pressure increasing when running central heating saftey valve opening looseing water until pressure drops then boiler cuts out

Richard, March 2010

Expansion vessel may need Re-charging or pipe to expansion vessel may be blocked.

To re-charge vessel:-
Open safety valve (keep open)
Put bike pump onto expansion vessel (if water comes out of connection vessel may be faulty). Pump up to 1 bar.
Close safety valve and re pressurise system.

Paul, March 2010