Ducts are one of the most crucial components of any heating or cooling system. They carry the heated or cooled air throughout your home. Without ducts, your furnace or air conditioning system would not do anything.
Ducts are usually insulated and sealed. The ducts connect to openings in each room, where the hot or cold air is vented. Ducts can be rectangular, oval, or round. The materials they are made from usually include plastic or fiberglass.