Rectangular concentric transition

Before you start

• Confirm the large and small duct sizes, transition length, airflow direction, pressure class, joint type, and required support.
• Inspect the transition for racking, dented corners, bowed flanges, split seams, and incorrect size.
• Field-check both duct centerlines before lifting.
• Do not use a transition to bridge a gap longer or steeper than the approved fitting.

Lay it out

1. Mark the large-end and small-end centerlines.
2. Confirm the transition is centered in both planes.
3. Locate supports on the adjoining duct bodies so the transition is not carrying either run.

Set and support it

1. Install adjacent supports before closing both joints.
2. Set the transition at the correct elevation and keep it square.
3. Support both duct runs independently.

Make the connection

1. 1

   Align and connect the large end first.

2. 2

   Square the transition body and recheck both centerlines.

3. 3

   Bring the small duct to the transition without pulling the fitting off center.

4. 4

   Complete the small-end mechanical joint.

5. 5

   Install required corners, cleats, bolts, or fasteners evenly.

6. 6

   Seal required joints and seams after the mechanical connection is complete.

7. 7

   Load the supports and verify the body remains centered.