How is airflow adjusted in a VAV system?

In a Variable Air Volume (VAV) system, airflow is primarily adjusted by modifying volume rates. This is achieved through the use of VAV boxes that regulate the amount of air delivered to a specific zone by altering the position of an air damper within the box. As the demand for heating or cooling changes in a space, the VAV system responds by adjusting the volume of conditioned air supplied to that area, rather than changing the fan speed or duct sizes.

The ability to control airflow by modifying the volume rates allows for enhanced energy efficiency and improved comfort in individual spaces, as zones can receive precise amounts of air tailored to their specific needs. This method of airflow control is more efficient than simply altering fan speeds since it does not rely on the central fan to deliver different flow rates; instead, it adjusts the airflow at the point of delivery, ensuring that each area receives appropriate ventilation without wasting energy.