How does the duct system get dirty?
Dirt, dust and lint collect in the heating and cooling system(s) of all forced air systems. Every heating or cooling system depends on the flow of air. As this air circulates, it picks up some of the lint, dust particles, cobwebs and other kinds of dirt, which normally occur in every home or business (regardless of the furnace), and deposits it within the ductwork where it collects and builds up. Dirt, dust and debris fall into vents and make their way into the ductwork.
