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Sealing Heating & Cooling Ducts Can Save Money

Submitted by Lorene Bartos, UNL Extension Educator

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Cold weather is just around the corner and it seems energy bills will be rising. There are many ways to reduce the energy used during the cold weather season. Sealing heating ducts will help save energy during this time.

Many heating and cooling air duct systems are not properly sealed or insulated and lose a lot of energy from leakage and poor insulation. Leaks at seams and joints mean the conditioned air is going someplace other than where you want it to go. Ducts that leak heated or cooled air into unconditioned spaces, such as crawlspaces or attics and unused and unfinished basements can add hundreds of dollars a year to heating and cooling bills.

Ducts made out of thin metal materials easily conduct heat. Uninsulated or poorly insulated ducts in unconditioned spaces can lose 10 to 30 percent of the energy used to heat and cool the home through conduction, according to the U.S. Department of Energy. The heating equipment then has to make up for the heat loss by conditioning more air using even more energy. When ducts lose heat through conduction, rooms served by long duct runs can experience "cold air or cold blow" during the winter because they may have lower heating-supply temperatures.

Sealing and insulating duct systems is usually cost-effective and helps to ensure the rooms will receive conditioned air at even temperatures. Although minor duct repairs are easy to accomplish, ducts in difficult to reach areas should be sealed and insulated by qualified professionals using appropriate sealing materials. Some heating and cooling and weatherization professionals conduct duct testing to determine the extent of leaks in the duct system.

Look for separated duct sections, leaks at seams and obvious holes. Inspect the ducts from the heating unit or furnace through to each end of the duct run, and inspect return air ducts. Use mastic or foil-based tape with the Underwriters Laboratories (UL) logo to repair these duct leaks. Mastic is a paste that can be brushed onto the seams. These materials may be available at hardware and home stores, lumberyards, or heating and cooling equipment and service businesses. Regular duct tape can degrade, crack and lose its bond with age and with the stress of the heating and cooling cycles.

After sealing the ducts, insulate ducts and especially those in unconditioned spaces. Tape or seal any seams in the insulation as well to prevent leaks through insulation seams. If you have water pipes and drains in unconditioned spaces, they could freeze and burst if the heat ducts are insulated. There would be no heat source to prevent the space from freezing in cold weather. Electric heating tape wrap on these pipes can prevent this - read directions and use it safely or have a qualified professional insulate the ducts and install the electric heat tape warp.

For cooling ducts, use a well-sealed vapor barrier on the outside of the insulation to prevent moisture condensation and buildup.

For more information on other ways to save energy at home, visit the U.S. Department of Energy: Energy Efficiency and Renewable Energy Web site at http://www.energysavers.gov or go to http://extension.unl.edu/publicatons and search for "energy efficiency."

Now is the time to check your home's ducts help save energy this fall and winter.

Ask Lorene

(This resource was added September 2008 and appeared in the Lincoln Journal Star Newspaper Sunday edition. For information on reproducing this article or using any photographs or graphics, read the Terms of Use statement)

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