Cold air return ducts in ceiling or floorCold air return ducts in ceiling or floor. . . . . . be served by a below-the-floor duct system. . . easily install a true cold air duct . . . It is best to position the return high, near the ceiling, for . the location of the return air openings. 3. . . floor application. . . AsktheBuilder. Short "jump ducts" (typically located in ceilings) that allow room air . It is best to position the return high, near the ceiling, for . applications, a power cold-... more