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.

  1. pam kueber says:

    Okay I’ll leave this comment as general guidance but REMIND everyone: Consult with a properly licensed professional of your very on on issues like these.

  2. Anastasia says:

    My Mother-in-Law’s old place was the same way. They used a HUGE dehumidifier in the winter & opened the small skylight in the summer.

  3. 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. 🙂

  4. Chad 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.

  5. pam kueber says:

    “Okay I got unlazy” — haha, it’s only Monday morning and I already have a quote of the week!

  6. Mary Elizabeth says:

    Not new to me, Kate. We had the same problem with birds in our old condo. Small sparrows, especially, love to get into the vents for dryers, bathrooms, etc. It was very funny that it took us a couple of springs before we figured out where all the cheeping was coming from in our downstairs powder room. We finally saw the parent birds flying in and out of the vent flaps with worms in their beaks. Then, of course, we disconnected the fan rather than kill the cute birdies! A simple solution is to install a wire cage over the vent so small animals–mice, birds, etc.–can’t get in.

  7. Mary Elizabeth says:

    Yes, when my DH was working as a handyman he found a least 50 bathroom fans that were venting into attics, some from relatively new construction. The owners would complain when the fan seemed ineffective or when they saw mold growing on the ceiling! It is against code in our area, but it sometimes happens when the plumbers, HVAC guys and the roofers don’t coordinate. A similar thing happened with our range hood in the 1959 house, which used to vent through the roof, but was covered over by the roofers, who didn’t tell the owners. Since no one was living in the house at the time and using the stove, no one had thought to check the vent. So for the first few weeks, the hood rained water and cooking grease back down on the stove. Eech! So my husband did a quick check of the roof and found no vent there.

  8. 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!

  9. 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.

  10. K slunder says:

    We just bought an old house that has an exhaust fan in our bathrooms just like this one, but we can’t find the model numbers on them anywhere…do you know what model number and brand this one is listed?

  11. Linda says:

    This may sound idiotic, but is the electrician the person to call to install one of these? I have one in my bathroom that is pretty much nonfunctional, plus it vents into the attic. I’d like to have one directly over my tub but was unsure whether to call a handyman, HVAC person, or electrician.

  12. Will says:

    An extremely easy and cheap way to check proper fan operation is to put a square of TP on the grille. If it holds then it’d working good if it falls than there’s an airflow issue somewhere.

Leave a Reply

Commenting: Information

All comments are moderated, generally within 24 hours. By using this website you are agreeing to the site's >> Terms of Service, << which include commenting policies, and our >> Privacy Notice. << Before participating, read them in full.

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.