Southwark Metal fb_21-1/2x28-1/2 Return Air Furnace Box

Product Description

The SOUTHWARK METAL fb_21-1/2x28-1/2 is a return air sheet metal furnace box fabricated from 26-gauge hot dip galvanized steel. It measures 21.5 inches by 28.5 inches by 18.5 inches and is built to serve as the return air plenum box in residential and light commercial forced-air heating systems. The hot dip galvanization process provides corrosion resistance suited to HVAC duct environments. This type of component is typically installed by licensed HVAC technicians or sheet metal contractors as part of a furnace duct system assembly.

This furnace box is intended for return air applications in residential and light commercial HVAC installations. It is sized to fit standard furnace openings requiring a 21.5-inch by 28.5-inch face dimension with an 18.5-inch depth. The unit meets applicable industry standards set by ACCA and SMACNA, making it appropriate for installations where code-compliant duct construction is required. It is suited for new construction and replacement duct work in forced-air gas or electric furnace systems.

Key Features

• 26-gauge hot dip galvanized steel construction for durability and corrosion resistance
• Return air configuration for use as a furnace plenum or duct box
• Dimensions of 21.5 inches by 28.5 inches by 18.5 inches for standard furnace fitment
• Compliant with ACCA and SMACNA standards for sheet metal duct construction
• Applicable for both residential and light commercial HVAC systems

Compatibility

Designed as an OEM-style sheet metal return air furnace box for residential and light commercial forced-air HVAC systems requiring a 21.5-inch by 28.5-inch by 18.5-inch return air plenum box built to ACCA and SMACNA standards.

Installation Notes

Installation should be performed by a licensed HVAC technician or qualified sheet metal contractor in accordance with SMACNA duct construction standards and local mechanical codes. Shut down and lock out the furnace and air handler before beginning any duct work. Seal all seams with code-approved duct sealant or mastic to meet ACCA Manual D airflow requirements. Do not use this box in supply air applications; it is rated for return air service only.

Technical Specifications

• Dimensions: 21.5 inches x 28.5 inches x 18.5 inches
• Material: Hot Dip Galvanized Steel
• Gauge: 26
• Box Type: Return Air
• Applicable Standards: ACCA, SMACNA, NATE
• Application: HVAC, Residential and Light Commercial

Standard Information

• Brand: SOUTHWARK METAL
• Manufacturer Part Number: fb_21-1/2x28-1/2