AHU (Air Handling Unit) and FCU (Fan Coil Unit) are both terminal HVAC devices used for air conditioning, but they serve different scales and functions within a building system.

1. AHU – Air Handling Unit

An AHU is a centralized air treatment system designed to condition and distribute air to multiple zones or large areas.

Main Functions

• Air filtration

• Cooling and heating

• Humidity control

• Fresh air ventilation

• Air distribution via ductwork

Key Components

• Supply and return fans

• Cooling/heating coils

• Filters (pre-filter, HEPA optional)

• Dampers

• Mixing box (fresh + return air)

Typical Applications

• Hospitals

• Airports

• Shopping malls

• Industrial facilities

• Large commercial buildings

Characteristics

• Large capacity

• Connected to duct systems

• Can handle outdoor air

• Supports precise humidity control

2. FCU – Fan Coil Unit

An FCU is a smaller, localized air-conditioning device serving a single room or zone.

Main Functions

• Cooling and/or heating

• Air recirculation

Key Components

• Small fan

• Cooling/heating coil

• Basic filter

Typical Applications

• Hotel rooms

• Apartments

• Offices

• Small commercial spaces

Characteristics

• Compact

• Usually no fresh air intake

• Zone-level temperature control

• Lower airflow capacity

Core Differences

When to Use Each

• Use AHU when you need centralized ventilation, humidity control, and large airflow capacity.

• Use FCU when you need simple zone-level temperature control without complex ventilation requirements.

Summary

An AHU is a central air processing unit serving large areas with ventilation and humidity control, while an FCU is a smaller, localized unit primarily for temperature control within individual rooms.