Cheers, gone through the process again and as soon as i closed off cold water inlet, only 2seconds of water ran out of tap but none from pressure valve.
Anyway, seems to have done the trick as dripping has stopped outside.
Due for a service so will get it checked out properly.
Have had water dripping rapidly out the overflow 'outside' the house for a few days....prior to this the pressure relief valve was running so i assumed the megaflo needed charging as not been done for around a year....
I've followed the instructions on the megaflo as follows;
I've turned...