Lambro Industries bd04 Back Draft Damper 4 Inches

Product Description

The LAMBRO INDUSTRIES bd04 is a 4-inch back draft damper constructed from white plastic, designed to prevent reverse airflow in residential and light-commercial ventilation systems. The damper installs at the termination point or inline within a duct run to allow conditioned or exhaust air to flow in one direction while blocking outside air from entering when the system is idle. It is typically installed by HVAC technicians or sheet metal contractors as part of bathroom exhaust, dryer vent, kitchen hood, or range duct systems. The 4-inch opening width suits standard round duct sizes common in residential ventilation.

This damper is suited for residential ventilation applications where a gravity-operated or pressure-differential damper is required to stop cold air infiltration, pest entry, and backdrafting through exhaust ductwork. Typical install scenarios include bathroom exhaust fan terminations, range hood duct connections, and dryer exhaust outlets. The white plastic construction resists corrosion and works well in low-moisture exhaust environments where metal dampers may be unnecessary.

Key Features

• 4-inch opening width fits standard residential round duct
• White plastic construction resists corrosion in exhaust duct environments
• Prevents reverse airflow and cold air infiltration when system is off
• Lightweight design simplifies handling and positioning during installation
• Suitable for bathroom exhaust, dryer vent, and range hood duct terminations

Compatibility

Designed as an OEM-style replacement or new-installation back draft damper for 4-inch residential exhaust duct systems including bathroom fans, dryer vents, and kitchen hood exhaust runs.

Installation Notes

Back draft dampers of this type are installed by HVAC technicians or contractors following local mechanical codes and manufacturer duct-installation guidelines. Power down the exhaust fan or appliance before accessing the duct connection. Verify airflow direction before securing the damper to ensure the flap opens with system airflow and closes freely by gravity or pressure differential when the system shuts off. Do not restrict the damper flap with excess sealant or fasteners.

Technical Specifications

• Opening Width: 4 inches
• Material: Plastic
• Color: White
• Country of Origin: China

Standard Information

• Brand: LAMBRO INDUSTRIES
• Manufacturer Part Number: bd04