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
I’ll never stop thinking about how dumb it is that someone slapped their name on a thing people have been making for decades…
Are you talking about the Kennedy center?
I don’t mind it. Their contributions include showing how efficient the design is (a lot more efficient than many commercial consumer air purifiers) and also popularizing the design, which the name helped a lot with. Not the particular name, but just giving it any name helps a lot with popularizing the design.
It’s not like they’re making any money off it.
I should also point out that in science it’s extremely common to name things after people who researched them, even if those things were well known long before they got that name. Especially funny is when taxonomists will name a species that already had a name known to the indigenous people of that area for literally thousands of years, and they name it after Bob the taxonomist who visited the area in the 1970s…
This is the story behind a lot of tech. Wankel engines are a good example. Wankel developed the seal tech that made rotational piston engines viable.
Haha, agree. These have been a fixture in woodshops for… quite some time. I suspect they’re also used elsewhere.
Maybe their contribution was the instrumentation that showed that filters that are not rated for HEPA level filtration will still basically eliminate viral load with enough passes.
on a thing people have been making for decades…
there were no square boxes before 2020.
Corsi was Dean of Engineering at UC Davis, he should be embarrassed.
im curious why its so complicated. would taping a filter to both sides of a fan and turning it on be to much stress on the fan?
Having 4 filters in a box setup reduces the strain on the fan and allows for more airflow versus just a single filter. The larger surface area also means everything can run longer before the filters get too clogged.
feels like something that is perfect for 3d printing where all the filters could slide in with a nice cradle on top to fit a standard fan (how standard are box fans?)
The most common box fan size seems to be 20" which is also a super common air filter size so it works out pretty nicely. There’s actually a handful of 3D printable frames on printables if you search for Cori Rosenthal
thanks.
You could absolutely print this, but going straight plastic seems wasteful. Theres also the size angle - this thing is big. Mixed material for stuff like this is where it’s at IMO. Wood’s cheap, won’t be here for forever after I’m dead, and is pretty sustainable.
Speaking of which, I intend to design and print some brackets to hold the wooden uprights in place better. Right now it’s just the tape holding things together.
But yes, you can more or less slap a single filter on the back of a fan though.
Sure, no one’s stopping you from doing that, but it’s gonna be less efficient and will put more wear and strain on your fan.
The principle behind the CR design is tipping the scale towards high flow, because when doing the CADR calculation between a low flow HEPA compared to a high flow design with “lower quality” filters often the high flow design wins out. Because of the probabilistic nature of particle capture (Brownian motion and electrostatic capture), you don’t need a filter with super small holes to catch super small particles. So using a filter with bigger holes it turns out nets you so much flow, that the extra air changes results in cleaner air than the more restrictive filter.
So I would guess that a single filter would be too restrictive to be as effective.
deleted by creator
More surface area = more air flow for a given fan.
which is why wood shops have done this 40 years before 2020.
I’m confused by the fan you used in there - wouldn’t it mainly suck in from just 2 of the sides?
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!
As long as there’s actually a gap between the fan and side filters ofc
Fear not, there’s a pretty decent sized gap.
There’s plenty of gap around the sides of the blower and pressure equilization will help even out flow, but you’re right - the flow through all four won’t be perfectly balanced. That shouldn’t be a big deal and I can always rotate the filters if needed.
I like the motion sensor idea.
Thanks! The fan doesn’t pull a ton of current, but it seemed wasteful. Now it kicks on when it sees a human or a cat, runs for 15 minutes, and turns off.
If you need something a lil more presentable for the main house, there are some kits from nukit tempest and cleanairkits that also use heater filters
My wife bought some small black box “HEPA” filters from Amazon for the main floor. I would love to run our HVAC fan 24/7, but the thing pulls far too much juice for that to make sense :(
Yeah the ones I mentioned are boxes around size of a computer tower. Seems fine to put that in the room you spend the most time in
I have an idea for a solar kiln floating in my head. And construction probably going to mirror this box shape design. Cubed with 5 sides with tape around the edges.
If that can’t hold up you could put a wooden from to go around the center
deleted by creator
