I am currently trying to install a digital thermostat. The old one has two wires coming out of the wall, one red and the other white but are not labeled. On the digital thermostat the connections are: Y, G, RH, RC, & W. which wire goes where?

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If this is a heat only unit use RH and W. I hope the thermostat will work on battery only since you have no extra wire for a C common leg. COLOR wire placement is simple RH to Red and W to White. It actually will not make a difference since you only have two wires to start with. All of this should be in the owners/install manual.

Okay, I'm pretty confident I can actually answer a thremostat install. FINALLY. This is as basic as it gets. If you only have two wires(red and white) coming out of wall, then just hook red to rh, and white to w.. Don't worry about the stat running off batteries, as since you don't have a C terminal on the stat, it will be powered off tranformer in furnace though the red wire. However, if there is a spot for batteries, put them in, because they will save any settings on stat if power goes out.

Now, and this is important,, you will most likely have to set a heat cycle rate in the stat. Its different from steam, gravity systems, 80%, 90% and hot water heat, electric furnaces etc. Set down, read the complete install manuall, and set thermostat up to work most efficeintly with your heating system. Strange how a two wire stat can be so involved inst it?

With your two wire system, it really is easy, just read the lit that comes with the stat, and come back if you need help. Make and model of stat would help.

Some digital thermostats do not support power stealing from the red but we have no idea which thermostat he has to start with. LOL

Yep, so much for simple two wire stat hookup, lol.