In a home that has central air, forced air heating or a combination of the two, you will find duct-work inside the walls that directs the air to different areas of your home. These ducts are meant to get the air from the source to the room with as little loss of energy as possible. Unfortunately, this might not always be the case. There could be leaks in your system that severely impact the cost of running your heating or cooling system.
Most leaks will occur near the unit itself. This is because of the pressure being higher, and more likely to do damage to the ductwork. This doesn’t mean, however, that if you don’t find a leak near the unit, your system is running at full efficiency. While the ducts leaking into an occupied space might not be a major issue, if there were to be a leak into a crawlspace, basement, or attic, this would not only make it so you lose energy, you will also have the unconditioned air, as well as smells and dust, being pulled into your ducts.