Ducting Accessories

Ducting accessories — the fixings, clamps, sealants, and access components you need to complete and maintain a ventilation duct installation. We stock jubilee hose clips in every standard size from 100mm to 203mm, Systemair FK fast clamps and FSAF matching flanges for spiral ductwork, plenum back boxes for ceiling supply and extract terminals, duct access doors for inspection points, QRL quick release locks, and intumescent fire sealant for fire-rated penetrations. Everything you need alongside the ducting and fittings — next-day delivery on all items.

Access Doors / Hose Clips / Tape & Sealant / Ducting Fittings

What size jubilee clip do I need for my ducting?

Match the jubilee clip to the duct's external diameter, not its nominal bore size — the clip needs to fit around the outside of the joint. For standard Domus rigid PVC: use a 100mm clip for 100mm duct, 125mm for 125mm duct, and 150mm for 150mm duct. For flexible ducting, the outside diameter is typically 10–15mm larger than the nominal size because of the corrugated wall thickness, so go one size up — a 125mm clip for 100mm flex, or 150mm for 125mm flex. Jubilee clips are essential wherever flexible duct connects to a rigid spigot, fan, or grille — the push-fit alone won't hold flex securely.

When do I need a duct access door?

Any duct run that will need inspection, cleaning, or filter access over its lifetime should have an access door fitted at the relevant point. Building Regulations and good practice require access for cleaning in kitchen extract ducting (particularly commercial), and it's strongly recommended near filters, fire dampers, and any component that needs periodic servicing. Access doors are available in square tabbed versions for rectangular and spiral ductwork. Fit them in an accessible location — there's no point having an access door above a fixed ceiling with no access panel above it.

What is a plenum back box and where is it used?

A plenum back box — sometimes called a plenum chamber or distribution box — connects a round duct to a square or rectangular ceiling grille or diffuser. It sits above the ceiling tile or plasterboard, with the round duct spigot on top and the open face fitting flush to the ceiling. Plenum boxes are standard in MVHR supply and extract installations where each room has a ceiling terminal connected back to the main unit. They're also used in commercial ventilation wherever a round duct needs to transition to a square ceiling grille.

What are Systemair FK fast clamps for?

FK fast clamps are a quick-connect system for joining circular spiral ductwork sections. Instead of using screws and mastic, you slide the clamp over the joint and lock it — creating a secure, airtight connection in seconds. They're the standard fixing method for commercial spiral duct installations. Each clamp matches a specific duct diameter — make sure you order the right size for your spiral duct. Fast clamps work with Systemair spiral duct and most standard gauge spiral ductwork from other manufacturers.

Do I need intumescent sealant for my duct installation?

Yes, if the ductwork passes through a fire-rated wall, floor, or partition. Building Regulations require that any penetration through a fire compartment boundary is sealed to maintain the fire rating — an unsealed gap around a duct is a route for fire and smoke to spread between compartments. Intumescent sealant expands when exposed to heat, sealing the gap around the duct penetration during a fire. Apply it around the full perimeter where the duct passes through the fire barrier. This is separate from any fire damper requirement — you'll typically need both the damper and the intumescent seal.

What are matching flanges and when do I use them?

Matching flanges (like the Systemair FSAF range) are bolted connection plates used to join sections of spiral or rectangular sheet metal ductwork, or to connect ductwork to equipment like air handling units, fans, and attenuators. Each duct end gets a flange riveted or welded to it, and the two flanges bolt together with a gasket between them for an airtight seal. Flanges are the standard connection method for larger commercial ductwork where push-fit isn't an option. They're also used wherever you need a demountable joint — for example, either side of a fan or silencer that might need replacing in the future.