I have a glow worm boiler which was just doing the same thing. I was resigned to calling out an engineer but then after finding the manual it says that for initial lighting you have to set the temperature to minimum. If not then the boiler may trip due to air in the system. I duly did this and it all started fine. I wish I'd done this earlier though cos I've been freezing my nuts off all night.
Stella Dave, January 2009
