Boiler on the blink, help needed :)

[sinto607276]

The AARV should be at the top of the heat exchanger, it might have a knurled knob that must be loose so that any air in the heat exchanger can vent, The PRV is the safety valve, so if the presure rises to 3 bar it vents to the outside , the other valves are service valves and can be closed so you don't have to drain the whole system, if you close them make sure they are open before pressurising the system (I dont know how or when you do the expansion vessle?) the filling loop is used to fill the system to 1 to2 bar.

Thanks chaz,
I think I've been a bit mixed up with all this.
It's leaking through the pipe outside, takes about 40 mins to build up any pressure (just about 1 bar) to be able to use the boiler, then it loses pressure overnight. So I think it's as I've quoted above, prv replacement job.
Will empty the vessel so no pressure on the prv, take out and replace, pressure up the vessel then hopefully it should work?
Thanks, Colin