How to install a thermostat if you don’t have Y or C wires

thermostatthermostat-c-wire

My thermostat is a LuxPro LUX PSP511LCa. I looked behind the thermostat and I see the following:

  1. A red wire connected to RC
  2. A jumper connecting RH and RC
  3. A white wire connected to W
  4. A green wire connected to G

I see no Y or C wires.

Now, I have a new Honeywell RTH6580WF WiFi thermostat. The instructions tell me I need an R, W, G, Y, and C cables.

I have a few questions:

  1. Can I assume that my current RC cable is the same as the R cable, so I just plug it into the R slot?

  2. What do I do about the C and Y cables? I don't have either. I read that Y is for cooling. My house has no cooling, nor do I want it. Can I just ignore the instructions that tell me to connect the Y cable?

Attached is a picture of the thermostat wiring:

ThermostatWiring

HeaterWiring

Best Answer

You have * power(R) * heat (W) * fan (G)

(note that on some furnaces R and W are reversed).

Standard answer is that either:

  • you have more wires in the thermostat cable that are not connected behind the thermostat one of which you can use as a C wire

  • you have some the willingness and ability to pull more cable to pull a c wire

  • you can get a 24v transformer near the thermostat and wire it to Rc and C, and wire your thermostat to Rh, W, and G.

You won't need to use the Y wire.