My bathroom exhaust fan didn’t work — and I find out why

Last week, our electrician installed a new bathroom exhaust fan in our green hall bath. During the install he made a shocking discovery — the old fan hadn’t worked properly since day-one. It was doing nothing. Zero. Zilch. Nada.  Apparently this problem is somewhat common, so I made a video to help others learn about my bathroom fan problem and why it wouldn’t work.


Kates-bathroom-graphic3Since beginning construction on my retro pink master bathroom, the hall bathroom has been seeing a lot more action. We’ve never had guests complain about the moisture issues in there, even though we knew they existed. But when we started using it full time ourselves, we realized just how bad it was. So when the electrician returned to finish working on the pink bathroom, I asked him to install a new fan in the green bathroom too.

In case you don’t have time to watch the video, here’s the gist of my bath fan woes:

  • Before we began work on the pink bath, both fans vented into the attic instead of outside. That’s a code no-no these days. Also stupid, because you don’t want wet moist air pouring into your attic.
  • The fan in the green bath didn’t seem to do much other than sound like an airplane landing — our towels wouldn’t dry and funk grew back quickly on shower tiles as soon as four or five days after being cleaned.
  • As long as we were paying the electrician to come finish up our master bathroom work and vent that fan out of the roof, we had him replace and vent our hall bath fan at the same time, saving $$$ since he could do it all in one trip to our house and one trip into the attic.
  • When the electrician removed the old fan he discovered a problem that went back to the fan’s initial install: The damper that opens when the fan is on (to let air out through the ductwork), and then closes when the fan is off (to prevent back drafts), was stuck in the closed position. This meant that no air could be pulled out of the bathroom through the fan.
  • The reason the damper wouldn’t open was that when the ductwork was attached to the fan, it was mushed up against the damper, impeding its ability to function.
  • The old fan — probably installed in the 1990s — never did anything but use electricity to make noise for all that time.
  • Since the installation of the new fan, we’ve noticed a huge difference. The mirror is no longer completely fogged when we get out of the shower — in fact it usually has no fog at all. Also, our towels have been drying and there has been no “funk” regrowth since the last bathroom cleaning.

The moral of the story here — if you suspect the fan in your bathroom only sounds like it is working, it might be worth checking (or having a professional check) the exhaust vent. If the damper does not move freely, or there is an obstruction in the ductwork, your bath fan may not be able to do its job.

Read all of the stories related to my pink bathroom remodel project here.

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  1. Scott says

    Exact same thing here, all noise, no action. I’ve been blaming myself for the last decade or so that it was my fault for not spending enough on the fan to get a good one. Never considered it wasn’t installed or vented right.

    Great timing, I’m getting my bathroom painted next weekend! Three guesses what just got added to the list!

    • Scott says

      PS Kate I see the new fans are rated by Sones and CFM, is there a certain number I should be looking to be at or above to be sure the fan is effective?

          • Scott says

            Okay I got unlazy and looked up the terms at least, CFM is cubic feet per minute and Sones is a measurement of sound.

            Wish I kept the box for my old fan so I would know how much is not enough. :-)

            • says

              I had already decided on a Panasonic bathroom fan, and when I was trying to figure out how to size it I found a chart on their web site to convert volume of your bathroom (cubic feet) to required fan capacity (cubic feet per minute). Oversizing it won’t hurt anything except your wallet. I assume that this is per code.

              • Mary Elizabeth says

                Yes, Chad, we used those stats, too, when installing a fan in the bathroom of our new addition. The bath is only about 7 feet by 8 feet, but because of a last minute change in the roof design, the bathroom is tucked under a 14-foot slanted ceiling. Hence there are more cubic feet in that bath than the one with a flat 7 1/2 foot ceiling. And the fan works beautifully with all the proper venting, because my husband installed it in consultation with the roofer and siding people. Second Pam’s constant advice to consult with a professional or two when doing things like poking a hole in your roof or siding!

  2. Alice says

    Oddly, our 1957 rancher does not have exhaust fans in any of the four full baths, only in the 1/2 bath that does not have a tub or shower. That one vents into the attic. We don’t use it, but then, you generally don’t generate a lot of steam just washing your hands at the sink.

    What is amazing to us is that the other baths don’t get steamy, they are all wallpapered and the original wallpaper is still in tact and looking good to this day. No signs of mold, peeling, discolor etc. We can’t figure out how they engineered this to be the case. Each bathroom does have an HVAC intake and output vent.

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