How it Works

• A standard thermostat regulates the temperature with a type of thermometer that contains one or more components that expand or contract during a temperature change, completing or otherwise breaking an electrical circuit and signaling the air conditioning or heating unit to turn on or off when the temperature reaches a certain point.
  
  

Uses in Applicances and Equipment

• Thermostats are widely used to regulate the temperature in air-conditioning systems, refrigerators, ovens and water heaters. You'll find thermostats everywhere heat is used as an energy source, from an automobile's internal combustion engine to computer components to battery chargers. They are even in hot glue guns.
  
  

Standard vs. Programmable

• Programmable thermostats are available for most home air conditioning and heating systems, and provide a convenient way to control not only the temperature, but also costs. "Good Housekeeping" says: "For every degree you set your thermostat back over eight hours, you'll save about 1 percent on your heating bill each year." Maria Vargas, an EPA spokeswoman adds: "Programmable thermostats can save significant energy . . . when programmed correctly." Many thermostats have pre-programmed settings designed to cut heating and cooling costs by up to 20 percent.
  
  

Price and Installation

• As of January 2011, a new thermostat will cost anywhere from $35 to several hundred dollars, depending on its features. Replacing a thermostat is a quick and easy job and most likely won't take any specialized skills beyond twisting a screwdriver. Instructions are included in the box and at most will require drilling new holes for mounting.