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
- Here’s a Reddit post for a DIY/buy guide
- An Information post
- A tall computer fan box
- Triangle box fan
Sorry for the Reddit links, they just have a lot of conversations going on there currently.
I don’t think we have those here
They are also known as HVAC or MVHR filters, which appear to be available in the UK
Based on this chart, you’d want an M5 or M6 rated filter to remove car exhaust particulate, something like this (though I have no idea if that’s the best deal to be had, that site was just the first one that popped up from searching UK HVAC Filter).
Edit: Hm, I guess the bigger problem is that you guys don’t really have box fans over there, and the ones available online there need a 120v step down transformer. Bugger :\
I guess you could still attach a 4" or 3" thick filter to the back of a large round fan, then tape cardboard cutouts on the corners that the fan doesn’t cover, and seal the sides of the fan with tape so it doesn’t try to draw air from the sides, and exclusively pulls from the filter… That should still be pretty effective.