On the bottom of the boiler, front right hand corner as you look at it, will should see the brass pipe fiiting, one of them has a slot in the it, like the head of a normal screw, turn the slot with a screwdriver, it should fill back up. This is the only advise I can offer without knowing the boiler model and not the manufature
LTGF
August 2008
Ensure radiator valve is shut on the radiator in question. Open two taps on the underside of boiler (Filling loop). You will hear water enter the boiler and see pressure gauge rise. Do not overfill.
Phil
August 2008
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