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.

  • InputZero
    3·
    8 hours ago

    A box fan with a filter slapped on each side would probably work nearly as well for half as long. This is assuming that the filter doesn’t starve the fan of air. Filters are more or less all about surface area. Two filters instead of four means half the surface area doing the same amount of work.

    Tldr; the cube is better, but even a single filter on a fan is better than nothing.