ACT Engineering Training Center

HVAC duct fittings are components used to connect, direct, and regulate airflow within an HVAC duct system. They help ensure efficient airflow distribution, reduce pressure drops, and accommodate changes in duct direction, size, and shape.

Common Types of HVAC Duct Fittings

1. Elbows

90-degree elbow – Changes airflow direction at a right angle.

45-degree elbow – Provides a smoother directional change, reducing resistance.

Long-radius elbow – Reduces pressure loss compared to sharp turns.

2. Reducers & Increasers

Conical reducer – Gradual transition between different duct sizes.

Tapered reducer – More compact than conical but still effective.

3. Tees & Wyes

Tee fitting – Splits airflow into two perpendicular directions.

Wye fitting – Creates a smoother branch connection with less turbulence.

4. Transitions

Rectangular to round transition – Converts duct shapes for system compatibility.

Offset transition – Adjusts the duct path while maintaining efficiency.

5. Dampers & Louvers

Volume damper – Controls airflow volume within ducts.

Backdraft damper – Prevents reverse airflow in ventilation systems.

6. Boots & Takeoffs

End boot – Connects ductwork to floor registers or grilles.

Side takeoff – Extracts air from a main duct into a branch.

7. Plenums

Supply plenum – Distributes conditioned air from the HVAC unit.

Return plenum – Collects return air for recirculation.