How do i restore the pressure in my expansion vessel?

if the prv is leaking there is a copper pipe that gos through the wall to outside the house thats where it will drip.
when you have stopped the leaks on that rad open the two valves one each end fill the rad and bleed it.
then check your gauge is at about 1.5 bar.
if your gauge is going up to 3 bar when heating turned on then dropping again when heating turned off your expansion vessel is either split or needs re-charging.
the prv is factory set to discharge any pressure above 3 bar.
on your vessel is a schrader valve (car tyre ) you can put a tyre gauge on that to see what pressure it has in it.
or you can push the centre of the valve if water comes out its split and a new one required.
or the pressure maybe just low and can be increased with a car foot pump, but the system gauge on the boiler must be empty first before filling vessel with pressure.

hi-spec plumbing
May 2007