How to Replace Your Thermostat

Most homeowners get nervous when they need to know how to replace a thermostat. Working around electricity can make anyone a little anxious if they do not have the know-how to carefully get the job done. Fortunately, replacing your thermostat is a fairly easy task to accomplish.

Materials Needed:

  • New thermostat
  • Screwdriver
  • Needle-nosed pliers
Step 1 – Prep

Make sure the new thermostat you are using to replace the old one with is compatible to your 110-volt housing circuitry.

Step 2 – Switch off the Power

Always turn off the electrical power to the home thermostat at the power panel or circuit breaker box. Once you’ve located the correct circuit breaker and have switched it off, place a piece of masking tape over the switch so no one will turn it back on during your replacement installation process.

Step 3 – Remove Old Unit

Remove the old unit by snapping the cover off or unscrewing it if is attached by set screws. Pull the unit away from the wall and slide it off the mounting plate. Be careful not to damage the wires.

Step 4 – Disconnect Wiring

Remove the electric power supply wiring from the back of the thermostat. Be careful not to allow the wires to fall back into the wall. Wrap these around a pencil to keep them from being able to go through the entry/exit hole. If the wires are not color coded to the new thermostat, mark each one noting which terminal to which they were attached. Remove the mounting plate.

Step 5 – Attach New Mounting Plate

Place the new mounting plate for the new thermostat against the wall in the same spot as the old one was. Now pull the wires from the wall through holes in the back of the new mounting plate. Screw it onto the wall. Make it is square to the wall before tightening the mounting screws. Adjust the unit for leveling before fully tightening the screws.

Step 6 –Carefully Connect Wires

When connecting the wires, make sure the green wire is connected to the terminal marked “G” or the same color. This operates the furnace fan blower. The white colored wire colored wire goes to the “W” marked terminal to operate the heater while the “Y” is for the yellow wire that connects to the air conditioner. Make sure if the wires were not color coded when you remove the old thermostat that you mark each correctly before connection to your new unit. Do not cross wires. If in doubt, call a professional electrician.

Step 7 – Place on Mounting Plate

Place the unit on the mounting plate by sliding it into place. Turn your power back on and check to see if your new thermostat is working properly. Follow the manufacturer’s instructions for setting up the LED display panel that gives you access to temperature control.

If there are more than three wires coming from the wall, ignore them. They were put there by the original homebuilder for possible use for another item that was never installed.

Need a new thermostat? Compare brands, types and prices with our Thermostats Buyer's Guide.