worcester bosch highflow 400 problem with radiators being on intermittently even when radiator thermostat is turned completely off! also hot water not as fast as it used to be,could it be heat exchanger and if so what is the best way to descale it? anyones help would be appreciated thanks.
sounds like a blockage in the domestic heat exchanger,tricky job to do but there are other possible causes such as the diverter valv or the non return valve on the central heating flow and return pipes,
it is most likely to be the heat exchanger as this can block and the heated water will try another path of circulation.
do you plan to try this yourself?