How to Build a Corsi-Rosenthal Box

[@NoelBarlau]

I made one of these on a whim about 8 years ago to deal with the spring pollen here in Georgia. Turns out I forgot to take the time to name it after myself!

[@parislawrence]

same here lmao

[@peterresetz1960]

Parallel engineering universe.

[@CoincidenceTheorist]

He even built his face into the unit. You can hear him struggling from rebreathing his exhalations. Osha has known how horrible this is since the org began.

[@richardthompson6079]

@@CoincidenceTheorist Bizarre. So you guys really think surgeons, car painters and the entire silicon chip industry are all dying from 'breathing their exhalations'. When did this genius idea first come to you, given that masks have been used since the Civil War to stop the spread of disease?

[@JeremyCaron]

First to publish gets the credit.

[@SalivaYOUTUBE]

I use 4in thick filters for better flow and less stress on the motor over time. Also for everyone asking why not use filters on 5 sides, it's easier to find packs of 4 lol

[@actionjksn]

My furnace has a 4-inch filter box and they are quite a bit more expensive. I get a 2 pack at Home Depot for about $40. They do last a lot longer though.

[@AaronAlso]

I have been taping two 1" filters directly to the box fans for years. Not the cheap ones either; I find that a Merv 14 primary and a Merv8 pre-filter works really well to keep allergens down. Same fans, very little stress on the motor.

[@NukeChiefMech]

Stress on the motor? Ridiculous.

[@RobinCernyMitSuffix]

@@NukeChiefMech it is... If they would know a little bit about fluid dynamics they would know that the air resistance for the fan actually decreases with less airflow (i.e clogged filters), because it produces a lower pressure zone, which reduces drag. But hey. I'm just a guy on the internet.

[@rclewis01]

with 4 filters, Merv 13, you will get 70-80% of the normal airflow for that fan. Funny thing is, when you choke off the input of an impeller-type pump or fan, it uses less power. You can verify this with an amp meter. The only real problem is that at some point you will not have enough air flow to cool the motor. I've run with one filter on a hot day and didn't see any increase in motor temperature. So, cooling effect goes down, but power consumption goes down as well as you throttle the input of the air flow.

[@georgewuzheer]

Homie really testing the limits of his engineering degree here

[@TheBeesox]

🤣

[@Raii_Chu]

he’s showing you a simple at home DIY project and you feel the need to insult him out of pocket? 🤔😵‍💫

[@dewfall56]

He realizes that the mental preparation of young students produced by the department of education these days means this is about all most can understand.

[@justindy333]

🤣working alone while wearing a dust mask in what appears to be a dust-free environment 😂 cant make this stuff up 🤣

[@darwinwins]

​@@justindy333you can see the second camera moving

[@FCWW87]

I’m a woodworker, and I’ve been using this for years. My grandpa had one in his workshop back in the 80’s. So…. It’s just a redneck air filter, not a Corsi-Rosenthal box.

[@iloveitUbet]

This is the “it took a 1/2 million dollar education and pHD version. Btw: phd stands for post hole digger wannabe

[@DR-cm4hi]

The two nutty-professors.

[@yalejohnson4687]

Nah he clearly invented it.

[@JimmyRussle]

@@iloveitUbet ok ill tell my robotics engineer friend he wasted his time and that his 300k job is for losers. I'm sure he will be happy digging holes, competing with illegal immigrants for jobs.

[@iloveitUbet]

@@JimmyRussle exactly you tell em!

[@BigFrankieC]

My only difference, was that my fan shroud was on the intake side of the fan. I used the other half of the fan box, and cut a hole in the middle of it that was 2 inches in diameter smaller than the tips of the fan blades. I think it might be a better shield to keep air from coming in the corners. I also used tape to shroud off the corners on the outflow side of the fan, just to be sure. I use 1" MERV 8 filters on the outside to catch larger dust particles and hair and stuff, then 2" MERV 13 filters for the inner core. When we have forest fires up here in Oregon, it really clears the whole apartment in short order.

[@SalivaYOUTUBE]

And we get the smoke from your forest fires in Idaho 😂😭

[@BigFrankieC]

@@SalivaKZbin They're not my fires. Blame the weirdos who go out into the woods.

[@scootermom1791]

​@@SalivaKZbin and in Utah, too.

[@DistracticusPrime]

@@BigFrankieC I blame the weirdos who delay until the blaze is big enough to get federal money.

[@BigFrankieC]

@@DistracticusPrime I blame fire. I think that in this situation, fire's the real jerk. Stupid fire.

[@jtedd57]

ALL WHILE MASKED. THANK YOU. DUSTY✌️

[@Foxxorz]

All I do is plop a filter behind the fan and the suction keeps it attached. Works decent to collect dust and is a lot easier to replace the filter.

[@foobarmaximus3506]

Until the fan motor burns up. Yes, that is a great idea. Stand by with the fire extinguisher.

[@TheLastHonk]

I've been doing this for a lot of years to filter sawdust in a woodshop, I wasn't even aware it had a name lol. Who decided these guys were the first ones to realize a box fan with filters on it operates like any other commercial air filter system?

[@feds27]

Woodworkers have been making these for decades. Not sure we should be calling these Corsi Rosenthal.

[@wango556]

Because they made a video. Lol

[@skeptigal4626]

Guy standing by himself wearing a mask has no credibility.

[@markb6295]

​@@skeptigal4626 More than you

[@thefinerbs7157]

@@skeptigal4626 it's probably in California. You gotta wear a mask while you sleep

[@bryanseitz8137]

Been making these for a couple years now. I use a sheet of formica cut to size for the top & bottom, and put 1/2" weather stripping around the edges of the fan.

[@scottmcm6658]

How long ago did this become known as a Corsi-Rosenthal box? I built a super size one these 20 years ago using wood frame with casters to hold 8 filters and a 5000 cfm drum fan. It was big but it filtered a lot of air quickly in my workshop. The more I think about it and reed all the comments, Dr.Corsi being a dean of a College of engineering and a international expert taking credit for this idea is crazy. It would be like naming fixing a torn piece of paper with tape and calling it ".....'s paper repair system".

[@espressomatic]

Don't you love how this guy just loves saying his own name? And his build skills are up there with my son's - when he was 6.

[@jonfranklin9361]

We had these in middle school in wood shop in the 1990’s. This is not new.

[@truantray]

yeah...this is not new. Also, duct tape is not actually the best way to do this, you really need the aluminum tapes HVAC actually uses to seal ductwork. Duct tape dries out. Frankly, a better design is with two filters forming a triangle with the fan.

[@metsrock15]

@@truantray Why would you think the triangle one is better? Curious cause I built a triangle one with aluminum HVAC tape and planning on upgrading to a square one like what is shown

[@TheLastHonk]

I was wondering the same thing, this is nothing new but they just put their names on it and act like they are the first ones to put furnace filter on a fan.

[@devilman3806]

I made one of these out of wood years ago to help control dust in my shop. I copied the design from someone who didn't claim to be the inventor. Most people call this a "Box Fan Filter."

[@johnklein338]

This one uses MERV-13 filters and is intended to filter virus out of the air, so its purpose is a bit different even if similar in implementation.

[@linsen8890]

@@johnklein338 I built mine years ago and used MERV-13 filters. Woodworkers have built these for like decades. There's absolutely nothing nothing new that these self-important professors have built here.

[@johnklein338]

@@linsen8890 actually important profs have saved countless lives. Sorry you're sore about it. Not sorry.

[@linsen8890]

@@johnklein338 😂🤣😂🤣 I'm sorry that your reading comprehension is so poor. Not sorry.

[@glenesis]

I've always just slapped a 20x20 furnace filter to the intake side of a Lasko, but I needed a solution for a larger space, and this is a great idea. Thanks!

[@DistracticusPrime]

Eight months after your comment, sorry for the necro! I learned recently about fans and "static pressure". Anything that changes the intake vortex drastically reduces the efficiency. By putting the filter on the intake side, it should still work, but not well. That's why the box shape. Allow some space in the intake side to get more pressure.

[@bubba8876]

I've been building those for years with five filters, feet, pre-filters and pretty white tape, it's actually called "The Bubba Box".

[@truantray]

Most home workshops used this for decades. Sad they felt the need to take credit for this.

[@jhwatchlist6927]

@@truantray Making an instructional video to help people isn't "taking credit" for it.

[@coya4321]

would love to see an instructional video of this one that you make..

[@croro7023]

@@jhwatchlist6927 Naming it after yourself pretty much is….

[@hometownmedic7355]

@@jhwatchlist6927Slapping your names on it and repeating them over, and over, and over again is though, so there’s that.

[@hvacdoc]

The balls people have by taking something that has been made for years and calling it there own

[@austinlyons2558]

The fact that you named this "box", after yourself is hilarious. Woodworkers have been doing this for years.

[@RichardHarlos]

He didn't name it after himself. The fact that you assume you know things that you never bothered to research is pathetic. Stop making-up stories so you can pretend that you know what you're talking about. Here are the facts you couldn't be bothered to discover on your own. I share them here for the benefit of others: In August 2020, Richard Corsi, an environmental engineer and the incoming Dean of Engineering at the University of California, Davis, spoke with Wired reporter Adam Rogers about an idea he had for combining multiple store-bought filters with a box fan to improve the efficiency of home-made air filter designs. Rogers contacted Jim Rosenthal, the CEO of filter manufacturer Tex-Air Filters, who had collaborated with Corsi at the University of Texas and in the Texas chapter of the Asthma and Allergy Foundation of America, to run some tests on a single air filter attached to a box fan. Inspired by Corsi's idea to use multiple filters, Rosenthal later came up with a five-filter design. **Rosenthal named it after Corsi,** although after a New York Times article mentioned the boxes by that name, **Corsi tweeted that Rosenthal really deserved the credit,** and that he preferred the name Corsi-Rosenthal Box.

[@blipco5]

You don’t call a PhD "Piled high and Deep" for nothing.

[@jamesrobinson9176]

Yup

[@RichardHarlos]

@@blipco5 How embarrassed are you to realize that the guy in the video didn't name the box after himself? How embarrassed are you that you believed the commenter, whose ignorance led you down that path, and you weren't smart enough to avoid the trap? Probably not at all, because you likely share that ignorance. A smart person would realize their mistake and correct it. Will you? Probably not. So, maybe it's only the stupid people who refer to "PhD" as you do.

[@cmleoj]

It’s for viruses, not sawdust! No woodworker thought this was reducing viral particles in the air. Source: I’m a woodworker.

[@lintonrentfro]

This design was in widespread use prior to 2020 when it was “invented” by these guys and they put their name on it.

[@looncraz]

I was going to say, this was really common when I grew up as a cheap way to filter paint booths... and you can probably find many KZbinrs using similar solutions for makeshit paint booths as well. It's also really common to filter wood shops on the cheap...

[@SilverBullet93GT]

​@@looncrazfun fact, they also invented the Corsi-Rosenthal mouth and nose muzzling device

[@jasonwong7140]

But don't forget this guy has a PHD! PhD: pretentious huge douchebag

[@TonyMueller]

Not sure when this was named after him... but I've been building thee for at least 10 years as a cheap option for workshop air quality. And it wasn't my original idea when I started. Pretty sure I saw it on a woodworking channel on KZbin.

[@inkblue28]

I built this a month ago, its been running by my front door to protect us from my unmasked neighbors. I also have a very expensive airmega coway. This works better! In my 1000 sq ft 2 bedroom on high speed I can get PM 2.5 and PM 10 to 0. There is no way my coway could do that. It's a little loud on speed 3 so most of the time its running on 1 speed. My dog also has unexplained environmental allergies so she licks her feet and has watery eyes. It's completely cleared up now as well as my own dust allergies. Thank you so much for this!! I got my filters from costco - 3m 2200 and the box fan from Walmart, a little under a $100. My husband has a CR box running in his office where he is the only one that is masked. We are both still covid free while his entire office has had covid multiple times.

[@Hectoraka300]

🤣🤣🤣🤣🤣🤣🤣

[@EMleRoux]

I can't wait for them to release the video on the Corsi-Rosenthal Paper hat. - UC Davis Engineers are on the cutting edge of innovation!

[@vernpierce8836]

LMAO 🤣👍

[@Leith-t4e]

What's up with the industrial mask? OH yeah it's California. Idiot capital of the world.

[@cmleoj]

It’s a novel method to reduce viral loads in the environment, not sawdust.

[@mylesdeportado2004]

Doubles as emergency toilet paper!

[@muslehed]

Great DIY project. If I may suggest, use the other side of the box as a template and cutout the face of the fan. Tape that down so the sides do not create a space as with the corner pcs. Thanks for the video!!

[@motomuto3313]

These have been around for decades. I built 1 back in the 80's to clean the air when I was cleaning the basement where I lived.

[@blessedandbiwithahintofmagic]

S4A sent me here, and I'm quite happy he did

[@TheSimoncio]

I did my own version of this box, I did add a UV 300nm light inside the box, pretty easy thing to boost the cleaning effect. Patent pending ;)

[@tobygathergood4990]

Why not use a fifth filter element on the bottom as well and hang the entire filter box? I build filters for my shop like this more than 30 years ago using five filter elements. The fan was one of the old style box fans which were heavier and much more powerful that the ones available these days. I vented the fan into a duct I made from sheet metal to the outside. Instead of simply taping the filters to each other, I constructed a sheet metal frame with slide in filter element holders sealed with silicon "O" ring type gaskets. The entire thing was air tight except through the filter elements.

[@Phalenx15]

It's a great thought, but it is extremely dependent on how powerful your fan is. You need a certain amount of static pressure to pull air in, too much and your fan will actually pull in surrounding air around it without actually pullling all of the air through the filters and push it back out too easilyy, something people forget to mention. Imagine placing a plastic straw into a bag and you start sucking on it. Well, you mouth creates perfect suction, but fan blades attempting to pull air out don't. errors in curvature of the blades, etc, will not pull 100% of air through the filters. This is an easily provable experiment. Take a filter and place it in front of your fan where your fan has to push air through the filter. seal all air gaps off. If you hover your hand over the back of the fan, though it only pulls air in, opposite of the filter, you will feel air blowing backwards back towards your hand. Perplexing right? Your fan can only pull air once way, so how can it come back at you? That is all of the immense amount of air not being filtered and being backflowed.

[@ModelLights]

@@Phalenx15 'It's a great thought, but it is extremely dependent on how powerful your fan is.' Exactly, but you have it reversed. More filter surface area means more area for the air to be drawn through. That makes it easier on the fan with 5 filters, not harder. Restrictions reduce as you add more pathways.

[@corwind3888]

What's the point of making one of these only to vent it to the outside?

[@ts109]

If you close the top off to 2 " smaller radius than the fan blade it will greatly reduce the vortices of unfiltered air from circulating.

[@catsfpv603]

Shouldn't an engineer know that? Especially the dean of the engineering school!

[@ypcomchic]

You can use less merv rated filters with thin foam to lay on top of them sprayed lightly with oil and that will attract and hold much more dust and extend the life of your filters. Just wash the foam and reapply the oil.

[@elmerkilred159]

The problem with this design is that the box fan is not designed to pull a static load. it's designed to move a volume of unobstructed air in one space. This is why sitting a box fan in a window doesn't run air though the entire house when you open another window on the opposite side of the home. The fan does not create enough static pressure. What you need to make this work efficiently is a tube-axial fan (drum fan) that is commonly used in forcing air through long large diameter conduit. It moves an enormous volume of air like a box fan, but it performs more like a centrifugal fan like on most HVAC units. Tube-Axial fans are used in paint spraying booths where the filter is placed directly over the intake shroud (Which, is already round). and usually have the motors located where flammable fumes cannot ignite with the electrical sparks that are created on the brushes with induction motors. The actual design of the "Corsi," fan is mimicking that of an exterior air conditioner heat pump housing. The box fan is a great idea until the filters start to clog, and the fan motor will burn out. However, for $65.00 it's not much of an investment to lose sleep over.

[@geoncic]

That's exactly what I was thinking... and this is the dean of engineering that names a simple box filter after himself that thousands and thousands of people have already "invented" and built themselves to try to keep sawdust down in their hobby shops.

[@linsen8890]

Well, woodworkers have been building and using them for years. I have a similar dust filter in my shop, built using two filters stacked, and I've been using it for years without any problems with the fan. They create plenty of pressure for this kind ot application.

[@bandittwothree3765]

excellent comment. Can a basic test of static load on a fan be done with a sealed box (or metered output), a manometer, and a fan? Trying to understand the concepts at play here

[@BuildWall]

Good comment, thanks. I've done the two windows one box fan trick for years, though, and I can feel the air being pulled through the house. I'm sure a drum fan would be more effective but, as far as I can tell, a box fan works too.

[@herrpez]

Thank frick someone finally said it. And like wph above said, that THIS guy tries to put his name on such an old DIY thing is something else. Incredibly distasteful if you ask me.

[@scottallen5601]

Wow a man that gets right down to the point no long winded conversation. Hats off to you sir very well demonstration THINK YOU !!

[@loungelizard836]

Nice idea, DIY air filter. Another neat trick is to wrap activated-charcoal fabric around the filters so you eliminate toxic hydrocarbons. I do this on all our AC units and circulating fans. Just shake or vacuum them when dirty, don't use water on charcoal cloth or you will lose the charcoal.

[@catsfpv603]

You can now buy air filters with an activated charcoal layer.

[@Swish36]

What would the difference be when the fan sucks in the air and air would be filtered out?

[@sango_wilko851]

I love how Dr. Corsi starts off by saying "What's become known as a Corsi-Rosenthal box" and then proceeds to awkwardly say "Corsi-Rosenthal box" more than a dozen times, it was like a comedy skit where can he work it in next. I remember seeing a bunch of these in New Orleans after Katrina in 2005 and the greatest benefit was that they use readily available materials which let people produce them easily in the close aftermath of storm flooding.

[@tombiggs4687]

He jumped on the Covid Cult train in a sad attempt to make a name for himself. Sad.

[@maxwellsmart3156]

@@tombiggs4687 At least he's trying to do something and not whining about having to where a mask or pretending that pharmaceutical companies making huge profits means that a vaccine is "bad".

[@sango_wilko851]

@WeavingBird if I had tried to apply my name to a concept as trivial as this much less one that I didn't come up with myself I would have been expelled for violating the honor code. You're not talking about the discovery of some novel method for extracting DNA from a cell you're talking about pulling air through a filtration medium with a fan... something that was first done over 150 years ago. I can't imagine any scenario where I'd want to look at research into something generic like this from a specific person where I wouldn't just search for research done by the person's name. It's the exact same outcome - people find the research searching for your name with the difference being you don't have to name something after yourself which you didn't create. The culture in academia is bonkers, in my experience outside of government politics I'm not sure I've seen bigger egos present anywhere. I'd say the number of times the guy mentions it - even to the point of it being awkward - makes his intentions clear.

[@ZxAMobile]

I love how he is celebrated like this expert, but he has no idea what he’s doing. MERV 13 filters do not filter the “cold”. He’s using toxic duct tape to seal it, and no pre filter no carbon filter. It’s amazing! I’m not an engineer, just a nobody, and I know 10x more than he does about his own job! Amazing!

[@siewkimng1085]

⁠​⁠​⁠@@ZxAMobile pre filters are not needed for merv 13 filters. Pre filters are only used to extend the life of HEPA filters. Almost all cold virus travel in aerosolized particles which just about any air filter will trap (they are relatively huge). HEPA filters also outgas, so that’s not much different. Carbon filters don’t actually filter particulates. It just reduces VOC / odor until it is saturated. Most air filters don’t have the carbon filters sized correctly for the CFM. So they don’t do anything after a while. Dunning-Kruger.

[@1e2werks15]

I have one of these running in my basement all the time except I used one 4 inch 20 x 20 filter on the intake. Great for kidney looping air to lower allergy particulates. My hvac guy said we have the cleanest air he has ever measured.

[@espy0008]

Dude watches a few videos on wood workers building shop filter systems then makes a video of one he made and named after himself as if he just invented something new. Really shows the value of college education.

[@MannyDer]

prob in a room all by himself too, looking like a platypus or something.

[@Spiritof_76]

Marketing. It's not who had the idea, it's who sells the idea.

[@nomchompsky2883]

that's how probably half of all "discoveries" and "inventions" are made... someone with an education sees something made by someone who is a real world pragmatic problem solver, steal their idea, maybe improve upon it, maybe not, then name it and patent it...

[@espy0008]

@@Spiritof_76 Edison....

[@Spiritof_76]

@@nomchompsky2883 Got any statistics?

[@45BradB]

My dad has been doing this since the 70’s. It’s not a secret amongst tradesmen working in enclosed spaces. Where do you get off putting your name on something that’s been around for 50yrs?

[@truantray]

He's a clueless academic who thinks he invented this and then has university PR promoting it to exploit the pandemic.

[@tirdkat6104]

Guess your dad should have put his name on it and then repeated it over and over again.

[@steveky7829]

I was looking into a basement filter for my wood working shop in my basement, 10 years ago. I built two of these they work great to get small particle saw dust out of the air... I don't even remember if I saw the design or just copied the way a commercial filter works. But they are cheap and work great, even if a little ugly...

[@alexrapada]

Used this method with regular air filters during renovations. Worked really well to keep the fine construction dust to a minimum. Also helped with my allergies during windy season.

[@feds27]

Woodworkers have been making these for decades. Not sure we should be calling these Corsi Rosenthal.

[@raymondhudson1288]

how you replace filters i have to keep building one every 3 months

[@BGP369]

building it in reverse to filter wood dust from a workshop is also effective, if the fan can manage over 500cfm. combine with a typical dust collection system and it will greatly help in air quality in the shop.

[@foobarmaximus3506]

That makes no sense.

[@Swish36]

Yes, sucking IN the dust and blowing out clean air

[@travelingman21000]

During the "lock downs" the employer I'd worked for at that time had our Air Conditioning Techs (myself and others) build very similar device and installed in a building for our covid-19 positive patients and in their "wisdom" said we had to exhaust this now filter air to the outside. There was no upgrades allowed to the AC system in anyway. This was a state run hospital.

[@kwyj]

_"eject all that clean, filtered air outside at once!"_

[@SamehKhan]

I've never seen someone in a suit build something so complex. Wow.

[@PatricioGarcia1973]

I use this kind of system in my garage for painting, except I have the filters in a row and the fan pushing air out. I put them below the garage door seal, so it would be floor, filters, door. All the overspray gets trapped by the filters and not into the neighbors. For fan I used a radiator fan from the junkyard.

[@BrandtHambrick]

Dude is taking credit for something nearly every woodworker has "invented" when they needed it.

[@montee827]

I wonder if anyone else has named something that has existed before? Something for me to think about at my next soccer game.

[@BrandtHambrick]

@@montee827 You should ask the British, who gave Association Football the nickname Soccer.

[@AdamsHangar]

This is just a home made air filter that we all made years ago. There's no name to it, lol. This is a huge version. You can also just attach 1 filter to the intake side of the fan and seal it with tape. Done, and cheaper.

[@aarondilley5266]

no actually. if this guy was any good at explinations you realize but its a stolen design. the point of four filters is noit that 1 wont work but that 4 has better air flow

[@dallasswim9890]

Thank you - was squirming about the price of commercial units. Q. Would removing the protective plastic cage from the underside of the fan increase efficiency?

[@DistracticusPrime]

Removing the finger guard would not help, except by giving you access to improve the fan. If you can add a duct just larger diameter than the fan blade tips, that improves static pressure. This way, a smaller device can clean more air.

[@NukeChiefMech]

Agree. No reason for anyone to feel so magnanimous as to think this is an original idea that warrants naming after themselves. Ridiculous.

[@WoodUCreate]

Wood workers have been doing this for many many years. How does someone put their name on something based on someone elses' design? How is this different?

[@joehahn9493]

My furnace uses 20x25x4 MERV 12 filter. Can’t I just turn on the furnace blower fan?

[@dawnd2517]

Thank you for the video and detailed instructions! I looked around and wasn't able to find directions regarding the best speed at which to run the fan... low/medium/high? Also, how often should the filters be changed?

[@GeeAre]

I just searched a bit, and three sources said the filters should last 6 MONTHS, but if they look dirty, change them sooner. I also read that because of the noise, LOW or MEDIUM is good for occupied rooms, but running it on HIGH will "move more air" so maybe more effective on high?

[@RJLalumiere]

@@GeeAre is correct, it is a trade-off between noise and the Clean Air Delivery Rate [CADR]. Most fans will list dB for each fan speed and it may be worthwhile to include that in consideration when selecting a fan.

[@emma70707]

Medium is usually the happy medium. You can find a number of CADR estimate papers online and there's a reasonable jump between 1 to 2 but less between 2 to 3 for most fans/designs. But if the room is unoccupied and if you want max cleaning for a shorter period of time (say a teacher who wants to eat in their room after students leave), definitely run it on max. Electrostatic filters are good for 90 days only, unfortunately. And you really need the electrostatic properties to catch virus-containing particle sizes of things.

[@froggydoodle808]

​@@emma70707Do you mean they last 90 days if they're running 24/7, or they last 90 days regardless of how long the fan runs?

[@breilly2750]

So, you've managed to come up with a name for a contraption that's been in use for decades. Good job! However, when you take an existing design and call it your own, that's considered "plagiarism". Edit: There are videos I found promoted on this very page that describe how to make these contraptions that pre-date this video by YEARS.

[@montee827]

Boy you are gonna be really upset when you learn what they are calling "tool with stone head". The youngsters are out of control.

[@cppctek]

Take a shot every time he says Corsi-Rosenthal. Genius filter box though. I’ll be making one for sure 😊

[@bobk3840]

Woodworker’s have been building these for years to clean the airborne dust out of their shops.

[@iswm]

leave it to academics to jack themselves off about slapping some filters on a fan. these people are beyond useless.

[@ghassedir]

For a hot second I was concerned that the pom poms were a required element and I hadn't secured any - but no, that's just a charming touch of school spirit. Thanks Dr. Corsi!

[@croro7023]

Maybe I should stick a stick in some juice then freeze it and name a popsicle after myself. This box filter idea has been around forever.

[@rogermccaslin5963]

People, myself included, have been making them for decades for shop air filtration. We didn't have a fancy name for them and no real engineering went into it, just that old "necessity is the mother of invention" thing.

[@wfdTamar]

A variation of this is cut the filters to the shape of the inlet of a wall mounted split system air conditioner (which is usually on top of the unit out of sight). I have a HEPA and a carbon filter (for the neighbours wood heater smoke) on mine and it works really well. It has minimal impact on the air con and keeps the insides of it clean.

[@matthewpeinado2047]

Take a drink of your beverage every time he says Corsi Rosenthal Box.

[@artistlofter]

This is exactly the same design as the Blueair 211 which I bought prior to Covid, many many years ago. The advantage of the Blueair 211 is it looks prettier, and is an off-the-shelf solution

[@aarondilley5266]

i knew he didnt invent anything except another way to take credit for somone elses work I did not know it was commericaly available thanks

[@mattmilford8106]

I've done something similar as a dust collector by letting a single filter get sucked to the back of a box fan. I didn't feel the need to call it a Milford box 20 times in a video. LOL

[@j.thomasgough4284]

Now, is that special Corsi-Rosenthal tape, or can I just use the duct tape I have already? And what about the Corsi-Rosenthal box fan? I sure hope there’s a kit I can get somewhere…

[@saras1487]

How often do you have to change the filters?

[@AAWOLFE-zc6ly]

about as often as he changes his ineffective n 95, lol

[@YouTrolol]

can you use the sides of the box to create a circular shroud on the inside of the fan? that way the box is completely used. back panel for the bottom, front panel for the top (with circular hole cut out in the diameter of the fan blades), and hten the remaining thin edges would be used to create the circular shroud.

[@RiffHarvester]

I built a mini-Corsi-Rosenthal box. I used a 10" mini box fan with 10x1 mirv 13 filters. Worked decently enough even though the mini fan wasn't as strong as a full-sized 20" box fan.

[@HiNinqi]

These do not filter as small as a hepa filter does, however. Why is it perpetuated as if it does? Please explain

[@logans3365]

He was comparing virus filtering capabilities, which a MERV 13 can do almost as if not as well as a HEPA, HEPA is better for small particles though.

[@HiNinqi]

ok thanks! That makes more sense@@logans3365

[@FCWW87]

Thank goodness our Uni’s are out their reinventing the wheel. Where would we be without them!?

[@LukePighetti]

Kinda wish the flow direction was reversed so the box would be a container for all captured particles

[@LukePighetti]

Actually I take that back because it relies on negative pressure to not blow debris through the duct tape joints

[@alals6794]

For a city man such as myself, this is great stuff. I regret though that I only found out about this circa 2023 not 2020 but hey, I did buy myself 2 retail air purifiers and now I can afford to build my own. GREAT.

[@jeromenewzelande1957]

The problem with all those kind of videos is that they are talking about CFM but nerver justify there sayings. They should mesure te air flow before and after building the box and then compute the CFM or M3/h. I think we would have some surprises with the results.

[@LakesideAcres]

This would make a good drinking game. Take a drink every time he says Corsi Rosenthal box.😂

[@arcadegeek]

huh - weird, created during the "pandemic"? I saw 3 of these in our wood/metal shop in high school in the 1980s - yes - using simple box fans and air filters constructed exactly like this (using metal tape). Now it's someone's named creation? 👍

[@iswm]

yes, the "pandemic" significantly accelerated the transfer of power in our society to the useful idiots and communist busybodies who are now all stunning and brave geniuses, and in fact are themselves in all their sanctified glory, The Science.

[@brainwashingdetergent4322]

And here is an example of how an idea is taken, renamed, and then sold as new.

[@sandyallen1523]

I have run a 20" fan with a filter attached to it for years. It works great for taking dust out of the air. I have allergies

[@danielweston9188]

We had these at OSU in 1974? Used in the ag lab when cleaning seeds (puts a lot of fine dust in the air).

[@INoIFearIGaming]

High quality filters are way too expensive to be using 4 at a time. I just buy 1 good quality filter and slap it on the back on the fan and call it done.

[@andros2112]

It's a neat idea, and will doubtlessly be helpful during pollen season, but I'm skeptical that these filters can stop and capture viruses.

[@kayakdog121]

The inside corners of the box fan are what most people overlook. Its amazing how much unfiltered air gets sucked in there only to be blown right back out to become airborne again.

[@RichCadwalader]

The Cadwalader Air Purification System: Tape the filter directly to the back of the fan. Cheaper, faster, and I did it 25 years ago during the Central Florida Muck Fires. My house was the only house in the neighborhood that didn't smell like boiled swamp.

[@RichCadwalader]

Interesting, This Old House has a video three years older than this one building the exact same thing...

[@TexMex421]

Great idea. You could add cheap filters to the front of the expensive filters. Replace the cheap ones often.

[@TexMex421]

@Blank Name If the goal is filtered air for less money than no, it's more efficient. If the goal is just to move air, than yes any filter lowers efficiency.

[@TexMex421]

@Blank Name Why not just remove the one filter? You'll move much more air.

[@TexMex421]

@Blank Name What is the point of the air filter you built? How would I know that?

[@aarondilley5266]

i do that to my aic because of the dods, the single pleat green ones fit over the good filters and save a forrtune

[@williamsistrunk504]

Do have to say, if you know what you are doing, you can move the cord to the top of the fan by moving the back grate to the front to allow for better seal to the box.

[@PhoenixWoody]

Great for an air filter, but does not stop viruses.

[@DistracticusPrime]

I noticed the prof was careful to always specify "aerosol particles". Those are big enough to get stuck in some filters.

[@gidgettrophy]

I built stuff like this when i was a Toddler.

[@dylanowens3173]

Uhh these been around decades and aren't named after you. I built one in the 80s in woodshop. A better design is 5 filters, the 5th filter in on the bottom and raised off the ground. and have fan airflow pointed down so the fan is pulling air down and isnt blowing air turbulence upwards blowing particles around. For wood shop or air spray use to 8 to 9 filters stacked on a frame and a very high flow fan . But this requires building a structure.

[@007galaxie]

What a great idea, wish I had stumbled across this video when all of those fires were affecting us in the Bay Area.

[@joepauly2311]

Oops, accidentally stumbled onto a Coof Cult video.

[@alanrcrews]

The only addition I would propose is adding the determination of fan flow direction and adding the flow direction arrow.

[@tfinnegans_wake6182]

This dude *loves* saying his own name. He thinks if he keeps saying it, we'll start to think he actually came up with this decades-old DIY shop filter.

[@ModelLights]

Posted 'Apr 15, 2022'. But pretty sure it was actually invented on April 1st.

[@jasonwong7140]

He's pretentious as f

[@darwinjina]

Watching the video since I think the idea is useful for those looking to reduce PM 2.5 (burning season pollution).

[@skaramicke]

How did something this basic deserve a double creator name like that? It’s not the first time someone builds something similar.

[@suziyantra]

I have a question about this, I built one but my nose is worst that before. I feel Stuffy nose and feel kinda of dizzy. Why is this happening? Thank you

[@gethype5064]

Just put my first one together!! I used black gorilla tape but look forward to making more with more fun duct tape colors. I like how you did your school colors. Very grateful for yet another tool to fight this pandemic.

[@gethype5064]

@US2A_ARMS No cuz I had Flu A couple months ago

[@abbylynn8872]

School colors were great.... Dollar Tree sells fun duct tape as well as Michael's craft store if you're looking for local vs ordering online. I'm not a huge online shopper. You can also use any duct tape and buy craft vinyl from Dollar Tree and cover the duct tape to really make it uniquely yours.

[@foobarmaximus3506]

This isn't going to help with any airborne disease.

[@StringBeanWoodworking]

Not his concept. Been around for quite awhile. But great job trying to take credit.

[@cal30m1]

What my generation were doing in grade school is now a college level project…

[@TR4zest]

I would like to see a performance comparison with one assembled in the opposite flow direction : the fan pushing air through the filters, rathe than pulling air.

[@alexkitner5356]

Wonder what would happen if you double stacked two fans. Would it compound, as if the force imparted on the air is constant so each stage like a turbo is just a set increase? Would it increase volume at a more static pressure, or just get in its own way?

[@wagu7003]

More is more

[@aarondilley5266]

you have to test. it could make vortexes that push back air . make a video!

[@Ryan-dj5ku]

Fans in series sum static pressure. Fans in parallel sum flow rate. Look up pump curves for parallel and series. So two fans in series would result in slightly more flow due to shifting right on the curves due to the increased static pressure.

[@alexkitner5356]

@@Ryan-dj5ku but air and water behave differently as does a fan shape versus a volute body like a water pump. And you don't have a sealed system that doesn't have any losses

[@morgank.1249]

The naming might be obnoxious but hey these are really good instructions!

[@UNINOIZ3]

Facts, I could give two shits if "woodworkers have been building these for years hurr durr" well one of them should have fucking named it already then.

[@TheDrewbalicious]

So. You watched the video from 'This Old House' & stuck your name on it. Interesting.

[@truantray]

This is the Corsi-Rosenthal video service.

[@CowboyTech]

Just tape a filter to the back of the fan. It takes up less space and the filter is easy to replace rather than building a new box every week or so.

[@CowboyTech]

Or, tape one to the back and front.

[@jameo6381]

Dr Corsi! I ran into you on twitter and totally geeked out to “meet” THE Dr. Corsi. Thank you for keeping my family safe and healthy the last few years. Many science-minded people are quietly paying attention, and we love you man!!

[@foobarmaximus3506]

I guess you've never been to any university then. LOL There is nothing special about some who calls themself "Dr".

[@vernpierce8836]

​@@foobarmaximus3506< 👍 😂

[@tnt6715]

Saved my life!

[@colonelradec5956]

i just took a filter and put it on a fan. worked like a charm. not sure if it will effect the fan life but... who cares for 24 dollars and 10 for a filter 😂

[@foobarmaximus3506]

You might care when the fan motor ignites.