Do I need another bathroom exhaust fan?

[PatDIY_Dad]

Hi

We have a double shower with 2 shower heads. Wife and kids love staying in there too long with the water really hot to create a sauna effect

We had just a regular exhast fan that only pulled about 300m3/hr of air ( those standard ones that builders supply)

The bathroom would have water running down the walls. This can create mould so I took out the fan and installed this:

https://www.bunnings.com.au/deta-250mm-high-capacity-exhaust-fan_p4441224

I think its better but I still see wet walls on the high spots of the walls. Which means also the ceiling is probably also wet

( check video link cant upload videos https://photos.app.goo.gl/SJ7UxjvoDzNecjkdA )

Two questions

1. Would I just need to install another fan thats closest where the most steam is settling?

2. Our exhaust fans are just vented to the roof cavity. Would it be better to vent out into the roof? If so what do I need in order do this? If I install a 2nd fan can I join 2 ducts into one larger one to just install 1 roof cowl? or would 2 roof cowls be needed ? ( more work )

Thanks !

[EricL]

Hello @PatDIY_Dad 

I'm always a bit hesitant when penetrating the roof, I recommend ducting to the eave as I feel this is a much safer option. 

Eric

[PatDIY_Dad]

Its alot easier yeh. If it were a rangehood for cooking I would go on the roof so no grease sticks to my walls or eave but if its just shower steam eave would be find I feel

I was thinking something today if I could install 2 fans and duct both of them out to the eave but just have one vent with a Y adapter just at the end. It would save cutting out 2 holes for 2 outdoor vents

I dont think id get any back draft because I would do it right at the end of the ducts

But I just need to find some sort of Y shape PVC or pipe or something that can connect 150mm connections on all 3 holes

like this but unsure if all are 150mm:

https://www.ozlighting.com.au/products/fantech-trade-y-pieces-and-branch-take-offs?variant=397567126...

cant find anything at bunnings like that

[Dave-1]

Good Evening @PatDIY_Dad 

I like your thinking, Ive just been trolling through looking for that Y shape adaptor and 😕 cant really find one within bunnings. You could make a join with the duct pipe itself tho, as in a 30 degree diagional cut (long) so the two pipes merge into one and then duct tape them on the outside? You could wrape plastiuc around the joint first kind of like a bandaid effect and then ducttape the lot?

Dave

[JacobZ]

Hi @PatDIY_Dad,

The closest I can find is this Holman 150mm 45° PVC Junction. You could join it using the zip ties and insulated duct tape, as mentioned above.

You could give it a try, but if you have any backdraft issues, you might have to remove the join and duct to two separate vents, so maybe leave the ducting long enough that this is possible if you have to remove the adaptor.

Let me know what you think.

Jacob

[scottjepp]

Firstly, you MUST vent it outside,  it fails code by only venting i to the roof space, it creates an environment perfect fir growing mould so beware, i would get it checked. You need to run the ran whilst shower is in use, and keep them as short as possible, if walls are still wet you do need better extraction, but you also need a source of fresh air yo come in and replace what's extracted, without a window cracked open you create negative pressure in the room which stops extraction due yo the higher pressure outside. So I would have 2 or 3 fans, one centre and 2 corners, a windows cracked open or larger gap under the door. You likely have mould already if the Aussie has existed for months, start saving now for ceiling replacement and mould testing for the roofspace and likely i solution replacement due to mould, plus treatment of the frame, again, gof mould.. good luck mate, sorry you got a bad build..