maybe its to aid the flue in its "pull" of the POC 
Why do oil burners purge
- Thread starter ryan3
- Start date
Yeah but what about solid fuel boilers .. Over where you are , Kev. Yo gotta watch out for the " Person " in the woodpilesheeite muslims
they blow up so quick these days
You`re thinking like bleedin RGI`s FFS 
. The flue can`t draw because the only inlet for air is through the bleedin` oil burner fan etc. IF it was a solid fuel boiler/open fire the draught would be natural and constant . Please feel free to ignore me - at least i`m honest in my profile
. The flue can`t draw because the only inlet for air is through the bleedin` oil burner fan etc. IF it was a solid fuel boiler/open fire the draught would be natural and constant . Please feel free to ignore me - at least i`m honest in my profile The pre-purge is to remove any unburnt 'explosive' fuel vapour in the combustion chamber before it lights up! If it didn't and some oil vapour was present it could go bang.....well phutt more like. Same as on a gas boilers but more risk of big bang on those.
In my experience post purge doesn't happen on small oil burners.
In my experience post purge doesn't happen on small oil burners.
Pre purge is not just to clear combustion chamber.I understand now from reading thoses last two posts thanks lads
During prepurge, the control box will also check to ensure that there is not already flame being sensed,& that the circuitry of the solenid is sound in some cases, (Riello) .
Quite a few small boilers also have post purge, desirable in the case of low level discharge horizontal flues to prevent evacuation back through the burner
Pre -purging was developed in the 1970's to greatly improve the initial light up of the fuel on pressure jet burners, the theory was that by getting the air flow established before introducing the fuel oil the light up would be much smoother (it was a complete sucess) prior to this, burners used to start after an ignition only stage, the motor, (fan & oil ) would all start together, the light up was often best described as "Bumpy" untill the flame established and the up-draught started to take the POC's away up the chimney, there are still old boilers with burners that have no pre-purge, but they are few and far between, History of oil firing lesson ends.
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