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.

 

[ShaunCorbs]

You need a vent / ventilation for the shower area as that fan isn’t doing nothing where it’s positioned

Also supply air is needed

 

[snowhead]

The first thing you should be considering is, is there enough air getting into the bathroom to replace the amount you are currently trying to extract.
Is there a vent in the wall / door or is the bottom of the door cut to leave a gap, connecting with rooms ouside the bathroom.

 

[gmartine]

That's a rather opulent bathroom, couldn't you get some slaves to waft the steam out of the door?

 

[gmartine]

On a more sensible note, you could swap out the shower downlight with a combo downlight extraction fan.

 

[Murdoch]

On a more sensible note, you could swap out the shower downlight with a combo downlight extraction fan.

bad idea. Those are rubbish imho

 

[Murdoch]

What is the fan duct made of ?

 

[Murdoch]

I suspect you have a number of issues here

1. how long does the timer stay on for after the lights are switched off ?

2. how big is the gap under the door ?

3. what is the fan vent made of?

4. how is the room heated?

 

[Pgeddon]

thanks for so many replies already folks, already things that i obviously haven't considered such as sucking air from outside the room.

I suspect you have a number of issues here

1. how long does the timer stay on for after the lights are switched off ?

2. how big is the gap under the door ?

3. what is the fan vent made of?

4. how is the room heated?

1) I've left the lights in for 2hrs after a shower to see whether the timer was the issue, still had misty mirrors and water on the tiles and grout / felt muggy when entering the room.

2) slightly undulated, 8mm at the most, 4mm at the worst.

3) looking from the outside of the property back through the external vent, it looks like a tin foil type, so i'd assume a flexible aluminium? It's circular too, not the flat type.

4) Two ways, there's a wall rad on the right hand side between the basin and door. and it has an electrical type UFH too. Though when using the bathroom so far i havent had either of these on.

One other thing i've just noticed, when I hold my hand over the external vent I should feel air coming through there when the fan is on right? obviously I appreciate the stupidity of that question but I'm just not feeling it....it feels slightly warm, but not as if it's blowing onto my hand.

 

[Pgeddon]

The first thing you should be considering is, is there enough air getting into the bathroom to replace the amount you are currently trying to extract.
Is there a vent in the wall / door or is the bottom of the door cut to leave a gap, connecting with rooms ouside the bathroom.

No vent no, hadn't considered this. But I have showered once with the door wide open, didn't appear to make a huge amount of difference.

 

[Pgeddon]

You need a vent / ventilation for the shower area as that fan isn’t doing nothing where it’s positioned

Also supply air is needed

I think it's going to be a little bit of a pain in the backside to do that now. As the ceiling joists run front to back in that room and the channel i'd run the ducting down from the shower will have a whopping soil pipe between that and the external wall... so not even sure its possible. on the attached, blue is the proposed shower vent, green is where the soil is running horizontally.




That said, most of the moisture is on the other side of the room, the far back side, furthest from the shower... so it's like the vapour is just not being sucked up by the extractor fan as it passes by.....

 

[Murdoch]

If the red x is where the fan is, it is in the wrong position imho.

it would be more effective over the shower so the air drawn under the door pulls more air through the shower area and out

aNS as the shower has its own ceiling then the air directly above it is unlikely to clear

 

[Pgeddon]

If the red x is where the fan is, it is in the wrong position imho.

it would be more effective over the shower so the air drawn under the door pulls more air through the shower area and out

aNS as the shower has its own ceiling then the air directly above it is unlikely to clear

Yes, I see what you're saying, though I replied to a separate comment about how im not sure thats even viable due to the joists and soil pipe positions... (attached below) blue is proposed fan over shower, green is soil pipe, red is where current fan is. I cant see how i could then duct it to the external wall at the back with the soil pipe in the way like that.

As its unlikely I can get it vented above the shower.... I guess.... where's the next best place for it? even further from the shower would be bad, right?

 

[ShaunCorbs]

The problem is with the room being on the larger size and not being in the correct / ideal position your going to have to up the output eg increase the dia to increase the air changes in a room

I would say a 6” would struggle 8” would be better as it would change the room air once ever 2-3 minutes

 

[Pgeddon]

The problem is with the room being on the larger size and not being in the correct / ideal position your going to have to up the output eg increase the dia to increase the air changes in a room

I would say a 6” would struggle 8” would be better as it would change the room air once ever 2-3 minutes

Interesting, I cant say i've seen any centrifugal type ones yet that have bigger ducting than 4"....

Plenty of axial types but they're generally less powerful arent they? Icon60 by Airflow was the biggest axial / hybrid type I saw and that was 6" but it got lots of awful reviews. So thought a 4" vent-axia centrifugal might be enough, based on the flow rates they advertise they look pretty powerful to be fair, over three times the extraction im getting currently. Louder ofcourse as the trade-off, but that's not an issue really.

Vent-Axia Lo-Carbon Quadra TM With PIR & Timer (439253)

Vent-Axia Lo-Carbon Quadra TM With PIR & Timer (439253). Fast and Free Delivery Available. Trade Quality with Low Prices.

www.electrical2go.co.uk

says it'll do 60l per second, vs my current one which does about 19.