Your boiler should only go up to near 3 bar when you have had your heating on as the water in your system expans when heated and should return to 1.5 when water cools back down.1.5 bar is the normal setting,if you have not had your heating on I suggest water is passing through your quick fill pipe .
To reduce your pressure drain some water from the system via a drain cockor radiator
jimmy mc, May 2011
