Insane bathroom condensation

[MartyJ]

Are they recommended when they have 1.4m of ducting to go through?

I find it very hard to believe anyone would recommend one of those extractor fans if it was doing anything but going straight through a wall.

What does the TLC fan size calculator recommend?

Yup https://www.vent-axia.com/domestic-fan-installation-compliance-checker
Almost all of that type have literature stating that that length of ducting won't be an issue unfortunately.

Can you get into the space above the ceiling?

not easily. I think for now short showers & larger gap under the door is the temporary solution. At a later date I will take up the loft floor board but unfortunately as per the pic below, the loft floor stops a good metre or so short of the ducting and it doesn't look like there is much crawl space to work with.

I can't see why you just would not open the window! There is no better way to get ventilation and better air movement and reduced pressure for the fan, and better than any crappy 10mm door undercut. It's just so simple.

Probably too late now, but the fan or input should have been placed over or near to the shower or bath (better extract at source), and perhaps should have been an inline centrifugal fan (most efficient) with a 125 or 150mm flexible duct and no sharp bends (smooth massive air movement).

So unless those are to be altered, the window is the only practical option.

For at least half the year I'd be making the matter worse not to mention the cost of letting re-heating the room each time. Re fan placement, I tried to place between the bath and the shower for that very reason but alas, not good enough. Inline fan is the "proper" solution, just wish it was more commonly recommended. Even searching back on this forum, vast majority of recommendations are for the type I've installed but I guess the caveat is, they are absolutely fine for "normal" shower use, just not for teenagers!

 

[mikeey84]

Yup https://www.vent-axia.com/domestic-fan-installation-compliance-checker
Almost all of that type have literature stating that that length of ducting won't be an issue unfortunately.

That's crazy imo.

Did you put your room dimensions into the TLC vent check? I have a pretty small bathroom and I had to get an inline fan to hit their recommendation

 

[JohnD]

vast majority of recommendations are for the type I've installed but I guess the caveat is, they are absolutely fine for "normal" shower use, just not for teenagers!

Not by me

And no, they're not.

A 100 cu.m/hr fan is fine for a WC and, if run for long periods, will keep a bath under control, but is inadequate for a steamy shower.

Builders often fit 4-inch wall extractors because they are cheap and easy.

 

[Ivor Windybottom]

Opening the window creates an easy route for fresh air from the window to go straight back out of the fan, leaving most of the air in the room untouched. Often the extractor is quite close to the window.

Also an open window allows the wind outside to push steamy or smelly air under or around the door into the rest of the house. An extractor in an otherwise closed room ensures that the air only goes one way past the door.

Having a gap under the door is the best way. It's at floor level, the fan is at the top so the whole room gets swept upwards. The warm steamy air wants to go upwards anyway, so it partly removes itself. But you need to ensure there's a reasonable supply of air to the adjoining room. Not a problem with wooden floors, could be an issue with a ground floor on concrete.

 

[mikeey84]

Just to echo the door point- I recently had my doors replaced, and went from having a 10mm gap under my bathroom door to a very small gap, maybe 2-3mm, and condensation has gotten noticeably worse.

 

[aveatry]

Can you fit another fan - an inline one in a more accessible space in the loft

 

[freddiemercurystwin]

I open a window, all condensation disipates within a few minutes, works every time no matter what the weather. Faffing about with extractor fans when you have a window lol.