Central-ducted evaporative coolers install outdoors and connect to ductwork to deliver cooled air throughout a building. They're typically placed on the ground outside a building or mounted to the roof. These swamp coolers pull in warm surrounding air, pass it through wet media (evaporative pads) to remove heat, and blow the cooled air into the attached duct. At the end of the cooling season, these coolers can be drained and their media can be dried out for long-term storage.