Deciding on an Exhaust Fan
Published: November 28, 2017 Last Updated: November 06, 2020
When it comes to buying a new or replacing an old exhaust fan there are many different brands and styles to choose from. Today we are going to explain the benefits of exhaust fans, how Electricians decide which exhaust fan is best for your needs, and the specifications they use that you can keep in mind when buying an exhaust fan.
Benefit of an exhaust fan
Bathrooms and laundries are highly prone to moisture build up due to high humidity from steam and heat. When you have a hot shower you create steam which fills the room. This steam then cools and becomes water resulting in condensation. Condensation build up over time can create and feed mould and in extreme cases can cause structural rotting. This can be avoided by installing a good exhaust fan in your bathroom or laundry.
An exhaust fan will expel the humid air and steam from the room before it has a chance to cool down and become water. Typically the air will be ducted outside of the house via a ventilation pipe on the back of the exhaust fan.
Exhaust fan ratings
Exhaust fans are rated by air movement which is measured by metres cubed per hour. Depending on the size of the room you will be installing the exhaust fan into will determine what rating you will need.
Determine exhaust fan size
The rate of air flow is determined by the number of complete changes of air within the room per hour.
Rooms without a shower ie. Toilet, Laundry (No Dryer), Office. Require approximately between 6 and 10 Air Changes per Hour.
Rooms with a shower ie. Bathroom, Ensuite, Laundry (With Dryer). Require approximately between 15 to 20 Air Changes per Hour.
To determine the minimum fan capacity you will need you must first calculate the volume of the room. This is done by measuring the length times the width times the height (L x W x H = Volume). Then you times the volume by the number of air changes required per hour depending on the room type. This will then give you the minimum capacity you require for the room.
Sound confusing? here is an example:
Lets say our bathroom is 4 metres in length 3 metres in width and 2.5 metres in height. Our minimum requirement for a bathroom is approximately 15 air changes per hour and we know that it is measured by metres cubed. So our equation will look like this:
4(Length) x 3(Width) x 2.5(Height) = 30(Volume)
30(Volume) x 15(Air Changes Per Hour) = 450m³/h
Positioning of the exhaust fan
When it comes to the positioning of your new exhaust fan will depend on a few factors.
One of the main things to consider when looking into the placement of an exhaust fan is the airflow within the room. Does the room have windows and doors etc? Exhaust fans will remove steam out of a room so long as there is new airflow that can come in to take its place. Without proper ventilation, your new exhaust fan useless from the get go.
Times like these are when it is time to call your local electrician to help you find the optimum position for your new fan and professional advice on how to maintain it as well as being able to install it for you.
Exhaust fan styles
This comes down to personal preference and practicality. As a good example some exhaust fans come with built in heat lamps, these are great for the winter months to help you dry off faster but they will cost more on your electricity bill as well as the expense of replacement bulbs. You will also need to factor in where it will be placed in your room, there would be no point in having heat lamps if it is near the back of the room or even over the shower itself.
So now you have the same knowledge as an Electrician when it comes to buying and placing new exhaust fans in your home.
If you are ever in doubt it never hurts to call or consult your local electrician.