What IS PU Pre Insulated Ductwork? Let Project Case Explain

1. PU Pre Insulated Ductwork and Engineering Case

1.1 Introduction to PU Pre Insulated Ductwork Panels

GFI Duct’s PU Pre Insulated Ductwork panels are high-performance composite insulation materials, manufactured with a rigid closed-cell PU foam core and double-sided aluminum foil facing. This advanced Ducting Foam structure offers exceptional thermal insulation, airtightness, and lightweight strength, widely used in HVAC duct construction.

1.2 Project Case: WF International Mall

The WF International Mall is a steel frame with shear wall structure. The construction site area is 3,684 m², with a total building area of 38,000 m²—12,000 m² underground and 26,000 m² above ground. The building consists of 4 underground and 9 above-ground levels, with a maximum eave height of 37 meters. While traditional galvanized sheet metal ducts were used for underground parking ventilation, the above-ground mall ducting system uses double-sided aluminum foil PU Foam Ducting, covering over 13,200 m³ of ducting space.

2. Advantages of PU Foam Ducting in Steel Structure Buildings

WF International Mall adopts a steel core-tube structure. During HVAC duct construction, the ducting system required installation beneath and through steel beams. PU Foam Ducting proved ideal due to its material properties:

1. Smooth, flat surfaces facilitate easy threading through narrow prefabricated beam spaces.
2. Lightweight structure is suitable for installation in steel-framed buildings.
3. Fast production and installation reduce project timelines significantly.
4. Superior mechanical strength and performance thanks to specialized manufacturing and flange connection methods.
5. Extremely low air leakage and thermal conductivity.
6. Hygienic, easy to clean, and made with eco-friendly materials free from formaldehyde emissions.

3. Fabrication and Installation of PU Pre Insulated Ductwork

3.1 Technical Specifications of PU Pre Insulated Panels

The aluminum surface is non-combustible, while the PU foam insulation core achieves B1 flame-retardant classification. All connecting elements (flanges, reinforcements) are of equal or higher fire performance. Adhesives, aluminum tapes, and sealants are material-compatible and environmentally compliant.

3.2 Installation Steps

1. Duct-to-duct connections: Use special flange inserts. After inserting H-shaped connectors, seal all four corner openings with silicone sealant and install the cover angle.
2. Duct-to-valve/equipment connections: Use high-strength H-profile connectors made from PVC or aluminum alloy. Apply flexible sealing gaskets and align connectors tightly with no distortion. Bolt spacing should not exceed 100 mm; all four corners must be bolted.
3. Duct-to-diffuser connections: Use adhesive-mounted H-connectors or self-tapping screws to secure F or h-type joints.
4. Branch duct connections: On large side branches, open a cut on the main duct and bond the branch directly or use a UPVC connector. Seal joints internally with silicone and externally with aluminum tape. Ensure cut edges are curved or sloped to reduce airflow resistance.
5. Sealing for medium/high-pressure systems: Use additional gaskets or other sealing techniques between flanges.

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4. Technical Advantages of PU Foam Ducting

4.1 Air Leakage Comparison

1. PU Pre Insulated Ductwork utilizes specialized flanges and H-connectors across the entire duct interface, minimizing leakage points. Traditional sheet metal ducts use flanged bolts, prone to localized leaks.
2. Longitudinal joints are sealed with professional-grade adhesive, while transverse joints rely on tight mechanical and adhesive connections. This ensures optimal airtightness and energy efficiency.

4.2 Weight Comparison vs Traditional Ducting

Additional weight-related advantages:

1. Large duct systems using PU Foam Ducting weigh only 1/4 to 1/8 of galvanized steel ducts, reducing structural load.
2. PU ducts require fewer hangers (every 3–4 meters vs. every 2 meters for steel ducts), saving labor and cost, and enabling more refined and aesthetic installations.
3. Lightweight and easy installation greatly reduce the risk of workplace accidents, increasing on-site safety.

PU Foam Ducting also combines duct fabrication and insulation into one process, increasing installation speed by 4–5 times. Ceiling mounting saves indoor space and reduces overall building costs.

4.3 Aesthetic and Functional Benefits

1. Highly regular geometry and sharp edges allow for open-ceiling designs without compromising appearance.
2. Washable inside and out, preventing microbial growth. No fiber shedding, ensuring hygiene for cleanroom and food-grade environments.
3. Non-toxic, non-polluting surfaces resist dust buildup—ideal for clean air zones like electronics plants, hospitals, and cold-chain facilities.
4. Closed-cell foam effectively resists moisture penetration, keeping internal surfaces dry and extending HVAC system service life.

5. Conclusion

1. PU Pre Insulated ducts panels are lightweight and provide superior thermal insulation. The integrated design reduces structural load and speeds up installation, leading to shorter construction periods.
2. The system’s airtight joint design minimizes thermal loss during operation and supports easy cleaning and maintenance, reducing operational costs.
3. Compared with traditional galvanized steel ducts, PU Foam Ducting not only simplifies fabrication and installation but also delivers outstanding energy efficiency and environmental benefits, aligning with global energy conservation regulations.

Looking for high-performance ducting solutions?

GFI Duct specializes in manufacturing advanced PU Pre Insulated Ductwork systems that meet modern HVAC demands for energy efficiency, lightweight installation, and long-term reliability. Trusted by engineers and contractors across commercial and industrial projects, our duct panels are engineered for excellence and supported by expert service.
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