AIR HANDLING UNIT (AHU)

An Air Handling Unit (AHU) is used to re-condition and circulate air as part of a heating, ventilating and air-conditioning system.
An Air Handling Unit (AHU) is used to re-condition and circulate air as part of a heating, ventilating and air-conditioning system.
The basic function of the AHU is take in outside air, re-condition it and supply it as fresh air to a building. All exhaust air is removed, which creates an acceptable indoor air quality. Depending on the required temperature of the re-conditioned air, the fresh air is either heated by a recovery unit or heating coil, or cooled by a cooling coil.
In buildings, where the hygienic requirements for air quality are lower, some of the air from the rooms can be re-circulated via a mixing cham-ber and this can result in significant energy savings. A mixing chamber has dampers for controlling the ratio between the return, outside and exhaust air.
The AHU is a large metal box containing separate ventilators for supply and exhaust, heating coil, cooling coil, heating/cooling recovery sys-tem, air filter racks or chambers, sound attenuators, mixing cham-ber, and dampers. AHUs connect to ductwork that distributes the condi-tioned air through the building, and returns it to the AHU.
A heat/cooling recovery exchanger is normally fitted to the AHU for energy savings and increasing capacity.