Zone wiring--3 zones 2 thermostats wire so 1 zone runs if either of the 2 come on

[lamby22]

1 zone per floor --1st floor zone 1, 2nd floor zone 2 and basement zone 3 .. nest thermostats on 1st and 2nd. i DO NOT want a thermostat in cellar. right now cellar(3rd zone) has a modine that comes on when 1st floor calls for heat BUT we have a fireplace which keeps 1st floor from coming on sometimes.

so I would like to know if I can wire both thermostats to the same zone controller so if either zone calls for heat it will trigger cellar(3rd zone) to open or will this short out the nest thermostat if both call at same time.

 

[hj]

It will probably tie all 3 zones together so the ALL work whenever any thermostat calls for heat, unless you do it through relays.