Variable air volume. A central air handler supplies air at about 55 degrees F, and a terminal box in each zone modulates a damper to deliver more or less air on its thermostat's call, often with a reheat coil for heating and minimum airflow for ventilation. The supply fan's speed follows a duct static pressure setpoint. VAV is the most common system type in North American mid- and large-size offices.
VAV box in 304 is stuck at minimum, the actuator's stripped, so that corner office cooks every afternoon.
When a VAV zone complains, check the box's airflow reading against its setpoint before touching the thermostat.
Also heard as
- variable air volume
- VAV system
Related terms
AHU
Air handling unit: the cabinet of fans, coils, filters and dampers that conditions and moves air through a building's ducts.
Static pressure
The pressure air exerts outward on duct walls, the resistance a fan works against, measured in inches of water column.
Damper
A blade or set of blades in a duct or opening that controls, balances or shuts off airflow.
Throw
How far a supply air jet reaches into a room before it slows to a chosen speed, such as 50 feet per minute.