u need 2 check the data bage and it tells u clearly the burner pressures on min and max,take it ur regestered!that boiler has a modulation gas valve on it!i have found in the past that some1 alredy messed up the settings on them that doesnt know what thay are doin,its unlikly that the valve is faulty just been touched when shouldnt have!check and see if it modulates,could be a blocked heat exchanger!
peter dublin
November 2010