Round ducting and fittings are essential components of any modern HVAC system. Engineered to support optimal airflow and energy efficiency, these elements play a crucial role in maintaining system integrity and overall performance. Alnor delivers industry-proven, high-performance round ducting solutions, trusted across residential, commercial, and industrial applications.
What Are Round Ducts & Fittings?
Round ducts are cylindrical conduits—typically made from galvanized steel—used to transport air from central HVAC units to various delivery points. Complementary round fittings include elbows, tees, reducers, and connectors that facilitate directional changes, diameter transitions, and branching. Together, they create a consistent, sealed air distribution system that enhances indoor climate control.
Key Features and Benefits of Round Ducting
Superior airtightness – factory-mounted EPDM gaskets significantly reduce air leakage and energy losses.
Enhanced airflow performance – round geometry minimizes friction and turbulence, lowering fan energy consumption.
Fast, efficient installation – standardized sizes and push-fit joints simplify assembly and reduce labor time.
High mechanical strength – especially in spiral ducts (Spiro), ideal for demanding environments.
Architectural flexibility – clean, minimal appearance supports exposed installations in modern interiors.
Types of Round Ventilation Ducts & Fittings Available
Alnor offers a broad selection of round ductwork components, including:
Spiral ducts (Spiro) – robust, pressure-resistant ducts ideal for long runs and industrial use.
Reducers (concentric and eccentric) for diameter transitions
Couplings, end caps, and nipples for secure joining | male couplers, female couplers
Dampers (control, shut-off, and backdraft, iris dampers) for airflow regulation
Wall and roof-mounted air intakes and exhaust vents
Acoustic silencers to reduce noise
Available in galvanized steel by default, with optional versions in stainless steel or aluminum. Most components are equipped with integrated sealing gaskets.
Applications of Round Ducts & Fittings
Round ventilation systems are versatile and widely adopted across sectors:
Residential buildings – mechanical ventilation and heat recovery units (HRUs)
Commercial spaces – offices, retail, restaurants, and hotels requiring efficient HVAC systems
Public facilities – ventilation in schools, administrative buildings, and hospitals with M1 certyfication
Industrial environments – air distribution for production halls, warehouses, dust collection systems, smoke system.
Installation & Best Practices
To ensure reliable performance and system longevity:
Connection techniques – use push-fit joints, secure with screws or rivets, and seal with appropriate tape or mastic
Mounting systems – hangers, clamps, or rail suspensions should provide stable support
Maintenance advice – perform regular inspections for integrity and cleanliness, especially in high-demand environments
Technical Specifications & Compliance
Material quality – DX51D galvanized steel with Z275 zinc coating for corrosion resistance
Diameter options – available in a comprehensive range of nominal sizes
Standard lengths – optimized for modular installation
Compliance – meets PN-EN 1506 (dimensions) and PN-EN 12237 (mechanical strength and airtightness)
Sealing performance – Class D airtightness achievable with gasket system
Certifications – verified by ITB, TÜV, RISE (SITAC); includes hygiene approvals (PZH) and Declarations of Performance (DoP), M1 cleanliness classification.
By choosing Alnor's round ducting solutions, you ensure lasting efficiency, regulatory compliance, and adaptability across diverse HVAC installations. Contact our experts today for tailored advice or to request a quote.
