130mm Slim Exposed Fan Coil Unit Design Explained for HVAC Engineers

As HVAC engineers, we understand that space constraints and system compatibility are critical when selecting terminal units. The 130mm slim exposed fan coil unit provides a compact, wall-mounted solution tailored for 2-pipe hydronic systems in residential and light commercial applications. With its ultra-thin profile, quiet DC operation, and enhanced coil geometry, this unit meets both aesthetic and performance demands in modern HVAC design. In this article, we explore the key structural and functional elements that define its engineering value.

Ultra-Slim Structure with Optimized Coil Design

With a total thickness of only 130mm, the slim exposed FCU is built for space-constrained applications where ceiling ducting is not feasible. The heat exchanger consists of hydrophilic aluminum fins (0.105mm thick) and 3 rows of 7mm copper tubes, with a total coil depth of 38.51mm and a 21×12.68mm tube pitch.

Cooling Capacity (at 7°C chilled water): up to 3.36 kW (YG-30 model)

Heating Capacity (at 60°C): up to 5.65 kW

Water Flow Rate: up to 0.61 m³/h

The enlarged coil surface and efficient tube pattern improve the heat exchange efficiency significantly, allowing the unit to deliver high output in a compact body.

Technical Insights into the 130mm Slim Exposed Fan Coil Unit Design

Low Noise, High Stability Operation

The unit utilizes a low-noise cross-flow fan driven by a five-speed DC motor. The fan impeller is constructed from ABS reinforced with glass fiber and is dynamically balanced to reduce vibration and ensure stable airflow at all speeds.

Key silent designs include：

Anti-vibration rubber motor mount

Air deflector blades to reduce turbulence and dead-angle noise

Foam-insulated ducting channels inside the chassis

Concentric motor-fan shaft alignment for smooth operation

At 1200 RPM, the noise level is as low as 34 dB(A) for the smallest model and 39 dB(A) for the largest—ideal for bedrooms, guest rooms, and quiet workspaces.

Flexible Installation and Drainage Options

Despite its slim profile, the FCU allows both horizontal and vertical installation, with dual drain pans inside. The side panel is removable, enabling easy water pipe connection and reversing inlet/outlet positions if needed.

Key technical considerations:

 Water inlet/outlet connection: DN20FT (threaded)

 Electrical input: 190–250V, 50/60Hz, single-phase

 Water-side pressure drop: 10–70 kPa, based on flow rate and fan speed

The inclusion of a small auxiliary drain pan under the vent valve prevents accidental dripping, enhancing safety and installation versatility.

Conclusion

From a technical design perspective, the 130mm slim exposed fan coil unit offers a rare balance between form factor and functional depth. The increased heat exchange surface, DC-driven multi-speed fan, and concentric motor alignment reduce vibration and airflow noise, making it suitable for acoustically sensitive zones. Combined with RS485 smart control, dual installation orientation, and a modular maintenance design, this unit is more than compact—it’s engineered for the evolving demands of modern hydronic HVAC systems, especially where ceiling space is not an option.