Air Flow Products RE1816 Reducer Increaser 18 to 16

Product Description

The AIR FLOW PRODUCTS RE1816 is a duct reducer-increaser fitting designed to transition between an 18-inch and 16-inch round duct diameter. This type of fitting is a standard component in forced-air HVAC systems, used wherever the duct layout requires a step-down or step-up in duct size. It maintains airflow continuity across the transition, helping preserve static pressure balance in the distribution system. HVAC sheet metal mechanics and duct installers handle this fitting during new construction trunk-and-branch layouts or retrofit ductwork modifications.

This reducer-increaser is suited for residential and light commercial forced-air systems where an 18-inch main or branch duct must be reduced to a 16-inch section, or conversely, a 16-inch run must be opened up to 18 inches. It fits into standard round duct runs and is installed with conventional sheet metal connection methods. Typical applications include main trunk transitions, branch takeoff adjustments, and equipment connections where duct sizing changes along the air distribution path.

Key Features

• Transitions between 18-inch and 16-inch round duct diameter in a single fitting
• Supports both reducing and increasing airflow direction for flexible installation
• Sized for standard round duct systems used in residential and light commercial HVAC
• Designed for integration into forced-air distribution layouts requiring diameter changes

Compatibility

Designed as an OEM-style duct fitting for standard 18-inch to 16-inch round duct systems in residential and light commercial forced-air HVAC installations.

Installation Notes

Installation is performed by licensed HVAC technicians or qualified sheet metal mechanics. Shut down the air handling unit and ensure the system is fully de-energized before modifying any duct section. Secure the fitting with sheet metal screws and seal all joints with UL 181-rated mastic or foil tape per local mechanical code requirements. Follow applicable SMACNA ductwork standards and local building codes during installation.

Technical Specifications

• Large End Diameter: 18 inches
• Small End Diameter: 16 inches
• Fitting Type: Reducer-Increaser

Standard Information

• Brand: AIR FLOW PRODUCTS
• Manufacturer Part Number: RE1816