Granted, I used a blower fan as instead of the box fan the canonical design uses.
Due to a series of unfortunate events, we've found ourselves with a reasonably clean basement. One of my wife's biggest complaints about the basement had always been dust. Dust from my very infrequently used wood-shop. Dust from the litter box. Dust from... well, dust.
The new basement seemed like a good excuse to take a crack at the dust situation and this design sprung into mind.
I built it with four 16x25 MERV 11 filters, some plywood, some 1x4s, some plumber's tape to hold the fan in place, and the aforementioned blower fan. I could have gone for a higher MERV rating, but I didn't feel the need to go super overboard. I can also crank the fan for multiple consecutive passes. That's the whole idea of the design after all.
The box itself is only held together with tape and the weight of the fan. Now that the basement is more together I might model and print some brackets to make the box more solid.
One cheap motion sensor plug later and the air down there is honestly pretty fresh
Potentially; but the more the side filters fill/clog up, the more resistance they'll create, causing more air to be drawn from the other less-resistant filters. (As long as there's actually a gap between the fan and side filters ofc)
I tried this with a single filter on a standard box fan a month ago, but it didn't have enough pressure to draw much air through a single filter; prefering to pull air through the fan itself, around the edges of the fan blades in the gap between its rotor and box frame.
A carpet blower like what op used would have much less issue with that.
If you put a flat piece with a hole cut in the center over the fan face it will keep the flow coming from the filter and not the sides of the fan. Like this example, the cardboard forces the air to come from the back and not the sides.
Spot on!
Fear not, there's a pretty decent sized gap.