Conscious Choice: Fireplace Efficiency

November 2001 | Sensible Home

Fireplace Efficiency

by James Dulley

Dear Jim: I know most fireplaces waste energy, but we love to sit in front of a raging fire. Are there any simple, low-cost things we can do to make it produce heat and to reduce the smoky smell in the room? — Thomas M.

Dear Thomas: People seldom realize the typical wood-burning fireplace sucks more heat out of a house than it produces. This makes the furnace run longer and drives up utility bills. Even though you feel toasty warm directly in front of the flames, the rest of the house gets very chilly.

There are several simple things you can do to make your fireplace much more efficient and change it into an overall energy producer and money saver for your home. Many of the same improvements also help reduce smoky conditions.

The two key improvements are: (1) reducing the amount of already-heated room air lost up the chimney and (2) directing more heat from the fire out into the room. By running your furnace blower on continuous air circulation, the heated air in the fireplace room will be distributed throughout your house.

Most of the heated room air is lost up chimneys when there is no fire burning because of a nonexistent or poor sealing chimney damper. To seal the chimney and provide insulation, I use an inflatable chimney pillow in my fireplace. It is clear plastic and you blow it up like a mini-air mattress.

Another option to block room air loss is a tight-sealing damper assembly that is mounted on top of the chimney with silicon caulking. Long narrow cables hang down in the chimney to easily open and close the damper. Chimney exhaust fans also seal well and can eliminate a smoky fireplace condition.

Tight-fitting glass fireplace doors with adjustable air openings help when the fire is burning. Some doors use magnets and others use cams to keep them tightly closed. High-temperature silicon gaskets provide an excellent seal. Polished nickel, copper, and pewter finishes are very attractive.

Install a heat-circulating grate in the fireplace. The grate is made of steel pipes with a built-in fan that draws cool room air in one side and blows heated air out the other. The base is only 1.5 inches high so it fits under the glass doors. The heat output is as high as 40,000 Btu per hour.

Models with a built-in thermostat and a variable-speed blower provide the most control over the heat output and the sound level. The thermostat turns the blower on automatically at 110 degrees F. and off at 90 degrees F.

A heavy cast-iron plate (fireback), placed in the back of the fireplace, gets very hot. This helps radiate more of the fire’s heat out into the room before it is lost up the chimney. Many have decorative patterns cast into the face.

Write for (or instantly download) Update Bulletin No. 553, buyer’s guide of fourteen manufacturers of heat-circulating grates, glass doors, firebacks, chimney pillows and chimney damper/draft fans, and efficient fireplace usage tips. Please include $3.00 and a business-size SASE. James Dulley, Conscious Choice, 6906 Royalgreen Dr., Cincinnati, OH 45244.

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