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.