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 goes up the grille on the center bottom of the diffuser box. The concentric 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 concentric diffuser box include ceiling flush mount diffusers, drop box diffusers with grilles or drum louvers. Other options include an additional return air filter for supplemental air filtration and 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 drop box diffuser options without duct kits and for supply only, see Plenums Drop Box Diffusers.
