Oil Boiler Fumes - Intermittent

[rpevans]

I have a Worcester Danesmoor CF 15/19 oil fired boiler with Electro Oil Inter B9 burner. Occasionally there is a strong smell of combustion fumes in the kitchen where the boiler is located, and outside the house. The smell is like unburned fuel. This only happens occasionally, at other times there is no smell at all!
The boiler was serviced just under a year ago and all was well.
My thoughts are that the ignition probe insulation may be cracked and/or the ignition transformer may be goosed.
I can call out the service tech but sods law says it will be working fine when he attends.
Any thoughts please?

 

[Burnerman]

If you could be a little more precise, maybe....
Does the smell occur when the burner starts up after a rest period, i.e over night? This could indicate dribble from the nozzle, making the combustion chamber damp with fuel.
There should be a round foam gasket between the burner and boiler, and the chamber lid (under the boiler top cover) should have a rope seal.
Was the boiler cleaned out during the service, do you know?
John

 

[rpevans]

Thanks for the reply John.
It seems to occur randomly. Yesterday for instance, I have heating set to come on at 4.30pm and when I arrived home at 4.45pm there was a smell of fumes in the kitchen (not outside on this occasion). This morning the heating came on at 5.00am and when I went down to kitchen at 6.30am there was no smell. I will keep an eye on it though. What would be cure for leaking nozzle?
As far as I know the OFTEC guy cleaned the boiler. I know that the foam gasket is there between burner and boiler but not convinced that this is a good seal (it's difficult to tighten locking screws while holding burner in place). I will check the chamber lid for rope seal when I get home.
Richard

 

[oilhead]

Is there a possibility that you have a little contaminant in the fuel, so that after a cold start, for a short time, you are getting re-ignition? Once the muck has been dissipitated, then things carry on as normal.

 

[rpevans]

Thanks for your reply oilhead.
What could contaminant be? The tank is only about a quarter full and in cold garage so may be water in tank.
Richard

 

[Burnerman]

It would be a good idea to be there when the burner first starts up I think....if the nozzle is dripping kerosene this is due to a valve in the oil pump not shutting off fully and may cause a bit of a kickback when the burner first starts up. The same symptom can occur if the ignition electrodes are too far back.
The same applies to any contamination of the fuel really....if the burner starts, then fails, then starts again etc there's sure to be a little smoke / fume coming back. In this case I would imagine the fume would come back through the air intake (plastic box, bottom right) rather than from the burner seals.
Its common practice to push the burner into the boiler as far as it will go and then tighten the screws in the top - personally I find you needn't be too fussy here.
If the burner chuffs a few times from cold this could indicate incomplete combustion or incorrect pressure / air settings so there's quite a few possibilities here!
John

 

[rpevans]

Will try to be there when burner first fires. Does tend to start with a 'woosh'.
Richard

 

[Burnerman]

B9's are pretty quiet as oil burners go - especially if they have a balanced flue and therefore live in a box.
It may be worth checking the electrode settings - dead easy to do with the blast tube off (2 countersunk allen screws).
John