the pressure should normally be set between 1- 1.5 bar, if you need to top it up, follow the pipework down under the boiler, there should be a silver braided hose connected between one of the bigger pipes and a smaller cold water pipe. One end of this should have a tap or isolating valve on it, open this tap slowly to increase the pressure, ensure this is turned off correctly once it is done though
gary.wright53@googlemail.com, August 2007