Home Winterization. During the winter heating season, homeowners with uncovered central air conditioning vents and ceiling vent drafts spend more than $200 in unnecessary heating costs that could be saved with Draft Shields central AC vent covers. Our product is designed to prevent heat loss, conserve energy, and save money by covering central air-conditioning vents, and preventing icy drafts from entering your room through open vents. Closing the louvers in your grilles will not stop airflow and associated heat loss because it is not a total seal. Draft Shields central air vent covers are available for all standard-sized central air conditioning vents, and can be mounted on walls or ceilings in seconds without any tools. They can also be used to cover the return air grill (item # 4740-CA2424). Home Winterization Saves Money Hot air produced by heating systems in fall/winter lose thermal values of 30% or more through the central air duct system. Heated air rises, and is drawn through unsealed central air conditioning vents into ductwork in the cold attic. The air is re-introduced as icy drafts through lower vents. A 15 to 20 degree difference often exists between upper heated room air and lower register re-cycled cold air, emitted from lower air ducts. Draft Shields central air vent covers will block cold drafts; prevent moisture from entering your AC system; inhibit the growth of mold and mildew; and keep your home comfortably warm. Using Draft Shields central air vent covers to insulate against heat loss will result in hundreds of $$$ in energy savings each year.