To winterize your home with ceiling AC vent covers, place the covers over your air conditioning vents using any of the methods listed in the ceiling vent instruction manual, such as suction. These covers prevent the warm air in your house from escaping into the chilly ductwork.
Most of the vents within a home are located in the ceiling. Even if you decide to reverse your ceiling fans to keep the warm air moving downward, some of that air escapes through the vents. You can close the small louvers on the vents, but warm air can still get through the gaps.
Attaching vent covers throughout the house provides insulation that keeps the warm air inside the house rather than in the ductwork. Vent covers are available in a wide range of sizes, so it is possible to cover all of the registers, return vents and attic fan openings to keep the warm air where it belongs.
If you own a separate delivery system for your furnace, you can benefit from having the gaps and holes in your walls and ceilings insulated. Keeping the warm air inside the house cuts down on winter heating bills and reduces the consumption of fossil fuels.