How to Make a Wood Furnace More Efficient

Wood furnaces are most efficient when used for space heating and as a backup heat source.
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Your old wood furnace may seem like a smoky drain on your wallet, but it doesn't have to be. There are a handful of ways to make your wood furnace more energy and cost efficient. Most wood furnaces simply require a little maintenance, a few repairs or the right wood to burn; others may benefit from an equipment upgrade. The environmentally smart choice is to make your existing wood furnace more energy efficient, instead of shipping it off to the scrap yard and buying a new one.

Practice Preventive Maintenance

Creosote buildup, cracks in the unit, broken seals around the ceiling and other damage can make your wood furnace work overtime to produce heat. Smoke and dangerous carbon monoxide also present a risk when using damaged wood furnaces. According to the U.S. Department of Energy, you lose 50 percent of the heat transfer efficiency from a dirty wood furnace with just one-tenth of an inch of soot buildup. Call a professional to inspect, clean and make any necessary repairs at the beginning and end of every cold season. (See Reference 1)

Burn the Right Wood

The fuel you burn in the wood furnace can limit the energy efficiency of the unit. Dry, seasoned wood produces more energy per cord than wet wood does. The most efficient fuel for your furnace is wood that has been split to a 6-inch diameter, which has sat stacked and covered for at least six months. The species of wood matters as well. The U.S. Environmental Protection Agency suggests using hard, dense woods like rock elm, hickory, sugar maple, beech or oak. These will burn hotter and for a longer period of time than softer woods. (See Reference 2)

Stop the Smoking

According to the EPA, smoke is the most visible sign of an inefficient wood furnace; hot-burning fires create little smoke. Smoke could indicate a closed damper, dirty furnace or wet wood burning inside the stove. Eliminating the cause of the smoke will make your wood furnace operate more efficiently and keep its heat in the home. (See Reference 2)

Look Into Upgrades

Today's wood furnaces can be up to 80 percent more energy efficient than older models; they burn hotter using less wood. Modern wood furnaces are pricier than older models, but they make up for the cost difference by burning wood more economically. Not all older furnaces need to be replaced, however. An upgrade may be all you need to make your existing furnace more energy-efficient. According to the DOE, a catalytic damper is one upgrade that can make your furnace burn hotter and use less wood. A catalytic damper also burns off the creosote more quickly. (See Reference 1)

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