Old "R" connected to new "R" which is jumpered to "RC" Old "W2" AND "E" connected to new "aux" and jumpered to "e" Old "Y" connected to new "Y" Old "O" connected to new "O" Old "G" connected to new "G" Old "C" (blue wire) not connected?? Honeywell tech support said it is not needed. IS...

Hey everybody, I hope you can help me with the problem I am having converting my old Trane Mercury thermostat model #3AAT80A1A1 to a Honeywell Digital thermostat model #RTH7600B. I currently have a multi-stage heat pump system. The Trane has wires that are connected to O, R, T, G, Y, B, W and...

I have a five wire system. I have a green, red, white, yellow, and blue. This is an electric heater attached to the air handler and a separate air conditioning system. THis system was controlled by a Lennox mercury thermostat. Could you tell me what each color wire does? Example: Yellow...

We have an older home that we are renting. It has an outdated, unreliable mercury thermostat and we want to upgrade to a digital thermostat. I checked and all the wires are there as we have the heat and a/c. Is it OK to do that?