worcester bosch 24cdi , high pressure ?

i have just drained the system to move a rad, something i have done on a couple of previous times , i refilled the combi to about 1.2 when off when i turned the boiler on the pressure went up to 2.5 then up to 3 on the pressure gauge. i tried to drain the water out to drop some pressure back but the water came out at a trickle , and gauge never dropped the pressure one bit . i have since drained some more water and still no change in the pressure reading . the boiler is just short of three years old, and a worcester bosch 24cdi. i would very pleased with any help . regards simon johns