Extractor fan for bathroom

[shappaeye]

I have a bathroom 1.82m x 3.16m x 2.30m which desperately needs ventilation. It has 2 outside walls and 2 internal walls. 2 windows, 1 internal and the other to outside and of course a door.

I am working on the basis of the room requiring 20 changes of air an hour so looking at a fan extracting 245m3 plus or around that. So this points me to a 150mm fan.

I an intending to wire it to the switch so when someone uses the bathroom the fan cuts in.

One issue, the external wall is 1 metre thick, the ceiling goes up to a lean to/office which has a sloped slate roof.

Does all this make sense and add up and whats my best bet for venting the steam, which wall or roof?

 

[jj4091]

This may help you with the electrical side of things. //www.diynot.com/wiki/electrics:lighting:fan . As far as which is the most efficient method then as steam rises logically you would think a ceiling fan would be the best solution & also you would be able to use an in-line model that will over come the problems of size ( I've never seen a 150mm ceiling mounted one) & the need to notify as it will be outside of a "special area"

 

[Taylortwocities]

I an intending to wire it to the switch so when someone uses the bathroom the fan cuts in.

You'll probably find you'll need to wire it to the light, rather than the switch. Depends on how it is wired.

In line fans are practical only if you have accesss to the roof space above the room. 5" (and larger) ones are available.
Like these
http://www.tlc-direct.co.uk/Products/SLTD350SILENT.html
http://www.tlc-direct.co.uk/Products/SLTD350T.html

 

[bernardgreen]

Remember that that air removed from the room has to be replaced by air from outside the room. Most often by a wide gap under the door. Fan ratings of air flow assume this replacement air has no obstruction. A door with very little gaps can reduce fan air flow to less than a 1/4 of the rated flow.

 

[shappaeye]

This was the fan I was thinking of using:

http://www.toolstation.com/shop/Ele...+Extractor+Fan+Standard+Fan/d190/sd280/p58082

 

[shappaeye]

Thanks to your replies I have decided to go for an inline extractor. Noise is reduced and it won't put any weight on the plasterboard ceiling as a normal fan would.

What I am slightly confused over is air changes per hour.

Some people say 20, most people say between 3 and 10! This means any calculation I do for my bathroom can rapidly alter the cost of the fan as some have higher throughput than others.

Is there an exact science with air change per hour or is it as varied as it seems?

 

[Taylortwocities]

SUGGESTED FAN SIZE CALCULATOR