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How to connect flexible ductwork

PU flexible ducting

Flexible ducting is often a popular component of choice within a ventilation system due to it’s, you guessed it, flexibility. Some of the popular materials used for flexible ductwork include aluminium, polyurethane, PVC, silicone, galvanised steel and neoprene-dipped polyester. Flexible ducting is affordable and diverse as it can fit into areas limited in space, where rigid metal ducting will struggle to fit.

In order to benefit from all of the features of flexible ducting, it’s essential to install it properly. In this article, we’ll look into how to connect flex duct together in detail, look at what a flexible duct connector is, and more.

How to join flexible ducting

When you require flexible ducting to span a longer distance than the length it is sold you will need to join more than one length of flexible duct together. It’s worth noting that flexible duct functions in a similar way to a spiral. The flex is considered the female part, or large end, while fittings are male, or small end. In order to join two lengths of flexible ducting together, you will need to use a male connection piece. There are different flexible duct connector sizes available, you will need to use the corresponding size to suit the size of your duct. It’s advisable to use j-clips to ensure the ends of the flex are tightened around the coupler. Let’s look at the process in more detail.

How to connect flexible ductwork step by step

First, gather the parts you require. To connect two lengths of flex together you will need your two lengths of flexible ducting, a male connection piece and two j-clips. Start by taking the worm drive hose clips and slide them over the ends of the flexible ducting. Next, take your male coupler and slide the flexible ducting over each end of the connector. Position the j-clip so that it is over the flex where it covers the metal coupler and tighten. This can be secured with either a screwdriver or easily done with a 7mm hex head drill bit in a battery drill.

How to attach flexible duct to an existing spigot

Sometimes you will be connecting your flexible duct to an existing metal spigot. For example, on an extractor fan, connecting to a machine or from a branch off a spiral duct run. To start, you should measure the distance from the spigot that you want your flexible duct to span. Using a utility knife, cut the flex duct to the length you need and use wire cutters to snip the wire helix.If you are using an insulated flex, the next step will be to roll back the outer jacket and fiberglass insulation from the internal foil layer. Next, apply a bead of mastic sealant along the end of the spigot and slip the flex duct over the spigot and the mastic glue. Make sure the duct covers a minimum of one or two inches of the outlet. You’re now ready to get the metal hose clamp. Make sure to tighten the clamp using a screwdriver or battery drill. For a further seal you can also apply duct tape over it. For insulated flex the final step will be to unroll the fibreglass on top of the inner core to ensure that it covers the spigot and pull over the outer jacket to cover any exposed insulation. You can use another lot of duct tape or larger j-clips about an inch away from the jacket’s edge to secure.

What to avoid

You can eliminate friction by extending the duct to ensure it is pulled tight and doesn’t sag. You can use metal or plastic support straps, like suspension clips, or wire rope for support depending on whether you’ll be hanging it vertically or horizontally. Also, you need to ensure that any bends are more than one duct diameter bend radius. Finally, get rid of any excessive duct length by cutting it off.

We hope this article will help you enjoy a seamless and stress-free flex ducting connection in the future. If you have questions and need help from professionals, make sure to contact Ducting Express right away. We have what it takes to assist your business with any ductwork!