Corsi–Rosenthal Box - Wikipedia
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With the recent wildfires and the gestures broadly at the world I just wanted to share this link to the Corsi-Rosenthal Box. A simple homemade air filter that can be made with a box fan or several computer fans using off the shelf merv 13 or higher filters from your local store.

Yes, these have existed since before COVID. I had someone elsewhere get made at me because “it shouldn’t be named that! Those two didn’t invent it!” but like, I didn’t choose the name lol. Anyways, I’ve made two for my house (former hoarder house we inherited and we haven’t had the ducts cleaned yet but everything else is clean) and I can say, we both sleep better at night and they worked great through the wild fires.

Anyways, just wanted to share this as a quick little easy project. Or you know, not so quick if you wanna be like the people on Reddit’s r/CRBoxes who 3D print fancy housings and do elaborate computer fan builds. Whichever you prefer.

Edit to add: Someone posted a Build Guide (non Reddit link) on Reddit for making boxes with PC fans.

I know we don’t love Reddit links but

Sorry for the Reddit links, they just have a lot of conversations going on there currently.

  • ProdigalFrog@slrpnk.netEnglish
    5·
    9 days ago

    Personally I use a single 4" thick HVAC filter taped to the back of a box fan, which has similar advantages to the Corsi box, but in a smaller footprint, and allows it to still be pointed at things besides the ceiling.

    The 4" thick filter has far more surface area than a single 1", giving it much less flow resistance, so no danger of potentially overheating/straining the motor.

    • MaximilianKohler@lemmy.worldEnglish
      1·
      8 days ago

      I tried the single-filter design some years ago, and it worked pretty poorly. It didn’t seem to do a good job of cleaning the air, and it stressed out the motor a lot. I’d consider this 4-filter design for the future.

          • ProdigalFrog@slrpnk.netEnglish
            2·
            7 days ago

            Off ebay (though I’ve seen thicker ones in hardware stores too), they should pop up from searching 20x20x4 Merv filter (or whatever dimensions your fan is).

            The thicker ones are much freer flowing compared to the thin ones due to their increased surface area, making them comparable to a Corsi box, but easier to move around.