How Much Do Extractor Fans Cost To Run?

Under UK buildings regulations (The Building Regulations Document F) it is illegal in new-builds to not install an extractor fan in the bathroom. This is because modern homes are so well insulated that moisture cannot escape. If left unchecked warm, damp conditions can lead to mould and mildew forming.

This is not only detrimental to your health but can also cause structural problems within the home too. So it’s very likely you have an extractor fan in your bathroom, but have you ever wondered how much it costs to run? That’s what we’ll explain to you in this post and we’ll be having a look at other related costs as well.

Please note: this is a guide that explains how much extractor fans cost to run, if you’re looking for a guide to buying extractor fans, you can visit our dedicated page for that here.

What Will You Need To See The Running Costs Of A Bathroom Extractor Fan?

To work out how much it costs to run your extractor fan you’ll need to find a few figures out, you need to know:

  • The Wattage rating
    The Wattage rating refers to the amount of power entering the appliance, in the case of extractor fans it usually ranges between 5 to 36 Watts.
  • How to convert Watts to Kilowatts
    This is a simple calculation and once you’ve learned how to do it, you’ll never forget.
  • The price per unit of electricity
    Look at your electricity bill for this information.
  • How long the fan is operating per day
    As it’s powered by electricity it only consumes power when it’s in operation.
  • The formula to work it all out with
    Don’t worry about the formula, we’ll show you how to do that in easy to follow terms.

How To Find The Wattage Rating Of An Extractor Fan

If your bathroom extractor fan was already installed when you moved in, it might be difficult to tell its wattage rating. Have a close look at the fan unit, it might have a make or model number if it does check online for that make or model to find out the wattage.

How to convert Watts to Kilowatts

To convert watts to kilowatts you simply divide the watts by 1000. For example, 40 watts is 40 divided by 1000 which equals 0.04 kilowatts. 2000 watts is 2 kilowatts and so on. 

Why Convert Watts To Kilowatts?

It’s necessary to convert watts to kilowatts because utility companies charge by the Kilowatt, so to get an accurate figure we need to use their figures.

How To Work Out The Running Costs Of An Extractor Fan

Use this simple formula to determine how much it costs to run your extractor fan. 

Watts divided by 1000 multiplied by the amount of time you use the fan multiplied by the price per unit of electricity.

So let’s say your extractor fan has a wattage rating of 12 watts and let’s take the average cost of electricity at 16 pence per unit (Kilowatt per hour) and you use your extractor fan for 30 minutes per day. The formula will look like this

12 ÷ 1000 =  0.012. 0.012 x 16 = 0.192 per hour. 0.192 ÷ 2 (for the half-hour) = 0.096 pence

So in this instance, it would cost just over 19 pence per hour to run the fan, which works out to around 9 ½  pence per half-hour. So we would round that up to 20 pence per hour and work it out accordingly.

Other Costs

There are no other running costs to consider but let’s have a look at the costs incurred by buying an extractor fan, having an extractor fan installed etc.

Work requiredTime needed (average)Cost of materials(average)Cost of labour(average)
Replace an extractor fan with no extra materials for ducting etc1 hour£60£25
New installation-extractor fan plus ducting and wall vent6 hours£80£60
New installation-extractor fan plus ducting through the roof to external wall vent1 to 2 days£90£200

Types of Extractor Fans

Extractor Fan

There are a few different types of extractor fans, let’s have a quick run through them and then look at the average prices you can expect to pay just for the fan (not including installation costs).

Wall Fans

These are the most common extractor fans found in older properties as they are the easiest to install. They are installed by drilling a hole (usually 4 inch-100 mm) through the wall. The fan is fitted inside the bathroom with a ducting tube running through the wall connecting to an outside vent.

Ceiling Fans

These are fitted to the ceiling usually above the bath or shower, connected with ducting pipes through the roof eaves to a vent in the outside wall.

Axial Fans

An axial fan is a fan that spins on a central pin or axle, causing the air to flow it in the direction of the blades to pass along and out of the room or pipe.

Centrifugal Fans

Centrifugal fans rely on kinetic energy created by impellers to increase the airflow which moves against any resistance caused by ducts etc. They are used to change the direction of the airflow (usually by 90 degrees).

Inline Fans

Inline fans are usually used in ducting in roof spaces, they are mounted inline, actually in the ducting to increase airflow. They are usually very quiet.

How Much Do Extractor Fans Cost – Supply only?

Let’s look at the average price you can expect to pay for each type of extractor fan on a supply only basis (not including installation).

Fan type (supply only)Average price
Wall fan£15 to £60
Ceiling fan£30 to £60
Axial fan£20 to £80
Centrifugal fan£40 to £90
Inline fan£50 to £110

Window Fans

There is one other type of extractor fan we’ve not mentioned so far and that’s the window fan. The reason we’ve not mentioned the window fan is that extraction works best with the window open to allow the correct airflow. If the fan is connected to the window, opening that window would be counter-productive.

If you are interested in window extractor fans you can expect to around £80 pounds for materials, £150 for installation and anywhere between £40 to £70 pounds supply only.

Frequently Asked Questions

How much do bathroom fans cost to run?

Bathroom fans cost around 20 pence per hour assuming a unit price of electricity at 16 pence per unit and a fan of 12 Watts.

Is it bad to leave the bathroom fan on?

It is bad to leave the bathroom fan on continuously as you can burn the motor out. Or any lint or dust caught in the fan can catch fire over time. 

How long should the bathroom fan be left running for?

The bathroom fan should be left running for around 15 minutes after the light goes out.  

Does a bathroom fan help with smell?       

A bathroom fan can help with smells, as the moist air is extracted any smells will get caught up and leave too.

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