How to Make Your Fireplace More Efficient

Image Gallery An open masonry fireplace seems cozy, but it's not efficient for home heating. ISTOCKPHOTO/OLIVER MALMS

As you sit by the fireplace enjoying the glow on these cold winter nights, are you content knowing you’re using a renewable fuel to warm your home? Depending on the type of fireplace you have, it may actually waste more energy than it creates throughout the season. The problem is that most heat goes up the chimney, drawing cold air into the house to replace the heated air. When a fire isn’t burning, warm air can still escape through the chimney. But there are several things you can do to increase the efficiency of your fireplace.

1. Add a fireback. A fireback is simply a heavy sheet of metal (traditionally cast iron) behind the fire. In addition to protecting masonry in the back of the fireplace, a fireback reflects heat into the room (instead of all the heat going up the chimney). Estimated cost: $75 to $350.
2. Replace the damper. The damper is the metal plate that regulates airflow through the chimney. Some dampers fit snuggly when they’re new, but frequently warp within a year or two, producing a loose fit and allowing air to leak past them. Chimney cap dampers close the entire top of the chimney. Estimated cost: $10 for a damper inside the flue, which won’t stop much air; $160 to $400 for a chimney cap model.
3. Add doors to the fireplace. Doors reduce the amount of air that would otherwise be siphoned up the chimney. Depending on the type of glass in the doors, some heat still radiates through the doors into the house. Estimated cost: $200 to over $1,000.
4. Install a grate heater or radiator. These units aren’t as large as complete fireplace inserts (see below), but capture a significant amount of heat from the fire and force it into the house. Estimated cost: $410 to $615.