Fan coil units are generally smaller units designed to condition air within individual rooms or zones, primarily focusing on sensible heating or cooling using chilled or hot water. Air Handling units on the other hand, are larger, centralized systems that handle the air for larger portions of a building or even the entire building, providing more comprehensive air treatment including temperature and humidity control, filtration, and introduction of outside air.

Key Features of Fan Coil Units & Air Handling Units 

Mechanism:

FCU: An FCU typically consists of a fan and a heat exchanger (coil). This coil is connected to a source of chilled water for cooling or hot water for heating. The fan circulates the air in the room across the coil, transferring heat and thus conditioning the air. 
 
ACU: An AHU typically includes components like fans (supply and return), heating and cooling coils, air filters, mixing boxes (for outside and return air), dampers, and sometimes humidifiers or dehumidifiers.

Application: 

FCU: Best for hotels, offices, or apartments (small spaces). Operates at 0.5–5 tons cooling capacity. 

AHU: Used in malls, airports, or hospitals (large zones). Capacity ranges 5–50+ tons. 

Efficiency: 

FCU: Zonal control cuts energy use by 15–30% vs. AHUs in partial-load scenarios. 

AHU: Better for 100% fresh-air systems (hospitals/labs), with MERV 13–16 filters vs. FCU’s basic MERV 8. 

Cost: 

FCU: USD 500–500–2,000 per unit (plus installation: USD 1,500–1,500–5,000). 

AHU: USD 10,000–10,000–50,000+ (installation: USD 15,000–15,000–100,000).

Maintenance: 

FCU: Clean/replace filters every 3–6 months (cost: USD 20–20–50). 

AHU: Quarterly filter changes (cost: USD 100–100–300) + annual coil cleaning.

Which One Should You Choose ?

Choose Fan Coil Units If: You need per-room control, lower upfront costs (<USD $10,000), or retrofitting older buildings.

Choose Air Handling Units If: Centralized air quality, scalability (>10,000 sq. ft.), or strict ventilation codes (e.g., healthcare) matter.