How to Install a Programmable Thermostat

By Gene and Katie Hamilton

Tools Required
  • Screwdriver
  • Wire stripper
  • Drill with 3/16-in.-dia. bit
  • Hammer
  • Torpedo level
Materials Required
  • Programmable setback thermostat
  • Masking tape
  • Ball-point pen
  • Pencil

Before You Begin

Most residential thermostats run on low-voltage wiring, which doesn't present a shock hazard. However, it's better to be safe than sorry, so begin by turning off the electricity to the furnace and central air conditioner at the main electrical panel. If your old thermostat is connected to thin wires coming directly out of the wall, then it has low-voltage wires. But, if the thermostat is wired into an electrical box, then it's probably running off of 120V current; don't attempt to replace it with a new setback thermostat without first consulting a licensed electrician.

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  • Step 1 : Remove the cover plate

    Remove the cover plate

    After turning off the electricity to the furnace and central A/C unit, pull off the cover plate from the old thermostat. If it doesn't pop right off, pry it off with a slotted screwdriver, being careful not to scratch the wall.

  • Step 2 : Remove the mounting plate

    Unscrew and remove the thermostat from its mounting plate, but don't disconnect any wires.

  • Step 3 : Use tape to label wires

    Use tape to label wires

    Identify each wire with a small piece of masking tape. Label each piece of tape with a letter that corresponds to the terminal screw - that way you can easily reconnect them later. Once the labels are marked, disconnect the wires from the terminal screws.

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