when i put the cover back on with the gasket on the boiler goes out and if i lift the cover off slightly the boiler fires back up. as though there is a airflow problem

mick, February 2011

check & clean fan, venturi tube (venturi tube is just above fan with a plastic or rubber tube on it)

brian, February 2011

Check the flue is intact and clear, then you're down to pressure switch not operating correctly (could be tubes blocked etc), or fan not running at sufficient speed.

If you establish the flue is intact and correct, replace the pressure switch first, cheaper than the fan.

Carefree, February 2011