How to Install an Energy-Saving Programmable Thermostat
Save on your energy bill with controls that automatically change the temperature settings
Q: I'd like to put in a new programmable thermostat to better control my energy costs. Can I install it myself?
—Sam Aleksy, Chicago
Lance Marques, HVAC contractor, , replies: Sure you can. Upgrading to a thermostat that automatically changes the indoor temperature setting is fairly easy, and it can trim about $180 off your annual heating and cooling costs, according to the EPA.
Simple models that only control heat are sold at home centers for around $25. More expensive products, such as the that I installed here, handle many more functions, including cooling and humidifying. Typically they're purchased through and installed by HVAC contractors, but you can also buy them online.
Before you buy a replacement thermostat, however, take a peek at your existing wiring. If there are only two wires, the simplest solution is to get a replacement with a battery-powered display. Full-featured devices like the Prestige need power from a third wire, something best installed by an HVAC or electrical contractor.
Remove the Old Thermostat
Cut off power to the furnace using the emergency shutoff or breaker switch, then unscrew the thermostat's mounting bracket. As you disconnect each wire from its terminal, label the wire with the letter of the terminal it came from. Tape the wires to the wall so that you don't lose them. Some older thermostats contain mercury; for information on proper disposal, go to the .