1.
Choose a Powerful Fan.
This sounds so obvious I don't blame you for thinking you're wasting your time reading this guide.
Many domestic buyers, however, place so much importance on noise levels and aesthetics that they forget what the fan is supposed to be doing in the first place, which is suck steam and damp air out of the bathroom.
A fan's power is measure using one of two metrics: m3/hr (meters cubed per hour) or L/s (litres per second).
Building regulations state that a bathroom fan must extract at least 15l/s (54m3/hr).
To be honest this wouldn't blow out a candle on a birthday cake and fans this weak are few and far between.
As a rough guide you should be looking for a fan at around 85m3/hr (23L/s) for an average size bathroom.
Standard 4 inch axial fans are commonly available over 90m3/hr and these will really make sure your bathroom is free of moist air.
2.
Understand the difference between an Axial and Centrifugal Fan.
Ok, so this is a bit more technical! The single biggest cause of extractor fans not operating properly is due to an ill informed home owner or corner cutting electrician installing an axial fan when it should have been centrifugal.
We do not need to go into the technical differences between the two, beyond stating that the impellers of a centrifugal fan move in a different direction to those of an axial fan.
This means that centrifugal fans creat greater air pressures, which in turn allows them to push air down far longer duct runs.
Standard axial fans cannot cope with duct runs longer than 4 metres.
Quite simply the air pressure in the duct behind the fan is too great for it to expel any air...
and if it can't expel air, then it can't extract any either.
Even duct runs over 2 metres will impair its performance as will any kinks or bends in the duct.
Centrifugal fans, on the other hand can sit on the end of huge duct runs up to 50 metres and still operate at 50% capacity.
3.
Buy a Timer Fan.
If you are installing a fan into a new bathroom choose one with an integral over-run timer.
These keep the fan running after you have turned off the lights.
The reason I always recommend timer fans is that for no extra effort and negligible cost you multiply the effectiveness of the fan.
Most timers may be set upon install to run from one minute to over twenty.
This dramatically increase the amount of air extracted and is far more likely to prevent any damp build up.
Roughly speaking, if you have a 90m3/hr fan and set the timer to 20 minutes, you will extract an extra 30m3 of air.
If you are replacing an existing fan you will first have to check the cabling as timer fans require both a 'permanent live' and 'switch live' feed.
The timer switches the fan via electricity provided by the permanent live, while the switch live feed runs directly between the light switch and fan.
4.
Understand the Bathroom Zoning System.
Electricity and water do not make a happy couple.
In fact when they get together sparks fly! For this reason very strict regulations govern how electrical items are installed in the bathroom.
A zoning system dictates that any bathroom extractor fan installed within a certain distance of the bath, shower or basin must be either SELV (Safety Extra Low Voltage), which is 12 volt.
Should a fault develop 12v will still give you a nip, but it will not be your last shower.
Google 'bathroom zones' to see a diagramatical explanation of this.
In recent years a new type of fan has been introduced which is also suitable for installation in zones one and two.
Whilst this fan is not low voltage it is rated to withstand water, this rating is described as IP45 - (Ingress Protection against low pressure jets from any direction).
These types of fan are much easier to install because they do not require a transformer as SELV fans do.
Transformers do complicate installation of SELV fans as whilst the fan may be in zone 1, the transformer must be housed outside the zoning system.
i.
e in the wall or above the ceiling.
Choose a Powerful Fan.
This sounds so obvious I don't blame you for thinking you're wasting your time reading this guide.
Many domestic buyers, however, place so much importance on noise levels and aesthetics that they forget what the fan is supposed to be doing in the first place, which is suck steam and damp air out of the bathroom.
A fan's power is measure using one of two metrics: m3/hr (meters cubed per hour) or L/s (litres per second).
Building regulations state that a bathroom fan must extract at least 15l/s (54m3/hr).
To be honest this wouldn't blow out a candle on a birthday cake and fans this weak are few and far between.
As a rough guide you should be looking for a fan at around 85m3/hr (23L/s) for an average size bathroom.
Standard 4 inch axial fans are commonly available over 90m3/hr and these will really make sure your bathroom is free of moist air.
2.
Understand the difference between an Axial and Centrifugal Fan.
Ok, so this is a bit more technical! The single biggest cause of extractor fans not operating properly is due to an ill informed home owner or corner cutting electrician installing an axial fan when it should have been centrifugal.
We do not need to go into the technical differences between the two, beyond stating that the impellers of a centrifugal fan move in a different direction to those of an axial fan.
This means that centrifugal fans creat greater air pressures, which in turn allows them to push air down far longer duct runs.
Standard axial fans cannot cope with duct runs longer than 4 metres.
Quite simply the air pressure in the duct behind the fan is too great for it to expel any air...
and if it can't expel air, then it can't extract any either.
Even duct runs over 2 metres will impair its performance as will any kinks or bends in the duct.
Centrifugal fans, on the other hand can sit on the end of huge duct runs up to 50 metres and still operate at 50% capacity.
3.
Buy a Timer Fan.
If you are installing a fan into a new bathroom choose one with an integral over-run timer.
These keep the fan running after you have turned off the lights.
The reason I always recommend timer fans is that for no extra effort and negligible cost you multiply the effectiveness of the fan.
Most timers may be set upon install to run from one minute to over twenty.
This dramatically increase the amount of air extracted and is far more likely to prevent any damp build up.
Roughly speaking, if you have a 90m3/hr fan and set the timer to 20 minutes, you will extract an extra 30m3 of air.
If you are replacing an existing fan you will first have to check the cabling as timer fans require both a 'permanent live' and 'switch live' feed.
The timer switches the fan via electricity provided by the permanent live, while the switch live feed runs directly between the light switch and fan.
4.
Understand the Bathroom Zoning System.
Electricity and water do not make a happy couple.
In fact when they get together sparks fly! For this reason very strict regulations govern how electrical items are installed in the bathroom.
A zoning system dictates that any bathroom extractor fan installed within a certain distance of the bath, shower or basin must be either SELV (Safety Extra Low Voltage), which is 12 volt.
Should a fault develop 12v will still give you a nip, but it will not be your last shower.
Google 'bathroom zones' to see a diagramatical explanation of this.
In recent years a new type of fan has been introduced which is also suitable for installation in zones one and two.
Whilst this fan is not low voltage it is rated to withstand water, this rating is described as IP45 - (Ingress Protection against low pressure jets from any direction).
These types of fan are much easier to install because they do not require a transformer as SELV fans do.
Transformers do complicate installation of SELV fans as whilst the fan may be in zone 1, the transformer must be housed outside the zoning system.
i.
e in the wall or above the ceiling.
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