Cheers gas4you. I sorted out the ball valve in the feeder tank (you're right it was stuck... mainly a build up of calcium stopping the ball valve from closing). That's sorted out the o/flow problem, but still worried about the lack of hot water flow. D'you think unfirring the system is the best...
Recently moved into a flat. We went away 2 days ago and all fine. Returned to find that there is no flow at all (not even a gurgle) from the hot taps (the whb and bath tap, nor the downstairs kitchen sink).
We have a very, very old gas boiler on the ground floor which feeds a small cylinder...