Oil boiler going out when it rains?

Hi Gje
Soot in my experience, A bad burn, and flame,
Nozzel problem. or air mix.and you will have smoke.
How ever the common factor here is rain.
Can rain be drawn into the flue and causing a elec short,
From what you say you have checked a lot.the only
other sugestion i have is look again at the simple things, dont dive into oil pumps,or elec controls.
Good luck Be careful of electrics.
Nick

nicholas smith
August 2009

It's all very odd - I've taken the cover offthe flue and cleaned it out. I've cleaned inside the flue as best I can. It fires up lovely with the flue cover off.

We put the flue cover back on and BAM - boiler refuses to fire up. The Danfos box clicks and clicks and shuts down.

GJE

GJE
May 2009

I see - so either you have a balanced flue, where the combustion air enters through the outer grille and the exhaust passes out of the middle section of the flue pipe, or you just have a standard horizontal chimney. No matter either way really, but if you have a balanced flue, the burner will be enclosed in an air tight aluminium box. I hope you have success with this one...in difficult situations like yours I like to run the burner on the bench, which discounts any chimney or boiler flue problems. An OFTEC engineer, should you call one in, will first do a smoke test on your system - if that proves ok he will then do a gas analysis, looking for about 12% CO2. Regards!

John
May 2009

Hi John,

I've taken the front off the outside exhaust and left the pipe open for now. The boiler has fired up and is running smooth.

The Danfos box is not clicking at all.

I've washed the cover to get rid of the soot and when the pipe goes cold again I will wash the outside.

Seems to have fixed it for now. It will all be tested when I put the cover back on and it rains hard like today.

Thanks again for your answers,

GJE

welsh_gje
May 2009

Cheers John,

I'll start cleaning it out again including the outside pipe which takes the fumes away. This is looking black and sooty.

Hopefully it will sort things out for me.

GJE

welsh_gje
May 2009

Hi GJE
I meant the oil pump on the burner - but no matter. As its pushing out 120 psi that should be fine - but of course we don't know how good the nozzle is! Anyway, the oil supply is controlled by a solenoid coil on the side of the pump which magnetically controls an internal valve - both could give problems. However, the main problem with oil boilers is soot build up inside, as this produces back pressure which interferes with combustion. I always clean the flue ways out first - this is done by lifting the boiler top casing away, to reveal an inspection hatch beneath held down with a couple of nuts or bolts. With this off, the baffles are revealed which can be lifted out for cleaning with a wire brush, and the complete assembly vacuumed out - preferably with the burner unit withdrawn. There must be no restriction to the chimney or balanced flue either. With the boiler completely clean, then we must consider the burner - but its really only possible to set these up properly by using gas analysis equipment....however, by setting the air door as per the instructions is a good start. Too little air causes smoke and soot build up - excess air can blow the flame out or cause it to inpinge on the back of the boiler heat exchanger - both undesirable! Any OFTEC guy would go for a good clean out before fiddling further.

John
May 2009

Hi John,

Thanks for coming back to me. When you say pump do you mean the oil pump or the pump that sends water around the system?

I'm not sure what oil pump we have. It is the only thing we have never changed.

There is a lot of soot on the external part of the boiler (not sure what it is called - the exhaust LOL).

I have played with the air slider which is there. It is set on 2 (as per instructions).

GJE

welsh_gje
May 2009

The clicking in the control box sounds like the flame is disappearing, then re-igniting and so on, until it finally packs in, causing a lock out. What make of pump do you have? Why this should occur only when it rains I have no idea - when windy though, it points to excess soot on the boiler baffles or not enough air.

John
May 2009