Systemair 411115 Round Backdraft Damper 8 Inch Duct

Product DescriptionThe SYSTEMAIR 411115 is a round backdraft damper designed for circular duct applications in residential and commercial ventilation systems. Built from 24-gauge G90 galvanized steel, the damper features two spring-loaded H14 aluminum blades that open under positive airflow and close automatically to prevent reverse airflow. The casing measures 8 inches in diameter by 3.5 inches in length. An EPDM synthetic rubber gasket seals the blade edges, and a stainless steel torsion spring provides consistent closing force. HVAC technicians and sheet metal contractors install this damper as part of supply, exhaust, or makeup-air duct assemblies.The 411115 is suited for circular duct systems in both residential and light commercial installations. It fits into 8-inch round duct runs and can be mounted vertically or horizontally, making it adaptable to a range of duct layouts. Typical applications include exhaust fan discharge points, inline duct runs, and air-handling branch takeoffs where backflow prevention is required. The galvanized steel construction holds up in unconditioned spaces such as attics, crawlspaces, and mechanical rooms.Key FeaturesTwo spring-loaded H14 aluminum blades open with positive airflow and close automatically to block backdraftG90 galvanized steel casing resists corrosion in unconditioned or humid environments24-gauge sheet metal construction provides rigid, durable housingStainless steel torsion spring delivers reliable, consistent blade return forceEPDM synthetic rubber gasket reduces air leakage at blade seatVertical mounting capability expands installation flexibilityCompatibilityDesigned as an OEM-style replacement or new-installation backdraft damper for 8-inch round circular duct systems in residential and light commercial HVAC ventilation applications.Installation NotesInstallation is typically performed by a licensed HVAC technician or sheet metal contractor. Shut down the air-handling unit or exhaust fan and de-energize associated electrical circuits before working in the duct system. Secure the damper to the duct using sheet metal screws or approved duct tape rated for the application, and verify blade orientation relative to intended airflow direction before final connection. Follow local mechanical codes and SMACNA duct construction standards for proper support and sealing of the duct joint.Technical SpecificationsDuct Diameter: 8 inchesDamper Length: 3.5 inchesCasing Material: G90 Galvanized SteelCasing Gauge: 24 gaugeBlade Material: H14 AluminumSpring Material: Stainless Steel Torsion SpringGasket Material: EPDM Synthetic RubberDamper Type: BackdraftDuct Shape: Round (Circular)Series: RSKStandard InformationBrand: SYSTEMAIRManufacturer Part Number: 411115