Seal Your Ducts and Save Money
Many duct systems are poorly insulated or not insulated properly. Ducts that leak heated or cooled air into unconditioned spaces (spaces that aren't heated or cooled, like crawlspaces) can add hundreds of dollars a year to your heating and cooling bills, so insulating these ducts is usually very cost-effective.
Although minor duct repairs are easy to accomplish, ducts in unconditioned spaces should be sealed and insulated by qualified professionals using appropriate sealing materials. For minor repairs, look for duct sections that should be joined but have separated, and then look for obvious holes. If you use duct tape to repair and seal your ducts, look for tape with the Underwriters Laboratories (UL) logo.
Note that water pipes and drains in unconditioned spaces could freeze and burst if the heat ducts are fully insulated, because there would be no heat source to prevent the space from freezing in cold weather. However, using an electric heating tape wrap on the pipes can prevent this. For cooling ducts, be sure a well-sealed vapor barrier exists on the outside of the insulation to prevent moisture buildup.
The above Energy Saver tip was provided by the U.S. Department of Energy. For more information on other ways to save energy at home, visit http://www.eren.doe.gov/energy_savers/.