Shower/wetroom extractor fan questions

gg3390

hello,
Hoping to get some advice on fitting a shower extractor fan during a bathroom renovation.

Bathroom is being retiled at present - there was never any extractor fan - we just opened the window after showers. However, we have had some mildew/mould on the tiles nearest the ceiling and on the ceiling itself. Additionally, some paint flaked from above the shower.

Hoping an extractor fan, together with a small cut from the bottom of the bathroom door will rectify this when the room is complete. I'm struggling though with how to complete the extractor. I have (left over from a friend) a Vortice Ca100 inline fan, but Ive read conflicting reports on what ducting to use, and to where.
We have no vents in the roof slates - all vents are every metre or so along the soffit. I was hoping to install the fan outer vent in the soffit (obviously will be pointing down). However, reports say that this will allow moist air to reenter the attic through the adjacent existing soffit vents.
Also, as the attic is converted I've just about enough access to get to over the shower, so I'd need to turn the ducting from above the shower 90degress immediately over the ceiling, before running to the inline extractor, then continuing horizontally over the insulation to the wall plate and down to soffit.

My questions, if anybody would advise, are: -

1. Is it ok to vent to the soffit - or am i better off venting to one of the gables (longer run)
2. Do I need to use insulated ducting?
3. Will moisture condense in the ducting, and if so how do I get rid of it
4. The fan output/input is 4in/100mm - would I be better off using rigid piping, with a slight fall to the soffit - but this would assume that if there was condensate, it would occur after the fan, and not between fan and shower

I have read that roof exits built into the tile/slate are the better option, but this would be very awkward, so I'm hoping the soffit is acceptable, if I place the exhaust between two existing vents - approx 1.5-2 m from each one.

In relation to the roof vents, considering that the fan would be piped nearly vertically, where does the condensation go - does it drop back down to the shower.

I'd appreciate any advice at all, as I'm pretty confused with probably information overload on this.

Many thanks in advance.

If there is a window in the room it must be on a external wall.
I'd drill a **** load of long 6mm holes and break out a 4" hole and save the messing.
Yes you will probably damage the outside render but a bit of sand and cement and its fixed.
Straight through with a bit of solid pipe,expanding foam around it for good measure.
You'll need to put an isolator on the fan so keep that in mind.

keithdub

Dont have it over your shower!!! if I was you I would get reci in. You will need to wire it through a isolating switch. The shorter the duct the better.

Lumen

I went through this whole thought process (including centralised mechanical extract) and am now at BrownFinger's suggestion - what's the point in venting through the attic if there's an external wall right there in the room?

I might go with decentralised HRV or just keep it simple and live with a bit of heat loss from a humidity-controlled fan dropping to trickle, and undercut the doors to pull fresh air through the other rooms.

gg3390

Thanks all - yes, understand in relation to the wiring, and I can deal with that as have an electrician to deal with that end, which appears easy as I can get to whatever wiring required in the crawlspace.
It's the other stuff/wall as a poster stated thats the issue.
I do have an external wall, but it's at the opposite end of the bathroom from the shower, and the room is pretty large. I just thought that the inline fan in the attic would be simplest, but appears that there are lots of caveats....

GolfNut33

I was in exactly the same position as you. I didn't want to have the vent on the external wall as its brick on the outside and it would be an eye-sore.

I installed an inline fan which is in the attic and vented through the sofit via an uninsulated duct. The length is short, maybe 3 meters in total. It's in about 3 years and working perfectly, no moisture coming back in to the attic and no condensation coming back in to the attic.

MegamanBoo

I put mine in the attic and wired directly to a pull switch outside the bathroom door. I think the standard on this is to wire with the bathroom light but that can be a pain if you don't want the fan coming on at night.

Chicoso

I think out the roof is supposed to be the best method?

How well does a wall fan work if the wind direction is against it

Chicoso

I fitted inline fan to soffit, that wouldn't be the best way of doing it. Watch the turbulence and water run-off.

Wired it to come on automatically when the shower heater elements kick-in, wouldn't be many bothering to go that trouble but it's very convenient

gg3390

I was thinking that the wind might not have a huge effect when the vent is in the soffit - should be pointing downwards, and unless theres a huge air differential going upwards (on a 2 storey house) it should be ok.

Also read that roof is the best place, but have issues with leaking velux windows already and don't want any more. Having said that, if the roofer has to lift tiles to fix the velux, might be option to put in a vent tile for the fan also. Will see what he says.

@chicoso - you mention water run-off - could you elaborate? Again, I read some stories of standing water in the pipe. There is a post with pics here on boards of a situation where that occurred.

gg3390

I know you can put a condensation trap inline with the fan - maybe that's an option...

Chicoso

I used sewer pipe with a bit of flexible both ends , covered it with fibre glass,easier to run off the water and better airflow

I would buy a good fan if you're going this route

Chicoso

Wall fan you would.need to confirm with the spark because of the bathroom zones

No point just knocking out a hole first

gg3390

very true. Thanks