Fireplaces rank among the most desirable features in a home, according to This Old House. While there's no question that fireplaces add charm and romance to the home, traditional fireplaces actually do surprisingly little to heat the home. Fireplace inserts combine the beauty of a wood fire with the efficiency of a modern wood stove, allowing them to serve as an effective heating system for a single room or even the entire home.
A fireplace insert fits inside an existing fireplace and uses the existing chimney to vent combustion exhaust. These units use glass doors to display the fire and control the flow of air, and a flue collar provides an airtight connection to the chimney to maximize efficiency and direct smoke and fumes outdoors. These inserts essentially function just like a wood stove, but are designed to burn wood, pellets, propane or natural gas, depending on the model you choose. Many feature a blower to help distribute heated air through the room or to other parts of the home.
Old-fashioned fireplaces are notoriously inefficient, and some actually allow more heat to escape from the home than they produce. The California Air Resources Board reports that traditional fireplaces offer an energy efficiency of -10 to 30 percent. Old, noncertified inserts rate between 35 and 50 percent, while modern inserts certified by the U.S. Environmental Protection Agency offer an energy efficiency rating of 60 to 80 percent, making them about as efficient as a standard wood stove, according to the U.S. Department of Energy.
By improving energy efficiency, fireplace inserts improve occupant comfort. The doors and construction of these inserts controls air flow and prevents heated air from rushing out through the chimney, keeping the room warmer than a traditional fireplace. Inserts certified by the EPA, which includes the majority of modern inserts sold in the U.S., use 30 percent less wood and produce 70 percent less pollution than older, noncertified inserts, according to the EPA. Inserts also provide greater fuel options than fireplaces, which allows you to swap fuels based on availability or price changes, depending on the unit you choose.
As with all heating equipment, the size of a fireplace insert affects everything from comfort and performance to energy efficiency and safety. A unit that's undersized does little to heat the home, while one that's too large wastes fuel and can increase the risk of fire. Consumer Reports recommends choosing an insert rated to provide between 25 and 30 British thermal units per square foot of space that you want to heat. For example, a 200-square-foot room requires an insert rated at around 5,000 btu.
A new fireplace insert costs between $2,000 and $4,000 as of May 2013, according to This Old House. This figure includes the stove itself as well as professional installation to properly vent the stove through the existing chimney.