Fight Mold and Mildew with an IoT Bathroom Fan

Delicious sheets of wallboard coated with yummy latex paints, all kept warm and moist by a daily deluge of showers and habitually forgetting to turn on the bathroom exhaust fan. You want mildew? Because that’s how you get mildew.

Fed up with the fuzzy little black spots on the ceiling, [Innovative Tom] decided to make bathroom ventilation a bit easier with this humidity-sensing IoT control for his bathroom exhaust fan. Truthfully, his build accomplishes little more than a $15 timer switch for the fan would, with one critical difference — it turns the fan on automatically when the DHT11 sensor tells the WeMos board that the relative humidity has gone over 60%. A relay shield kicks the fan on until the humidity falls below a set point. A Blynk app lets him monitor conditions in the bathroom and override the automatic fan, which is handy for when you need it for white noise generation more than exhaust. The best part of the project is the ample documentation and complete BOM in the description of the video below, making this an excellent beginner’s project.

No bathroom fan? Not a problem — this standalone humidity-sensing fan can help. Or perhaps you have other bathroom ventilation needs that this methane-sensing fan could help with?

24 thoughts on “Fight Mold and Mildew with an IoT Bathroom Fan

  1. Cool the builder hacked something together, but when I thought about it as part of my home auto, I researched a bit and most bathroom vent fans come with a humidistat nowadays, even the under $20 ones.
    So it was cheaper to swap out the noisy worn out original fan for one with a humidistat and not have to worry about it going wrong or being nonstandard for the next owner to fix.

    1. But with IoT the advertisers and government (handy f they want to accuse you of some crime) can nicely track when and how often you shower though.
      And it’s time consuming and unreliable to manually report that.

    2. Hey, I built this. I always do a “let me see if they sell this already” search when I build something I think is a new idea. Originally I was going to have it just sense the humidity and turn on the fan. I added the Blynk and WiFI as a concept building exercise and some “cool” features. I never really changed anything in the fan either just interrupted the plug, so removing it for the next owner wouldn’t be and issue.

  2. I made almost the same but adding a more responsive SHT31 (instead of DHT11) and a PIR to detect when you come in the shower. So I can start the fan before the humidity increase too much.

  3. Where exactly is the fan venting to ? If it’s an attic space with no roof exhaust, all he’s doing is eF’ing up his attic (dumping from bathroom space into attic space) – even if the attic has ridge vents/soffit vents, it’s still not a valid solution.

    1. It would be smart to check. In many places, building codes have required ventilation to go to the outside for a long time. My house was built over 20 years ago and the bathroom vents were ducted to the outside through the attic.

  4. If you continuously forget to turn your fan off, why wouldn’t you just get a bathroom fan with an auto sensor? I mean, how often are you going to need to randomly turn your bathroom fan off/on. Like Mike said solution searching for a problem.

    1. All true. However everytime I use the bathroom (number 2) I turn it on. Also if I had a “find a solution to your problem by Google searching and buying something” YouTube channel I would have done that, however I do not. My channel is about creating and building things yourself. I do realize that if you had to buy all the components it would cost as much as just buying the fan. I had all these on hand, and love experimenting.

      1. InnovativeTom – My comment comes off as kind of snide, which wasn’t the intention, so apologies for that, I should think about things a little better before I hit enter. Given the effort you have gone to, to create the app yourself I will eat some humble pie here.
        Had I thought a bit longer/harder this would be a good solution for retrofitting an already installed fan and who isn’t a fan of mobile controlled home appliances. Its good to have that option.

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