[6DoF]

so i watched a furnace air filter comparison that had some great data in it. long story short, this was actually better! these are the cheapest filters i could find, so any advantage is good.

filter set-up #1:
2 stacked filters ... was thinking why not double filter it. one filter area, but had to pass thru 2x the thickness of material.

filter set-up #2:
2 filters in a triangle for double the surface area, single thickness.

the larger surface area means slower air speed over the filter, less pressure to pull junk thru. you can also see a more even distribution of the dust, so it's using a larger area of the filter more efficiently.

these 20x20 filters are $11 for a 3pack at Home Depot, and there's no dust worth worrying about on the stuff behind my fans. the box fans can't generate much pressure like a squirrel cage fan, so they don't flow a ton of air thru the filters to catch everything. any dust they don't catch however is generally dropped on the floor between me and the filters for easy sweeping later.