Non-motoring > Shower extract fan Miscellaneous
Thread Author: BobbyG Replies: 18
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New Tue 2 Apr 13 16:59 
 Shower extract fan - BobbyG
Silly question, if I want an extract fan fitted in the ceiling, with ducting through the loft to a vent on the roof eaves, do you need to drill the vent hole from the outside?

In other words can all this be done from inside the loft including fixing the vent on or will a contractor need ladders etc?
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New Tue 2 Apr 13 17:05 
 Shower extract fan - Zero
>> Silly question, if I want an extract fan fitted in the ceiling, with ducting through
>> the loft to a vent on the roof eaves, do you need to drill the
>> vent hole from the outside?
>>
>> In other words can all this be done from inside the loft including fixing the
>> vent on or will a contractor need ladders etc?

Nah you need to put the outer part of the vent on from the outside. Unless you just want a hose poking out.
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New Tue 2 Apr 13 18:02 
 Shower extract fan - Fenlander
Adding to Zero's comment...

It is very unlikely you could get a drill in from the loft to drill the eaves even if you were happy with a dangly hose.

I assume a normal house not bungalow and you don't want to be up that high drilling on a ladder?

Recently I put an extractor in both bathrooms and managed to fit both exhaust grilles in place of an existing eaves vent grille so it was just a case of enlarging the hole a little.

If you want a proper job put a turbine extractor in the loft with just a grille in the bathroom. Many fan units that sit in the ceiling haven't enough puff to power air through any length of duct.

Something like this is good...

www.fantronix.com/acatalog/Loft_Mounted_Extractor_5__diameter.html
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New Tue 2 Apr 13 18:10 
 Shower extract fan - henry k
>>If you want a proper job put a turbine extractor in the loft with just a grille in the bathroom.
>> Many fan units that sit in the ceiling haven't enough puff to power air through any length of duct.
>>
....and this avoids the complications of installing a SELV fan
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New Tue 2 Apr 13 18:15 
 Shower extract fan - Zero

>> If you want a proper job put a turbine extractor in the loft with just
>> a grille in the bathroom. Many fan units that sit in the ceiling haven't enough
>> puff to power air through any length of duct.

Minimum length of run, and as few bends (those you do have should be shallow) as possible is key to max airflow.
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New Wed 3 Apr 13 09:09 
 Shower extract fan - Fursty Ferret
Fantastic - sorry - just ordered two of these to replace the rattly ceiling fans in the bathrooms. Both pipes run through the loft along with the wiring so easy job.

Have a careful look at the roof before drilling holes - my house has three "vent tiles" but only two hoses connected, leaving a spare outlet (which now takes a hose from an air conditioner.)
Last edited by: Fursty Ferret on Wed 3 Apr 13 at 09:10
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New Tue 2 Apr 13 18:25 
 Shower extract fan - Mapmaker
I think you'd get a very rough hole if you drilled from the inside outwards.

However, sticking the vent bit on the outside from the inside is a doddle. (ish). A piece of rope down to the ground; tie the vent on, hoist it up, and use some nomorenails. Yes, you'll regret it when you come to replace it in twenty years, but with any luck you'll burn down before then.
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New Tue 2 Apr 13 18:36 
 Shower extract fan - Zero
>> I think you'd get a very rough hole if you drilled from the inside outwards.
>>
>> However, sticking the vent bit on the outside from the inside is a doddle. (ish).
>> A piece of rope down to the ground; tie the vent on, hoist it up,
>> and use some nomorenails. Yes, you'll regret it when you come to replace it in
>> twenty years, but with any luck you'll burn down before then.

I defy you to stick it on int he right place using that method.
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New Tue 2 Apr 13 19:20 
 Shower extract fan - R.P.
Did that - doddle as said.
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New Tue 2 Apr 13 19:15 
 Shower extract fan - rtj70
So with that thought Mapmaker, I hope your house burns down sooner than twenty years ;-) What a thing to say on here!
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New Tue 2 Apr 13 20:53 
 Shower extract fan - Fullchat
Now this I have some recent experience! I had two above shower fans fitted connected to purpose made roof vent tiles. They can be purchased to suit your tile. Roofer job to fit these. Remove a tile, slit the felt and then fit the vent tile. All connected up using that plastic 4"expanding vent hose like they use for tumble driers. My mistake was fitting the tiles a bit low on the roof.
After about a year, move forward to February I started some work in the loft, increased insulation raised loft boarding - still on the go:( I noticed that there was quite a lot of water which had condensated in the low part of the pipe.
So I've rejigged the routing to get a gradual climb with no low spots but have also used specific acoustic/insulated flexible ducting - www.fantronix.com/acatalog/Acoustic_Ducting.html
Really the tiles should have been higher to get a near vertical climb but that can create problems in that condensation can run back down the tube. This kind of item can be fitted vertically near the bottom of the ducting - www.fantronix.com/acatalog/Plastic_Condensation_Trap.html ,however it needs a drain pipe running out of the eaves similar to an overflow.
I have wound up the run on timer to 15 minutes so try and clear steam out of the ducting. I'm using these fans with the run on timer - www.fantronix.com/acatalog/TT_Mixed_Flow_Fan_4_dia.html do a good job of clearing both shower and bath steam.
I have a dicky one in that it has stopped working, it was a new replacement for an existing noisy one. Although under warranty to save messing about I bought a replacement timer circuit board for £7.25 which has still to be fitted. Yesterday I was in the loft when the fan started running on its own accord then stopped after 15 minutes although everything was switched off. The run on circuit is permanently live.
This needs some careful planning and access to get right. Certainly the acoustic ducting has quietened down the extraction noise but it is a bit fiddly to fit as you have a perforated foil hose wrapped in clear plastic, wrapped in fibreglass insulation, wrapped in foil.
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New Tue 2 Apr 13 23:31 
 Shower extract fan - Fenlander
Yes condensation can be an issue in ducts... but not if they are very well insulated. Mine are all wrapped in loft roll tied on.

>>>the fan started running on its own accord then stopped after 15 minutes although everything was switched off.

This is a sign moisture has reachd the electronics. There is an issue with many of these fans, and the company linked has some affected, in that there might not be a seal where the motor wires come from within the fan duct body to the electronics compartment. The action of the running fan produces a positive pressure which tries to push moist extracted air into the electronics compartment. If the fan body is exposed to cold in the loft this moist air condenses onto the electronics and you find the fan running from time to time of its own accourd. After a while doing this the timer board usually blows.

The cure is to take out the timer board before you fit the fan and seal the motor wire entry with silicone or similar.
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New Wed 3 Apr 13 00:19 
 Shower extract fan - Fullchat
Thanks Fenlander, that sounds like a good explanation. Silicon gun at the ready.
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New Wed 3 Apr 13 09:12 
 Shower extract fan - Fursty Ferret
>> Thanks Fenlander, that sounds like a good explanation. Silicon gun at the ready.
>>

You can get a run-on timer which senses humidity - plonk the sensor in the duct and it will run until all the steam is gone.
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New Wed 3 Apr 13 00:23 
 Shower extract fan - BobbyG
Cheers rtj, but don't waste your breath on mappy.
He is showing his true colours tonight.
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New Wed 3 Apr 13 00:26 
 Shower extract fan - Mapmaker
It's called irony, rtj! Once upon a time Bobby's house burned down and he's been the butt of jokes on here ever since! Obviously it's better for a house to burn down than to have to get a set of scaffolding in...

But anybody following my own bodge-it-and-scarper techniques deserves all I'm going to get (though clearly RP got there first and has bodged it too!)
Last edited by: Mapmaker on Wed 3 Apr 13 at 00:28
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New Wed 3 Apr 13 08:39 
 Shower extract fan - Cliff Pope
You could treat it like feeding a chimney liner down a flue from the outside. They have a cap on the end which just pulls down tight over the chimney pot.

So you could attach the grill to the pipe rather than the wall, and pull the pipe up and through with a cord. It might help to be able to poke it from outside with a long pole, fruit-picker, window cleaning thing, etc to persuade it to align with the hole (gash !) in the wall.


Just theoretical you understand. I've never done it, but I did once connect a loo pipe out through an attic wall and down the wall, standing on a garage roof and wielding a long length of pipe like a caber at the highland games.

Last edited by: Cliff Pope on Wed 3 Apr 13 at 08:39
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New Fri 5 Apr 13 11:14 
 Shower extract fan - Ambo
These fans ar usualy mounted high up, presumably as hot air rises. How would one three feet down and venting to an external wall work? The reason I ask is that I have a simple grill there, in an old gas shower unit exhaust vent. It involves showering in an icy blast if the wind is in the east.
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New Fri 5 Apr 13 11:29 
 Shower extract fan - Zero
>> These fans ar usualy mounted high up, presumably as hot air rises. How would one
>> three feet down and venting to an external wall work?

It wont, the steam (which is want you want removed) is up higher. By the time it gets low its already condensed on your walls.
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