I have an ISTOR HE325 Boiler which has developed a leak and which seems to be coming from the top of the filling loop which connects at the other end to the Cold Water in pipe.I have turned the bolier off completely but the incessant leak is now causing damage to the ceiling below the boiler which I cannot control.I thought the best thing todo might be to try to drain the cylinder but even if this is the right thing to do the drain valve is awkwardly positioned so I donot think I will be able to attach a hose pipe at all easily.Even if I did willl the cylinder just refill unless I cut the water off and if so how do I do that?Any suggestions gratefully received.