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8 Steps To Successfully Install An Extractor Fan

Bathroom With Tub

Installing an extractor fan into your home isn’t complicated and, as long as you follow instructions and do it right, there’s no risk of accident.

A key rule of thumb to always have in mind throughout the process is to never cut corners!

You’ll need:

  • A circuit tester
  • A circuit breaker
  • An electrical screwdriver
  • Electrical wire
  • A chisel
  • Plaster

What is an extractor fan?

It’s a mechanical device which removes smoke, steam and unpleasant odors from any room. It’s also brilliant for getting rid of excess moisture from the home or in an office, and it can also help prevent damp from developing.

What Size of Fan Do I Need?

The type of fan you choose has to have the right extraction rate while also being suitable to the location of installation. To give you an example – some fans, such as in-line fans, have to be installed midway between the exhaust vents and the intake.

There are three main types of bathroom extractor fans – centrifugal, axial, and inline. The least powerful of the three is generally the Axial but they’re still perfectly suitable for the majority of situations.

They ideally should never be ducted any more than 2-3m which, in layman’s terms, means they really should only ever be put somewhere that has direct access to the outside of the property. Ducting the fan any further than this would mean looking towards the centrifugal fan which has more power than the axial and is more efficient in larger bathrooms, though they do tend to be noisier.

You’ll find that a centrifugal extractor fan is used primarily in buildings that require elongated ducting, so really you’re talking about industrial and commercial properties. They turn the air through a 90-degree bend within the fan itself and this increases the air pressure and, in doing so, enhancing the fan’s power.

An inline fan could be centrifugal or axial but rather than being installed on ceilings or walls they are usually positioned in the attic just above the ceiling. The inline fan is generally more powerful than the centrifugal and is fully able to provide high performance ducting over a long distance.

No matter what fan you decide on, always follow the manufacturer’s guidelines on installation location.

Installing the fan – the wiring

Installing A Bathroom Fan

  • Find the correct cubic feet per minute or CFM (Meters cubed per hour) rating for the bathroom where the extractor is to be fitted. Doing this allows you to choose extractor with the right fan strength, bearing in mind that a bigger bathroom could require a fan with higher cubic feet per minute.
  • Keep in mind the sound rating of the extractor fan you’re about to install and this is measured in sones. Many new fans will have a sound rating ranging from 0.5 sones which is very quiet, to 6 sones which is very loud.
  • Extractor fan location – This is important. For maximum ventilation, you should aim to install it midway between the toilet and the shower. For larger bathrooms, more than one fan may be necessary.
  • Be conscious of your attic layout – The new extractor fan needs to be situated between two joists, in a space without obstructions or pipes. If replacing an old fan, simply install the new extractor in the same place (unless you specifically want it installed elsewhere).

Your Toolkit:

  • power drill
  • Pad Saw
  • screwdriver
  • combination pliers

Materials You’ll Need:

  • Screws
  • flexible duct pipe
  • caulk and wire nuts/connectors
  • vent cap

Components You’ll Need:

  • Fan
  • External grill
  • Flexible pipe

The Method

The method below is simply for reference and ideas. The method you decide on for the actual installation will very much depend on the construction of your house.

  1. Installation
  • Drill a hole as a reference and then make a mark on the ceiling. For the reference hole (where you plan on installing the fan) use power drill with a 3⁄4 inch (1.9 cm) spade drill bit. Take a measurement of the vent fan housing.
  • Find your reference hole in the attic and clear away all the insulation surrounding it. Use the measurements of the fan housing to make certain that the fan will fit in where you want it to go (between your two chosen joists).
  • Back in the bathroom, measure the intake port of the fan. These measurements will ensure that you cut the correct sized hole into the ceiling.
  • Use a pencil and a framing square to mark the outline of the intake port of the fan on the ceiling, following the measurements you’ve just taken.

2. With the pad saw, cut away the part of ceiling you marked. If you don’t have a jigsaw, then use a reciprocating/drywall saw. Support the rectangular piece of ceiling with your free hand and gently place it on the floor.

3. Position the fan, but before lowering it into the hole connect a 90-degree duct elbow (you’ll later secure the duct pipe to this) to the proper outlet port with foil duct tape.

Insert a cable connector in through the removable knockout hole which can be found on the side of the extractor fan’s housing, then bring the supporting metal brackets into place. Center the fan over the hole in the ceiling and gently lower, making sure that all connection points are aligned correctly.

4. Attaching the fan to each joist – Once in position, lengthen each metal bracket of the extractor until it reaches the joists in the attic. Use drywall screws to secure each bracket.

Now that the fan is secured attach one end of the flexible duct tape to the 90° duct elbow with the foil duct tape.

(This would be a good time to put a new or existing electrical cable through the connector on the fan housing. Tighten the screw on the connector to attach the cable *if your fan also has a light you will have to use a 3-wire cable).

5. Finding the right outlet point for the duct pipe – This will be the shortest and most direct path from the housing fan to the outside of the property. A longer duct pipe will mean a less efficient fan.

The fan exhaust absolutely must be vented outside. If it were to be vented directly into the attic this would encourage the growth of mold which could then potentially cause rotting


6. Attachment of the vent cap – For an outlet point on the wall, choose a spot in between two wall studs. Take reference measurements inside to help you find the same place outside. Using a 4-inch hole saw cut through the wall from the outside and then attach the vent cap securely in place.

Attach the end of the duct pipe to the vent cap’s connector duct in the attic with the foil duct tape.

7. Wiring your connections in the housing unit – You might have to wire the connections either from the attic or the bathroom very much depending on which type of fan you’ve chosen. Always read the manufacturer’s instructions and be absolutely certain that all power is off before taking the next step.

*We do always recommend to get a registered professional to do any electrical work*

8. Almost there. The next step is to connect the grille and plug in the blower motor to the electrical receptacle and secure it with the screws provided.

Put the mounting wires of the decorative plastic grille into the slots of the housing unit, always ensuring that it’s flush against the ceiling – for more tension simply spread the mounting wires if necessary.

Switch your power on again and test the extractor to ensure that it works.

Tip of the Trade

If the flexible pipe is not fitted correctly it can become a trap for excess moisture, leading to a build-up of water! As long as the flexible pipe is supported and tight this won’t be a problem. Where possible always go with solid piping.