Dometic hob difficult to light and then yellow flame

[wallport]

Hi, would appreciate some advice on how best to diagnose and fix.

Hob is only 2 years old and hasn't been used very much. It was fine last year but after being layed up for the winter we took it out this week and found it very difficult to light. It would light when the window was open. However, it would burn with yellow flame leaving black soot on bottom of kettle.

Researching this it sounds like insufficient oxygen for good combustion. Some suggest dirt or cobwebs in the pipes. Others suggest blocked nozzles.

I suspect this is a common issue but please could I ask for advice on what steps I should go through and in what order. At what point do I get worried and go to a dometic service engineer?

Thanks in advance

 

[quattrodave]

Please don't use the hob until you have it checked out !
There's a serious risk of carbon monoxide poisoning if you have a yellow flame and yes it's due to lack of oxygen for combustion.
Blocked jets are possible or corrosion/dirt.
A campervan or caravan dealer should be able to help or point you in the right direction.

 

[AdL]

As above....but you could also just be running out of gas. The jet needs gas velocity to draw air into the mixture. Low pressure will give you a rich (yellow) flame.

 

[quattrodave]

....or was the gas bottle too cold due to cold weather ?

 

[Salty Spuds]

Lift off the burners & check for spiders & bugs.

 

[wallport]

I was aware of the potential danger but the door was open the whole time we used it. I do want to fix it before we use it again.

Despite the recent weather, it was only 4 degrees overnight. However, we had this problem in the evening too so I don't think it's the root cause. I took the gas bottle out and shook it, its not running low.

 

[Dellmassive]

Take it to a caravan place and have the gas system tested/serviced.

 

[Bargy62]

I was aware of the potential danger but the door was open the whole time we used it. I do want to fix it before we use it again.

Despite the recent weather, it was only 4 degrees overnight. However, we had this problem in the evening too so I don't think it's the root cause. I took the gas bottle out and shook it, its not running low.

take the gas bottle out and leave in a warm place and try again then at least you have eliminated the is it cold problem

 

[CAB]

Often it is the Regulator, they do fail.

 

[Bargy62]

Often it is the Regulator, they do fail.

good shout there has been a couple recently on here

 

[wallport]

OK so the bottle seems fine and in my opinion not close to empty though difficult to be 100% sure without swapping. I unscrewed the burners and everything looked clean though I didn't unscrew the jet.

Gonna take it to a caravan centre for a service. I agree it's too dangerous to play around with. Does anyone know what they might charge me for diagnosis?

 

[wallport]

Was just reading elsewhere about weighing the gas cylinder to tell how full it is but a bit confused by the labels. It's a blue 904 cylinder and says 1.8kg on the top - I think this is the weight of the gas only when full?

Elsewhere on the bottle base it says 2kg and then 2.8kg (see photo). One of these numbers must surely be the empty weight?

The actual weight currently is 3.6kg. I think either way, it's not empty but would like to understand which number is correct.

 

[Anakin]

2.8kg is the tare weight, i.e. the weight of the bottle when completely empty. It can take 1.8kg of butane, so should weight 4.6kg when absolutely full. Yours, at 3.6kg should have 0.8kg of gas left in.

 

[wallport]

Thanks. So 44% full.

Will measure this from time to time and lose that fear of running out mid cooking!

Nice to be sure my problem isn't an empty cylinder though - that would have been a stupid mistake!