12 months ago boiler wouldnot start. Service engineer came out and cleaned the motor bearings. every thing went ok for 6 months then boiler lockout occurred. SE changed control box ok for 1 week then repeated boiler lockout - SE changed oil pump and drive. 1 hour later boiler locked out again. re-set boiler ran for 3 weeks. Again lockout occurred. SE changed non-return valve in fuel line - next day locked out again. Now SE changed solonoid coil. Next day lockout. The burner is a monoflame minor 4 12 years old. Does anybody have a clue as to the cause of the problem. I have had several different SE and I still have a problem. It may take several starts to fire up the boiler but once the burner starts then it runs for the rest of the day apart from one occasion. Secondly, the problem appears to be first thing in the morning at the initial startup.We do not run the boiler on a night time.
Any clues please? Thanks for your help!!!!!!!!