pressure on system running hgher than normal?

YEP.
should be 1 bar cold, and why isnt the system pressure venting?? the pressure relief valve should operate with a banging sound at 3 bar.....
if its still hitting 3+bar when youve dropped the COLD pressure to 1 bar, then as said, the expansion vessel is ruptured and needs renewal, or a cheaper option, fit an external 18litre vessel on the return pipework to the boiler and leave the faulty vessel where it is.
yes, this IS allowed!!

Mark properjob
February 2012

dump some water out of system to 2bar hot or 1bar cold can have a difference of 1bar hot or cold also check air pressure in your exspansion tank could be low should be 10lbs ish if its got water in the the air side its had it

kevin the boiler man
February 2012