Condensation In Bathroom With No Window - Best Extractor Solution?

[Pgeddon]

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.

 

[Murdoch]

Flexi vent is 100% rubbish on anything other than runs that are short or need to go around corners

concorde was shaped as it was for airflow reasons

 

[Pgeddon]

Flexi vent is 100% rubbish on anything other than runs that are short or need to go around corners

concorde was shaped as it was for airflow reasons

Sure - but if the problem is fixed, i'll stop there.

if it comes back with a vengance in the colder months as you rightly pointed out - i'd swap the ducting then I guess.

 

[Timmy D]

Sure - but if the problem is fixed, i'll stop there.

if it comes back with a vengance in the colder months as you rightly pointed out - i'd swap the ducting then I guess.

We appreciate your replies/updates 👍🏼

 

[Pgeddon]

Update on this one,

So i've had the crappy extractor fan swapped over to a Vent Axia Lo Carbon Quadra, Centrifigual type extractor fan.

At maximum speed setting (220 m3 per hour), it is preventing moisture in the room, but by god is it loud, its deafening when you're in the room at round 50decibels.

Not something i'm going to be able to get used to unfortunately. So i've tried setting it to half speed (110 m3), noise is then a bearable 37db, and it does keep the moisture off the surfaces for i'd say about 5mins of shower time, but anything longer than that the room does start getting quite cloud, as if it that there's just too much vapour for it to deal with eventually. At which point it does start to form on the tiles/mirrors etc.

That said, I left it running after 10-15mins after the shower stopped and after that time, the room is quite dry again.


If it only stays wet in the room for 10-15.... will that still be an issue with damp / mould eventually, or is that OK?

 

[ShaunCorbs]

That should be ok

 

[Murdoch]

I thought you said the red lines were marking where the vent runs ????????

extractor fan swapped over to a Vent Axia Lo Carbon Quadra, Centrifigual type extractor fan.

At maximum speed setting (220 m3 per hour), it is preventing moisture in the room, but by god is it loud, its deafening when you're in the room at round 50decibels.

You haven't been using it for long enough to draw any conclusions - and remember its a warm dry time of year

20 minutes minimum for the over run timer IMHO

 

[Pgeddon]

You haven't been using it for long enough to draw any conclusions - and remember its a warm dry time of year

20 minutes minimum for the over run timer IMHO

Yeah fair enough, I need to cut a hole now anyway as the spark seems to think the ducting vent on the exterior wall has been cored out too low, meaning the ducting wont be running straight acrosss the ceiling cavity but instead will S bend down for some reason. He advised that needs addressing, so we're gonna cut a nice hole over the bath and see about fitting an Inline ACM125T in there instead.

125T is 30db at max speed of 330 m3 per hour. Just a case of whether we've got enough room in the ceiling cavity, but we need to cut the hole anyway now to see whats going on with this ducting regardless so can't hurt to try and fit one in there at the same time!

 

[Murdoch]

You need to have a steamy shower and see how the fan gets on, then do it again and partly open and see if it clears quicker - if it does then the gap under the door isn’t enough

 

[gpbeck]

Narrow ducting will be noisier, higher velocity and turbulence.

 

[Ben-gee]

Look at Manrose MF125T, 310m3/hr at 25dB

I’ve used the 4” version a few times when there’s a long ducting run as axial are rubbish unless just pushing through a wall.

Again, I use rigid duct where at all possible.

 

[Murdoch]

Fwiw concealing an inline fan above the ceiling needs access

 

[Pgeddon]

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.

 

[ShaunCorbs]

You can cut / notch this timber it’s only there for cross support and tbh 2” is fine

 

[Ben-gee]

204 x 60 is 5” equivalent
220 x 90 is 6” equivalent.

 

[Pgeddon]

204 x 60 is 5” equivalent
220 x 90 is 6” equivalent.

thanks - don't have any where near the width for that. So notching out it is!

cheers

 

[Pgeddon]

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.

 

[Pgeddon]

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.

 

[Murdoch]

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 ..................