ABSTRACT
The basic VAV box is not much different than a zone damper. A typical “cooling-only” VAV box consists of a damper, an actuator, a controller, and not much else. Construction of a VAV box is more robust than that of a zone damper. This chapter deals with VAV systems, how they operate as a whole, and more specifically, how the “terminal units” operate and what they need in terms of controls requirements. The primary air damper is functionally equivalent to the zone damper. Fan powered boxes incorporate the use of a fan as part of their operation. Like zone dampers, VAV and fan powered boxes will have an onboard controller. A VAV box with reheat has the ability to provide both heating and cooling.
