Dometic oven problem (1 Viewer)

[Johnnyb]

We have a combined Dometic oven and grill, the type that sits on top of the fridge freezer. When I lit the oven yesterday the flame wouldn't go any higher than the minimum setting whatever the position of the rotary knob. The grill works fine as do the gas burners on the hob so I don't believe it's a gas supply issue.

After a quick search on Google it seems to be pointing to the oven thermostat or the flame failure device (should this not shut the gas off completely?). Is there anything else obvious that I'm missing before I contact a gas engineer? Any recommendations for someone in the South Yorkshire or North Derbyshire area would be great too.

 

[dulvil]

Take the rotary knob off and put some thing small into the knob where the shaft goes. This lets the knob push the shaft in further,that cured my new one the other week. Hope this works

 

[Johnnyb]

Interesting idea but the knob also controls the grill which is working fine, worth a look though.

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[peterc10]

Not sure I understand. The oven is controlled thermostatically so the flame is always the same size and does not change as you turn the knob. Instead when the temperature set by the knob is met the flame goes out leaving only a small pilot on. And it comes on again when the temperature drops.

 

[jonandshell]

The mother in law has the same problem with her oven.
I think it is the gas valve assembly at fault. The thermostat comes prefited.
Replacement cost for the part is £157.00.
I'll be looking again at the fault later in the week.

 

[Johnnyb]

Thanks for the replies, I'm not at the motorhome until the weekend so will have another look then.

Peter, That sounds like a different design to our oven as the flame did adjust in size depending on the setting of the control knob.

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[peterc10]

Peter, That sounds like a different design to our oven as the flame did adjust in size depending on the setting of the control knob.

Well mine is the Dometic Tec Tower, with fridge freezer and oven in a 2015 motorhome. Flame is the same size on all setting of the oven, just switches to pilot quicker the lower the setting.

 

[wigster]

My oven works the same as peter, flame same size , thermo controls what settings.
Try cooking something , allowing longer than you would maybe on your bricks and mortar oven.
Saying cook something sounded as if i was taking the pee i wasn't honest. Might be the best way to see if it works tho .

 

[Johnnyb]

Hmmm, you're making me think I may be going mad now. Ours is a 2010 oven so may be different from the one you both have? This is it.

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[peterc10]

Mine is the updated version of yours. There are only two ways that a gas oven regulates its temperature. Old fashioned ones do it by varying the size of the flame, which stays on all the time - do you remember the old "Regulo" numbers that gas ovens used to use instead of a temperature. The other, modern, way is a similar way to how electric ovens work in that they have a thermostat which switched the flame off (or more commonly to pilot) when the set temperature is reached.

You have said that you have a thermostat in which case the flame will be the same size no matter what temperature you set it to.

 

[Johnnyb]

I need to try cooking something in it and see what happens

 

[peterc10]

Our oven is OK, although it takes longer than our oven at home to cook or heat up things. Mind you we never use it for roasts - to much faffing about. While we are way we would much rather go to a carvery. The grill is not very good at all.

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[Johnnyb]

We've used ours quite often and that is what got me started with this thread. I could swear the flame was much bigger before. I'd agree about the grill though.

 

[Johnnyb]

Small update but no quick fix.

We've just spent the weekend away in the motorhome so I decided to test the oven. On lighting the oven the flame is quite low and as mentioned the control knob has no effect on the flame size or heat output. I left it to heat up for half an hour and then checked the temperature inside the oven. In the past when opening the oven door there would be a good blast of heat in your face if you were standing too close, now it's just warm and I could easily place my hand in the oven comfortably so definitely not hot enough to cook.

So according to Google there are a number of things that could be causing this, a partial blockage in the gas pipe supplying the oven, a partial blockage in the gas jet in the oven, a faulty flame failure device or faulty thermostat. Things are never simple are they

 

[peterc10]

If you have a flame, no matter how small, it won't be a faulty flame failure device. If the flame is still the same as when you started then it is probably not a faulty thermostat.

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[Johnnyb]

Thanks Peter. I thought the same about the flame failure device. Yep, no change in flame size at all.

 

[peterc10]

I think the first thing would be to look at the jet. But I do not know how you can get to it.

 

[Johnnyb]

I thought I'd update this thread for anyone who has a similar problem in the future.

The fault was the gas control valve assembly which is the device attached behind the control knob. There is a very thin piece of copper tubing which runs from this assembly to the rear of the oven and connects to an upright sensor probe. This copper tube had been rubbing on a sharp edge under the oven and had eventually worn through causing it to stop working. From what I understand the copper tube and sensor contain a fluid and once this escaped the valve wouldn't function properly. All replaced and we now have a fully functioning oven

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[Lenny HB]

Well mine is the Dometic Tec Tower, with fridge freezer and oven in a 2015 motorhome. Flame is the same size on all setting of the oven, just switches to pilot quicker the lower the setting.

Pilot? They are spark ignition no pilot our last one was a 2015, 8505 and current one is 2017, 8505 both work by altering flame height for temp regulation, it is a very small variation hardly noticeable.

 

[peterc10]

Pilot? They are spark ignition no pilot our last one was a 2015, 8505 and current one is 2017, 8505 both work by altering flame height for temp regulation, it is a very small variation hardly noticeable.

AFAK it works thermostatically - the flame is the same height to begin with whatever setting you have. When it gets to the temperature it turns the gas right down low - the only flame you can really see is the one at the end, hence my use of the word "pilot". When it cools down too much the full gas comes on again. Mind you know where near as accurate or consistent as a domestic electric oven.

 

[mitzimad]

most ovens dont go up and down with the knob they light on full and then the thermostat takes over and gradually reduces the flame to match temp desired there is a bypass to keep the oven alight when it has reached temp otherwise you would have to relight.while the oven is open it will not reach temperature
thats how a basic oven works im sure there are some electronically controlled ones nowdays but i doubt if the dometic is amongst them but i could be wrong

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[jack2022]

I thought I'd update this thread for anyone who has a similar problem in the future.

The fault was the gas control valve assembly which is the device attached behind the control knob. There is a very thin piece of copper tubing which runs from this assembly to the rear of the oven and connects to an upright sensor probe. This copper tube had been rubbing on a sharp edge under the oven and had eventually worn through causing it to stop working. From what I understand the copper tube and sensor contain a fluid and once this escaped the valve wouldn't function properly. All replaced and we now have a fully functioning oven

Thanks for updating the thread, I think I have the same issue with my oven/grill where the flame doesn’t increase when I turn it up, it just stays at a constant heat. Would you be able to let me know where you got your oven fixed as will need to do the same to ours? Many thanks.