The answer to 'what does air duct sealing do' is that air duct sealing is the process of closing any gaps, cracks, or leaks in the ductwork of a home's HVAC system. This helps improve the efficiency of the HVAC system by preventing conditioned air from escaping the ducts and unconditioned air from entering, which can lead to energy waste and higher utility bills.
Air duct sealing involves inspecting the ductwork for any areas that need to be sealed, then using specialized sealants or mastic to close those gaps and leaks. This can be done on both the supply and return ducts to maximize the system's performance. Proper air duct sealing can also help improve indoor air quality by preventing the infiltration of dust, pollen, and other contaminants.