Firstly, it needs to be 1-1.5bar when cold, if you overfill it to 2.5bar you will get the safety valve lifting when the water is hot and hot water expelled out the relief pipe and end up back to where you started (or worse, the valve will not re-seat and water will constantly pour out until you replace the valve)
Top up, look for a metal braided flexible hose (usually under the boiler on in a hot-press) it has a small black handle, slowly open and slowly raise pressure to 1-1.5 bar
T, July 2008
