Bathroom Ventilation

14 Aug 2010
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United Kingdom
We had an extension built about a year ago which included a bathroom. The builder fitted a cheap & nasty ceiling extractor fan and ran about 8 metres of flexible ducting across the loft to a ventilation tile which he'd put there because it was easy to fit it next to the velux window in the loft. The useless fan coupled with the long ducting is next to useless. Needless to say, the bathroom gets completely steamed up every time the shower is used so we need to get this sorted.
The problem is in the colaboration between an electrician to fit the extractor and a roofer to fit the necessary ventilation tile. The sparky has recommended an in-line fan which has a 100mm duct but he has also advised NOT to reduce the duct size by using what I've posted as a "squashed adaptor." This, apparently, reduces the effectiveness of the fan. The roofer on the other hand has suggested using ventilation tiles in the picture I've labelled "Our roof" which require said adaptor.
Is it possible to fit another type of ventilation tile to this type of roof which looks more like the "Round adaptor" picture, thus not reducing the size of the ducting nor the fan's efficiency? Thanks.
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Thanks Mw Roofline, this is an option we thought of but the data sheets of extractor fans show how much their efficiency is reduced by long & flexible duct runs. In our case they're mostly reduced to zero efficiency by the length of the duct run already there.
This means we really need to put a new ventilation tile in the roof above (or very near) where the fan will be. We'd rather get the right type put in first time than pay a roofer twice to firstly put in one like the picture, then, if we find it reduces the fan's efficiency too much (as the sparky says it will), get them back to do it again.
Interesting thread,I have a similar problem. The extractor fan isn't actually a cheap n nasty one but the long duct length renders it useless.

My problem is now compounded by the fact we have had the loft converted so I can't just the duct easily out of the roof!
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A ventilation tile is for ventilation, and a roof terminal is for extract fans.

You need a centrifugal fan, and anything over 3m of duct and 2 bends could do with a 150mm fan and duct

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