Variable Air Volume System

Variable Air Volume (VAV) systems are a type of HVAC distribution system designed to efficiently regulate indoor air temperature and airflow by varying the volume of conditioned air delivered to different zones. Unlike constant volume systems that deliver a fixed amount of air, VAV systems use modulating dampers and controllers to match airflow to a zone's specific heating or cooling demand.

This chapter provides an in-depth overview of VAV system components—including VAV terminal units, actuators, sensors, and controllers—along with typical configurations such as single-duct, dual-duct, and fan-powered boxes. It also explores system benefits like energy efficiency, enhanced zone control, and compatibility with building automation systems (BAS). Practical considerations such as design strategies, sequence of operations, commissioning steps, and common troubleshooting issues are covered to support field application and maintenance.

Includes:

• Diagrams of typical VAV layouts

• Control sequence flowcharts

• Real-world VAV terminal unit photos

• Comparison to CAV systems

• Installation tips and field notes