Southwark Metal 17_20X8-16X8 Trunk Duct Transition 20x8 to 16x8

Product Description

The SOUTHWARK METAL 17_20X8-16X8 is a sheet metal trunk duct transition reducer designed to step down a rectangular duct from 20 inches x 8 inches to 16 inches x 8 inches. Fabricated from hot dip galvanized steel, this fitting provides a tapered-to-one-side offset reduction, keeping one face of the duct flush while the taper occurs on the opposing side. This geometry is common in residential and light commercial forced-air systems where trunk duct runs must reduce in cross-section as supply air is distributed downstream. HVAC sheet metal installers and mechanical contractors use this fitting during new construction and retrofit duct fabrication work.

This transition fits into rectangular trunk duct systems sized at 20 inches x 8 inches on the inlet side, reducing to 16 inches x 8 inches on the outlet side. The tapered-to-one-side design is particularly useful in tight ceiling or floor joist cavities where a centered concentric reducer would not clear obstructions. It is appropriate for low-pressure supply or return trunk applications in residential and light commercial forced-air HVAC installations. Fabrication meets ACCA and SMACNA standards, which govern duct construction quality and dimensional consistency across the trade.

Key Features

• Reduces trunk duct from 20 inches x 8 inches to 16 inches x 8 inches in a single fitting
• Tapered to one side, keeping one duct face flush for easier installation in confined spaces
• Constructed from hot dip galvanized steel for corrosion resistance in HVAC duct environments
• Fabricated to ACCA and SMACNA standards for consistent dimensional quality
• Suited for residential and light commercial rectangular trunk duct systems

Compatibility

Designed as an OEM-style sheet metal fitting for rectangular trunk duct systems with a 20 inches x 8 inches inlet and a 16 inches x 8 inches outlet. Compatible with standard rectangular duct sections and accessories that conform to SMACNA dimensional specifications.

Installation Notes

Installation should be performed by a licensed HVAC technician or sheet metal contractor following SMACNA duct construction guidelines. Shut down the air handling unit and de-energize the system before connecting or disconnecting duct sections. Secure the fitting to adjacent duct with sheet metal screws and seal all joints with UL 181-listed foil tape or mastic to maintain system pressure integrity. Verify that the tapered side is oriented correctly within the available clearance before finalizing fasteners.

Technical Specifications

• Material: Hot Dip Galvanized Steel
• Inlet Size (Size A): 20 inches x 8 inches
• Outlet Size (Size B): 16 inches x 8 inches
• Taper Type: Tapered to One Side
• Applicable Standards: ACCA, SMACNA

Standard Information

• Brand: SOUTHWARK METAL
• Manufacturer Part Number: 17_20X8-16X8