put a hose on boiler drian point release pressure to 1 bar. fire boiler and whatch pressure if this starts to rise above 2.5 bar. I would suggest the expansion vessel as deflated. I would allso be thinking why as PRV NOT activated is this faulty.
kw
November 2009
Yep - bleed off water at a convenient radiator valve. Be patient - you'll need a few pints removed.
John
November 2009
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