Does the DuoHeat radiator need both off peak and direct-acting [day rate] energy together?
Yes, for the DuoHeat radiator to work correctly it needs to work both energy sources together. It requires an off peak energy connection for the stored heat and a peak [day rate] energy connection for the direct-acting panel. However, in the summer/spring when a very small amount of heating may only be required, it is OK to have the peak supply only with heat coming from the radiant front panel.