Air Flow Products 840-1-RATD20-000004 Stick-on Takeoff with Damper

Product Description

The AIR FLOW PRODUCTS 840-1-RATD20-000004 is an airtight stick-on takeoff fitting designed for round duct pipe installations that require a built-in volume damper. The fitting attaches directly to the trunk line using an adhesive-backed collar, eliminating the need to cut and collar traditional sheet metal. At 4 inches in diameter with a 2-inch standoff, it provides a compact, low-profile branch connection suited for residential and light commercial forced-air duct systems. The integrated damper allows airflow balancing at the takeoff point without adding a separate damper assembly. HVAC sheet metal mechanics and duct installers are the primary trades working with this fitting.

This takeoff is used in residential and light commercial HVAC duct systems where round branch runs are tapped off a rectangular or round main trunk. The stick-on design is particularly useful in retrofit and repair scenarios where cutting into an existing trunk line is impractical or where a faster installation method is preferred. The 2-inch standoff positions the branch outlet away from the trunk surface, making flex duct or rigid pipe connection straightforward in tight plenum and attic spaces.

Key Features

• Airtight adhesive collar mounts directly to trunk line surface without cutting a traditional collar hole
• Integrated volume damper allows airflow balancing at the branch takeoff point
• 4-inch round outlet diameter for standard branch duct connections
• 2-inch standoff keeps the branch outlet clear of the trunk surface for easier duct attachment
• Designed for airtight duct construction to reduce conditioned air loss

Compatibility

Designed as an OEM-style replacement and new-installation fitting for 4-inch round branch takeoffs on rectangular or round trunk duct systems in residential and light commercial forced-air HVAC applications.

Installation Notes

Installation is typically performed by a licensed HVAC technician or sheet metal mechanic. Power down the air handling unit and confirm the system is de-energized before working inside the plenum or on active duct runs. The adhesive collar surface and trunk duct surface should be clean and dry before bonding for a reliable airtight seal. Local energy codes and ACCA Manual D duct design standards may govern takeoff placement and airflow balancing requirements.

Technical Specifications

• Outlet Diameter: 4 inches
• Standoff Height: 2 inches
• Damper: Integrated volume damper
• Mount Type: Stick-on adhesive collar
• Duct Type: Round pipe
• Seal Type: Airtight

Standard Information

• Brand: AIR FLOW PRODUCTS
• Manufacturer Part Number: 840-1-RATD20-000004