it is.

100% no viewing hole for the pilot light. I've checked from inside out the outside. I think there are a few RM400 series, mine don't have that. Back to the thermometer, I checked earlier when the fridge was pulled out to see if gas still came or after it was lit and the ignition was turned off, it does! So be careful when you have the fridge on gas without the ignitor switched on, if the flame goes out, you'll need to get rid of the gas before igniting due to the build up of gas. That said, not much we can do when the ignitor continues to flick even though the gas has ignited. Despite that I've purchased a thermometer from Wilko, £12 down to £6 atm. Its the type you can put the probe in the oven whilst you cook with the plastic digital display outside, so I'm gonna put the probe down the flue vent and the display in the cupboard draw where the gas taps are. At least I'm have some kind of idea if it's slight though it takes a few minutes to warn up.

 

[GaryGavlaar]

100% no viewing hole for the pilot light. I've checked from inside out the outside. I think there are a few RM400 series, mine don't have that. Back to the thermometer, I checked earlier when the fridge was pulled out to see if gas still came or after it was lit and the ignition was turned off, it does! So be careful when you have the fridge on gas without the ignitor switched on, if the flame goes out, you'll need to get rid of the gas before igniting due to the build up of gas. That said, not much we can do when the ignitor continues to flick even though the gas has ignited. Despite that I've purchased a thermometer from Wilko, £12 down to £6 atm. Its the type you can put the probe in the oven whilst you cook with the plastic digital display outside, so I'm gonna put the probe down the flue vent and the display in the cupboard draw where the gas taps are. At least I'm have some kind of idea if it's slight though it takes a few minutes to warn up.

I've tested mine, it has a thermo couple for when the flame goes out. It takes about 30 secs I think, info on my checks in this thread somewhere I think. So worse case for me is the fridge warms up without me noticing. I tend to check most times I walk in and out the motorhome though that it's still lit as the vent is right by the door.

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