After several minutes of running the boiler trips. Manually resetting allows the boiler to begin it's purge cycle but trips before this is complete. Resetting again allows the boiler to complete a successful purge then fires. Firing lasts for several mins then trips. This continue to happens. I have changed the control box, checked and cleaned the pump and filter. Changed the ingnition tranny ( although this was ok) Changed the electrodes and cleaned the nozzle. When running the boiler I have removed the solenoid ( oil feed to pump) and the flame goes out ( obviously) the boiler however continues to run regardless. This seems to me that it's not a loss/blockage of fuel that is causing the trip. Checked the flame photo cell and believe this only checks for ignition and initial flame. Removing this once the boielr has fired has no effect and boiler still runs.
So.....what next?
Going to check replace the baffle thsi weekend but that's because I don't know what else to try.

Wayne, July 2012

Ok in relation to the problem of burner tripping after a few minutes ( this is still a question not an answer) I purchased a new photocell and soleniod coil. Fault still there.....it seems I'm loosing the 240v to the solenoid coil, therefore shutting off the oil. I have purchased another 2 control units but still no luck. I have also removed the control stat the high temp manual reset stat and the auto reset stat from their pockets just in case they were seeing high temps but still the burner trips after a few mins. It seems like it must be a temperatire issue as the burner will run fine for several mins. No spluttering just a good burn. What will cause the 240v to drop? I do not have any schematics of the control unit so can't see what to link out to test.

Wayne, August 2012

the photo cell will look for continous flame not just pilot and initial fire it may be going soft ie malfunctioning the solenoid also causes this, as it heats up it will lose its magnetism and drop and shut off oil hope this helps u may also change the nozzle maybe atomiser is faulty.

billy, July 2012