Home Improvement How-To's: Installing a Thermostat

Forget the stock market. Few hour-long home-improvement projects will pay year-in, year-out cost-savings dividends like replacing your old thermostat with a new programmable - or "automatic setback" - model. Depending on the severity of the winters where you live, you could realize a savings of up to 35 percent on your yearly energy bills. Who wouldn't want to do that?

When shopping for your new thermostat, check the thermostat package to ensure it is compatible with your home's system.


You can buy, install, and program your new thermostat all in the space of a morning.


Programmable thermostat
Masking tape

Step 1 Turn off the power to your heating and air-conditioning system at the main service panel. Remove the old thermostat cover plate.

Step 2
Unscrew the thermostat mounting screws, and remove the thermostat body.

Label the low-voltage wires to identify their screw-terminal locations using masking tape. Then disconnect the wires.

Remove the thermostat base by loosening the mounting screws. Tape the wires to the wall to prevent them from slipping into the wall cavity.

Thread the low-voltage wires through the base of the new thermostat. Mount the thermostat base on the wall using the screws included with the thermostat.

Connect the low-voltage wires to the appropriate screw terminals on the thermostat base. Follow the installation diagram in your new thermostat's owner's manual.

Locate the low-voltage transformer that powers the thermostat. The transformer usually is located near the heating/air-conditioning system or inside a furnace access panel. Tighten any loose wire connections, and make sure the wires and sheathing are in good condition.

Install the battery or batteries in the thermostat body, and attach the body to the thermostat base. Restore power, and program the thermostat as desired.