Hi, I too have the same problem. An engineer has diagnosed a temperature sensor, this has been replaced - now have hot water without switching the boiler off, fingers crossed. Also diagnosed that an inverter valve was needed; this should pump the hot water round the boiler and not into the radiators when the heating is switched off. There is a pipe which comes out of the left hand side of your boiler at the bottom, this should be cold, if boiling hot you may need a new valve. Not cheap! but if it fixes it, all good.
Claire, December 2009
