Eccentric Duct Adapter 125mm

A robust, high-flow duct adapter designed to transition a standard 125 mm round bathroom exhaust duct into a low-profile 220 × 90 mm rectangular flat channel. The design features a pronounced vertical offset to navigate tight ceiling or wall spaces without compromising airflow.

What it's for

This part connects two dissimilar ducting systems. It is strictly female-to-female, intended to slip over an existing 125 mm round male pipe on one end and accept a 220 × 90 mm flat duct on the other. The 72.5 mm vertical offset is specifically tailored to align the flat duct closely to a wall or ceiling plane while maintaining the round pipe's original centerline.

Dimensions

• Round Socket: 126.5 mm inner diameter, 30 mm deep (includes a 1.5 mm entry chamfer for easier fitting).
• Flat Socket: 222 × 92 mm internal dimensions with 5 mm corner radii, 30 mm deep.
• Overall Dimensions: 220 mm total length, maintaining a continuous 2.4 mm wall thickness.
• Offset: Centerline shifts vertically by exactly 72.5 mm over a smooth 160 mm internal transition.

Print notes

Print this model standing upright on the round flat face. No supports should be necessary for the interior loft, as the transition angle is steady and fully convex. PETG or ABS is highly recommended over PLA for HVAC applications, as the exhaust air and environmental moisture can deform standard PLA over time. Ensure your slicing profile is set to completely fill the 2.4 mm walls (usually 3 perimeters depending on nozzle size) to keep the assembly watertight and structurally sound.