/diy/ pioneered this well before Corseti-Rosenthal. We laughed at an "engineer" who didn't understand airflow.

>>2846369
I just tape a 20x20" filter to the back of 20" box fan. Easy, quick, and efficient. Not sure what you'd get by wasting 4 fucking filters, especially since 90% of the flow will come from the back one.

>>2846378
>Tape a 20x20 filter on fan
Seems simple enuff. What's the point of the other filters, beyond wasting money? Maybe that's what (((Rosenthal))) wants.

>>2846372
>We laughed at an "engineer" who didn't understand airflow.

>>2846378
>especially since 90% of the flow will come from the back one.

Wow, speak of the devil.

>>2846418
>What's the point of the other filters, beyond wasting money?

Axial fans in general (especially box/pedestal fans) produce abysmal static pressure. Furnace filters are made to be paired with blower fans that produce a solid order of magnitude more pressure than a typical box fan. Using more than one filter helps avoid choking the fan too much.

Fuck air filters
I like catching a nail on a huge half crusty booger in my nose, feeling it tear loose way up in my skull.
Then rolling it around inmy fingers until its dry enough to throw at my fucking dog who eats it

>>2846429

I don't like how much that spoke to me.

>>2846422
>Axial fans in general (especially box/pedestal fans) produce abysmal static pressure.

Where did you get that dumb idea?

>Furnace filters are made to be paired with blower fans that produce a solid order of magnitude more pressure than a typical box fan.

The static pressure of such fans is perfectly sufficient to push air thru a furnace filter, which is why these DIY air filters work perfectly fine.
Matthias Wandel has various videos on youtube where he builds and tests the cleaning efficiency of such DIY builds vs commercial products and they clean faster (albeit they use more power and are louder since unregulated, but also cheaper)

>Using more than one filter helps avoid choking the fan too much.

Totally unnecessary as DEMONSTRATED by simpler and highly effective designs.

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I have never used any form of air filtration/purifying before. was I supposed to?

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I can show that one 4 fan method is technically better than one 1 fan method with this picture, from chang et al https://aaqr.org/articles/aaqr-16-10-tn-0437 <- source

The faster air flows through a filter—also known as face velocity—the more particles can penetrate without being captured. Interestingly, as velocity decreases, especially for ultra-fine particles, fewer particles penetrate. This lower velocity is beneficial for CR boxes, as they generally operate at much lower velocities than HEPA units. This is largely due to CR boxes typically having a much larger filter surface area, often with four filters, which provides significantly more filtration area.

1/2

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>>2846445
2/2

i don't know the efficient maximum when cost is factored in. It's possible that the cost of 4 filters and 4 fans compared to say, 8 filters and 2 fans, makes it worth it.

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>>2846440
op here. I got into it because I was looking at my PC filled with dust and thought: "Why don't I just take the dust out of the air before it gets to my PC instead of taking it out of the inside of my PC?"
I bought an off the shelf filter, I am disappointed in it. I would like to diy a better one myself.

>>2846429
>I like catching a nail on a huge half crusty booger in my nose, feeling it tear loose way up in my skull.
based optic nerve puller

>>2846445
>>2846448

Nice try Mr. Rosenthal, but I'm afraid you'll have to find another way to boost the sales of Rosenthal Air Filter Limited.

https://youtu.be/6nZcRGLJJDg?t=171

This simple solution already outperforms commercial products dramatically

https://youtu.be/rDZ9yUdM2wA?t=431

>>2846450
The last time I thought about these was thinking to cut out most of the case door and use these to pump cleaned air into my case. Would only need just the one fan since it would create positive pressure in the case. I currently just put some fine mesh on the front of the case and that has kept the dust down.

>>2846440
I made a hepa filter box with 2 pc fans as I get sinus pains from too much dust and shit. works good though now I've just acclimated and never want to leave my room.
sometimes the filter gets infected with mold or bacteria and I spray it down with h202, try not to breath peroxide air.
also I use a little ion generator thingy with the carbon brushes to get the really ultra fine particles out of the air.

>>2846456
I couldn't breathe and felt sick all winter for years. Tried a humidifier but they always get moldy and you have to deal with the filters and ion cartridges and so on. A few years ago I sealed off both the forced-air heater registers in my room with magnetic covers and lots of tape. Voila, problem solved. I also run 2 5-stage air purifiers in here. I have to clean the pre-filters about once a month. In summer, less than 5 seconds after the central AC starts blowing I can see the air quality lights on the air purifier units go to red.

HVAC technology has been a disaster for human health.

>>2846378
Holy shit is it him???

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>>2846378
made what you suggested anon but they only had 20x20x1 and not 20x20x2. poor man's air purifier

>>2846665
Have your hvac cleaned. It's a thing, you know? Companies that do it.

>>2846369
Not specifically. But use four filters and have it point up. Don't be like mr 1-filter.

>>2846450
Btw, the bearings in those fans are not designed for horizontal operation.
Good for your fan-selling business though.

>>2846378
The longer you make it the more assistance you get from air pressure to have air cross the filter barrier NUMBSKULL
>t. aerospace engineer

>>2846887
does that mean this one sucks? >>2846867

>>2846891
Probably. It comes down to the airflow the fan is trying to move, how well the edges are sealed, etc.
imagine the filter is perfectly impermeable, and perfectly sealed at the edges of the fan. Turning on the fan couldn’t move air, because there’s nowhere for the air to come from. Now imagine that filter slowly becoming more and more permeable, until it vanishes. The flow rate of the fan will increase until that point. The question is, how much will the flow rate be reduced by slapping the filter on the back, and are there better designs? The benefit of the box in the OP is that the volume allows for the regular movement air particles to improve the amount of air available for the fan to move. Without seeing it first hand, I couldn’t tell you if the two designs have a significant difference in performance or not. But I’m inclined to believe the filter on back design is worse.

so why is a Jew trying to take credit for a box fan filter idea that's probably older than he is?

>>2846896
covid made people diy filters and he capitalized on it.

>>2846891
I posted fucking VIDEOS demonstrating how these DONT SUCK you fucking retard.

>>2846894
>Probably.
>t. aerospace engineer

At Boeing? kekw.

>>2846904
Your two “supporting” videos show
>how much better a sponsored filter is than his autistic box fan filter
>that his box filter can filter the space 1.5 feet away from the filter and nowhere else
I was right to guess they suck and you’re retarded

>>2847004
>>>2846904
>Your two “supporting” videos show
>>how much better a sponsored filter is than his autistic box fan filter

You can't even read the graphs? You just claimed you're an engineer.

>>that his box filter can filter the space 1.5 feet away from the filter and nowhere else

Ah so the other purifiers with slower fans magically teleport air from further away into themselves and clean it?

>I was right

Bro I doubt you'll ever be right in your entire life.

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>>2846867
improved it a bit. sloppy cut on the cardboard but that should help the fan output better

>>2846369
>Corseti-Rosenthal box
a what now??? here down south we call that a swamp cooler, but we do it a little differently. see, we fill a container (usually a cooler) with ice and a little water, and put a fan on it so the fan blows cool air into the room. not sure why youd wanna build one for winter though, unless you live in the southern hemisphere? but then wouldnt our winter be your summer?

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>>2847211
those side panels are filters. The fan on top draws air up and as the air passes through the filters it scrubs the room's air supply of air particles.
big 20x20x30 boxes can be used in shops to clean out sawdust while you do woodwork, or you can use them as a diy solution for keeping your house air clean if you want to prevent dust from filling the place up

>>2847026
I’m not spending 10 minutes watching some product placement. I zipped to the end (which is more than you deserve) and he said (surprise surprise) the product he was shilling was the best in the line up.
>Ah so the other purifiers with slower fans magically teleport air from further away into themselves and clean it?
Air speed is irrelevant, filters are measured by throughout. A system pushing 100m3/s at 2m/s is a more effective filter than one pushing 1m3 at 200m/s. Unironically starting to think you’re shilling your own channel. You type as autistically as he talks.

It seems pretty obvious that putting the restricting device so close to the fan blades is inneficient.

remember not to use hepa for recirculation
hepa is great on air supply in a system designed for hepa (this shit needs a fan with lots of static pressure)

for air recirculation inside the room a generic merv14 filter will be better
hepa will filter closer to 100%, but just think about it
1000m3 of air filtered at 75% means more contaminants filtered than 500m3 filtered at 100%, and hepa severely limits the airflow
(but hepa is obviously still better for fresh air supply if you can afford it, since you only need a set amount of fresh air, and it's better to filter that at 100%)

you would think that a furnace filter working at 75% means that it filters only big particles, and none of the small particles
but nah, those were the values at the smallest particle size they rate merv and hepa at (0.3 to 1.0 microns)
surprisingly enough at smaller particle sizes than 0.3 microns filters get even more effective anyway (Google MPPS if you don't believe it, but that's the way it is)

>>2846429
I still eat it bros its so yummy. I hate it when I blow my nose in public and have to throw away an absolute nugget because it's not socially acceptable to eat your boogers

>>2847264
>I’m not spending 10 minutes watching some product placement.

I linked the timestamp at which he shows the graphs of the performance curves. No need to watch the entire video.

>>Ah so the other purifiers with slower fans magically teleport air from further away into themselves and clean it?
>Air speed is irrelevant, filters are measured by throughout. A system pushing 100m3/s at 2m/s is a more effective filter than one pushing 1m3 at 200m/s. Unironically starting to think you’re shilling your own channel. You type as autistically as he talks.

You complained about his solution "only cleaning the air around it". A higher output speed will cause more agitation of air in the room, due to it propelling air further out before it is slowed by ambient room air, increasing circulation and thus whole-room cleaning performance.
Your inability to recognize this obvious connection demonstrates the severe limitations of your cognitive abilities, which make you totally unsuitable to have this discussion.
I would recommend you refrain from further postings which could obviously only serve to embarrass you further.

>>2847326
>It seems pretty obvious that putting the restricting device so close to the fan blades is inneficient.

>>2847336
>hepa is great on air supply in a system designed for hepa (this shit needs a fan with lots of static pressure)

This is simply not the case as shown in the videos linked in this thread measuring effectiveness.

>>2847350
Yeah sorry, I don't need an experiment to know that a more restricted airflow cleans less air than a less restricted airflow.

>>2846369
>Corseti-Rosenthal
Why did someone put their name on nigger rigging filters on a boxfan????

>>2846897
well air purifiers are going to be essentials in all building going forward

>>2847349
In a normal sized room the natural diffusion of the air is sufficient for the purposes of filtering. You don’t need high velocity air to mix or circulate. Our fans are fast because free convection is so much slower.

>>2846369
This thing was a godsend when canada was on fire last year

>>2847350
I skimmed them and there was no mention of what filters where those different designs using using, they use different fans, not an apples to apples comparison at all
from simple common sense, my schooling as HVAC engineer and the tests I've seen CADR (clean air delivery rate) is what matters
and HEPA gets you lower CADR with the same fan

at high enough volume (really loud) HEPA with output directly in your face (and close to your face) is better in a really contaminated space (you get "clean air bubble")
but since most people just plop it in the corner, merv is better

and as i mentioned before HEPA is best as a filter of supply air, but only if the room has positive pressure (so there are no contaminated air leaks through gaps)

well that was a walk of text, but maybe you just misunderstood HEPA as air supply? if you design a clean room with 3000m3/h of clean air supply (and positive pressure) it's best to use HEPA on that fresh air supply (air moved into the room from outside the room), since with hepa you introduce (almost) no new contaminants into your clean room (but it requires a stronger fan for the same airflow)
this is how it's done commercially

>>2847466
>>2847523

Are you fucking retarded? You can't even follow a logical train of thought 3 long.
Just stop posting and wipe that drool away you no doubt just produced.

>>2847536
non sequitur
I think you don't know with whom you are arguing not about what you are arguing
try to formulate what was your point when crying about >>2847336
because I think it's just miscommunication

>>2847523

You’re an HVAC engineer for commercial clean room environments? I’ve done a few years of residential hvac with duct calculations, I’ve built flow hoods for personal use with HEPA filters, I’ve worked in clean rooms and seen lots of the components. What is the coursework/degree/certs/occupation that would tie all this together? You seem like you do what I have an interest in doing or at least adjacent to it, industrial mycology and cultivation

>>2847868
NTA, but you’ll either need an MET degree and luck or an actual degree in Mechanical Engineering. Even if you can already do the work, a lot of places will want to know you have an accredited, well rounded background.

>>2847868
I'm not from USA. But here there's nothing stopping you from designing clean rooms if you have the certification to design ventilation in general (which requires a relevant MSc degree, 4 years of design practice under licensed design engineer and passing additional examination). ISO clean rooms are generally a standard manufacturers want to implement due to specific production needs (e.g. some optics need to be assembled in ISO-7 room to achieve required quality, etc), not something forced by the country, so it's not overly controlled. I'd be amazed if it was government-controlled in the US (beyond general mechanical design engineer certification), but you better check locally.

Yes do it
Plan for having a big box on the floor

op here. the last week my air has been clean for the first time in ages and there's less dust on my floor. i don't wake up to a sore itchy throat or allergies either.
considering my city has the 14th for the worst air quality in the world, I should've done this sooner.
I will update with a new thread next time I touch my janky budget air purifier.

>>2846429
it aint a real booger if it didnt yank a tear out with it.

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Slapped this piece of shit together just to do something, and I am quite pleased with it. Sunbeams are gone and I can smell the air freshener I hung in it on all three floors of my hovel.
Not bad/10

>>2846440
How can your cat fly

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>>2850482
won't the air come in like this, reducing the effectiveness of the filter?

>>2846369
Any tips for building a smaller one for a smaller bedroom? These seem good for living room or big rooms in general but annoying in a small room. The thing is filters and box fans tend to come in sizes that fit nicely together. I'm not sure how you would make a smaller one. Cut out a piece of the filter and fit it to a smaller fan? I'm not sure what smaller fan would work best.

>>2850597
see >>2847207 >>2846867
it is more effective to have one fan with a large, lower-velocity airstream as shown in >>2846445, but that isn't to say that one fan with a single filter isn't proportionally as or more useful. mine has been working great as a 20x20x6 inch box under a desk instead of a huge 22x22x22 inch cube.

>>2850597
depends on how much sound you are willing to tolerate. There are very compact high static pressure blower fans that can push a lot of air but they're loud. There are also smaller versions of these filters in all kinds of stores, usually meant for other applications than the furnace filter slot.

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Yes.
It works great

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>>2850596
Yes.

why face it upwards, I don't understand. that's not how a box fan is supposed to work.

>>2850603
god that cut is so clean. 10/10

>>2850604
turbulent fast flowing air is more likely to deposit dust onto surfaces. This means pointing the fan up and having the fastest air be directed up towards the ceiling and the most turbulent air at the highest point in the room is good. The intake is also closer to the floor, which is where the dust travels as it settles.

>>2850605
I get that, but most box fans aren't designed to be used in this orientation. I feel like a proper blower fan would fit this application a lot better.

>>2850603
What do you cut the circle with? Jigsaw?

>>2846369
what kind of pretentious ass name is that? was it invented by two different people?

>>2846369
>Corseti-Rosenthal box
yeah nobody actually calls it that except rosenthal, and you know a gorillion other people came up with that shit before he did and had the sense to know it was such a simple idea that it is psychotic to try and take credit for it.

>>2850597
I made a box type one out of an Amazon 11" fan (they call them 15" now, they count the base), 12X12X12 cardboard box and 12 X 12 filters.