Gas Burner not staying lit.

[slowdriver]

I have an integrated sink/hob unit, with two burners. It was manufactured by the Italian company - Can. My van is three years old.
Recently the small burner will ignite but after about 45 seconds it goes out whether or not there is a pan on the burner.
It has been suggested that the thermocouple for that burner has failed. Therefore I have:

1. Cleaned the thermocouple (It was not particularly dirty).
2. Removed all debris.
3. I have checked that the thermocouple is in the flame, (it is as close as the other burner, and in any event, if it was not sufficiently close to a source of heat it would presumably send a signal to close the valve immediately after initial ignition rather than run for 45 seconds).
4. I have tried "flicking" the thermocouple as suggested in earlier threads.
5. The second larger burner works perfectly.
6. I have a new, full, French, 9kg bottle of propane.

Three questions:
Any suggestions as to what the problem might be?
Any further diagnostic checks I can make?
Any suggestions for a mobile, habitation/Truma/gas-qualified engineer, in the Oxfordshire area?

 

[scotjimland]

Check the connections of the thermocouple, if they are ok then replace the thermocouple.

You can test the probe if you have a multimeter with millivolts scale.. when hot it produces a very small voltage ~ 25mV

Not sure who thought that 'flicking it ' was a good idea, or what it would achieve. nor do they need 'cleaning' .. as they are easily damaged ..

Broken Link Removed

 

[Hettie's Crew]

I bent the thermocouple very gently and very slightly further in towards the flame when ours did the same and have had no problems since.

 

[slowdriver]

I am not very technical. When you say replace the thermocouple, I assume that just the probe rather than the whole mechanism from the probe to, and including, the valve mechanism. i.e. The bit numbered 28, above?

 

[slowdriver]

I bent the thermocouple very gently and very slightly further in towards the flame when ours did the same and have had no problems since.

Thank you. Was your problem similar, in that it ignited, ran for nearly a minute, and then cut out, or did it fail shortly after you released the gas control nob.?

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[Silver-Fox]

It’s more than likely to be a thermocoupler issue.

Tip not in the correct place in the flame.

Thermocoupler caput

 

[scotjimland]

View attachment 798009

I am not very technical. When you say replace the thermocouple, I assume that just the probe rather than the whole mechanism from the probe to, and including, the valve mechanism. i.e. The bit numbered 28, above?

yes, just the probe, but try moving it closer to the flame as suggested. the fact that it stays alight for a bit before dropping out suggests that may be the problem.,.

 

[Hettie's Crew]

Thank you. Was your problem similar, in that it ignited, ran for nearly a minute, and then cut out, or did it fail shortly after you released the gas control nob.?

It’d go out straight away if we didn’t leave the knob pressed long enough but then went out after anything from 15 seconds up.
It appeared worse when another burner was on.
I bent it inwards just using a dining knife handle but did it very gently and gradually.

 

[Thornebt]

I tried bending the thermocouple on my fridge and I don't think it bent at all before snapping! Maybe this was down to it's age but I wouldn't try bending one again.

 

[slowdriver]

yes, just the probe, but try moving it closer to the flame as suggested. the fact that it stays alight for a bit before dropping out suggests that may be the problem.,.

Presumably, I could test this by igniting the gas and then supplementing the heat source using a small gas torch. If the burner stays on then the thermocouple needs to be repositioned slightly. If it makes no difference it needs to be replaced?

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[scotjimland]

Presumably, I could test this by igniting the gas and then supplementing the heat source using a small gas torch. If the burner stays on then the thermocouple needs to be repositioned slightly. If it makes no difference it needs to be replaced?

yes.. could try that
but only the tip of the thermocouple should be in the flame..

 

[slowdriver]

Very good, that's this afternoon sorted. I'll post an update.

 

[slowdriver]

Or not sorted. Despite providing supplementary heat to the tip of the thermocouple using my go-to tool, aka my wife’s small gas cooking torch (now back in the cupboard) it still persists in cutting out.
I’ll have to find a man who can fix it on a call-out. Any suggestions gratefully received.

 

[tonyidle]

Make sure the sleeve nut at the burner end is tight.

 

[Thornebt]

Or not sorted. Despite providing supplementary heat to the tip of the thermocouple using my go-to tool, aka my wife’s small gas cooking torch (now back in the cupboard) it still persists in cutting out.
I’ll have to find a man who can fix it on a call-out. Any suggestions gratefully received.

Is it difficult or expensive to replace? I would just replace it.

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[slowdriver]

Is it difficult or expensive to replace? I would just replace it.

Very difficult to source Can parts apparently, based on today's phone-around, although it may be that the thermocouple itself (and possibly all its gubbins) are fairly standard stuff. Unfotunately I am not qualified to judge that so Im going to need to get someone qualified to make that call, and getting hold of them at short notice - we are scheduled to go to France at the end of the month, is also proving tricky.

 

[slowdriver]

Update and resolution.
Finally got this sorted today in France at Emeraud Evasion (a La Strada dealer) in Dinard across the river from St-Malo, at no cost! https://www.emeraude-evasion.com/

It appears that the Italian Can integrated sink and hob unit EITHER uses the body of the hob as earth and therefore the body of the thermocouple needs to be in contact with it in order to reliably operate. In my case, we live in a hard water area and calcification is a regular issue on anything metal. In this instance, the layer of calcium wasn't obvious when looking from above but nevertheless was there, between the thermocouple and the hob - a gap of about 0.5-1mm. The dealership owner cleaned it out with the point of a Stanley knife from above and it did the job. He did not reposition the thermocouple in relation to the adjacent flame.
ALTERNATIVELY if removing the calcification fixed the issue and yet the hob body is not used as a return current then there must be another explanation as to why this cleaning and wiggling solution is the most commonly proposed. Maybe the thermocouple touching the hob via the calcification interferes with the circuitry and cleaning it eradicates the problem?

He indicated this was something they see reasonably often on various different makes of van.