Oil smell only when boiler is off.

[Craigveigh]

When our oil boiler is switched off a strong smell of unburnt heating oil fills the utility room where it is installed. This is noticeable after a few hours and is unbearable when we return after a weekend away.The smell disappears when the boiler runs for any length of time. The floor of the boiler is perfectly dry and I've lined with tissue paper when off to identify any small seapage but nothing observed. The smell that is created contaminates any laundry in the room. Any ideas on how to cure the invisible leak?

 

[gigz]

It'll need opening up to further investigate, could be coming from a few places. When was it last serviced ?

 

[oilhead]

What boiler/burner is it?
Open or balanced flue?

 

[Craigveigh]

It's a Worcester Danes-moor 26/32. Balanced Flue. Fully serviced 6 months ago. Runs clean. Opened yesterday and looks spotless.

 

[Burnerman]

Just a few suggestions, depending on how far you want to go......
Check any flexible pipes within the boiler casing and their connections;
Check any taps that are inside the boiler casing;
Check the oil pump for external seepage especially around the adjustment screws;
The oil pump also has internal seals which wont be visible until the burner is extracted from its hole;
There is a possibility that the nozzle is dribbling into the firebox but that's fairly remote.
John

 

[Craigveigh]

Thanks for the replies so far
I've lined the floor of the boiler and where the inlet hose touches the side of the casing with blue tissue - no contamination at all. Could any seepage evaporate before contacting the base of the boiler?

 

[gigz]

I've had a few pump solenoids leaking lately (three on the bounce). Stinks but there was always oil in the drip tray.

 

[Burnerman]

Kero doesn't evaporate, or at least not in this case.....
If the burner nozzle or pump is leaking slightly into the combustion chamber, you may see some smoke - or stronger smell - on start up when the pong is strong.
John

 

[Craigveigh]

If I sniff the flue vent after the boiler has been switched off for some hours it smells of kerosene (volatile). Would this indicate a leak into the burner chamber which burns off when the boiler is fired up?

 

[Burnerman]

Have you taken the boiler top off yet Craig? There should be a drip tray under the burner and if I remember the pump is on the right side of the burner - is that correct? BFP 11 pump, Sterling 50 burner pointing downwards.
Another way but the combustion chamber has 4 nuts holding it on - access at the front - which would allow you to see the burner flame tube and nozzle (a mirror would help).
Of course there are seal issues here so maybe I'm out of order mentioning that.
John

 

[Craigveigh]

 

[Burnerman]

Dammit sorry! I got it into my head it was the 18/25
The same applies though - if the nozzle is dripping it could be flooding the floor of the combustion chamber. All looks clean on the outside from here.
John
Edit....that looks like an Inter B11 burner - I was expecting a Sterling 40
Oh well!

 

[oilboffin]

Incontinent burner

 

[oilhead]

If you can see no trace, then the pump shaft seal is a prime candidate. You need to remove the pump from the back of the motor to check this. There could also be seepage into the combustion chamber. This is not a balanced flue, just horizontal. The burner would be in an enclosed box if balanced flue.
Another item to check is the fusible head isolation valve. These often leak up the valve stem and the wet can be contained in the head. Remove the wheel, turn clockwise and the wheel comes off, it is a left hand thread. You may find a slight leak there. Often this leak can evaporate in use.

 

[Dan_shard]

When our oil boiler is switched off a strong smell of unburnt heating oil fills the utility room where it is installed. This is noticeable after a few hours and is unbearable when we return after a weekend away.The smell disappears when the boiler runs for any length of time. The floor of the boiler is perfectly dry and I've lined with tissue paper when off to identify any small seapage but nothing observed. The smell that is created contaminates any laundry in the room. Any ideas on how to cure the invisible leak?

Hi Craig
I wondered if you found the issue? I’ve got this exact same thing now. Only when my boiler is off it’s starts to smell and within a couple of days it’s unbearable. If it’s running there’s no smell at all
Dan