Think about it. Your fireplace and chimney vent directly to the outside. That means you must stop air from traveling through your house and out the chimney when your fireplace is not in use.

Ways to Prevent Air From Escaping
Most homeowners solve this problem by properly using their fireplace's damper. The damper is a moveable blade that prevents air from escaping through the fireplace and chimney. The damper must be opened before starting a fire, to provide required oxygen and enable smoke to move up the chimney. The damper should be closed anytime the fireplace is not in use, to ensure warm air stays in the house.

Another solution is to have a glass door enclosure installed around the fireplace.  To be effective and safe, the doors of this enclosure should be opened only when you are starting a fire.

Use the Damper Properly
Most homes built before 1950 do not have dampers in the fireplace. Consequently, these homes (and their homeowners) suffer from poor heat conservation. To remedy this, the Irish Sweep recommends installing a top sealing damper (figure 2).

To use the damper properly, remember to:

• Close the damper when the fireplace is not in use. This prevents heated air from escaping through your fireplace.
• Open the damper when you're ready to start a fire - and keep it open through the duration of the fire. In this way, you'll be providing the oxygen required to ignite the fire - and ensuring a safe passage for smoke while your fire is lit.