Image Number 2 for United States Patent #4709623.
A low profile ceiling duct assembly to be used with rooftop air conditioners. The unit combines an octagonal sheet metal ceiling plate which provides the upper portion of a plenum chamber; this extending into the roof space above a ceiling opening. The lower plenum portion is provided by the molded plastic octagonal air distributor box, mounted against the edges of the plate and extending into the room space sufficiently to afford air flow sidewardly outward from the plenum. The air distributor box has outlet grilles at alternate sides of the octagon. They discharge air in four directions along the ceiling line while return air is drawn centrally upward.