The problem being that when drawing water for a bath the other night, early in the year I know, all the upstairs rads became hot. I know that there is no diverter valve on this boiler, a two in one heat exchanger. The heating is selected off on the boiler facia. I think there may have been the old type of overheat circuit where the bathroom rad acts as a heat dump. The original boiler was a floor standing mexico and the current boiler was attached to the same rads and pipe work. Any theories?
