I have a rheem heat and air conditioner need to no how to hook up thermostate model rpnd-024j wire colors are brown/yellow/bluewhitestripe/red/black/blackgreenstripe/blue okay I have a honey well thermostat7850 wire colors are black/white/orange/brown/yellow/green/blue/which wires go to geather thanks [email protected] plzs help:eek:

I am trying to change out my old thermostat which uses a mercury switch to a Honeywell CT2800 programmable thermostat. The old thermostat which is also a Honeywell has just 2 wires connected to it and none of the terminal posts have any type of marking on them. There is no instructions on the ct2800 on changing out a thermostat with 2 wires. Can anyone tell me which terminals to connect the 2 wires to? This thermostat is intended for a natural gas forced air furnace.

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Originally Posted by Installer1

I am trying to change out my old thermostat which uses a mercury switch to a Honeywell CT2800 programmable thermostat. The old thermostat which is also a Honeywell has just 2 wires connected to it and none of the terminal posts have any type of marking on them. There is no instructions on the ct2800 on changing out a thermostat with 2 wires. Can anyone tell me which terminals to connect the 2 wires to? This thermostat is intended for a natural gas forced air furnace.

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Read the instructions for the CT2800. If it needs a common, it won't work on a 2 wire system. Otherwise, just connect the 2 wires to RH and W. If it doesn't work, reverse them.

Moderator:

There are two separate threads here.

kennethlkelley probably isn't getting any help, because he didn't provide the terminal numbers and the make of the first stat.

Installer1:
The CT2800 uses R and W for the heating contacts per the instructions.

The best that I can tell from your description of the wire colors is to use the black and the white wire. It will not matter if you reverse them.