Proper installation of flexible ducts is essential for maintaining system efficiency, ensuring compliance with building codes, and preserving the integrity of HVAC systems. ATCO’s flexible duct products are widely used in residential and commercial HVAC applications due to their energy-efficient design, durability, and compliance with industry standards. This article provides a detailed overview of ATCO Flex Duct installation procedures, best practices, and technical considerations based on the manufacturer's documentation, industry standards, and installation guidelines.
Installation Overview and Technical Specifications
ATCO flexible ducts are constructed with an airtight inner core made of polyester encapsulating a steel wire helix. This core is further wrapped in fiberglass insulation and an outer jacket, which provides thermal resistance and durability. The design ensures minimal air leakage and optimal energy efficiency in HVAC systems. These ducts are intended for indoor use and are compatible with various HVAC configurations.
The technical specifications for ATCO ducts include operating pressure and temperature limits, as well as insulation performance measured by R-values. These metrics are crucial for determining suitability in different HVAC applications. The ducts are UL Listed and must pass specific performance tests to maintain their certification. These include tension, torsion, and leakage tests to ensure structural integrity and airtightness.
Installation Best Practices
Support and Hanger Requirements
ATCO and the Air Diffusion Council emphasize that hanger or saddle material in contact with flexible ducts must be of sufficient width—no less than 1.5 inches (38 mm)—to prevent compression or restriction of the internal diameter of the duct. Local jurisdictions may have additional requirements, and compliance with these should be verified during installation.
Support straps or saddles must be placed at intervals no greater than 4 feet apart. This ensures that the duct does not sag more than ½ inch per foot between supports. Each connection between flexible and rigid duct sections should also be considered a support point. Factory-installed suspension systems are also an acceptable alternative when installed according to the manufacturer’s recommendations.
For attic or crawlspace installations, it is recommended to use saddle-shaped supports held up by poles attached to attic framing. These supports must exceed 5.5 inches in width along the duct’s length to provide adequate support and prevent sagging or distortion.
Avoiding Kinks and Sharp Bends
Kinks and sharp bends in flexible ducts can significantly reduce airflow efficiency and damage the duct material. ATCO recommends that all bends be gradual, with a radius greater than the duct’s diameter. Sharp bends should be avoided, particularly when the duct is routed across framing members or other obstructions.
During the design phase, HVAC technicians should perform a room-by-room Manual J load calculation to determine the required airflow for each space. Based on this, the duct layout should be planned to minimize bends and ensure the shortest, most direct routing. Coordination with framers, plumbers, and electricians is essential to prevent accidental compression or damage during construction.
If bends are unavoidable, especially in manufactured trusses, they should be treated as elbows in the Manual D calculation. For duct-to-boot connections, the use of metal duct elbows or plastic duct bend support products is recommended to reduce the risk of kinks. Flexible ducts should also be installed taut to prevent sagging or excessive coiling.
Cleaning and Maintenance
When cleaning ATCO flexible ducts, it is essential to use appropriate methods that do not compromise the structural integrity of the duct. Care should be taken to avoid introducing holes or tears in the polyester core, as this can weaken the material and affect its performance in tension and torsion tests. After cleaning, all connections must be resealed to maintain airtightness and thermal efficiency.
ATCO explicitly advises against using screws to fasten the polyester core of the ducts. Screws can introduce holes that compromise the material’s strength and lead to failure in UL certification tests. The duct must be able to withstand a 25-pound tension load and a 180° torsion test without damage. These tests are critical for maintaining UL Listing status and ensuring long-term performance.
Compliance with Industry Standards
ATCO flexible ducts are designed and tested in accordance with UL 181 standards for factory-made air ducts and air connectors. These standards define two categories:
- UL Listed Air Ducts—These ducts pass all tests in the UL 181 standard and are labeled with a square or rectangular label. They have no limitations on run length.
- UL Listed Air Connectors—These must pass only a limited number of UL 181 tests and are labeled with a round label that specifies a maximum installation length of 14 feet.
Compliance with these standards ensures that ATCO ducts meet industry expectations for performance, durability, and safety. The Air Conditioning Contractors of America (ACCA) also provides guidance for flexible duct installation through its Manual D recommendations. These emphasize the importance of avoiding sagging, kinks, and sharp bends, as well as following manufacturer-specific support guidelines.
Coordination with Other Trades
To ensure successful installation, coordination with other construction trades is essential. HVAC ducts should be installed in a sequence that minimizes conflict with plumbing and electrical systems. If ducts are installed first, it is important to communicate with plumbers and electricians to avoid compression or crushing of the ducts during their work.
Webbed trusses between floors can be used to allow ducts to pass freely through floor joists rather than being routed over them. This approach reduces the risk of kinks and sharp bends and helps maintain optimal airflow. Coordination during the framing stage is particularly important to plan duct routing and ensure that ducts are installed without interference from other systems.
Performance Considerations
The performance of ATCO flexible ducts is influenced by several factors, including installation quality, insulation effectiveness, and airflow resistance. Friction loss and R-values are key performance metrics that help determine the efficiency of the duct in different HVAC applications.
Friction loss is the resistance that air encounters as it moves through the duct system. It is affected by the duct’s diameter, length, and internal surface characteristics. ATCO ducts are designed to minimize friction loss, ensuring that the HVAC system operates efficiently.
R-values measure the thermal resistance of the insulation layer. Higher R-values indicate better insulation performance, which helps maintain system efficiency by reducing heat loss or gain. ATCO ducts are engineered with appropriate R-values to support energy efficiency in a variety of climate conditions.
Conclusion
ATCO flexible ducts offer a reliable and energy-efficient solution for HVAC systems when installed according to manufacturer guidelines and industry standards. Proper support, avoidance of kinks and sharp bends, and careful cleaning and maintenance are essential to ensure long-term performance and compliance with UL and ACCA standards. Coordination with other construction trades and adherence to best practices during the design and installation phases further contribute to successful outcomes. By following these guidelines, HVAC professionals can ensure that ATCO ducts perform optimally, supporting system efficiency and occupant comfort.