Firstly I'm no plumber or know YOUR boiler.
On mine under the boiler there are probably about 5 pipes. TWO of them are linked by washing machine type taps or isolating valves. You may see the linkage from 1 to other by a flexible pipe (silver?).
When they are opened water will go from the mains into your system therefore increasing the pressure. WATCH THE PRESSURE GUAGE AT THIS POINT!!!...and turn off when it reaches 1 bar. Job done MAYBE.
Let me know how it goes on. sjw722@tiscali.co.uk
Steve
November 2006