My oil fired Rayburn 680KCD was been working well, but at Christmas the boiler side stopped firing up automatically. Manual start worked well for a week or so but then the system locked out during the ignition cycle just about 10 seconds after ignition. Three engineers have visited since then replacing the solenoid valve, PE cell, control box and burner nozzle as well as checking the wiring of the photocell. and the pump pressure and oil feed. After each visit the system ran for about a week, the needed manual starting followed by system failure. Has anyone experience similar problems and if so let me know what the underlying problem is.

