The Luxair 100mm round to flat rectangular horizontal ducting adaptor
...converts a 100mm (4") round ducting outlet to a 220mm x 90mm flat rectangular duct, running horizontally — the transition piece used when your cooker hood has a round outlet but your ducting run needs to travel along the top of kitchen wall cabinets in a flat profile. Self-sealing push fit on both the round and flat ends, and the slim 220mm x 90mm flat profile fits neatly into the space between the top of a standard wall cabinet and the ceiling.
Why You Need a Round to Flat Adaptor
Most cooker hoods — wall-mounted, canopy, and telescopic models — have a round outlet, typically 100mm, 120mm, 125mm, or 150mm in diameter. But in many kitchens, the most practical route for the ducting run is along the top of the wall cabinets, across the ceiling void, or through a narrow space where round pipe simply won't fit cleanly. Flat rectangular ducting sits flush against the cabinet top, takes up far less visual space, and routes cleanly through tight gaps that round pipe can't navigate. This adaptor is the transition piece that makes that change possible — from round outlet to flat run — in a single fitting.
Horizontal Orientation — What That Means for Installation
This connector is specifically designed for a horizontal transition — where the flat duct exits the adaptor running parallel to the ceiling or cabinet top, travelling left or right away from the hood. If your ducting needs to transition from round to flat in a vertical direction — travelling upward through a cabinet or ceiling void — Luxair also stocks the 100mm round to flat vertical 90° elbow, which makes the same transition but with the flat duct exiting upward. Check which orientation your installation requires before ordering.
Dimensions — Round and Flat Ends
Round inlet: 100mm (4") diameter — fits directly onto 100mm round rigid ducting pipe or 100mm hood outlet collars. Flat outlet: 220mm x 90mm — the UK standard flat rectangular duct size used across Luxair's full flat ducting range. Both ends are push fit and self-sealing against their matching pipes and fittings. No ducting tape required at rigid-to-rigid connections.
Part of Luxair's Complete 100mm Ducting System
This adaptor connects seamlessly to Luxair's full range of 100mm round components on one side and the 220mm x 90mm flat ducting range on the other — including flat duct lengths, flat 90° horizontal elbows, flat 90° vertical elbows, flat inline connector collars, and flat ducting clips.
All the other components needed to complete your ducting run are available as related products at the bottom of this page — add everything to your basket in one visit without having to search for each part separately.
Is 100mm the Right Size for Your Hood?
100mm (4") ducting is correct for cooker hood motors rated below 450 m³/hr. For higher-rated motors, use larger ducting to maintain full extraction efficiency:
- Below 450 m³/hr → 100mm (4") ducting
- 450–750 m³/hr → 125mm (5") or 150mm (6") ducting
- 750–2000 m³/hr → 150mm (6") or 200mm (8") ducting
Luxair stocks round to flat adaptors in multiple sizes — all available in the ducting section.
