Installing an Inline Duct Fan

In this week's article, we'll be taking a look at what components you'll need to install an inline duct fan.

An inline fan is installed in the loft or ceiling void above the bathroom (or kitchen etc). Ducting is attached to each end of the fan with one length going to an internal grille in the ceiling of the bathroom and the other going to a grille on the external wall, soffit, or roof.

Duct clamps are used to connect flexible ducting to each end of the fan and to the spigot of each of the grilles. The back draught shutter may be installed on the exhaust ducting - that is to say, the ducting which runs from the fan to the outside grille, and is ideally situated as near to the inline fan as possible. It's worth pointing out, that the backdraught shutter must be fitted the right way round!

Unlike a wall mounted fan that is installed in the bathroom; an inline fan sits out of sight, within the run of ducting in the loft or ceiling. This offers the following benefits:

It can be ducted from directly above the shower or bath extracting steam and moisture at the source before it has time to condense, no coring through your bathroom brickwork is required, just a simple 4 inch hole in the ceiling that is covered by a discreet grille.

It's easy to install - in the attic, ceiling void or loft space - there are no electrics for the fan in your bathroom at all.

This means there is no making good to be done when the job is finished. No plastering, painting or re-tiling The fan can be mounted anywhere along the duct run - wherever is most suitable for wiring connections and secure mounting. Ducting is then connected onto both ends of the fan, one for the input side and the other for the exhaust side, totaling your full duct run length.

To prevent air from coming back into the room via the duct run, an in-line backdraft shutter can be fitted in the duct run. This will need to be installed on the exhaust side of the fan so it can be blown open with ease and held in place with duct clamps. You can also use external backdraft grilles either as an alternative to an iline shutter or alongside for additional protection. In this case we would suggest a no resist grille - in all extraction installations you want to minimise any resistance in the air flow to maximise both the extraction rate and the life of the fan motor.

Exit to outside requires a grille. We recommend the Energy Saver No Resist Backdraft Grille - which prevents backdraughts without adding resistance to the ducting system as mentioned above. Internally, a grille is fitted on the ceiling. We recommend using an open front grille to maximise the air flow and minimise both resistance and additional noise through air friction. If possible, using plastic grilles is advised as, due to the concentrated amount of humid air passing the grille can lead to accelerated rusting on metal fixtures.

To ensure the ducting system is entirely air tight - which maximises the efficiency of the fan - we recommend the use of both aluminium duct tape and duct clamps when attaching the ducting to the spigots of the fan and grilles. Clamps are not suitable for connecting solid ducting to spigots, usually these types of connections will be a tight fit by hand, but the use of aluminium duct tape can be used here as well to make sure an air tight connection has been made.

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You will need the following, all available from the accessories list below:
1 x Length of flexible aluminium ducting (sold by the metre)
1 x Internal back draught shutter
4 x Duct clamps
1 x Circular internal grille
1 x Fixed external grille - available in white, grey or brown
1 x Condensation trap (If the fan and duct are fitted vertically)

To view our full range of ducting, grilles, and accessories Click Here