How to fit a good in line bathroom fan in loft and reduce noise?

Buffman · 20 May 2022 at 14:57

Hi all,

Im renovating my bathroom and want to put a centrifugal fan in the loft.

Ive already got the electrics sorted I just want to know best way to dampen noise?

Should I make a timber frame hanging from the purlins?

Could I mount the fan vertically and point it straight out the loft almost? Any advice on how to avoid condensation?

Is there any particular brands that are good?

I was going to use this fan cover (probably size 100mm unless someone can convince otherwise?)

https://www.amazon.co.uk/dp/B004X4SZ92/ref=cm_sw_r_apan_i_RVAMDJVYHPQGBJDY35ME?psc=1

Considering this fan

VENTAXIA ACM100T Mixed Flow Inline Duct Extract Fan

Shop Mixed Flow Inline Duct Fan with timer for 100mm ducting. Offers 2.5 times pressure of conventional axial fans, and are dimensionally more compact.

www.i-sells.co.uk

Or would something like this be far better?

6''/150mm In-Line Duct Extractor Fan - Silent 500m3/hr c/w Timer | Soler_&_Palau (5211366400)

I was going to use 150mm flexible insulated ductwork which I already have from another project. In that case should i go with larger diameter fan or is it OK to jubilee clip ducting at ends?

Is there any issue with using Flexi ductwork? Rigid wouldn't work too well in my situation but I'll try avoid bends.

Im currently boarding my loft out and can see in situ progress pics below

The old fan is located behind the attached (can see white ducting) with the fan tied straight onto the ceiling header joist.

Other side of loft

The bathroom is not yet finished but is being tiled next month the fan will be going above where the shower is (on the right of this photo)

Buffman · 21 May 2022 at 18:37

ANDARIAL said:
Not a good idea with this type of fan as condensation`could`drip back into the fan .Mount horizontally with a drip loop in the ducting.Also insulate the duct or get some already insulated.Mounting the fan onto a flexible substrate like kingspan or rubber may help
But keep the fan open to the air to avoid overheating

when you say drip loop do you mean a condensate drop out line? I'll try without at first as even if it drops out it would be back into the shower tray. also I have some 150diameter ready insulated ducting so I think I'll use that

Buffman · 21 May 2022 at 21:38

Mysterae_ said:
I don't like the flexible ductwork as it's a place for condensation, moisture and fluff to accumulate then it'll slowly start to rot. It'll be okay if you plan to maintain it every year or so, checking for water build up.

Wow that's a neat install. Were you not tempted to tie it from rafters?

Ive gone for the 250quid fan above, but will just use insulated Flexi and see how I get on. I figure it's a 150mm diameter so should be fairly good.

Buffman · 22 May 2022 at 01:00

Mysterae_ said:
Thanks, never thought about tying it to the rafters in all honesty! I wanted a short as run as possible as I had to make a new hole in the outside wall for the vent - the previous owners didn't.

£250 for a fan seems like a lot, I think my Vent Axia one was half that price.

Yeah I've seen them tied to rafters before for the same reason of noise transfer. I think making it from fully rigid ductwork is good, but just a bit of a pain in the arse for a lot of setups

Buffman · 22 May 2022 at 14:25

Participant said:
In terms of what to mount it on, I've used gardeners' kneeling pads before to good effect.

Cheers that's a good idea! Might do the same and get a new one. Did you fit yours to loft floor or ceiling?

Buffman · 22 May 2022 at 14:26

ANDARIAL said:
We have got a soil pipe duct in the ensuite as well but we find it a bit noisy and echoy.
Re drip loop i mean in the length of duct make a section lower than the fan either side somewhere.Personally i do not think covering the fan is a good idea heat wise.Just my opinion

No I wouldn't insulate or cover the fan. I will insulate the ductwork /use insulated ductwork

Buffman · 25 May 2022 at 19:27

Gammawolf said:
Jesus, £250 for a fan. Screwfix has the Manrose MF100T 100MM for £100 which even still seems expensive as i'm sure i got my 3 for £60 each a couple years ago.

Aye a bit expensive but I guess the equivalent would be the same sized 150mm fan from manrose. It's a bit of a monster size but we'll see how it performs. I already had a 150mm holesaw so that's saved me 30 quid

Ive never had the novelty of a bathroom without condensation problems! For an extra 100 quid or so it's inconsequential compared to the rest of my new small bathroom, all costs are mental at the moment. Think it's gonna cost me around 8k to 10k supply and labour for my bathroom and I did a lot of the fitting myself (got a tiler/Plumber in for some of the harder bits)

Due to the position of the roof tile outlet I think I'll need to mount it to the floor boards.

Buffman · 3 Jun 2022 at 18:01

Fitted it!

Have to agree it was slightly OTT so gone for the lower speed setting. At least i think it's on lower setting..

Only issue I have is the old outlet leaks air back in. If I staple it back to felt and cover with duct tape is that sufficient

@Participant idea for using foam underneath the fan was a good one.

Cant hear any fan noise but the air movement noise is more of a deal than i appreciated!

Old outlet

Fan