by G Wallace Taylor

Created on: January 15, 2009   Last Updated: May 08, 2011

When it's functioning correctly, your home thermostat will automatically read the temperature of the room and respond by either turning on your heating and cooling units or by shutting them off. According to the American Society of Heating Refrigerating & Air-conditioning Engineers (ASHRAE), a home thermostat must regulate the room temperature to within 2-degrees of the temperature you select. Test the efficiency of the unit by bringing a reliable outdoor thermometer inside and comparing the numbers. The outdoor thermometer should register within 2-degrees. If it's way off, it's time to consider installing a new home thermostat.

Determine the voltage of your old home thermostat before buying a new one. The voltage, separated into three basic categories, high voltage, milivoltage and low voltage, determines how the unit will process the incoming electrical current and use it to regulate your heating and cooling units. Look on the underside of the old cover to find the current voltage and make sure the new one matches that voltage.

Establish compatibility standards. Does your current home thermostat control both heating and cooling? How many wires connect to the back? Before checking this, shut off the electricity. Many home units are battery-operated but don't remove it until you know you won't receive an electrical jolt. Write down this information and include the type of heating or cooling in your home. For instance, does your heat come from oil, gas or electricity? Record all the numbers on your heating and cooling units before you go to the store.

Consider your needs. If you want your home nicely cooled when you come back from work, a programmable home thermostat will turn on your air conditioning system an hour earlier. These units are slightly more expensive but if you use the features, they quickly pay for themselves in energy savings.

Remove the old home thermostat with simple flathead screwdriver. The existing wires will attach to the new unit in the same manner you removed them from the old one. You will see a combination of wire colors, including white, red, yellow and green. Match the colored wires to the corresponding color code on the back of your new home thermostat.

Complete the installation by adding a little insulation to the stud space in the wall opening. This is especially important if your thermostat is located on an outside wall because temperature variations within the stud space may alter a correct room reading. Install a fresh battery if your thermostat is battery-operated and set the specific features.

Connect your new thermostat to the wall, attach the front cover and you're set.

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