How to stop bathroom extraction fan dripping?

[PebblesCat]

I have installed a Martec Linear 3 in 1 fan in our ensuite bathroom. The fan was chosen due to limited space between ceiling and roof as it has a low profile, it is ducted using flexible duct to the adjacent roof space of the main part of the house. Our ensuite was added to the side of the house and as such has a sloping ceiling of approx. 13.5 degrees. 

My issue is that when cold the moisture being drawn into the extraction fan condenses and funnels down to the lower edge of the extraction fan damaging the plaster and causing a drip.

Does anyone have a suggestion on how to avoid this damage or of a replacement fan option?

[Jewelleryrescue]

Hi @PebblesCat 

Ummmm

Catching  those drips is a tight sort of  plumbing problem to solvie it that way.

There are fans  with one way butterfly shutters but they mainly designed for stopping cold drafts entering the house through and exosed fan opening in winter and not water tight.

Can I suggest the trialing the  fan staying on for a longer period manually at  first.  The idea  is to air dry the vent for a longer time.

 say 30 mins asa trial time.  Fans  dont use much  elecicity costs  certainly  less than  fixing the  damage.

Later if this mini  experiment works  put a timer onto the fan  switch for auto turn off after use.

Hope  this works for you,

Ps  Fun  fake fact  

"   Um   " is  the atomic symbol  for  confusion as per my first  sentence of the  post.

[JacobZ]

Hi @PebblesCat,

A warm welcome to the Bunnings Workshop community and thank you for your question.

It's hard to say what can be done without seeing the duct. If you have access to take photos, this will certainly help. 

Let me know if you need a hand uploading images, I'm happy to help if you need it.

It's great to see @Jewelleryrescue has already jumped in with some information.

Are you aware of how the duct sits inside the ceiling cavity? Does it run straight up from the exhaust or does it curve immediately behind the fan? Does it have any insulation?

You may be able to insulate the duct to reduce condensation forming on the outside of the duct. Wrapping the duct in some Moroday 750 x 10mm x 1.8m Foam should help, but I'm not sure it would totally eliminate the problem.

Allow me to tag @Nailbag and @Dave-1 to see if they have any thoughts.

Jacob

[Jewelleryrescue]

Hi @JacobZ 

I see you where seeing condensation on the outside of the duct.

I was  thinking bath room steam condensation inside the  pipe 

LOL  well now there  is solutions  for both scenarios  Merry xmas

[Dave-1]

Good Afternoon @PebblesCat 

I was just going through the instalation instructions for your fan unit Linear 3-in-1 Bathroom Heater with LED Light, Exhaust Fan and Heat Lamp and on the second page item 8 it implies that the duct should go to the outside of the house. In as straight a line as possible. Since there is a reverse stop on any air coming back through the unit (it actually sounds like a nice heater/exhaust) I think the air escaping straight outside would do away with condensation. 

Note it also recomends not to put things around the exhaust, not sure if it means the pipe or the unit.

Is there a chance you can exhause to the outside via the roof or through a side wall so the angle is always up and out?

As a fix tho not sure if it would work/warranty wise or safetywise, you could extend the duct so it goes up and out of that main house space by installing an inline fan that kicks in when the exhaust kicks in for the ensuite.

Dave