Air Flow Products RE043 Reducer Increaser 4 to 3 Inch

Product Description

The AIR FLOW PRODUCTS RE043 is a duct reducer-increaser fitting designed to transition between 4-inch and 3-inch round duct sections in forced-air ventilation and HVAC distribution systems. This type of fitting is used wherever airflow must be stepped down or stepped up between differing duct diameters, maintaining system balance and minimizing turbulence at the transition point. HVAC installers and sheet metal mechanics use fittings like this during new construction, retrofit, and duct modification work to connect branches of different sizes without fabricating custom transitions on site.

The RE043 is suited for residential and light commercial forced-air duct systems where a 4-inch to 3-inch transition is required. Common install scenarios include connecting supply trunk lines to smaller branch runs, adapting register boots to existing ductwork, or modifying duct layouts during renovation work. This fitting is appropriate for standard round duct systems using sheet metal or flexible duct connections.

Key Features

• Transitions between 4-inch and 3-inch round duct diameters
• Designed for use in forced-air HVAC distribution and ventilation systems
• Eliminates the need for custom on-site fabrication at transition points
• Compact form factor suited to tight mechanical spaces

Compatibility

Designed as an OEM-style replacement and standard fitting for residential and light commercial round duct systems requiring a 4-inch to 3-inch diameter transition.

Installation Notes

Installation should be performed by a licensed HVAC technician or qualified sheet metal mechanic. Shut down the air handling unit and confirm the system is de-energized before beginning any duct modification. Secure the fitting using sheet metal screws and seal all joints with UL-listed duct tape or mastic sealant per local mechanical code requirements. Verify airflow direction and duct layout before finalizing the connection.

Technical Specifications

• Inlet Diameter: 4 inches
• Outlet Diameter: 3 inches
• Fitting Type: Reducer-Increaser

Standard Information

• Brand: AIR FLOW PRODUCTS
• Manufacturer Part Number: RE043