probably fan or air pressure switch.
fixed one recently with same fault - was the fan.
assuming not a rectification prob and blr doesn't go to lockout.
If it keeps firing up and after a fashion heating eventually gets warm cos its going on and off suspect fan first.
does it do the same with hot water ?
If you take combustion chamber cover off and it stays on deffo fan !!! of course corgi regd to do what I've suggested !
gasbanni, December 2008
