I have an S-Plan system (two zone valves, one for DHW and one for central heating, with HR92's on all radiators. I believe there are two options for configuring Evohome on this system:
1. Configure Evohome to have no boiler demand, instead having 2 zone valves which in turn control the boiler/pump.
2. Electrically disconnect and manually open the central heating zone valve, and configure Evohome as having a boiler relay and just one DHW zone valve.
I'm just wondering what the benefits of each option are, especially in terms of pump overrun etc.
Thanks!