Fan Powered VAV units are the most popular design for office building because they are new products based on VAV terminal unit which are set up plenum fan in the cabinet. Fan powered terminals are available in two basic configurations: series or parallel flow. In a series unit, the fan sits in the primary airstream and runs constantly when the zone is occupied. In a parallel unit, the fan sits outside the primary airstream and runs intermittently.

Series fan terminals boost both induced air and primary air, so the inlet static pressure need only overcome the loss across the damper.

Parallel fan terminals require enough static pressure to overcome the losses across the damper, the downstream ductwork and diffusers.