0

Shipped within 1 day

Duct flanges for ventilation

Connect flexible ducting or a ventilation duct with a flange that fits. Choose Fertraso duct flanges, plastic flanges or Opticlimate Flowflens models. Check the connection diameter and mounting surface; we can help you select the right size, fit and fastening.

19 products

Shop plastic duct flanges

Which duct flange fits your connection?

Start with the spigot diameter, rather than the outside size of the mounting plate. Fertraso duct flanges have stated diameters of 127, 160, 200, 250, 315, 356, 406 and 450 mm. Plastic versions are available in 127, 160, 200, 250, 315, 356 and 406 mm.

Measure the inside diameter of the duct and the outside diameter of the connection. Check the plate, fixing points and available space as well. 125 and 127 mm are different sizes, as are 355 and 356 mm. A duct clamp secures a suitable fit; it does not correct an incompatible connection.

Joining different diameters? Browse our ventilation duct reducers. To join two sections in a straight line without a mounting plate, choose a suitable duct connector. Our guide to duct diameter and fit helps you check each connection before ordering.

Fertraso ventilation duct flanges, black plastic flanges and a blue Opticlimate Flowflens
  • Fertraso
  • Opticlimate

Choosing a Fertraso flange or plastic flange

A flange provides a round duct connection on a mounting surface, such as a suitable panel or appliance. Choose the required shape and fixing method first, then compare diameter and material. Browse plastic duct flanges for the plastic versions.

The nominal connection size does not specify the plate diameter, hole pattern or temperature rating. Check these details for your application before drilling or installing. A product photograph cannot confirm the fit; ask us to check the dimensions if the connection is unclear.

Opticlimate Flowflens: check the full size code

Opticlimate Flowflens is a separate range, with 250-250, 350-315, 355-355 and 355-250 versions in this shop. Check the full size code, the appliance connection and the other side of the joint separately. Do not replace a Flowflens with another flange based on a single diameter.

Keep the duct size consistent with the requirements of your installation. A smaller opening can increase resistance. Browse Opticlimate and its accessories and send us the appliance model and photographs of the connection if you need help checking the correct version.

Installing the flange and connecting flexible ducting

Check that the mounting surface and fasteners suit the flange. Secure the flange without distorting the plate. Slide suitable flexible ducting straight over the spigot, then choose a duct clamp with the right adjustment range for the assembled connection.

Use suitable sealing material and support the duct so its weight does not pull on the flange. Check for leaks, loose parts and kinks after installation. Read our full guide to connecting ducting to a flange with a clamp and seal.

Advice on flanges and duct connections

All duct fitting guides

Complete your ventilation connection

Frequently asked questions about duct flanges

Need help choosing a duct flange?

Send us the connection sizes, appliance model and a photograph of the mounting surface. We can help you choose a suitable flange, duct and fastening.

  • Inside duct diameter and outside connection diameter

  • Mounting surface dimensions and fixing points

  • Appliance model and photos of both connection sides

Contact us