Fan Powered Terminal 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.In addition to inherent
VAV economies,fan terminals utilize the free heat derived from
lighting,people and other equipment and induce this warmer plenum
air from the building core ceiling plenum space and re-circulated
it to rooms calling for heating.If additional heating is required,
optional supplementary heating coil may be activated.The need for a
central source of warm air is eliminated.
Fan powered terminals are available in two basic configurations:
series or parallel flow.Each contains a fan motor assembly and a
variable air volume damper to modulate primary air.
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 airatream and runs intermittently.
Although both terminals can provide central fan HP savings,each
terminal has different inlet static pressure requirements.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