can you help pls...my pilot light is on and the fan kicks in but the system isn't firing up..the pressure is also fine at the moment but will drop because nothing heating up....pls can you help...

dglass, May 2007

There is usually a brass tube with a plastic pipe off it inside near the burner clean down the tube this is the venturi which operates the air pressure switch and sometime gets blocked.
Also try removing the fan and cleaning the fan blades. The boiler will not fire up untill the fan has operated the air pressure switch. Turn the main power switch off before starting.

Ian., May 2007