Ceiling dampers are designed to function as a heat barrier in air handling openings penetrating fire resistive membrane ceilings. Model 556RDD has been especially designed to provide protection and simple installation in specific design wood truss ceiling assemblies.

Model 556RDD is designed for installation in the supply (or return) ductwork take-off from an AHU where it penetrates the ceiling and provides a single or multiple-outlet (up to three) plenum to feed 556RD/grille or diffuser assemblies. May also be used as a return.