Southwark Metal 17_12X8-8X8 Trunk Duct Transition 12x8 to 8x8

Product Description

The SOUTHWARK METAL 17_12X8-8X8 is a sheet metal trunk duct transition reducer used to step down rectangular duct from a 12-inch x 8-inch opening to an 8-inch x 8-inch opening. Fabricated from hot dip galvanized steel, this fitting is tapered to one side, which offsets the reduction to a single plane and simplifies alignment in tight trunk line runs. HVAC installers use this type of transition to maintain airflow continuity as a supply trunk reduces in cross-section moving away from the air handler or furnace. The galvanized construction resists corrosion in unconditioned spaces such as attics, crawlspaces, and mechanical rooms.

This transition is suited for residential and light commercial forced-air duct systems where rectangular sheet metal trunk lines require a reduction in duct size along a single offset plane. Typical applications include main supply trunk tapering in new construction and retrofit ductwork installations. The one-sided taper keeps the bottom or top of the duct flush, which is useful when working near joists, beams, or other framing constraints that limit vertical or horizontal clearance.

Key Features

• Reduces trunk duct from 12 inches x 8 inches to 8 inches x 8 inches
• Tapered to one side for flush-face alignment on a single plane
• Hot dip galvanized steel construction for corrosion resistance
• Meets ACCA and SMACNA applicable standards for sheet metal ductwork
• Compatible with standard rectangular sheet metal trunk duct systems

Compatibility

Designed as an OEM-style sheet metal fitting for rectangular trunk duct systems following ACCA and SMACNA standards. Fits standard 12-inch x 8-inch to 8-inch x 8-inch rectangular duct connections in forced-air HVAC applications.

Installation Notes

Installation is performed by licensed HVAC technicians or qualified sheet metal workers. The system should be powered down and the air handler or furnace shut off before duct modifications are made. Secure the fitting to adjoining duct sections with sheet metal screws and seal all joints with UL 181-rated mastic or foil tape per SMACNA installation guidelines. Avoid relying on duct tape alone as a sealant on metal duct systems.

Technical Specifications

• Material: Hot Dip Galvanized Steel
• Inlet Size (Size A): 12 inches x 8 inches
• Outlet Size (Size B): 8 inches x 8 inches
• Taper Type: Tapered to One Side
• Applicable Standards: ACCA, SMACNA

Standard Information

• Brand: SOUTHWARK METAL
• Manufacturer Part Number: 17_12X8-8X8