"Bob" wrote in message
oups.com...
Well the weekend has past and here are the results of my
troubleshooting. For the sake of being brief I will use bullet points:
- With the Window open for more air flow I still get condensation
insided the vent fan.
- With insulation around the air duct and bathroom fan I still get
condensation inside the vent fan.
- I switched to the smooth metal air duct instead of the flexible type;
condensation.
- I ran the fan for 5 minutes before running the shower and for 5
minutes after and still condenstaion.
- When I turn the fan on I can hold a piece of paper by the fan and the
paper will stick to the grille.

Also just to be clear the condensation will build up over 2 days to
form standing water and ends up dripping out of the fan.

The vent flap on the roof vent opens when the fan turns on, the flap on
the fan is opens as well. The condesation is not coming back from the
vents because I have a slight angle going down, away from the fan.

A couple of other items for thought. My bathroom fan is in the attic
about 3-4 feet away from a soffit vent. It's not directly by it but
it's in the area. Also I am using aircondition/heater vent insulation;
about 3/4" thick. Could these things be an issue?

The next thing I am going to try is remove the flap from the fan, to
see if this allows faster airflow. Also someone mentioned to me that
it's possible that the climate in my house and attic is just going to
produce this affect of condenstaion so I might need to figure out a way
to get the condensation out. Possibly there is a fan made with some
sort of drip that I can attach pipe to to channel the water out;
similar to how A/C. Any thoughts on this.


I don't think that I have ever heard of this problem before. A few things
come to mind such as the CFM and the size of the duct. I have seen
instances where a 4" fan outlet is reduced to 3" duct. I am also wondering
if maybe your bathroom is too cold. Perhaps a bathroom heater might help.
I am just guessing here as I thought that the insulation would have
corrected the problem. This is a long shot, but are there any water pipes
in the vicinity of the fan?

Before you use the shower and turn on the fan does it feel cold? Do you
feel cold air coming out of it? What would happen if you used the fan
without the decorative cover on? Where is the fan in relation to the
shower?