how do i fill my vaillant boiler?

Your boiler is filled via the 'filling loop' - would you believe. This is (usually) a flexible pipe connection with a tap that connects the boiler to the mains water supply- (15mm pipe). The tap may be a hand turn type or maybe a screwdriver type. Either way, your boiler is filled by turning this thing on - but careful not to overfill it as you'll have to drain it off again.

John
December 2007