Southwark Metal 35_4IN Trunk Duct Reducer 4 Inches

Product Description

The SOUTHWARK METAL 35_4IN is a sheet metal trunk duct reducer designed for use in forced-air HVAC ductwork systems. It reduces the cross-section of a trunk duct run, allowing airflow to be stepped down as branch takeoffs are made along the distribution system. Constructed from hot-dipped galvanized steel, this reducer delivers corrosion resistance and structural rigidity suitable for both new construction and retrofit installations. Licensed HVAC technicians and sheet metal contractors handle this type of fitting as part of a complete duct system layout.

This trunk duct reducer is used in residential and light commercial forced-air systems where rectangular or flat-oval trunk duct transitions are required. It is suited for installations that follow ACCA Manual D duct design standards and SMACNA fabrication guidelines. The 4-inch size designation applies to the reduced end of the fitting, making it appropriate for trunk-to-trunk or trunk-to-run transitions at the tail end of a duct system or where airflow demand decreases along the main duct run.

Key Features

• Hot-dipped galvanized steel construction provides corrosion resistance for long-term duct system performance
• 4-inch reduced-end dimension for stepped trunk duct transitions
• Fabricated to ACCA and SMACNA applicable standards
• Sheet metal construction supports standard drive-and-cleat or slip-joint connections
• Compatible with standard HVAC duct system layouts in new construction and replacement work

Compatibility

Designed as an OEM-style sheet metal fitting for use in residential and light commercial forced-air HVAC trunk duct systems built to ACCA and SMACNA standards.

Installation Notes

Installation is performed by licensed HVAC technicians or qualified sheet metal contractors. Shut down the air handling unit and disconnect power before modifying any section of the duct system. Connections are typically made using drive-and-cleat or slip-joint methods and sealed with UL 181-rated mastic or foil tape per local mechanical code requirements. Follow SMACNA installation guidelines and local building codes for support spacing and joint sealing.

Technical Specifications

• Material: Hot-Dipped Galvanized Steel
• Reduced End Size: 4 inches
• Applicable Standards: ACCA, SMACNA

Standard Information

• Brand: SOUTHWARK METAL
• Manufacturer Part Number: 35_4IN