Quote Originally Posted by HenGus View Post
I have HW Priority via a 2 valve bespoke system. The HW is on a standard motorised 2 port valve controlled by a BDR. CH has an inline power off open motorised valve. When HW is demand, the HW valve opens and the CH valve closes. Seems to work perfectly as my installer said it would.
Or you could just simply provide power to the A port on the BDR91 Heating receiver from port C on the BDR91 Hot Water. (Providing you have two NC MV in your setup).