I am trying to replace an old Lenox 2-wire thermostat with a Honeywell TH8000 (similar to the Honeywell RTH8500) programmable thermostat. The old thermostat has only a red and a white wire, connected to opposite sides of a coil device with no mercury bulb. I can find no markings for the wires.
The directions for the new thermostat indicate that I can connect it to a 2-wire system by connecting the power wire to the "R"/"RC" terminals (connected by a jumper) and the common side of the transformer to the "C" terminal. I connected the red wire to the "R"/"RC" terminals and the white wire to the "C" terminal. Although I've turned the thermostat to 75 degrees, nothing happens. (Yes, I turned the breaker back on :-))

I read the previous posting on this site regarding a 2-wire thermostat replacement, but it didn't seem to get to a successful conclusion. It looked as though the person inquiring just gave up.

Any thoughts? What happens if I got the wires backward?

Thanks!

Connec one wire to RH-RC and the other to W. make sure you have fresh batterys in the unit then follow the directions to set up the thermostat.

Thanks! It works now.

Glad you got it running it is cold outside.