hi im a heating engineer and cant find out the problem for this boiler.. the fan comes on, the relay switches over. the gas valve opens sparks but then goes out and does this every time for about 9 times and then fires.. ANY IDEARS!!! pcb or gas valve ie sticky solinoide valve that all i can put it down to... please help..

paul, December 2010

Checklist:
Condense clear?

Fan with constant voltage x2 on the board (pins 3&4)?

Gas meter position?
(If outside, could be governor freezing) check the input with manometer as boiler tries to fire, ensure 20mb (17mb minimum) is available.

Constant voltage at x3 plug on the board (pins 1 & 2) whilst trying to light? Also throttle adjustment correctly set? If yes, gas valve issue.

Sensing electrode correctly positioned and burner gap correct (7.5mm +/- 1mm?

Carefree, December 2010