EWC Controls Forum

My zone 1 thermostat has W Y RH/RC O B G C wiring My Zone 2 has W Y R, no C (working fine with a battery operated thermostat) If I add a C wire to my zone 2, I can use thermostats such as Ecobee. My question: will it work even though it has no O or B wire? I will leave my zone 1 thermostat installed ...