This video explains how a priority hot water system using a diverter valve is wired. It uses a simple line drawing to explain the component parts and how they interconnect in the wiring centre. The system is then built and tested.
Nicely explained but i can see one problem, all cables need a earth wire, as the earth wire protects the cable if someone was to cut through the cable or if there was a problem with in the cable.
I've seen systems where the earth has been used as a switching wire. Just remember the earth wire protects the cable and would cause the circuit breaker to trip if someone cut through the cable.
Instal a relay switch between room stat and zone valve. Relay powered by room stat, hot water off to common, normally open to feed zone valve. Programmer set to gravity so that hot water on is tied to heating on. Hope that makes sense. Good luck.
