'Kirk',you need to get some water out of the system.
The easiest way is to turn the heating off,open a radiator air vent and catch the water in a cup,a bit tedious but keep doing it until you get to about 1.5 bar which is normal when cold.
'Deco' you should have filling loop either on the boiler directly or on the pipework underneath,this needs turning on momentarily to fill up the system then turned of again.
Glen, October 2009