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

[GaryGavlaar]

Can any clever type tell me exactly how this igniter box works.

The main bit im interested in is exactly how the box knows to stop the igniter once the flame is lit.

The igniter itself is just one cable coming from the box to the gas flame area. The igniter works and flame lights ok, however the spark just never stops once lit.

I can't find the replacement box online so a bit stumped.

Cheers

 

[Nick A]

Can any clever type tell me exactly how this igniter box works.

The main bit im interested in is exactly how the box knows to stop the igniter once the flame is lit.

The igniter itself is just one cable coming from the box to the gas flame area. The igniter works and flame lights ok, however the spark just never stops once lit.

I can't find the replacement box online so a bit stumped.

Cheers

View attachment 718044 View attachment 718045

Ok I will try in my limited knowledge if it's the same as a water heater a voltage is applied to the ignitor that travels through the flame and the box should senses this and stop the ignitor bit I am happy to be corrected on this.if it's still clicking after the flame has been lite I would be concerned it will not recognise flame failure and not use it until fixed .

 

[2x2camper]

Can any clever type tell me exactly how this igniter box works.

The main bit im interested in is exactly how the box knows to stop the igniter once the flame is lit.

The igniter itself is just one cable coming from the box to the gas flame area. The igniter works and flame lights ok, however the spark just never stops once lit.

I can't find the replacement box online so a bit stumped.

Cheers

View attachment 718044 View attachment 718045

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.

 

[2x2camper]

Can any clever type tell me exactly how this igniter box works.

The main bit im interested in is exactly how the box knows to stop the igniter once the flame is lit.

The igniter itself is just one cable coming from the box to the gas flame area. The igniter works and flame lights ok, however the spark just never stops once lit.

I can't find the replacement box online so a bit stumped.

Cheers

View attachment 718044 View attachment 718045

The burner, thermocouple and jet can be bought separately.

Which model fridge do you have?

 

[GaryGavlaar]

Ok I will try in my limited knowledge if it's the same as a water heater a voltage is applied to the ignitor that travels through the flame and the box should senses this and stop the ignitor bit I am happy to be corrected on this.if it's still clicking after the flame has been lite I would be concerned it will not recognise flame failure and not use it until fixed .

The thermo couple is a separate device and works fine at shutting off gas if flame goes out. Fully tested today. The igniter is a separate single wire coming from a little box. I just can't work out what it is that tells the box to stop sparking. I really need to prove that it's the cable or the box or something else.

I can get a new spark cable but it's not cheap, but can't find the box if that's needed anywhere at all

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[2x2camper]

The thermo couple is a separate device and works fine at shutting off gas if flame goes out. Fully tested today. The igniter is a separate single wire coming from a little box. I just can't work out what it is that tells the box to stop sparking. I really need to prove that it's the cable or the box or something else.

I can get a new spark cable but it's not cheap, but can't find the box if that's needed anywhere at all

The thermocouple when the flame lights as i said above. What are you describing as the box?

 

[GaryGavlaar]

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 thermo couple seems to work fine and allows the gas valve to stay open once lit and also shuts the gas off when it's blown out. This thermo couple is in no way connected to the igniter box from what I can see, it's just a copper tube that goes back to the gas valve frome what I can see.

The igniter box seems to have 3 cables going to it. A 12v pos and neg (blue and red), and the black comes from the igniter switch on the front of the fridge.

 

[GaryGavlaar]

The burner, thermocouple and jet can be bought separately.

Which model fridge do you have?

It's an rm 4401 I think

 

[2x2camper]

The thermo couple seems to work fine and allows the gas valve to stay open once lit and also shuts the gas off when it's blown out. This thermo couple is in no way connected to the igniter box from what I can see, it's just a copper tube that goes back to the gas valve frome what I can see.

The igniter box seems to have 3 cables going to it. A 12v pos and neg (blue and red), and the black comes from the igniter switch on the front of the fridge.

The thermocouple generates a small electric charge when heated which signals the igniter to stop when a flame is present. If the igniter does not stop it is not getting the signal

 

[GaryGavlaar]

The thermocouple when the flame lights as i said above. What are you describing as the box?

Sorry .....that was a reply the other person. The box is the igniter box....blue box in the picture.

I have responded to you post separately sorry. The thermocouple has no connection to the blue box from what I can see, so can't see how it would communicate with that box and tell it to stop sparking.

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[GaryGavlaar]

The thermocouple generates a small electric charge when heated which signals the igniter to stop when a flame is present. If the igniter does not stop it is not getting the signal

How does it tell the igniter box to stop sparking when it has no connection to it?

 

[2x2camper]

How does it tell the igniter box to stop sparking when it has no connection to it?

See this thread for ideas

Dometic RM7501 still clicking when lit.

We have the above fridge and after lighting the gas, the igniter keeps clicking and light flashing. Got a nice steady blue flame. Any ideas please ?

www.motorhomefun.co.uk

 

[GaryGavlaar]

Already seen that one. None the wiser really. Sounds like the outcome was a new igniter box which from what I can tell doesn't exist to buy any more

It still doesn't really answer the question either.

Is the igniter cable/electrode also some kind of thermo couple maybe?

40 quid for a new cable/electrode, but will be a waste of it's not that, as I can no longer seem to get the control box. This is why I'm trying to understand how it actually works. I get a spark, and if that's the electrode/cables only function then buying a new one seems pointless as I get an ignition spark.

If someone can confirm that cable has two functions, one of which being sending a signal back to the box as well as sparking, then I guess it's worth a shot.

 

[pappajohn]

The igniter box seems to have 3 cables going to it. A 12v pos and neg (blue and red), and the black comes from the igniter switch on the front of the fridge.

I suspect the switch wire simply goes to earth via the switch as there's only one wire.
The switch could have an internal short circuit or the wire itself shorted causing the control unit to see it as a demand for spark.
Try disconnecting it and see if the spark stops.
New switch.....pennies
New control unit....pounds and it may not need one

 

[GaryGavlaar]

I suspect the switch wire simply goes to earth via the switch as there's only one wire.
The switch could have an internal short circuit or the wire itself shorted causing the control unit to see it as a demand for spark.
Try disconnecting it and see if the spark stops.
New switch.....pennies
New control unit....pounds and it may not need one

I can't find the control unit for sale anywhere. They all seem to be discontinued.

I did find the earth spade on the fridge today, and cleaned that up thinking it could be the issue to no avail. However you're saying it could be the igniter switch on the front of the fridge that's the issue? Is that the black wire in the picture above you are talking about?

I've attached a wiring diagram for the igniter unit if of any help to anyone.

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[PeterCarole29]

I have about 4 fridges that i was going to get round to ebay the parts as i have given up half my storage.
Unfortunately at the moment wife and are have covid and quite unwell at home feeling very sorry for ourselves (well me anyway)
in a few days if your not sorted i can go and look

 

[PeterCarole29]

I can't find the control unit for sale anywhere. They all seem to be discontinued.

I did find the earth spade on the fridge today, and cleaned that up thinking it could be the issue to no avail. However you're saying it could be the igniter switch on the front of the fridge that's the issue? Is that the black wire in the picture above you are talking about?

I've attached a wiring diagram for the igniter unit if of any help to anyone.

View attachment 718341

Tomorrow send a picture of your fridge front

 

[GaryGavlaar]

I have about 4 fridges that i was going to get round to ebay the parts as i have given up half my storage.
Unfortunately at the moment wife and are have covid and quite unwell at home feeling very sorry for ourselves (well me anyway)
in a few days if your not sorted i can go and look

Oh sorry to hear you have covid....its bloody awful i know. I'll keep that in mind though. Many thanks

 

[GaryGavlaar]

Tomorrow send a picture of your fridge front

 

[PeterCarole29]

Hi thanks for the photo will go and have a look in a couple of days and i do think i have one

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[Manic]

On our fridge, occasionally the sparkler on ours fails to stop clicking, when this happens I just turn the flashing ignition switch off. You just have to keep checking the burner is still a light.

 

[rb62]

Already seen that one. None the wiser really. Sounds like the outcome was a new igniter box which from what I can tell doesn't exist to buy any more

It still doesn't really answer the question either.

Is the igniter cable/electrode also some kind of thermo couple maybe?

40 quid for a new cable/electrode, but will be a waste of it's not that, as I can no longer seem to get the control box. This is why I'm trying to understand how it actually works. I get a spark, and if that's the electrode/cables only function then buying a new one seems pointless as I get an ignition spark.

If someone can confirm that cable has two functions, one of which being sending a signal back to the box as well as sparking, then I guess it's worth a shot.

Looking on this site they are possibly still available,if yours is AES,



Using the part number they are available from,

Dometic Ignition Electric | Dometic Spares | Leisureshopdirect

Buy a Dometic Ignition Electric | Dometic Spares | Leisureshopdirect

www.leisureshopdirect.com

 

[Orion]

I can't find the control unit for sale anywhere. They all seem to be discontinued.

I did find the earth spade on the fridge today, and cleaned that up thinking it could be the issue to no avail. However you're saying it could be the igniter switch on the front of the fridge that's the issue? Is that the black wire in the picture above you are talking about?

I've attached a wiring diagram for the igniter unit if of any help to anyone.

View attachment 718341

The ignition probe may also form part of an ionisation circuit. Once the pilot flame is established it is detected and the spark generator shuts down and stops the probe sparking. Failure to shut down could be deposits on the probe preventing flame detection, a bad earth path on the spark generator, or the unit itself defective. The thermocouple lead interfaces directly with the gas valve as a safety device and is not connected to the spark generator.

 

[PeterCarole29]

Can any clever type tell me exactly how this igniter box works.

The main bit im interested in is exactly how the box knows to stop the igniter once the flame is lit.

The igniter itself is just one cable coming from the box to the gas flame area. The igniter works and flame lights ok, however the spark just never stops once lit.

I can't find the replacement box online so a bit stumped.

Cheers

View attachment 718044 View attachment 718045

reading it all sounds as if you have no choice but to start with the cable .Dont know if it possible to do a resistance test or not ?

 

[68c]

Posts 2 and 23 explain the igniter detects the flame and stops the sparking. You need to follow this trail, not the thermocouple one, a bad thermocouple just means the flame will not stay on.

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[jockaneezer]

The fact that the "box" is actually making sparks would suggest it's ok, but it's not getting the message to tell it to stop, which would be down to the cable going to the burner ?

 

[GaryGavlaar]

The ignition probe may also form part of an ionisation circuit. Once the pilot flame is established it is detected and the spark generator shuts down and stops the probe sparking. Failure to shut down could be deposits on the probe preventing flame detection, a bad earth path on the spark generator, or the unit itself defective. The thermocouple lead interfaces directly with the gas valve as a safety device and is not connected to the spark generator.

Yes this is why I couldn't see how the suggestion of thermo couple issue made any sense.

Looking at the box it does have a marking on it that suggests there is some temperature measuring going on (70C). I just couldn't work out how it was doing it as the igniter just looked like a single cable so didn't know if it would have that functionality. Due to the blocked jets the cable had been melted ever so slightly when the gas flame had worked its way back to the air hole at the start of the burner tube.

Only one way to find out I guess, I have a new cable on order. Let's see what happens.

 

[GaryGavlaar]

Posts 2 and 23 explain the igniter detects the flame and stops the sparking. You need to follow this trail, not the thermocouple one, a bad thermocouple just means the flame will not stay on.

I have a new cable on order so we shall see. Post 2 didn't seem too sure and 23 I've just read, cheers. An ionisation circuit, sounds interesting. Off to read about that.

I just wanted to try and confirm that the igniter cable, which looked like a single wire, had the capability of sending a signal back to the box, before dropping £40 on something I didn't need.

I will hopefully know more tomorrow

 

[Toady]

Simple test to check the thermocouple using a multimeter on YouTube

 

[GaryGavlaar]

Simple test to check the thermocouple using a multimeter on YouTube

The thermocouple is working fine and doesn't seem to have any link to the igniter box. Thermo couple only looks to control the gas valve.

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