I am replacing my old Honeywell mecury thermostat with a programmable Honeywell RTH230B. I have two unmarked wires (red & white) connected to the old thermostat. I know, given my furnace, that I need to use connections "RH" and "W" on my new thermostat. What wire, Red/White goes to what connection on the new thermostat RH/W? Thanks

Hope this helps.

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Originally Posted by two dogs

I am replacing my old Honeywell mecury thermostat with a programable Honeywell RTH230B. I have two unmarked wires (red & white) connected to the old thermostat. I know, given my furnace, that I need to use connections "RH" and "W" on my new thermostat. What wire, Red/White goes to what connection on the new thermostat RH/W? Thanks

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Did you ever get a response to this question because I have the same problem... except I have 4 wires, 2 red, 2 white. Any Thoughts?

Yes I did. My one red wire goes to the connection on the thermostate marked "RH" and the white wire goes to the connection marked "W". I am not sure what your second set of wires should connect to. Does your system both heat and cool? If yes, might it have something to do with the dual system. Does the instructions, that come with your thermostate describe what to do in the case of a dual system now that you know where the red and white wires connect to? Good luck to you.

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