Thanks sjr56 for such a quick reply. Could you confirm that in your own case you were using a conventional tank thermostat, rather than a thermistor type sensor?
Regards, David
I have recently installed a new Ultracom 24hxi, with an external sensor, and Smart Wiring Centre, in order to be able to use the existing conventional tank thermostat. I was initially inclined to try having both heating and DHW on at the same time, but fortunately thought better of it, thus...