Problem with flame detector on gas hob

We have a small gas hob on our boat running from bottled propane.

It has the (mandatory on boats) flame detection failure shut off. Thus to light the gas you turn the knob, press it in to override the flame detector, light the flame and keep the knob pressed in for a few seconds until the flame detector thermocouple (?) has heated up to keep the gas on.

One of the three burners won't start at all, i.e. pressing the knob to override the flame detector doesn't allow gas through to the burner.

Does anyone know the likely cause? I.e. is it simply something sticking in the mechanism which might be fixed by a thorough clean or is there a specific part which may need replacing?

Reply to
Chris Green
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Failing to hold in after lighting is usually thermocouple failure. Failing to ignite in the first place sounds like a mechanical issue in the gas valve. I'm assuming it is not a failure of the igniter and you have tried a match etc and know there is no gas getting through.

Bob

Reply to
Bob Minchin

Chris Green brought next idea :

If there is definately no hiss from the gas to be heard, when the button is pressed, likely the jet is blocked up perhaps with grease. Usually if the burner is removed, you will see the brass jet which can be unscrewed. It should have a tiny hole in the end. If you cannot blow through it, it is choked up. You will need a really fine wire to clear it.

I had trouble with our caravan's grill, not getting hot. On stripping it down I found its jet had been drilled too small. I was able to drill it out to the correct size and it has been fine since. Possibly if your ring has never worked, this might be the problem. I was lucky, I already had in my workshop a set of the fine drill bits needed, but your best option might be a replacement jet, if this is the case.

Reply to
Harry Bloomfield

... or a jet blocked with crud?

Thomas Prufer

Reply to
Thomas Prufer

Yes but I had rather hoped the OP would have either checked that or seen gradual degradation in heat output as the jet diameter reduced.

Reply to
Bob Minchin

Yes, this isn't the issue.

It's manually lit anyway, so we always use a lighter or a match. There's no gas getting through.

Reply to
Chris Green

Hey, that's a point, I have to admit I haven't checked for that very obvious cause. Thanks Thomas!

Reply to
Chris Green

No, the OP hadn't thought of the obvious! :-)

While we would have noticed a slow deterioration it might well have got some dirt stuffed into it during fairly major works recently. I only tried to use the gas again after it not being in use (and the gas completely disconnected) for some weeks.

Reply to
Chris Green

If it's not the jet, the thermocouple is (almost?) always replaceable, often by a generic part. And AFAIK the electromagnet that the thermocouple feeds is also replaceable, sometimes.

Thomas Prufer

Reply to
Thomas Prufer

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