What distinguishes a register from a grille in HVAC systems?

A register is distinguished from a grille primarily by the presence of an air volume control device, such as a damper, which allows for the adjustment of airflow. This feature allows users to control the amount of air delivered to a specific space, making registers suitable for heating and cooling applications where precise airflow regulation is necessary. Registers typically have a more complex design, enabling greater control over indoor air distribution.

Grilles, on the other hand, are generally simpler and do not include adjustable features for airflow. They are mainly designed to allow air to pass into or out of a space without the ability to control the volume. This makes registers crucial in maintaining comfort levels in HVAC systems, as they can be adjusted based on heating or cooling demands in different areas of a building.