I spent 2 hours with Thermostat vendor, Ecobee and they couldn't help me. I have R,G,Y,B and the white lead is not connected. I need some guidance on how to get a Common wire. I tested voltage and R-G, R-B, R-Y all give me 26 volts.
Any suggestions on how to get the Common wire?
This is a Whalen unit, about 15 years old.