Transitions & Reducers · Transitions & Reducers
Round eccentric reducer flat on top
Maintain top clearance
ConnectionSlip/gasketed
SupportAdjacent supports
Before you start
- Confirm the flat side belongs on top and verify the reason—headroom, drainage, or equipment alignment.
- Mark TOP before lifting.
- Inspect the reducer for roundness, dents, damaged ends, and gasket condition.
- Plan supports that prevent rotation.
Tools and materials
Round eccentric reducer, approved slip or gasketed components, fasteners, sealant, marker, level, bands or saddles, and hand tools.
Lay it out
- Mark the large-end and small-end centerlines.
- Identify the intended flat side and centerline shift.
- Check that the top-flat position will remain clear through the run.
Set and support it
- Support both adjoining runs.
- Hold the reducer against rotation.
- Place support close enough to stop the fitting from rolling.
Make the connection
- 1
Seat and connect the large end.
- 2
Rotate the fitting until the marked flat side is on top.
- 3
Align the smaller duct to the shifted centerline.
- 4
Seat and mechanically fasten the small end.
- 5
Seal both joints.
- 6
Load supports and recheck the flat-side orientation.
Check the install
- The flat side remains on top.
- The reducer has no roll.
- The centerline shift matches the design.
- Both joints remain fully seated.
- No drainage or headroom problem is created.
Common mistakes
- Installing the flat side on the bottom or side.
- Failing to mark orientation on the floor.
- Letting the unsupported run rotate the fitting.
- Forcing the small run to the wrong centerline.
Stop and ask
Stop if orientation affects condensate, drainage, headroom, or equipment alignment and the approved position is not clear.