I have this model range fan from NuTone.
Condensation from steam (say when boiling water) forms on the underside of the unit and retaining bar that holds motor that drips back down onto the range. It's nasty and I have to wipe it down before it gets into the food (which is pretty much the entire time).
The fan is ducted outside through a long (> 20') flex pipe like this:
Here is a picture of the water condensed on the retaining bar (the mesh filter cover is removed so you can see what is going on).
It slides down this bar to the metal cover where it accumulates and then drips back to the range (or into the pot). The scrunched up paper towels are there to soak up the water before it drips back down. I have to change these regularly.
Typical boil during homebrewing..in fact this is the boil that caused dripping in photo above.
The damper is not closed. The duct has no blockage. The exhaust coming out of the duct is strong. It does this year round, hot outside, cold outside, a/c on heat on in house. Dry weather/humid weather.
Do I just need a better fan?