Step 2: Connect the New Thermostat

Line up the new bracket with the hole in the wall, and connect the wires to the terminals on the bracket, following the diagram in the instructions. This thermostat needs at least three low-voltage wires: a black one and a white one, which turn the furnace off and on, and one that powers the thermostat. If you have only two wires, call an electrician or HVAC contractor to run the additional 18- or 22-gauge wire.

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    Tools List

    • flathead screwdriver
    • needlenose pliers
      Needlenose pliers
    • drill
      Drill/driver, for mounting the outdoor sensor

    Shopping List

    Programmable thermostat