Which component is used at the exterior termination of exhaust ducts to make them weather tight?

The component designed for use at the exterior termination of exhaust ducts to ensure they are weather-tight is louvres. Louvres serve as an effective barrier against external weather elements, such as rain, snow, and wind, while allowing for the free flow of exhaust air. Their design typically features angled slats that block precipitation and debris from entering the duct system, thus preserving the integrity and efficiency of the HVAC system.

In contrast, back draft dampers are primarily utilized to prevent reverse airflow in ventilation systems rather than sealing ducts against weather conditions. Balancing dampers are used within the ductwork to control airflow and maintain the balance of the HVAC system but do not serve at the exterior terminations. Access doors are installed for maintenance and inspection purposes within the duct system and do not address the weather-tightness of the duct's exterior openings.