boiler problem

[dubgasman11]

hi all ,
this is my first time using this forum but i really hope someone can help
i have a sime format system boiler with a big problem ..
the boiler first had the problem that it wasn't firing at all but i changed the ignition transformer and it fired first time.
happy days i thought unfortunately it fired for roughly an hour and a half and locked out (red light).
if i reset it it would do the same thing. fire no prob and work for roughly the same although not exactly. some times it would work for one hour sometimes two hours but would always lock out before it was to be switched for.
i have checked the stats all they all seem to be fine. i talked to the boiler manufacturer and they said it might be a faulty ignition transformer or the gas valve might not be modulating properly. since then i've checked the gas valve modulating and it seems fine. i've change the ignition transformer aswell and this problem is still happening
id really appreciate if somebody with more knowledge could help cause im about to cry

 

[CBF]

did you change the electrode & check the wiring to make sure it's not earthing when you changed the transformer ?

 

[dubgasman11]

hi cbf,
should i have changed the electrode ?? it looked ok and was only sparking at the burner ..

 

[Agile]

Unless he is gas registered I certainly hope that he did not change any electrodes!

Nor should he be advised to!

 

[dubgasman11]

yes agile i am registered . i was just asking some advice as i'm fairly stuck on this problem and i cant figure out why it is happening .... so if any one can help me or point me in the right direction i would be very grateful ..