Air Terminal Accessories

Frequently asked questions

What is an air terminal device?

The part of a ventilation system where the air enters or leaves a room: a grille, diffuser, air valve or louvre. The accessories here sit behind or around the terminal to connect it to the duct and control the airflow.

What does a plenum box do?

It connects a round duct to a square grille or diffuser and spreads the air evenly across the grille face, which improves airflow and cuts noise. See our plenum boxes.

What is an opposed blade damper for?

It sits behind a grille or diffuser and lets you trim the airflow at that terminal during commissioning, so each room on a shared duct system gets its design airflow without changing the fan.

Do I need a roof cowl?

Where a duct terminates through the roof, a cowl keeps out rain and birds and helps the air disperse. See our roof and vent cowls.