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. 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.

  2. 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.

  3. 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?

  4. 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.

  5. 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!

    1. 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?

          1. 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. 🙂

            1. 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.

              1. 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. pam kueber says:

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

  6. Joe Felice says:

    UBC requires a bath fan only if there is no window. If you have an older fan, check to see if it is thermal-overload protected. As a property manager, I have seen several fires due to overheating motors in exhaust fans. Generally, fans manufactured before the ’90s were not protected. All fans now are required to be. What happens is that the motor can overheat (especially if left on for extended periods), and then ignite the “gunk” which has been referenced here, or the insulation. You would be amazed at the amount of gunk that collects up there, on the fan motor, the housing and in the ducts. Lint, hair and dust accumulate, and, hair spray, being very sticky, binds them together and to the fan parts. Once coated, the motor easily overheats. It’s not a bad idea to remove the grill and vacuum out the housing area every so often.

    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.

  7. Joel says:

    I think a lot of the venting problems are because the workmen are thinking the problem the fans are supposed to solve is odor versus moisture. I had my house built in 1995 and was irritated to find the electricians had installed the vent fans in all the bathrooms over the toilets versus nearer the showers and tubs.

  8. Kathy says:

    I bought my 1970 house three years ago, and I had an exhaust fan installed in the bathroom. Can’t tell you how many professional people told me I didn’t need it, since I had a window in the bathroom. I put one in anyway and haven’t regretted it.

  9. Carl says:

    We had the same problem in our bath…noisy fan, and when I went up into the attic to check on things, I found the usual venting into the attic with no ductwork at all. Replaced fan with a new Panasonic, and did the necessay ductwork (easy job,there was a vent out the top of the roof which just needed to be connected to the ductwork). Not especially fun to work in the attic in sunny South Texas, but such a nice change. Btw, your tub looks exactly like ours! Even the color….

  10. Jennifer Kepesh says:

    Our house, built in 1958 in a state that doesn’t worry that much about code, had three bathrooms, only one of which had a fan. We just demolished that bathroom. The second bathroom has a window. The master bathroom, just as tiny as the other two, has a skylight that doesn’t open. In the winter, we turn on the heater and that dries things up as it warms our toes, but in the summer–oh, well! The house is adobe; we have a flat roof, and I have no intention of getting rid of the skylight, so I guess we’ll just have to live with the consequences.

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