This is my parents house, it's always cold, not in small part because they installed a new boiler but the extra circulating pump was never connected to it, so I'm trying to help with pre-existing problems. I just had a ZVC406 installed for other reasons, there are 6 zones in all including indirect hotwater. So far it's working well except this one area.
This is my system diagrammed, or at least the part I'm interested in.https://ibb.co/rs0mXG3
For some reason, the radiant floor loops heating a big kitchen/dining room downstairs and the master bath upstairs has both a single circulator and zone valves. Both zones share the circulator. Each zone has it's own thermostat, which is goes to the ZVC406 panel and the panel opens the valves.
How can I control the circulator to turn on when either thermostat goes off? I have no problem buying a circulating relay for this, but I'm wondering about the thermostat wiring specifically.