Drop Box Concentric Diffusers are used with Roof Top Mounted HVAC equipment allowing the supply air to travel down into the building through a duct directly connected to the roof curb supply air opening. The supply air is distributed horizontally into the space to be cooled while the return air is ducted through a separate return duct, not connected to the drop box diffuser. The drop box diffusers are not specific to a particular HVAC Unit and can be connected with field fabricated rectangular duct or flexible duct. The options for air distribution on the drop box diffuser include grilles or drum louvers. Other options include manually adjustable dampers on each grille or drum louver to control supply air flow in the different directions.
For concentric diffuser options with duct kits, see Plenums Concentric Duct Kits. For concentric diffuser options without duct kits, see Plenums Concentric Diffusers.
