If you have a forced air HVAC system, you will also have vents going throughout your home to deliver the hot or cool air to all parts of your home. Since they might be travelling through areas of your home that aren’t temperature controlled, it is very important that they are sealed and that there are no leaks. Why is that? A leaking duct that is in your attic, for example, would be dumping out conditioned air and possibly taking in unconditioned air, along with possible smells into your ducts.
This would not only make your system less efficient, it will also increase your heating and cooling bills. The most common location for a leak is near the unit, since there is higher pressure through the ducts there, but this doesn’t mean that it can’t happen somewhere else. Sometimes, you will be able to find leaks quickly with the use of an infrared camera.