DIY Doctor

bathroom fan - exit flue location question

Postby allotmentboss » Sun May 22, 2011 9:51 am

Hi All,

I am thinking of adding an extractor fan to my existing bathroom. (Before I go any further - I understand this is notifiable under part P and have an electrician to do that bit.) The fan I have chosen far exceeds the mnimum extraction rates required for a new bathroom of the same volume.

As the bathroom is at the front of the house, and I don't want an ugly grille to be too visible, I am thinking of ceiling mounting the fan (manufacturer says ok to do so), then using about 2 metres of 4 inch flexible ducting to route through the loft to a downward facing grille from the soffits.

The soffit I am looking at is on an overhanging gable, so the grille wil be about 18 inches from each of two perpendicular external walls to the house, and about the same distance from the eaves ventilation.

I know this is an unusual configuration, but can anyone see any problem with it? My main concern is the likelihood that the moist bathroom air could immediately be drawn back into the loft through the eaves? Is this likely?

Thanks for your help

a. boss
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Simply Build It

Postby stoneyboy » Fri May 27, 2011 5:37 pm

You'll probably find it easier to fit a vent tile and duct to this.
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Postby Perry525 » Mon May 30, 2011 7:05 pm

Silavent make a extractor fan with heat exchanger.
This unit can be fitted in the ceiling and has two pipes to fit as you desire.
This unit will recover about 90% of the heat that you will otherwise loose with a normal extractor fan.
You are considering fitting a powerful fan, but have you considered where it will get the air from that it will eject?
It will probably pull the air from round and under the doors and through any holes and cracks you have in the bathroom, this will then produce drafts in the rest of your home, and will push up your heating bills, as you then have to heat the cold air you have dragged in.
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