Fireplace inserts improve efficiency by creating an airtight combustion chamber that allows the user to control the amount of oxygen that reaches the fuel. The typical open fireplace removes 300 cubic feet of air from the room every minute, according to the U.S. Department of Energy.
The insert transforms the open masonry fireplace into a more efficient unit similar to a wood stove, but the installer must place the insert properly for the greatest energy savings, notes the U.S. Department of Energy. Installers should examine fireplaces to determine if an insert is appropriate. An airtight fitting is essential for controlling the air supply and heat provided by the insert. The installer should fill any space between the outside of the burn chamber and the firebox of the fireplace with appropriate insulation. When the insert requires cleaning, the process requires the same attention to detail to ensure the insert remains airtight.
Unused fireplaces waste energy, warns the U.S. Department of Energy. Heated and warmed air in the home exits through the chimney. If a fireplace is not used, the owner should seal the flue. If the fireplace is used occasionally, the owner should shut the damper once the fire is extinguished. Inflatable fireplace stoppers are one way to stop leaks of heated air through the flue.