It took me about 50 minutes to build this Corsi-Rosenthal air filter box with parts from Home Depot here in Toronto. It’s a 20″ box fan, four 20″x20″x1″ 3M 1900 air filters (1″ deep), some duct tape and cardboard. The cardboard came from the fan’s box and from a grocery delivery, so you can use just about cardboard you’ve got around. The shroud has a 15″ diameter hole, as suggested by David Elfstrom on Twitter; he ran some tests on this particular fan model and so if you have a different model you may wish to consider a different diameter.
It took me about 50 minutes to build this Corsi-Rosenthal air filter box with parts from Home Depot here in Toronto. It’s a 20″ box fan, four 20″x20″x1″ 3M 1900 air filters (1″ deep), some duct tape and cardboard. The cardboard came from the fan’s box and from a grocery delivery, so you can use just about cardboard you’ve got around. The shroud has a 15″ diameter hole, as suggested by David Elfstrom on Twitter; he ran some tests on this particular fan model and so if you have a different model you may wish to consider a different diameter.
