Why is the bathroom fan completely ineffective


I just moved into my first home, and the bathroom fan is 100% ineffective. I can hear the motor run when I turn it on, and I remember going into the attic with the home inspector and tracing a flexible duct from the fan fixture out to a port on the side of the house. The fan was installed when the previous owners renovated the bathroom three years ago, so it's unlikely it's worn out from age.

But when I turn it on, it has absolutely no effect on the moisture in the bathroom. Water collects on the ceiling and fogs up the mirror and window. The only way to dry the bathroom out after the shower has been used is to open the window or open the hall door – both of which are very slow.

If I hold up a piece of tissue to the fan fixture, it doesn't blow around at all.

What can I do to fix this? Do I simply need a new fan fixture?

Best Answer

Various things to check:

  • Is there a way for air to ENTER the bath? A fan will expel air, but only when there is makeup air to replace it. Make sure there is a sufficient gap under the bathroom door. (An easy way to test this issue is to run the fan with and without the door open and see if there is a difference)

  • as others have stated, make sure the fan is clean.

  • as others have stated, check the flexible vent pipe

  • consider replacing the flexible vent pipe. Flexible pipes aren't very efficient in that they add a lot of resistance to the airflow and also snag lots more debris. Consider replacing with rigid vents.

  • as others have stated, make sure the vent on the outside isn't clogged (e.g. bird nest in pipe).

  • consider a larger fan. It could be that the fan is simply under-powered for the size of the room and length of the vent pipe.