Extractor Fan Series: What Types of Different Bathroom Extractor Fans Are There?

So you need an extractor fan but where do you begin when choosing one with all the different types available on the market? Which one is best for your bathroom?

The most common:

  • Axial - These connect directly through an external wall and are used when the air doesn't need to be moved long distances.
  • Centrifugal - These are designed for bathrooms that are not close to an external wall (over 1.5m away). They can move air long distances along their ducting, which means they have a more powerful extraction rate - and are often noisier. They are usually fit in ceilings. 

You might also hear of inline fans. These are normally fitted in the ceiling and can be used for extra long distances of 40 metres or more. Another term you might hear is ‘ducting’ when searching for your extractor fan. This refers to the hose that carries the old air from inside to the external vent, similar to what you might find in a tumble dryer. 

If your bathroom is a long distance from an external wall, or you are fitting it in the ceiling, you will require a longer 'duct run’. This also means you will need a more powerful fan - usually a centrifugal fan.

However, the most common type of extractor fan typically found in homes is the axial fan. 

Are bathroom fans a standard size?

Domestic extractor fans tend to come in two sizes: 4 inches/100mm and 6 inches/150mm. This size refers to the size of the impeller (the revolving part inside the extractor fan that sucks the air out).

How do I size a bathroom exhaust fan?

To know what size bathroom exhaust fan, you need, refer to the cm3 (cubic metres squared) measurement of your fan. If your bathroom is 100 square feet or less, you will need an extraction rate of at least 1cm cubed per square foot of room area. So, for example, if your bathroom is 54 metres square, you will need a 54m3/hr fan.

Generally, as a rule of thumb, it’s a good idea to get a fan with a little more power than is required. Most fans will offer a choice of two speeds and extraction rates, so you can adjust it depending on how much steam is being created.

See the next in our Extractor fan series - What extractor fan is best for my home?