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Cheap Covid air purifier DIY!

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  • Cheap Covid air purifier DIY!

    I’m late to learn about this great air purifier hack but thought I’d share in case it might help.... a scientist on aerosol diseases invented a way to make an air purifier using a box fan and 4-5 air filters. It reportedly is more effective at filtering Covid than expensive machines on the market and The cost to make is estimated between $50-$75. Some have used if household member gets sick to prevent in household transmission. Other reports on line are good from schools and other places with gatherings. Here are some links to directions to Corsi / rosenthal box fan air purifier: direct link ->
    Answers to the most frequently asked questions regarding the DIY box fan air filter solution, also known as the Corsi-Rosenthal box.
    Last edited by Suebee; 02-18-2022, 02:22 PM.

  • #2
    Yes I was excited to learn of a cheaper solution than the air purifying machines. Note, i found it important to get familiar with the MERV (min. Efficiency reporting value) ratings before I went to the store. I had never given much thought to the type of air filters in my home before Pandemic. They come in many dimensions and thicknesses. The CoSi diy hack says to use MERV 13 for the diy box Because it is able to capture small particles including viruses but isn’t so hard on the fan motor as a higher MERV. (The higher the MERV number the better the filter and I think generally higher the cost.) HEPA filters are even higher rated at MERV 17. We use HEPA filters in our a/c system. But for the cosi diy box hack, MERV 13 is reportedly best. The link I posted said if you can’t find MERV 13 filters due to supply chain issues it’s ok to use lower number, it’s just not as effective at purifying the air. I had to do some leg work to track down a few that were rated MERV 13 and 1” thick 20” square to fit box fan. It said thicker than 1” filter reduced life of fan motor. Good luck!


    • #3
      I made an air filter with a box fan this past summer, to clear the wildfire smoke out of the air in my house. Found a couple of helpful videos on YouTube and put one together. It worked really well.


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