I have a Potterton Combi boiler, the pressure slowely rises even when just HW mode is selected. Is this a fault with the filling loop ( on of those you open using a screwdriver ) it is set at closed yet water is coming in. It rises when water isn't running even. Only way I can stop it is to keep mains tap turned off

Cheers

Liz, May 2007

best way to check is disconnect it. leave the end on connected to the mains water pipe and disconnected the other end then open your stopcock slowly and see if it passes water.

if still rises when disconnected its poss your dhw exchanger is passing water across to the primary circult.

hi-spec plumbing, May 2007