We have just added a new radiator and now our a combi boiler (Gloworm 30cx) pressure keeps increasing from 1.0 bar to 2.5 bar when the heating is on and there is a leak of dripping water coming from under the casing on the front right hand side when the pressure reaches over 2.5 bar. When cold the pressure drops down to 1.5 bar, so we have been bleeding the radiators everyday to get it back down to 1.0 bar again. Could the expansion vessel just need re-pressurising? Could the leaking water be coming from the auto-air vent? Thanks for any advice.