Insulated Ducts are the special type of ducts which are used for thermal efficiency his insulated duct provides excellent acoustical and thermal control with the efficient airflow performance of single-wall round duct, these ducts are available in customized sizes, The insulation in double-wall duct and fittings acts as a thermal barrier, increasing a duct system’s effective- ness by helping to maintain the temperature of heated or cooled air being ducted through the system