What Extractor Fan Do I Need For My Bathroom?

What Extractor Fan Do I Need For My Bathroom?

What does every bathroom need? A toilet (Must have) Sink (Obvious) Extractor Fan? Having a bathroom fan is essential. This is because in every single bathroom there is moisture and condensation. Not having one will mean these issues will build up and cause mould.

The best way to combat the build up of condensation and mould is by having a bathroom extractor fan. This article will take you through the different bathroom fans available and what we recommend for you.

Do I need a bathroom extractor fan?

This is quite simple, yes. You need a bathroom fan. The building regulations for ventilation state that any extractor fan installed in your bathroom must extract atleast 15 l/s. This is a minimum rating but we recommend you choosing a bathroom fan that extracts atleast 22 litres per second.

What different types of bathroom fan are there?

There are three main types of bathroom extractor fan to choose from:

Axial - These are designed to be mounted and ducted directly out of the wall, normally with a duct run below 5 metres long. This is the most popular type of bathroom fan and is what people most commonly associate an extractor fan with.

Inline Duct Fan - This is the option that if you have space to install then you should be leaning in this direction. Inline duct fans are installed within the loft or ceiling void and due to this they are manfactutred to be a larger which in turn means you will get up to three times the extraction in comparison with axial bathroom fans. The higher performance levels mean you can duct them longer distances too, in most cases up to 10 metres.

Centrifugal - They can be installed on the ceiling or wall but their motors are specially designed to extract at a much higher rate over longer distances. Most options available will haver a 'trickle' function which means it will be continuosly extracting air and will boost to its maximum setting when humidity rises. (Humisitat models)

Are there different sizes?

The normal assumption when talking about size is its the size of the actual fan, but what we are talking about is the diameter of the spigot. (The back of the fan). Almost all bathroom fans in the UK have a 4 inch diameter which will mean the ducting and external grilles will need to be 4 inch to match. In larger bathrooms or rooms with severe mould and condensation issues you may want to look at larger versions. The only differences are the larger sizes extract more air and will create more noise but with technology continuously improving, like all fans these statistics will only get better.

How do I know what size bathroom fan I need?

Understanding what fan will suit your bathroom comes down to knowing every aspect of your installation:

Room size - Knowing the size of your room starts to give you a starting point of what extraction rate you need. To know what volume of air you needs to be extracted, you have to start by knowing what the volume of your room is.

This is calculated by multiplying length by width by height. Let's take an average measurement: 3m long x 2m wide x 2.4m high = 14.4 cubic metres. This means that in order to change the air in that room once an hour, a fan would have an extraction rate of 14m3/h. Building Regulations require rate 4 air changes per hour, so we multiply that by 4, giving us a rate of 56m3/h or 15l/s. The Envirovent SIL100 Bathroom Fan Range has an extraction rate of 97m3/h would give you 6.73 air changes an hour. This fan is the most powerful bathroom fan on the market as we speak in 2022.

Length of ducting - As soon as you put a fan on any ducting, the extraction rate is affected. The air pressure within the duct will cause the air to slow as it is pushed farther away from the fan. This is where a centrifugal fan can be useful as they generate more pressure to counter the greater length of ducting.

Installation position - Bathrooms are divided into zones depending on how close they are to the source of water. Which fan you fit will depend on what zone your are installing it in.

Which bathroom extractor fan is best for my home?

This is dependent on everything we have discussed above but also noise. Is the fan being installed in a bathroom away from other bedrooms? The decibel level of the bathroom fan you choose is vital. We recommend looking at fans that are below 25 dB. This level of noise is the equivalent to a whisper from 3 metres away, silent... almost!

What function should I choose for my Bathroom Fan?

All extractor fans are installed to either a lighting circuit or separate fan isolator switch so you can turn them on and off. On top of this there are different options that you can choose from.

  • Basic Bathroom Fan - This option is your standard on and off. Turn the switch on and the fan operates, turn the switch off and the fan will turn off immediately.
  • Bathroom Fan with Timer - This mode can sometimes be confused, it is not to set an actual time for the fan to switch on. Like the basic model when you turn on the switch the fan will turn on, but when you turn the switch off the fan will overrun for a set period of time. Most fans can be set between 2-25 minutes. Some manufactures now are incorporating a delayed start function for these fans, this is to stop fans switching on if you are only nipping for a quick wee in the middle of the night.
  • Bathroom Fan With Humidistat - These models will turn on automatically when humidity in the bathroom reaches a set level within the room, it will then continue too extract until the humidity levels drop back below the pre-set level. This specific operation is popular because you don’t necessarily need a light on when using the bathroom.
  • PIR Bathroom Fan (Passive Infra Red) - This operation will only turn the fan on if somebody enters the room, just like a floodlight outside your house!
  • Bathroom Extractor Fan With Pullcord - The pull cord operation is slowly being replaced by the above mentioned operations, but they are fairly self explanatory. They have a localised switch point.

Can I install my own bathroom extractor fan?

This is a definite NO. All extractor fan installations should be done by a fully qualified electrician. If you don't know one personally we recommend finding one using Electrician Finder.

The most important factor before choosing a bathroom extractor fan is the area you are installing it in. The UK Electrical Wiring Regulations split the bathroom into 3 zones, simply named Zone 1, 2 and 3.

Bathroom Extractor Fan Zones

In order to install a fan in Zone 1, you must adhere to IEE Wiring Regulations BS7671, Requirements for Electrical Installations Section 601 which basically says that if you are installing in Zone 1, the fan must either be Low Voltage or IP Rated to IP45. Zone 1 is normally the source of where steam will occur so its best to try and install here.

Most bathroom extractor fans made these days are designed to use as little energy as possible, so causing a minimal effect on your energy bills. How important is that in the times we live?

For example, the Envirovent SIL100 Bathroom Fan uses 8w of energy. To give this a little more perspective, an average bathroom extractor fan costs about £0.98 per day IF it is switched on 24 hours a day. In reality, you won't have your bathroom fan running all day every day.

Talking of costs - Installation, repair and maitenance may occur during your time with your fan. Installation varies between what electrician you choose and the area you live. We highly recommend you don't just go for your lowest quote, fully qualified electricians spend years learning their trade. You are not just paying for the installation, you are paying for their knowledge and the safety of a good installation. 

Choosing a bathroom fan

After reading this whole article we hope you are feeling we have covered all the neccassary questions, if you still have questions please do get in touch we will answer your enquiry and also add it to this page!

All in all for 95% of bathroom fan installations you will need either an axial fan or inline duct fan.

Take a look at our top picks for your bathroom below..

The Bathroom Fan You Need