have a thermastat system (four wire) that was disconected without being labled need to know the color code for the wires

Verify at your heating system but typically, R to red (there may be a jumper to R2), W to White, G to Green and Y to yellow. You may have a B or C terminal and a Blue or Black wire, check at the furnace cuircuit board and attach the same way to your thermostat.

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