Air Flow Products 77122018 Transition Boot 12x20 18 Inch

Product Description

The AIR FLOW PRODUCTS 77122018 is a straight transition boot with a flange, designed to connect square or rectangular ductwork to a round collar in residential and light commercial HVAC systems. Built to the 77F configuration, it transitions from a 12-inch by 20-inch rectangular opening to an 18-inch round collar. This fitting is used where a supply or return air duct must change geometry before connecting to grilles, plenums, or flexible duct runs. HVAC technicians and sheet metal installers handle this component as part of duct fabrication and system commissioning.

The 77122018 transition boot is suited for forced-air systems where duct layout requires a square-to-round conversion at a register boot, trunk line tap, or plenum takeoff. The flanged design allows secure attachment to the duct opening or air handler cabinet, reducing air leakage at the connection point. This fitting is appropriate for both new construction duct installations and retrofit or replacement work where the existing duct geometry must be maintained.

Key Features

• 77F straight transition configuration with integral flange for secure mounting
• Square-to-round geometry: 12 inches by 20 inches rectangular to 18-inch round collar
• Flanged design helps minimize air bypass and leakage at the duct connection
• Straight profile simplifies installation in tight or linear duct runs
• Suitable for supply and return air applications in forced-air HVAC systems

Compatibility

Designed as an OEM-style duct fitting for forced-air HVAC systems requiring a square-to-round transition at a 12-inch by 20-inch rectangular duct opening with an 18-inch round collar connection.

Installation Notes

Installation is performed by licensed HVAC technicians or qualified sheet metal workers. Power down the air handling unit and close the system disconnect before beginning duct work. Secure the flange to the duct opening using sheet metal screws and seal all joints with listed duct sealant or UL 181-rated tape in accordance with local mechanical codes. Do not operate the system until all connections are fully sealed and the duct run is complete.

Technical Specifications

• Configuration: 77F Straight Transition with Flange
• Shape Transition: Square to Round
• Rectangular Opening: 12 inches x 20 inches
• Round Collar Diameter: 18 inches

Standard Information

• Brand: AIR FLOW PRODUCTS
• Manufacturer Part Number: 77122018