Lambro Industries 235 Plastic Vent Adapter 4 to 3 Inch

Product Description

The LAMBRO INDUSTRIES 235 is a plastic vent adapter designed to transition between 4-inch and 3-inch duct diameters. It installs in residential and light commercial ventilation systems where a size change is needed along the duct run. The adapter works in both directions, fitting 4-inch to 3-inch or 3-inch to 4-inch configurations depending on installation orientation. HVAC technicians and installers use this part during new construction and retrofit work when connecting exhaust or supply duct sections of differing diameters. Plastic construction keeps the part lightweight and resistant to moisture in typical indoor ventilation environments.

This adapter is used in dryer exhaust venting, bathroom exhaust fans, range hood ducting, and general HVAC supply and return runs that require a diameter transition. It is suited for residential installations where duct routing requires a step-down or step-up between 4-inch and 3-inch round duct sections. The bidirectional design reduces the need to stock separate reducers and increasers for common 4-inch and 3-inch duct pairings.

Key Features

• Transitions between 4-inch and 3-inch round duct diameters in either direction
• Plastic construction resists moisture and corrosion in ventilation applications
• Lightweight design simplifies handling and installation in tight spaces
• Sold individually per unit of measure

Compatibility

Designed as an OEM-style replacement or new-installation fitting for residential and light commercial ventilation duct systems using 4-inch and 3-inch round duct connections.

Installation Notes

Installation is typically performed by a licensed HVAC technician or qualified installer. Power down any connected fan or air handler before working on the duct run. Secure the adapter to duct sections using appropriate metal foil tape or approved mechanical fasteners per local mechanical code requirements. Do not use standard cloth-backed duct tape on exhaust applications.

Technical Specifications

• Inlet Diameter: 4 inches
• Outlet Diameter: 3 inches
• Material: Plastic
• Weight: 1.08 pounds
• Unit of Measure: Each
• Package Quantity: 12

Standard Information

• Brand: LAMBRO INDUSTRIES
• Manufacturer Part Number: 235