Thetford N3150 not cooling on gas

[Evildoody]

Hi all,

Hoping one of you can help or steer me in the right direction

I have a Thetford N3150 that is not cooling whilst running on gas, cools fine on 12V and 240V and the van is level.
Everything seems to work, e.g. the AES selects gas and the burner lights and there are no error codes on the fridge LCD. What I have noticed is that the burner seems to go off anywhere between 15 seconds and 2 minutes after being lit, I hear the gas valve solenoid click and the gas instantly relights. The flame is blue but seems weak in my opinion (it might not be though as I am no expert).

I used some compressed air to blow the burner and up the flue, but both seemed pretty clean.

The gas cooker and water boiler are all working ok and I have plenty of gas, so am at a total loss as to what the issue can be. To make it worse I am away to a festival on Wednesday (warm beer for me I guess)

 

[Evildoody]

Another quick question, the gas pipe fitting that is fitted to the main gas pipe and goes into the fridge gas solenoid valve has a small piece of sponge in it, I was thinking perhaps this is clogged. But I for the life of me cannot find a replacement gas filter or replacement pipe! - Are these custom made?

I noticed if I tap the gas solenoid with a screwdriver the burner flame goes out and reignites - not exactly sure why I tapped it, but not sure if this is normal behaviour either

 

[The Wino]

We had a problem like that with ours I noticed we used to be able to hear the burner quite clearly but it had become almost silent so swapped the burner for a new one and sorted. The old one had some white deposits on it

 

[jockaneezer]

That flame doesn't look "fierce" enough, can you hoyke out that piece of sponge and see if things improve and clean the gas jet ?

 

[Evildoody]

That flame doesn't look "fierce" enough, can you hoyke out that piece of sponge and see if things improve and clean the gas jet ?

That's my plan mate, my thought process so far goes like this :-

The van is a 2004 vehicle, the gas regulator was changed last year for one that has a gas test port and my fridge was changed due to a circuit board issue that prevented it running on 12V (also a 2004 model), after speaking with a Thetford technician he is suggesting that the reason for the inline filter in the gas pipe may have been due to the old (original 2004 regulator) not having its own filter, but now that my new regulator does have a filter, I may have two filters and therefore am restricting the gas flow to the fridge burner. Only one way to find out

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[The Wino]

Did it work ok on gas before? if so the sponge was already there!

 

[Evildoody]

Did it work ok on gas before? if so the sponge was already there!

That's the problem, I thought it did - but my wild camping with the old fridge consisted of driving somewhere for a night and then switching the gas on and just assuming that the gas was cooling stuff when in fact it may have been a placebo effect - e.g. the 12V cooled the fridge sufficiently and it was only acting as a coolbox, but then again most of that was done with the old regulator.

Or did the old fridge with the old regulator actually work on gas but the new fridge with a new regulator did not? - will take the sponge (filter) out tomorrow and test

 

[The Wino]

My money still on it being the jet in the burner! (but as my wife says I'm often wrong!)

 

[Evildoody]

My money still on it being the jet in the burner! (but as my wife says I'm often wrong!)

I know the feeling mate, new burner will be here on Tuesday, bought one before I posted - I like chucking money away before I know the actual cause of the problem

 

[Bonkers the Dog]

Eeeech! I've got exactly the same issue with my 3-way auto Dometic in my pilote. It's on going... I stripped and cleaned it all a few weeks ago but the issue has returned. PITA!!!

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[jockaneezer]

Even though the supply pipe to the burner looks like galvanised steel, they do seem to develop "rust" particles inside the pipe. I shook a surprising amount out of mine (Dometic) when I had to unblock the jet which had a piece wedged in it.

 

[Evildoody]

Well I disconnected the lot, I removed the filter from pipe 1, removed the SOV 2 and pipe 3, dismantled the burner 4 and used compressed air on it, checked the operation of the solenoid. I still have the exact same problem - new burner arrives tomorrow so I hope that fixes the problem otherwise I will have to resort to removing the fridge and dismantling the flue.

 

[Evildoody]

Just a quick question, am I correct in assuming the solenoid valve just opens and allows the gas to reach the burner and therefore the burner flame is not controlled e.g. the flame does not increase or decrease with the temperature setting on the fridge but the fridge electronics just controls when the flame is switched off and on? I take it for example that the solenoid has two positions on and off and has no half open or intermediate positions?

 

[andy63]

I take it for example that the solenoid has two positions on and off and has no half open or intermediate positions?

I think that is the case.. simply switched on and off by the thermostat..
Andy

 

[Evildoody]

Although before actually removing the unit I will disconnect the original gas line gas inlet pipe and check that for blockages - also thinking of making a wc (Water Column - Manometer). I don't get beat easiliy

Knowing my luck I am imagining an issue and the van will be tilted 0.5 degrees off level

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[Evildoody]

I stuck the old burner in some boiling water for a bit, interesting all the crap that came out of it (this was after using compressed air on it!).
Anyway new burner element has arrived - time to fit and I will report back with an update

PS. My Mrs had a great idea, she said I should of stuck it in my sonic bath - well it would be great if I knew where it was - lol

 

[Evildoody]

My money still on it being the jet in the burner! (but as my wife says I'm often wrong!)

You can tell your wife you were correct, fridge is now working on gas

 

[The Wino]

You can tell your wife you were correct, fridge is now working on gas

Could you tell her for me when I'm out of striking distance!!