I have got a Worcester 28CDi combi boiler and the other day I noticed that the pressure had dropped down a few notches (I usually have it on 1.5 bar; I have been told that it should be between 1.0 to 2.0 bar). So this morning I decided to repressurise the system, but silly me filled it while the central heating was off, so now when I put the boiler on the pressure dial has shot up to one notch off the 2.0 bar. Is this safe, I don’t want it to blow up. If not how do I get the water pressure to go down?