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Feb 3, 2021
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united kingdom
Member Type
DIY or Homeowner
Hi all,

We recently had a ground floor bathroom/wet room finished off, It's about 3.6m long by 2.7m wide, tiled from floor to ceiling and has no window in there due to a future extension that will take place on the other side of the rear wall.

Unfortunately, i've Instantly noticed when showering that alot of condensation is forming on the tiles/mirrors and the room stays really wet and humid in there for hours afterwards, which even with the fact we jackoboarded most of the room....its still giving me cause for concern. As I can see wet patches and mould forming on the grout already just a few weeks in.

As part of the bathroom fit, the spark did install a 4" Mentis, Axial type extractor fan in there (pictured). Though doing a bit of research online i'm thinking that this may be the problem as the fan looks quite weak. It has an extraction rate of 73 m3 per hour....and the ducting it's venting through is about 2.5m long...obviously with a right angle bend in it too.... which i've read could well be too long for this fan too?

Anyway long story short, i'm looking at swapping it out for something much more powerful, ideally without having to change the 4" ducting to 6". In-line types not an option as there's no access to the ceiling cavity without making a big hole everytime it hypothetically breaks down.... so i'm guessing from my basic research online that my best bet is to go centrifugal, or mixed type. Either something like the Vent-axia Lo Carbon Quadra/ Vent-axia lo carbon revive, or Airflow Icon60? all seem to have an extraction rate of 220 m3 per hour, so three times as powerful as what i've got now, so hopefully would solve this issue.

Love to get some input on this, am I on the right lines to solving this? are there other things I should be considering too? and has anyone used any of the models above and can comment on their experience? they're all quite expensive so would like to get it right!


pictures below for reference.

extractor_fan_pos.jpgIMG-0909.JPGIMG-0912.JPGIMG-0911.JPG
 
Fwiw concealing an inline fan above the ceiling needs access
Yes, i'll update shortly doing the work now - we've added an access hatch for the ACM 125T Vent axia.

Quick question though - when swapping to the solid 5" ducting, we've found a horizontal piece of timber spanning the joists and it wont allow enough space to get the 5" ducting through.

As an alternative - is the flat/rectangle ducting any good? If so what size is equivalent in performance to 5" round? As that may be our only option short of notching out this piece of wood.... but it means ceiling down if so.
 
Update on this one - Couldn't get the ACM150T in there as there wasn't enough height clearance in the ceiling cavity.

But the ACM125T went in there.... just.... now with 5" solid ducting It's blowing super hard and really not that loud.

No condensation on the walls even during a long shower now, and id say leaving the fan on for about 5 mins post using the bathroom, even the glass shower door was bone dry.

Overkill, perhaps.... but we got there in the end, thanks for all your help.
 
Couple of photos im putting up too before i close the chapter on this one haha.

Forgot to mention when we cut a hole up there and found the old flexible ducting, the installers had nailed an electrical cable to a joist to 'hold' the ducting in place, I presume before the ceiling went up....but the cable was completely throttling it. I guess that explains why the original Axial fan I had did F-all. Certainly wouldn't have helped anyway.

And the other photos, ACM125T neatly in place, solid ducted up and a neat little hatch I made for an access panel should it ever break down in future 😀

thanks again all.

IMG-1413.jpg

IMG-1669.jpgIMG-1670.jpg
 
Not to dampen your enthusiasm for a job well done but until the winter arrives you won't know ho effective the solution is.

Bathrooms need a lot of heat AND ventilation ..................
 

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