Thermostat Wiring - From Two to One Thermostat
Currently my central a/c unit is hooked up to a Honeywell CT3500 Programmable Thermostat. I've noticed that the thermostat can handle heat as well as cooling. My furnace is hooked-up to an older manual thermostat. It is a simple 2 wire set-up - red & white. Could the furnace be hooked-up to the programmable thermostat which the a/c is currently using? The R & W slots on the prorammable thermostat are being used by the a/c, but is it just a matter of adding the R & W wire from the furnace to the slots also? I just purchased the home so I would like to find this out before I go out and by another programmable thermostat if I really don't need to. Also, I noticed when I was checking the wiring on the two thermostats, there was a blue wire that wasn't being used for the a/c. The unit seems to be working fine, but I just though I'd ask as the wire is just sitting in the wall and not connected like the other 4 wires. Thanks in advance for the help.