Air Handling Unit

An Air Handling unit, also known as AHU, is a component used for air treatment, regulation and circulation in large HVAC systems. Some of its functions include collecting air, removing dust particles and adjusting temperature and humidity.

Some of the Air handling unit functions include collecting air, removing dust particles, and adjusting temperature and humidity.

AHUs can be used in a wide range of buildings where fresh air isn’t easily available, such as shopping malls, restaurants, offices or industrial spaces. They are used for different purposes, among them:

Air purification and cleaning through filters. They can reduce and eliminate dirt, dust, and even bacteria.
Ventilation (bringing outside air in and optionally extracting dirty indoor air out)
Indoor humidity control to create comfortable environments
Regulating/conditioning the temperature (hot or cold)

AHUs vs Indoor Units vs Fan Coil Units
The key difference between an AHU and an IDU (indoor unit) - which may also be known as a 'fan coil unit' - is that AHUs bring in air from outside whereas IDUs or FCUs can only condition air that's already in the space. Therefore AHUs may be used simply to ventilate a space without conditioning (changing the temperature), or they may combine that with conditioning functions by integrating a fan coil which could use refrigerant-based conditioning, or water-cooling pipework sometimes known as Chilled Water (CHW) - especially in the case of chiller systems. AHUs are nearly always connected to ducting in order to distribute air to the appropriate spaces in the building."