I have a Nest 3G, I'm now considering to change my boiler due to age-related issues. Can someone tell me if I can connect the Heat-Link to both zone-valve (on/off contacts) and boiler (OpenTherm). I ask this because my home has 3 zones: toilets, downstairs, upstairs. Downstairs is controlled by nest (now on/off only) upstairs has an old Theben thermostat and toilets has a simple 1-temp thermostat.
Now each thermostat controls both zone valve (directly) and boiler call-for-heat (trough a relay). Now I'd like to keep this configuration for upstairs and toilets but I'd like to connect the nest to my new boiler via open-therm, so if only downstairs is asking for heat it'll modulate and if some other zone is asking for heat the boiler will behave as standard on/off.
Is this possible? Do I need some add-on boards for my boiler?
