I only have R and C wires attached to my old Honeywell thermostat. There are green, blue, and yellow wires, but they are not attached to anything. I have 2 zones, each with separate thermostats and each thermostat has its own panel board.
There is a main panel board that looks like it receive all the wires from furnace and HVAC. The wires are coming out of this main panel to each thermostat panel board. The cables going into has all the colors connected but the out cables that are going to the thermostat are only R & C. The nest thermostat always ask for W wire to be connected but in my case there is no a W wire coming out of the panel board.
Can C wire be connected to W port in Nest thermostat?
