How to Fit a Bathroom Extractor Fan

Fitting a bathroom fan of any kind can be a seemingly daunting challenge. But with this quick, easy-to-follow guide, you’ll be done in no time.

We cannot stress enough how important it is that any electrical wiring in your bathroom be performed by a qualified electrician and that it conforms to the latest IEE wiring rules and regulations.

However with that said, you can certainly make a start on installing your fan and leave the final wiring to your electrician.

Preparation is Everything

Before you install your bathroom extractor fan, you will need a couple of helpful tools. A stepladder, screwdriver, pencil, jigsaw, and twist-on wire connectors will all come in handy. And of course, you will need your actual fan and ducting, or preferably an all in one Extractor Fan Installation Kit.

The first step to the installation is to disconnect the power to the bathroom light or already existing fan. Do this at your home’s main electrical panel/fuse box.

First Steps

Now, if you are replacing a current fan unit then you should remove the entire fan fixture from the ceiling using your screwdriver. Remove the screws that mount the electrical box to the beams/joists that support the floor of the attic. Remove the box. This will leave a space in the floor through which you should be able to see the bathroom from above.

If you are installing a fan into a location that hasn’t previously held one, you will need to do some preparation work. First off, we suggest using a pipe/wire detector to check the location where you wish to install your fan. Make sure you double check this area for wires or other pipes before proceeding.

Once you are sure there are no obstructions, you can go ahead and drill a small pilot hole into the ceiling. You may find this is best done from the attic so you can ensure you avoid any joists or other obstructions from that side. You will need to make some accurate measures using your tape measure to ensure the center of the hole is where you want it in the ceiling.

Expanding the Hole to Match the Size of Your Fan

electrician fitting a new bathroom extractor fan

Now place the new fan unit over the hole with the opening of the unit covering the hole. You will now be enlarging this hole in the attic or crawl-space floor to make room for the new and larger fan unit. Use your pencil to trace the outline of the new fan unit fitting onto the floor. Remove the unit and use your jigsaw to cut out the space you just traced around the previously existing hole.

If you are mounting an inline fan then you will need to adjust the size of the hole you make to match the internal vent or grill fitting (the bit that points into your bathroom).

Ensure It Fits Securely

Place the extractor fan unit back into place. If it does not fit perfectly you may have to tweak the hole for it with a little more sawing. The opening of the fan should be facing toward the bathroom ceiling, and away from the attic. Using the mounting screws and brackets that came with the installation kit, secure the fan unit to the supporting beams of the attic floor.

Next, run the ducting from the extractor fan kit to the exterior wall and use your pencil to trace the shape of the hose opening onto the wall. Once you have done this, cut out the traced space on the wall with your jigsaw and mount the ducting to the wall using the screws that are included in the installation kit.

Make sure to tighten any clamps on the unit to make sure the wires and box are secure. If your fan or ducting is not securely mounted then it can vibrate during use, leading to an increase in the noise emitted by your fan. Never a good thing!

Attaching the External Vent

Now you will likely need to head outside and up a ladder to attach the external grill and back draught shutter, following the manufacturers instructions to the letter. Some vent grills will clip on and others will require you drilling into the exterior masonry to attach them via screws.

Go back down to the bathroom and set the vent cover over the new opening in the ceiling. Depending on the model of your fan, the cover will connect with either hooks, screws or some form of clips. When the vent cover is installed properly, you should not be able to see any part of the attic or the actual fan extractor unit and it should sit flush against your ceiling.

Safety First When it Comes to Wiring

Once you have fully connected the vent cover, and made sure all the fittings are well connected, you’re ready to connect up the wiring. Again you should have a qualified electrician handle the actual wiring, following the wiring diagram provided by your fan manufacturer.

For those that are installing a fan with a built in light you may need to deal with additional wiring, again this will be described in the wiring diagram you received with your chosen fan.

Final Checks

When the fan is running properly, the hose in the attic should not wiggle at all, even when the fan is in use. If any of the parts seem loose, turn off the power of the bathroom ceiling fixture again and tighten any screws.

There you have it, your new extractor fan should now be fully fitted and working like a charm.

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