Back Draft Damper

Function: A backdraft damper’s main job is to let air flow in one direction while blocking it from going in the other. They guarantee that air enters the space through the ducting system in the right direction, avoiding drafts, leaks, and backflow of air.

Operation: Usually, backdraft dampers have one-way flaps or blades that open to let airflow flow in the desired direction and close to prevent it from going in the other. In order to prevent backflow, the flaps or blades automatically close when the airflow reverses, which can happen during shutdown or when the ventilation system is not in operation.

Design: There are several different designs of backdraft dampers, such as blade-style dampers, gravity-operated dampers, and spring-loaded dampers. While gravity-operated dampers rely on gravity to seal the damper when airflow reverses, blade-style dampers have several blades or louvres that swivel on a central axis. When the direction of airflow changes, spring-loaded dampers use springs to automatically close the damper.

Construction: To endure the rigours of HVAC operation, backdraft dampers are usually made of sturdy materials like stainless steel, aluminium, or galvanised steel. Mounted inside a frame or housing, the blades or louvres may have gaskets or seals to guarantee an airtight closure.

Installation: Backdraft dampers are put in place inside ductwork at potential airflow reversal points, like supply air outlets, exhaust vents, and external air intakes. To guarantee that the damper functions properly and does not obstruct airflow when closed, proper installation is crucial.


Control: Based on the demands and particular application, backdraft dampers can be operated electrically, pneumatically, or manually. While pneumatic and electronic dampers can be remotely controlled via a control system or building automation system, manual dampers are normally changed by hand.

Code Compliance: In order to guarantee the safe operation of HVAC systems, backdraft dampers are frequently mandated by building codes and regulations. To guarantee that backdraft dampers are installed and maintained properly, adherence to pertinent codes and standards, such as the International Mechanical Code (IMC) or the International Residential Code (IRC), is necessary.