Because ductwork is out of sight, it's usually out of mind and can waste energy dollars if ignored.
Because ducts carry hot and cold air throughout your home, it makes sense to insulate them to keep air as cold and hot as possible on its journey. Insulating ducts in unconditioned spaces usually saves money. If buying a new system, look at pre-insulated ducting.
Ducts can waste energy through leaks that allow air to escape before it reaches its destination. Sealing ducts is important, especially if they are located in an unconditioned area such as an attic or crawl space. Look for sections that have separated and for any holes. Because traditional duct tape loses its adhesive quality relatively quickly, experts recommend using mastic or other heat-approved tapes.
Due to the danger of carbon monoxide buildup, always have a qualified professional handle major ductwork and repairs.