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How to Install a Thermostat

Getting a pro to replace a broken thermostat can be costly, but if you pay close attention, you can learn how to replace it yourself.


  • Step 1: Turn off the main electrical power switch to the heating and air conditioning unit.
  • Step 2: Pry the cover from your old thermostat. Unscrew the wall mount to separate the thermostat's wiring from the wall.
  • Step 3: Using masking tape, label each wire as you disconnect it from its terminal connector. Then slip the sub-base over the wires and remove it from the wall.
  • TIP: Loosely knot the wires together to prevent them from slipping back inside the wall as you remove the sub-base.
  • Step 4: Pull the wires through the feed hole in the new thermostat and place it flat against the wall. Use a level to position it, and then mark the top, sides, and screw holes with a pen.
  • TIP: Make sure the new thermostat is level so it will work properly.
  • Step 5: Drill the screw holes and hammer the drywall anchors into the holes until they are flush with the wall.
  • Step 6: Carefully connect each wire to the new terminal and screw the new thermostat sub-base to the wall.
  • Step 7: Replace the outside cover of the new thermostat and restore power to the furnace.
  • FACT: Did you know?If geothermal systems were installed nationwide, they could save several billion dollars annually in energy costs and substantially reduce pollution.

You Will Need

  • A Phillips screwdriver
  • Masking tape
  • A pen
  • A new thermostat
  • A level
  • A drill with a 3/16-inch bit
  • Drywall anchors
  • A hammer

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