I have had C4 throughout my home for the past 4 years. I wanted to install the C4 thermostats (3), but was told by my dealer that I could not because my thermostat wiring included only the red, yellow, white, and green wires; apparently no common wire (?). I believe I have read within this forum where others had the same issue, but a solution existed. If this is true, I would like to utilize the thermostats......please let me know if there is a "work-around" solution. Thanks all.

what is the furnace type?

forced air gas single stage?

forced air

with air conditioning?

yes

you should be able to do this with just the 4 wires. its described in the install manual

thanks