had the same problem with mine in last place i stayed, had to get new safety valve fitted and another part which at this moment i cannot remember but best thing is to get a corgi engineer out to sort it matey or contact hepworth heating and get their service guys out, obviously it's gonna cost but better to get someone who knows what they're doing, and the boiler is obsolete now anyway so good luck in getting the parts.
Andy, February 2009