Air handling unit

The air handling unit is an integrated piece of equipment consisting of fans, heating and cooling coils, air-control dampers, filters and silencers. Air Handling Units are often called AHU.The purpose of this equipment is to collect and mix outdoor air with that returning from the building space. The air mixture is then cooled or heated, after which it is discharged into the building space through a duct system made up of five-feet diameter pipes.
Air Handler is normally associated with heating/cooling (HVAC) systems in commercial buildings. These are normally very large systems moving 2000 CFM to 10,000 CFM and higher. They may be mounted on the top of the roof or in large mechanical rooms located in the building. They often have an economizer or inlet damper that allows for a small amount of outside air or make-up air to be pulled in through the air handler.