Which is the right extractor fan to choose for my bathroom?

This is another one of those decisions that you can find yourself in a black hole of technical details about on the internet when you suddenly need to make that decision. Ready for that day (or now that you know, earlier) we've summarised the trade offs you'll need to make when it comes to deciding on an extractor fan:

Not always, no, but you should get one anyway! In older properties in the UK there is no legal requirement to install an extractor fan (even though it's a good idea to avoid mould, condensation build up, and reduce odours) however you absolutely do need some form of ventilation i.e. a window. New builds have to have an extractor fan, even if there is a window.

Your extractor fan should be high up your wall or in the ceiling because hot, humid air rises, and placed outside of the bathroom electrical zones.

When it comes to fitting an extractor fan into your bathroom renovation plan, having one placed above your bath or shower would be a great way to remove steam quickly. They exist with lights built in too!

Where you are putting your extractor fan will determine the type you need to buy so with any luck you won't need to get this far into the technical details, but here's the low down detail:

Axial

Most common for wall installations. Why the name? Because air is moved along the axis of rotation in a straight line, pulling air in and pushing it out in a straight line - designed to be mounted directly into an external wall, because there's only a short distance the air needs to be pushed along.

Inline mixed flow

An inline mixed flow extractor fan is what you are going to be looking at if you want to have it hidden in your ceiling. A more complicated design that can push that air further, not only in a straight line i.e. from your bathroom to the outside along a duct run. More powerful, so used to carry moisture and odours over extra long distances.

Centrifugal

Also for use with ducting, centrifugal fans apply centrifugal force to move air outward from the center of the fan to the edges, making them great at handling complicated ducting runs and redirecting airflow. They can be a bit chunky in terms of their design, but shop around!

The minimum ventilation requirements for a bathroom are 15 litres per second/ 54m3 per hour - pretty much standard for bathroom extractor fans to meet these requirements, but check before you buy.

Look for a low db rating, we've seen fans around 15db - 25db which is super quiet! You do even get app controlled fans so you could set things like, don't come on when your partner gets up to use the bathroom in the middle of the night.

UK bathrooms are tight on space so as much as this might not feel important right now, it's worth knowing the exact dimensions of your extractor fan (we luckily *just* had space for a 150mm fan last time we did a bathroom taking into account the window frame). Extractor fans are most typically 150mm wide (6 inches) in terms of what takes up the space on your wall, not just the 'spigot'.

Pull cord extractor fans are those that have a cord for manually turning the fan on or off. Main disadvantage is you have to remember to use it.

Switch operated means that your fan will come on with your light switch (most common, avoiding the issue of forgetting!). Insider tip, this won't typically work with a dimmer switch if that was on your agenda you'll need to discuss with an electrician.

You'll find some debate on this, mostly with people unsure on how effective a humidity sensor will actually be, and whether humidity is the only reason you want that extractor fan turned on. Humidity sensors (humidistat) will turn on the extractor fan automatically during / after a shower for example. Timers will result in the fan staying on for a set amount of time after your light switch is turned off. And motion sensors are of course triggered by a person moving in the room. It's your call based on what you think will cover your usage best to keep moisture and odours out, though most common is a simple timer based extractor!