If it's your house and you're not the landlord of tennants in the property you are not prevented from tinkering with your boiler yourself - some of the the registered guys may say otherwise and vaguely quote this and that regulation and stress the potential dangers - they might be right about the potential for danger but the "regs" only apply to landlords and people being paid to do gas work - not to householders.
I would call in an engineer and observe him closely.
Good luck...
Peccavi, May 2009
