The primary difference between an AHU (Air Handling Unit) and an FCU (Fan Coil Unit) lies in their function, size, and application.
AHU: An Air Handling Unit is larger and typically serves as the central air processing unit in a commercial or industrial HVAC system. It handles air filtration, conditioning, and distribution for a large area. AHUs can provide both heating and cooling, and they distribute air through ducts to different spaces.
FCU: A Fan Coil Unit is smaller, often used in individual rooms or areas. It consists of a fan and a coil that either heats or cools the air that is drawn from the room. Unlike the AHU, FCUs are typically more localized and do not involve complex air filtration or large-scale air distribution.