AIR HANDLING UNIT
AHUs are encased assembly consisting of sections containing a fan or fans and other necessary equipment to perform air supply, air exhaust, filtration, heat recovery.

An Air Handler, or Air Handling Unit (often abbreviated to AHU), is a device used to condition and circulate air as part of a heating, ventilating and air-conditioning system. An air handler is usually a large insulated metal box containing a blower, heating or cooling coils, filters, sound attenuators and dampers. Air handlers usually connect to ductworks that distribute the conditioned air through the building and return it to the AHU. Sometimes AHUs discharge (supply) and admit (return) air directly to and from the space served without ductwork.