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
- MERV explained by the EPA (not a Reddit link) than you OatScoop
Sorry for the Reddit links, they just have a lot of conversations going on there currently.
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.
This is also a great idea
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.
Was it a 1" thick filter, or 4" thick?