System Principle of OperationA variable Air Volume, the by-pass system consists of VAV units connected to the supply air duct of a constant air volume source. A constant volume of conditioned air is supplied to each VAV unit. The primary damper modulates in response to a zone thermostat demand, to vary the amount of conditions air delivered to the occupied zone.
Damper operation On / Off or Modulating will range from full shut-off to fully open by supplying variable air volume, or to a minimum air volume to the conditioned zone. As the primary damper modulates in response to room thermostat, demand and once it is satisfied to reduce the air volume to the occupied zone, the excess air is diverted through the by-pass secondary damper into the ceiling plenum for free or ducted return.