University of Michigan Medicine published an instructional video on this in 2011[4] and there are many online discussions and DIY blog posts predating 2020[5]
Both those links are about 1-filter designs though. This is a five filter design which performs better than the sum of its parts. Couldn’t find any sources on that existing earlier, should be added to the article if so
Indeed.
Both those links are about 1-filter designs though. This is a five filter design which performs better than the sum of its parts. Couldn’t find any sources on that existing earlier, should be added to the article if so
Edit: found an imgur from 2018. https://imgur.com/gallery/hepa-filter-companion-cube-box-fan-jtECP9C
Found a triangle from 2012 https://marshallhansendesign.com/2012/01/02/studio-operations/
Unfortunately both those sources are not sufficient for Wikipedia