Parts of a Fan Coil Unit (FCU)

Parts of a Fan Coil Unit (FCU) – Complete Breakdown

A Fan Coil Unit (FCU) consists of several key components that work together to provide heating, cooling, and ventilation. Below is a detailed breakdown of its main parts and their functions.

1. Core Components of an FCU

A. Fan (Blower)

• Function: Circulates air across the coil.
• Types:
  • Centrifugal fans (common in commercial FCUs).
  • Axial fans (used in compact units).
• Motor Types:
  • AC motors (standard).
  • ECM (Electronically Commutated Motors) (energy-efficient).

B. Coils

• Function: Heat or cool the air passing through.
• Types:
  • Chilled Water Coil (for cooling).
  • Hot Water Coil (for heating).
  • 2-Pipe vs. 4-Pipe Systems:
    • 2-Pipe: Same coil for heating/cooling (seasonal switch).
    • 4-Pipe: Separate coils for simultaneous heating & cooling.

C. Filters

• Function: Remove dust and particles from incoming air.
• Types:
  • Panel Filters (basic, washable).
  • Pleated Filters (higher efficiency).
  • HEPA Filters (for hospitals, labs).

D. Drip Pan & Drain Line

• Function: Collects and drains condensate (in cooling mode).
• Key Features:
  • Must have a slope (1–2%) for proper drainage.
  • Includes a P-trap to prevent air leakage.

E. Control System

• Function: Regulates temperature and fan speed.
• Types:
  • Manual Thermostat (basic on/off control).
  • Digital Thermostat (programmable settings).
  • BMS (Building Management System) Integration (smart controls).

2. Additional Components (Depending on Model)

A. Casing (Cabinet)

• Function: Houses all internal parts.
• Materials:
  • Galvanized steel (durable, corrosion-resistant).
  • Plastic-coated (for moisture resistance).

B. Valves

• Function: Control water flow into the coil.
• Types:
  • 2-Way Valve (on/off control).
  • 3-Way Valve (bypass option for constant flow).
  • Thermostatic Valve (auto-adjusts flow based on demand).

C. Insulation

• Function: Prevents condensation & thermal loss.
• Applied to:
  • Pipes (to avoid sweating).
  • Casing (for noise & thermal insulation).

D. Air Vent (Bleed Valve)

• Function: Removes trapped air from the water loop.
• Location: Usually at the highest point of the coil.

E. Flexible Connectors

• Function: Reduce vibration transmission from pipes.
• Used in:
  • Water connections.
  • Drain lines.

3. Optional Accessories

4. How Do These Parts Work Together?

1. Air Intake → Filter removes dust.
2. Fan Blows Air → Across chilled/hot water coil.
3. Coil Cools/Heats Air → Then distributes it into the room.
4. Condensate Forms (in cooling) → Drips into the pan & drains out.
5. Thermostat Controls → Adjusts fan speed & water flow.

5. Common FCU Part Failures & Fixes

Final Tips for FCU Maintenance

✔ Clean filters monthly (or as per manufacturer’s advice).
✔ Inspect coils annually for dust & mold.
✔ Check drain lines to prevent blockages.
✔ Listen for unusual noises (indicates motor or fan issues).