Appropriate Bathroom Fan for high R insulated attic

7/7/2022 at 2:55:20 AM

If it is a basic fan, it totally can be installed, there are lots of pointless disclaimer's on all products to protect their butts for any possible issue such as a motor overheating and then burning out that is left running 2 days in a over insulated install. However some exhaust fans (very few) have a heat function or a heat lamp etc. and this is a thermally rated fan and may not be rated for certain insulations (check the manufactures install instructions. Personally in 35 years I have yet to hear of a fire from a exhaust fan itself! & have seen some pretty bad installs. 90% of exhaust fans generate no heat, the fan itself is in a closed metal box, what you do have to do, is make sure it does not compromise vapor barrier when installing in a attic ceiling, it is wired professionally and run the duct min 4" dia. to a point a foot to two from ridge with proper vent hood. The duct must be insulated or use insulted flex line...as well, a trick I learned years ago is to put a bend in it from vent hood before it gets to the fan to stop condensation from dropping through fan, as happens if line is too straight.