Is this on a boiler?
Yes it is on a Junkers.
Yes it is a Junkers
Are you able to bleed a radiator into a bowl to bring the pressure down?
I have bled all radiators, the boiler is still leaking, I have also turned all valves to and from the boiler, the pressure goes down after 30 minutes but when I turn the cold feed on the boiler leaks.
Are you running out of the PRV outside?