The Best Air Purifier Is A $150 DIY Option

[@Beregorn88]

Physicist here: I'm a great fan of your work, and you have become my reference when buying and suggesting monitors. The work you did here is quite interesting, but the methodology can be improved. First of all, I would wait 5 minutes between the introduction of the smoke and the moment you start the machines: this way the smoke can spread uniformely in the room and the results are less affected by the way the smoke enter into the room. In addition, you would also have a more accurate reading of the starting amount of particles, which you should use to normalize the results. Last, but not least, every time you perform ANY kind of measurement, you should repeat it at least 3 times (or even better 5): the first measurement gives you a value, the second one tells you the accuracy, the third one tells you wether the difference between the two is due to stochastic noise, or you have some problems in your methodology. Of course, the more measures the better, but you need to balance the accuracy of the measure with the time you are willing to spend, and 3 measures are usually enough to know if you need more. In addition, would be nice to see if 3 or 5 puff of smoke are enough to see a drop in the performances, giving you an idea of how long the filter would last

[@kidShibuya]

You have made the assumption that they don't do this already. You know that how?

[@TonyOstrich]

​@@kidShibuyago away

[@butterscotchpanda]

While the point about waiting five minutes is a good one, and pretty fair, I do think it's worth considering that having the purifiers on _while the smoke propagates_ helps determine the quality of the fans, since, as we saw in with the Dyson bladeless, some of them can actually prevent air from passing through the filters, and in this particular test that's a really useful data point to have in order to determine just _why_ certain purifiers which should have a significantly higher theoretical performance don't reflect that in practice. Regarding the multiple tests, that's standard M.O for any kind of technical testing as far as I'm aware, it just seldom gets brought up unless explicitly relevant because it's so well-known that in most cases it'd be comparable to dead air. That said, I don't think anyone who's working on doing analytics like this professionally is just doing one testing pass and calling it a day, which is a big contributor to why testing things like this can be very expensive and time-consuming, and a big reason why you should go give RTINGS your money, because they do good work!

[@Beregorn88]

@@butterscotchpanda when they described the monitor tests they specified the number of repeated tests and how they combined the results; here they didn't say anything about this, nor did they mention it on the article on the website. They didn't even mention a variability from test to test, which is VERY indicative of just one test being performed... The 5 minutes delay has 2 different functions: having all the system starting in more uniform conditions, and being able to accurately record said conditions, in order to remove any leftover difference during the analysis.

[@CanIHasThisName]

Christ, mate you’re not doing a public lecture, why the pretentious writeup?

[@crazylego98]

You guys really came out with this one day after I purchased an air purifier from Ikea

[@RTINGScomRD]

There's still time to return! 😂

[@8020Alive]

You got ripped off. Plus these builds are often better for your energy bills and vastly more efficient depending on fan purchases. Thus over 4 or 5 years IKEA will rip you off even more. Return it quickly 🎉

[@ThePwig]

This has been known for a few years, ever since Covid.

[@HanmaHeiro]

@@ThePwig But not widely known, I'd say

[@lemon9.9]

@@HanmaHeiro I searched for air filter comparison on youtube before and this design came up almost immediately

[@KaledTV]

Following their toaster PhD study, they come to deliver another unexpected banger.

[@RTINGScomRD]

Hahaha we always try to deliver, thanks for watching! 😄

[@m-ax729]

would have been nice to see a comparison with one of the bigger units (eg. iQair healthpro) that would be more similar to the dyi solution in terms of ugliness and footprint.

[@HanmaHeiro]

Take a look at their site. If it's not there yet, it could be in the future!

[@yarkee8128]

I imagine clean air stars filter recommendation tool, or housefresh would also have similar data

[@emmamitchell1582]

I would love to see some testing with 120mm computer fans strapped to a filter. They are optimized for static pressure to push air through radiators. I would recommend a push configuration versus a pull configuration, but testing both would be great. A cheap fan would be the arctic P12. If you use the PWM version they are even speed controllable. A high end option would be the Noctua NF-A12X25.

[@khawajadotd]

There are prettier designs available from "The 3d handyman" youtube channel. He has also done testing on a bunch of filters and fans, and found large differences between brands.

[@CaveyMoth]

I got his design that uses a 12" in-line fan, and added a secondary activated carbon filter inside. This thing is bananas. The fan is almost scary how powerful it is.

[@uguraktas8018]

Please test the CR box with Pc fans! they are much quieter and consume way less power. You should be able to find more about them easily. The 5 fan and 9 fan versions are very popular. They usually use arctic p12 fans. There are also companies selling cr inspired air filters with pc fans. One of them is Clear Air Kits. Regardless, its a very good video!

[@adriankoch964]

This! The reaon for Arctic p12 is that they offer high static pressure. Using models with low static pressure (i.e high flow or silent variants) will have worse results, since those will struggle to overcome the filter resistance.

[@MY-qi8wq]

@@adriankoch964 Arctic P12/P14 is good, but not because of "high static pressure", but that they are cheap and offer high noise-normalized performance against a wide range of resistance. In fact, the entire reason why CR boxes work so well is that they have 1. absolutely humongous filter surface area and 2. filter material with lower resistance, which makes resistance extremely low. (The lower air velocity through filters also boost filter efficiency far beyond the "75%" quoted on the box.) Thus, with properly chosen filters, the so-called "airflow" fans can work well (e.g. box fans!), though the most efficient PC fan designs nowadays are all-rounders that perform well across a wide range, instead of "airflow" or "static pressure" optimized. Yes this includes Arctic P-series (despite being marketed as "pressure fans").

[@YouTrolol]

I bought 4x noctua 200mm fans and an ac fan splitter that split into the 4 connections. I like it, a lot quieter than the box fan I have, but I feel like the fans are too quiet. on max setting they're really quiet, so I wish I had higher airflow fans even if noisier, because I could always turn them down, not up.

[@MY-qi8wq]

@@adriankoch964 Arctic P12/P14 is good, but not because of "high static pressure", but that they are cheap and offer high noise-normalized performance against a wide range of resistance. In fact, the entire reason why CR boxes work so well is that they have 1. absolutely huge filter surface area and 2. filter material with lower resistance, which makes resistance extremely low. (The lower air velocity through filters also boost filter efficiency far beyond the "75%" quoted on the box.) Thus, with properly chosen filters, the so-called "airflow" fans can work well (e.g. box fans!), though the most efficient PC fan designs nowadays are all-rounders that perform well across a wide range, instead of "airflow" or "static pressure" optimized. Yes this includes Arctic P-series (despite being marketed as "pressure fans").

[@MY-qi8wq]

@@adriankoch964 Arctic P12/P14 are indeed very good, though not because of "high static pressure", but that they are cheap and offer high noise-normalized airflow against a wide range of resistance. In fact, the entire reason why CR boxes work so well is that they have 1. huge filter surface area and 2. filter material with lower resistance, which makes resistance very low. (The lower air velocity through filters also boosts filter efficiency far beyond the "75%" quoted on the box.) Thus, with properly chosen filters, even so-called "airflow" fans can work well (e.g. box fans!) Do note however that the most efficient PC fan designs nowadays are all-rounders that perform well across a wide range of resistance, instead of "airflow" or "static pressure" optimized. Yes this includes Arctic P-series (despite being marketed as "pressure fans")!

[@LittIegator]

I've seen people use PC fans instead of box fans. There is also at least one company that makes fancy schmancy looking frames for Corsi Rosenthal boxes that don't look like actual trash.

[@Zinic_]

Yeah mine is in the mail and I'm going to use it as a template to make my own out of plywood.

[@Jaker788]

And PC fans are almost all brushless DC motors (3 phase AC synchronous). Those types of motors are in the range of 90% efficient, while most AC powered fans use a shaded pole motor which is around 20% efficient. If you don't want to use PC fans and want the ease of one fan for the filter box, you can look up brushless DC fan and brands like Vornado have one. The Vornado brushless DC fan is a bit over $100, more expensive, but also 70-80% more efficient than their standard fans and other fans using shaded pole motors.

[@meatbyproducts]

A box is simple to build out of scrap wood. My father built one of these in the 80s and made a nice frame for it and my mom could swap the filters with ease.

[@AJolly]

Yeah, I'd love to see rtings test the clean air kit PC fan based products instead

[@David.Elfstrom]

Whoops - the particle counts start at WAY over the count limit of the meter you're using. It's missing many of them at the start. This is visible in how it takes until below 100,000/L before the drawdown on the log scale vs time plot becomes linear. It also means the natural decay isn't representative of the actual natural decay. Is the data available for download? What is the size of the room used?

[@LurkerPatrol5]

I been sneezing my buns off in my bedroom, and now I'm considering making the ugly boy, thanks guys!

[@weslusk3798]

You might also want to check out Clean Air Kits.

[@RTINGScomRD]

Glad to hear we've been a good inspiration! 😄

[@SubFlow22]

As a hobby mycologist, I make all of my own laminar flow hoods. They work great for a fraction of the cost of a commercial brand.

[@tsmith6210]

Please tell me how you make it. I really need it for basements

[@carljones9640]

There was a guy in China, before the covid pandemic, doing his PhD research on this, basically showing that HEPA filters attached to box fans are better air purifiers than multi-thousand dollar units. I wish I could find his work again, but it has been basically impossible since covid. Seems like Corsi and Rosenthal beat him to publication.

[@tristanwegner]

sound like you are talking about the SmartAir blog

[@ChristianBehnke]

If you buy the pack of filters at Costco for $40, adding a $30 box fan can make the CR box build cost far below what you quoted in the video.

[@RTINGScomRD]

Even better! It seems that pricing is different depending on where you are in the world!

[@ChristianBehnke]

@@Weaver_Games Actually, je suis 🇨🇦, and yes, you can find the components for cheap.

[@homemini9254]

Yes. Cheaper

[@RennieAsh]

@@ChristianBehnke je ne veux pas le Canada XD

[@tyscam]

If you're going to just shove it in the corner, you really only need two filters.

[@Barnacules]

I've literally been doing this for many years now! And I didn't invent it, someone told me to do this that had also been doing it for many years. Also, if you have a forced air system in your house just find the cold air intake and place these filters over it and tape them in place to seal all the holes around them and it will also clean the smoke and other particulate out of the air of your entire house. We did both of these things for many years during the wildfire seasons because without it the house would be filled with a haze and our throats would be on fire. Also, it's not necessary to use 4 filters unless you need the capacity. Even a single filter the same size as the box fan taped to the back of it (intake) will work great for several weeks even with heavily contaminated air before it's clogged up and needs to be changed. We break these out every year during the wildfire season here in Washington State because without it our throats feel like they are on fire and our eyes burn. People have been doing this for a very long time though. PS: Credit to Adam (aka. KevlarCondom) for buying me a box fan and my first Hepa filter showing me this technique a long time ago.

[@Peace22_]

Hey Barnacules, you mentioned it's not necessary to use 4 filters unless you need the capacity, and also mentioned your use of HEPA filters. They did speak on both of these topics in the video as well. They said they didn't use HEPA filters in their testing because apparently a much stronger fan would be needed to overcome the extra resistance, and they also discussed that using only one filter strapped to a fan dramatically decreased the effectiveness of the filtration. Seems like if you want the best value it makes most sense to do the 4 filter box method. I feel like the HEPA filter should still do a really good job even with a box fan though.

[@tyscam]

Strapping one of these filters to a fan is ineffective. You do not want to force air across them, you want negative pressure to pull air through them. You still need to build the box in other words, just that 3 sides can be solid.

[@Cujobob]

@@tyscam you can strap a 3” filter to a fan and get decent results, but not to the same level of performance as a full box.

[@jotch_7627]

​@@tyscamokay, then strap it to the side of the fan that generates negative pressure. fans arent magic, they dont "force air" through anything. they work via pressure differentials just like anything else

[@crimson293]

If you're going to position the air purifier in a corner like shown, would it make a measurable difference for the corsi rosenthal box if you only have the two "exposed" sides with filters and just a mesh on the sides facing the walls?

[@Zaf9670]

I’m curious about the PC fan versions of the DIY air purifier as well. Really surprised someone hasn’t done up an ESP32 controlled version for basic stuff like timers, ambient lighting, or other “make it nicer” features.

[@edwardhsieh4644]

You guys make me want to work at rtings.

[@MurderMostFowl]

If you are comparing against Dyson… Pretty much anything wins. Underneath they are competent engineering, but they are 99% paying for the name and the image of buying something “cool“ Dyson would reinvent the wheel if it could and call it something ridiculous like “the 2D sphere” and charge he $5000

[@MayaPosch]

For some reason box fans do not seem to be a thing in Europe, which makes many of us rather sad...

[@weslusk3798]

Check out Clean Air Kits, they use quiet and efficient computer fans.

[@Zaf9670]

There are people who make them using PC fans. They are quieter and if you combine 4+ some claim they will perform on par or close. You can probably find a 3D print shop that makes the brackets and then just need a basic fan breakout that accepts DC or USB power.

[@playlist5455]

PC Fans for radiators (like P12 or Silent Wings 3) are abundant and work better than a box fan.

[@GeneralKenobi69420]

Just get a Winix. 90€ filter included with shipping. Efficient, powerful, looks sleek too. Replace filter once a year with third party ones which are like 20€. Done.

[@shubinternet]

You’re also not generating or monitoring for small enough smoke particles. You need to go down to 0.1 microns and smaller.

[@amb1gamermain22]

That would be a nice metric, but keep in mind those expensive mainstream "hepa" carbon activated etc air filters had much worse performance than the diy box. 0.1um won't add much to the conclusion if what is claimed to clean 0.1um (hepa) wasn't able to clean 10um effectively

[@computersales]

I'll take loud cheap and maximum air volume please. 😅

[@jon_escamilla_]

I would love to see reviews of some of Blue Air's purifiers. Their purifiers don't have housings but a washable cloth surrounding a ring of a filter. These could be in that middle ground of presentation and performance. Either way, excellent work with the video and testing!

[@yarkee8128]

Alot of blue air filters use an ioniser to game the calculated card in manufacturer testing, and it tends to produce ozone which can be bad for long term respiratory health

[@nottimothy5994]

Would be great to also compare replacement filter costs and expected lifetime. The more filter surface area (given a fixed volume of air being filtered), the longer the filter will last. Of course the finer the filter, the shorter it will last. Some manufacturers go with the razor and blades model, and make minimal margin on the purifier and extreme margin on the filters.

[@zncon]

The homemade box would win across the board. Furnace filters are made in such massive quantity that nothing custom for a purifier is going to beat that economy of scale. You can also buy the filters in large 10+ packs which knocks the price down even further. I have no idea how they managed to spend $200 to make that box though, the fan shouldn't cost more then $30, and the filters are around $25 each if you buy them at full retail price.

[@Weaver_Games]

@@zncon Everything in Canada is ridiculously expensive, you have no idea.

[@gg-gn3re]

@@zncon They also came up with the idea that this was invented during covid by 2 engineers and not like 100 years ago. Tons of youtube videos of these designs predate covid lmao.

[@zncon]

@@gg-gn3re Oh boy that's a whole separate rant that I wasn't going to get into, but I hate that two people just slapped their names on what has been a known 'box fan hack' for decades.

[@gg-gn3re]

@@zncon Yea I have a wooden one with 3 slots for filters and wheels on the bottom, hard top (so I use it as a table) and a blower/ air mover fan inside. Way higher static pressure/vacuum/air flow... and it's like 15 years old lol

[@Cryowatt]

Why test an inch away from the wall? I'm pretty sure the devices I own all recommend about a foot from any surface.

[@NekoOverflow]

Right?! Like I don't think Dyson is ever going to win in terms of effectiveness per dollar, especially not their fan models. But my BP-03 specifically says to have it at least 3.5 feet away from the wall. I laughed out loud when I saw that recommendation because I live in a small place. However, keeping it around a foot away from the wall makes its turn over rate feel so much better. If someone spends $1K on an air purifier, I think there's a good chance they're not going to shove it in a corner with a single inch away from the wall. The machine has wheels for goodness sake! Sure, 3.5 feet away from the wall is a ridiculous request for a consumer, so probably not follow the manual to the letter. But I would have liked to see them test a reasonable middle ground!

[@Mischievous_Moth]

I do a little woodworking, and you know... I could probably build a frame for one of these so the filters can be replaced more easily. Might even be able to SPRUCE it up a little! (Good ol' woodworking puns)

[@Ender_Wiggin]

You should consider testing the The 3D Handyman kits

[@jordanviray]

Too bad this design got named after Corsi and Rosenthal when Neil Comparetto was the inspiration for them. A couple things: how would 4" thick filters do vs the 1"? More filter media area means theoretically more airflow and the ability to run quieter or use smaller dimensions iso-CFM . Related to CFM would be different box fan types. There's an optimal static pressure and CFM fan for the best noise normalized filtration efficiency for a given MERV and it would be really cool if a review site could find that out.

[@dtemp132]

The problem with 4" filters is that they blow up the economics, they are WAY more expensive than 1" filters.

[@AhpgZfoc4s]

@@dtemp132 Maybe. The video is about the best performing air filter. The DIY box just happens to be fairly inexpensive. The main complaints are that it is loud and ugly. The ugly could be fixed pretty easily but the loud part offers a few possible avenues to look at like thicker filters for slower fan speed. Economics wise, a pack of 4 20x20x1 MERV 13 filters is $65. A pack of 4 20x20x4 MERV 12 filters (no MERV 13 available) is $108. I don't know what the area of the filter media is for the 4" filter. All else being the same, it should be quite a bit more which means lower pressure at a given CFM so you can run a fan at a lower speed. As well, they have the ability to hold much more dirt which means longer intervals between filter changes. So if the interval is twice as long, the economics is a wash. I would guess the interval is going to be over twice as long so the economics might be better. But I don't have any data to back that up. However, the 1" thick Filtrete 1900 has an unusually high number of pleats as Project Farm discovered. The static pressure drop is fairly high but the DIY box has an enormous amount of filtration area so it might not matter vs a single unit for a furnace fan. They might even get higher performance in the lowest number of small particles after an hour test if they used even finer media like the Filtrete 2800. They could compensate for the pressure drop by using 4 20x30" ones and even a 20x20 on the bottom with some legs for a 40% increase in surface area. Who knows, not worth testing for a regular guy but RTINGS routinely tests tens of thousands of dollars worth of TVs, monitors, printers etc so messing around with a couple hundred dollars worth of filters would make for an interesting review. To me, the key to getting it quieter would be to find a DC powered box fan though and seeing which one has offers the most filtration when normalized for noise. Box fans don't get the exotic technologies found in PC fans like liquid crystal polymers and exotic fan geometries but there might be some out there.

[@Zyxlian]

@@AhpgZfoc4s I was thinking about using a much quieter design by using 20cm PC DC fan instead of a box fan for just a bedroom. I would love to see some testing of this concept. Maybe even expanding to a 2x2 square of 20cm fans for a better surface area to noise balance if you did need a larger volume. Automating/monitoring it with a microcontroller would also get the benefits of the much more expensive mass market air purifiers as well.

[@jordanviray]

@@Zyxlian I think that would work. I had a watercooling radiator that used a 2x2 square of 20cm fans and it was very quiet. Plenty of fan controllers out there as well so I think that would be a winner!

[@dallasgombash5381]

You can, just isn't as efficient, but it's what I do

[@Bulldawzer]

Why didn't you mention using quiet PC case fans to solve the noise issue while maintaining same or higher CFM than a box fan?

[@fuxseb]

Computer fans create only a very low pressure, especially the quiet, low RPM ones. Their CFM figure is valid only at zero resistance. Add a filter and the flow is almost at a standstill. Obviously there are some stronger ones used e.g. in servers, but their noise profile and level is something between a hairdryer and industrial vacuum cleaner. They're not intended for use in inhabited rooms, which may imply legal liability, should someone damage their hearing or cut their fingers on the blades. A box fan on the contrary will have all required certifications and safety features.

[@tychay]

⁠@@fuxseb And yet an array of artic or SickleFlow computer fans get better performance in tests at about 1/10 the wattage and much much lower decibels than a box fan. Maybe because computer fans are not all low speed and they're designed to create a static pressure while a box fan is designed to create a breeze? Plus these are not HEPA filters and there is a lot of surface area to them, so it doesn't require much pressure to get air flow. If you want to talk "like a vacuum cleaner" try some of these commercial HEPA air purifiers at the max setting they are advertising at: either they are loud as a vacuum cleaner or they don't do jack at filtering air (looking at you Dyson).

[@mfs-ness]

Ikea makes a purifier built into a small table (STARKVIND), which makes it easier to have near the middle of the room.

[@user-Cata7sti7ma7]

you can get a bundle of 5 Arctic P12 Max fan for 50$ . wih a 10 buck controller. that could decrease the noise by alot and fine tune more since more control about fan speed.

[@adriankoch964]

Also use less electricity. Those box fans are around 100w. Wich adds up when running 24/7

[@JoelHernandez-tz3vk]

​@@adriankoch964Wonder how much of that inefficiency is due to the AC motor rather than the lack of static pressure.

[@Jaker788]

​@@JoelHernandez-tz3vkNearly all AC powered house fans use a shaded pole motor, those are just 20% efficient... PC fans use DC brushless, despite the name it's actually a 3 phase synchronous AC motor operated by PWM DC to replicate AC frequency. Synchronous AC motors are 90-95% efficient. You can also buy your standard home fans but with a brushless DC motor. Vornado has a model with one that claims 80% efficiency savings over standard fans. Vornado fans are also more pressure optimized than a box fan, partly because the housing is actually round so there's less air space around the blade and frame. Box fans are the worst option but still work. The main issue, regardless of motor choice, is the square frame. With that frame there's a lot of gap between the blade tips and it makes a lot of turbulent air blowback when there's resistance. The closer and tighter the blades are to the frame, the better your static pressure will generally be and a turbulence source is reduced. After that the remaining optimization is blade geometry and blade count to reduce turbulence between blades and optimize the noise frequency, there are trades to make in multiple ways.

[@ChetHanks-eh1md]

The problem with this box is that box fans themselves are unreliable. The lubricant wears out and the blades stop spinning. This wouldn't be a problem if fans were easy to dissemble , problem is they are not.

[@Calin8er]

How long do you expect them to last? In my apartment I use a merv 12 filter taped to a box fan to bring in air from outside. Another box fan to force air back out in another part of the room(no filter on that one). Both have been running for at least 5 years now. They don't run all the time just when the temperature and outside air quality is decent which it is outside of summer months. The fan with the filter had a plastic handle on it, it actually degraded and snapped off eventually. I replace the air filter once a month(it gsts to dark grey color). I have 5 HEPA air filters in my apartment as well 4 are whirlpool whispure(2 of which are over 10 years old), and I replace the filters on their suggestrd schedule.

[@ame7165]

well it's as if the universe were taunting me. my yearly rings insider subscription just renewed and I was shopping for air purifiers this week and then I see this video pop up. woohoo

[@RTINGScomRD]

Love to hear it!! 😄 Thank you for the continued support ❤️

[@ElectricEarth117]

Always wanted to do this but everyone thought i was crazy. Thank you

[@Ederick1936]

good lord, I had no idea that yall were from Montreal! no wonder you are reviewing Air purifiers :P

[@adriankoch964]

The better DIY alternative to the box fan design uses a bunch 120 or 140mm high static pressure PC fans. Uses the same filters. Cheap to build, cheap to run (pc fans use

[@3nertia]

How many fans does that require and do you have any references for your claims?

[@hotdogsarepropaganda]

@@3nertia its all about CFMs and how much pressure they have. the best PC fans for pressure and CFM are 120mm Artic P12 max or Artic p14 max for 140mm. they come in 5 packs for aound 35-45 bucks. the standard CFMs for a box fan is 1100-2500 for low and high. the p12max is 86 cfm per fan the p14 max are 95. so it would take roughly 11-12 (12 to make a perfect square) 14mm fans to equal the CFM of a box fan on low. there is not good static pressure information on box fans. the cost would be 3 boxes at 45 dollars each so 150. they might use less power around 100w and may be quieter because of blade tip surface area but the noise will also have a different and likely higher pitch than the box fan. the p14max fans are designed to push air through small gaps in computer liquid cooler radiators and may yield an advantage in pushing through the filters but wont be directly comparable without static pressure ratings from box fans

[@TheEchelon]

@@3nertia Googling will give you all the results... "DIY pc fan MERV air purifier"

[@Cujobob]

@@3nertiaa few brands sell kits based around this idea if you’re curious. Two are Nukit and Clean Air Kits.

[@MH-kc5jr]

10W for a pc fan even at full power is too much, more like 6-7W at max

[@EhNothing]

This is really neat, and I love the DIYness of it. As an exceptionally lazy person, I'd like the DIY option more if it could be built with a frame that the filters could sit in and more easily be replaced without having to fully retape the whole freaking thing just to replace filters.

[@Sashazur]

You can buy frame kits online. Search for “box fan air filter frame” etc

[@TruFalco]

That's what I was just thinking! Closest thing I've found on Etsy is box fan clips for 1 filter.

[@MrMoneyHelper]

Tape is cheap and makes a great seal.

[@dallasgombash5381]

Get some $1 fiberglass filters to use as a prefilter(and swap them out often), it significantly increases the life the the expensive filters.

[@headerahelix]

I guess merv ratings are American because I find nothing about them in Finland.

[@honeybee4889]

Would your team consider testing different streaming devices? Additionally comparing it to streaming directly from smart TV’s. I can’t seem to find an extremely clarifying answer to the questions I seek. What is going to provide the best image and audio quality for my TV. I’ve heard most either recommend Apple TV 4K or Nvidia Shield. I just purchased a S90D tv and would also be curious if these streaming devices provide an upgrade in quality to high end smart TV’s. Lastly if a TV does not support something like Donny Vision but I were to stream from an Apple 4K tv which does support such a feature would the streaming devices support translate to the screen? I know it’s a lot of questions but if anyone were to know/care about the answer it would be RTINGS! Been loving your KZbin channel and checking out your website also as a result!

[@RTINGScomRD]

Definitely could be something we do in the future, we just can't make any guarantees at this time. Sorry about that!

[@brianbuckley5204]

Sounds like this would be ideal to just store away in a closet and place down in a room while you're out of the house.

[@TheBautistrg]

You guys made this at the precise time. You just saved me so much money.

[@iamdmc]

philips air purifiers are probably the best on the market

[@_ch1pset]

there's another aspect not discussed, energy consumption. Box fans use axial fans, while most purifiers run on centrifugal fans. Centrifugal fans generate more pressure for a lower power consumption compared to an axial fan the same size. Sure, it's less air flow, but you really need that pressure to push air through the filter. The box fan contraption also has the downside of requiring 4 or 5 air filters that all need to be replaced at once, essentially you have to build an entirely new one each time you change out the filters. That's like $300 a year minimum. It's NOT necessarily cheaper.

[@WatsitTooyah]

Multiple filters in an environment will make them overall last longer. You have the same amount of contaminants in a duration of time wether you have 1 filter or 100. Changing them on a strict time frame can be a big waste. Every environment is unique. Also definitely true about the power consumption compared to typical purifier designs

[@3nertia]

Centrifugal fans are also about 3x more expensive on average, if you want to buy them in small quantities anyway heh

[@motley06]

If you’re burning through $300 worth of filters in this design, you’ve got other issues going on

[@_ch1pset]

@@motley06 if you only need something temporary with how well it works, I think you need to ask yourself why $150 is justified in the first place. Air purifiers are needed in environments where the extra filtration is needed. Chances are, if you have an air purifier, you are running it 24/7 or every day, consistently for months or years at a time. It is not unreasonable to replace the filters once every 6 months. This test doesn't take into account the long-term cost effectiveness of these units or this design. MERV13/HEPA filters are not super cheap, and running the units for long periods of time consumes a lot of energy.

[@thePavuk]

In my country (center of Europe) single one of these filters cost about $70-100... Just saying. There are cheap on amazon, but they don't ship them here or after adding shipping and tax you are back to 70-100.

[@mz1929]

how is the rosenthal box any better than just the homes Air Intake with the same filter/s...? weather the home has just 1 main central intake, or mini intakes in each room as well.

[@Collin_J]

I have yet to live in an apartment that uses a furnace.

[@dlewis9760]

@@Collin_J I live in a house heated by oil heat and hot water base boards. A couple of years ago I added a mini split AC/heat pump that cut the oil usage in half. Everyone is different. Why did you answer the question as some kind of flex? Neither you or I can answer the person's question. But it is a valid question.

[@michaelwyckoff7593]

Hi Abby❤😊

[@SianaGearz]

Why you didn't test IKEA filters? Many of the products you showcase are regional to North America, while IKEA by all reason are available in a lot of countries. They're also very affordable.

[@crazyman124ify]

I beg you guys make rting for air humidifier! Nice videos, love what are you doing guys, keep it up!

[@francistower5352]

Love the Vid. Just in time for my decision to clean my bedroom air!

[@RTINGScomRD]

Thank you for watching and glad you enjoyed the video! Hopefully our video and reviews can help you buy what you need! 😄

[@AlexSchendel]

I wonder if there's a version that could leverage a PC case fan for a much quieter and smaller build for apartments and the like. Maybe using one of those oval replacement filters for the Dyson purifiers... I've got a couple Noctua 5V PWM fans hooked up to a microcontroller for speed control. Modifying them to be air purifiers could be interesting 😁

[@MrMoneyHelper]

Years ago rented a room in a house. I noticed that I was coughing more than usual. An expensive air purifier was not in the budget. A 20" box fan was purchased and some MERV 13 filters were ordered. I taped one filter to the back of the fan and within a day I wasn't coughing. Later I bought a carbon pre-filter to remove odors. It was a waste of money. I cooked a meal in the room and four hours later the odor was still there. The MERV 13 filter was changed every few months. That was done for years. The fan was given away when I moved. Years later I lived in a house with smokers. I should have just made another air purifier. Instead I bought a big Winix filter. It worked well but cost a lot.

[@berkeleybernie]

Good video, but you need to look into mods (both commercial [Clean Air Kits] and open source) on the Corsi-Rosenthal design that keeps its very high CADRs (Clean Air Delivery Rate) while being much quieter (using PC fans). Lots of great info on this video: kzbin.info/www/bejne/nZK0hYyonticm6M And here's one mod that uses a much quieter fan than a box fan while preserving most of the benefit: kzbin.info/www/bejne/gamznGuvhK1gsJY

[@ianchoi8053]

I made one of these for our class room a few years ago, we're a project based school so we be doing alot of weird plant and chemical stuff which made the room stink. So I got approval from our teacher to build one and it worked amazingly.

[@TheStaniG]

I subbed for a hp laser printer review amd now not only has your TV testing been INCREDIBLE but you come up with these BANGERS I didnt even know I needed.

[@chronickat5453]

one thing that would be good to consider is how expensive replacement filters are, especially the proprietary ones.

[@Collin_J]

The name-brand ones for the Coway air purifier I bought during COVID are $60. For a 1-inch HEPA filter. That's something like a 300-400% markup

[@DaveNLR2]

OK seriously guys and gals at Rtings, why not design that duct tape filter with a real frame, with slip ins for the filters, and replace the box fan with a integral fan somewhat like the fan on an outdoor ac unit, then market it for 1/2 the cost of those rip off brands, and have some spare change to give yourselves a raise, and buy a microLED to test.

[@sermerlin1]

So it isn't HEPA filter... So what's the point of it then? You can get HEPA filter air purifier like xiaomi air purifier. Dirt cheap and works great. No need to have a large ugly box sticking out. Has proper engineered fan that can move air through the HEPA filter and filters easy replaceable (and damn cheap as well).

[@dlewis9760]

The fan is a major variable. So many on the market at different price points, air movement and noise. KZbinr Healthy Home Guide built one with a 160 buck fan. Supposedly extremely quiet and efficient. But it's a 160 buck fan. Yours may have the exact same results or better than his. But his has 10 speeds and a wireless remote. You could test the homemade design with an infinite number of fans, but that's not really the point of your company. Thanks for showing us the "Yeah, but........" with the homemade design, but the homemade design is it's own rabbit hole.

[@magicmanchloe]

Ok, how is there not a maker project based on the Corsi Rosenthal box that integrates some of those quality of life features, like a air quality sensor, Seven segment display and smart home integration with a low cost esp

[@tychay]

The AQ sensor probably should be separate/distant to the fan (My old Coway air purifier has one and it's incredibly unreliable). Plus a lot of AQ sensors measure VOCs in which they not the carbon filters are too small to do much to fix. As for smarthome, you have the right idea, but why put it in the device? I simply have a $4 zigbee power plug powering a CleanAirKit and have a HA integration that's better than whatever you can pay for allinone at any price: mine turns on/off based on outdoor AQ and peak/off peak/partial peak energy pricing, always turns on when the AC fan is running (since it sits near my HVAC intake), and always pauses whenever a door or window is open. Since the CleanAirKit uses PC fans, mine is incredibly quiet (louder than the Coway at its lowest setting but much quieter than the coway at the medium) and only draws 12W so fan speed control doesn't matter. You want the most air throughput anyway so if it's quiet enough to be a low hum and doesn't sound like a fan it's aces in my book.

[@PhilLesh69]

Get a five gallon bucket and drill a bunch of holes all around the lower few inches. Line the inside with a screen. Fill the five gallon bucket with activated charcoal granules. Find a fan that can be fitted onto the lid, blowing inward. It will not only absorb 2.5 micron particles like a hepa, but it will *_also_* capture odors, VOCs, smoke, and just about everything except oxygen.

[@gcs8]

There is a smaller version that someone on KZbin built that is as effective* using a 10-speed acinfinity fan and made some improvements to make it more serviceable.

[@kia8077]

Do robot vacuums and mops next please!!

[@Djuntas]

S8 roborock has been good for me

[@NekoOverflow]

Vacuum Wars has some pretty good coverage on vacuums and robot vacuums. Their methodology seems pretty sound and might be of interest to you.

[@samius1149]

It might be worth considering the 1 filter versions of this - which was the more popular version of this before Covid. Those are pretty effective too and with a far smaller footprint. Especially as with a smaller environment you can use a smaller 12 inch filter and regular 12 inch honeywell fan - which is pretty quiet and small. The filters need replacing more often but far less than 4x as often.

[@Collin_J]

I'm confused, didn't they do that?

[@XGD5layer]

They tested that. There was a difference by one order of magnitude, almost two

[@csimet]

More surface area and greater airflow, simple physics. I have one like this in my workshop built into the ceiling for shop dust, but I'll stick with a nice looking commercial unit for my living space.

[@user-jr1hm3jw2i]

That idea has been around since old days of this old house. To say someone invented it during covid is a joke

[@motley06]

After building my own CR box. Sure, it’s the best for filtering, but it’s too loud to actually use. It stays off most of the time, so it’s no good

[@DeenaMilkers]

no replacement for displacement. also, this design has been around LONG before covid.

[@Hfil66]

The problem with most of these reviews is they only look at cost and performance at time of purchase. What would be more interesting is how easy is it, and and what cost, to replace filters. What is the cost after two or three years of use (how long do the filters last and how much do they cost)? If one box is twice as good as another, can this be mitigated by using two boxes of the less effective variety - what is the cost and space usage penalty of doing so? Filters aside, some air purifiers also use electrostatic plates and UV light - what is the relative impact of these (they should not cost as much in terms of loss of airflow as a thick carbon or HEPA filter)?

[@Mark-h6k1w]

Could you please tell me where to purchase your particle counter and about what it would cost? Also what is the bottom panel material you are using (I couldn't understand what you called it in the video) and what is the brand name of the fan you are using?

[@fortyfukinseven]

How the crap is that thing $150? The fan is like $30, and the filters are maybe $50 total

[@dubsaru]

Very curious about the Blue Air filters.

[@SetTheCurve]

You tested a uniform large particle size from a fog machine that uses a volatile fluid. This is nothing like true pollution and dust, these results should be thrown out.

[@chahahc]

"There's no replacement for displacement"

[@dil6969]

I'd like to see DIY perks take this base design and dress up the exterior. This thing takes function over form to the extreme and is the only thing that would keep me from using it.

[@AGILISFPV]

Sorry but you say the CR box is the BEST. Yet you havent even tested one of the best ones to compare it to which is the Blue Pure 211+ Air Purifier. Housefresh actuall tested the CR box against the blue pure as well as many of the CR -style kits and found that even those didnt perform as well. So what gives?

[@RTINGScomRD]

Just clarify, we're not saying it's the best out of all available products, simply our top pick based on the one's we've bought and tested. Sorry for the confusion!

[@uss_04]

It might work well but I really appreciate cleanable prefilters. Still might be good in a pinch

[@AyAy008]

The fact that two guys gave it their name believing the "invente" it is hilarious. Guys all around the world have been using that in their shops or homes for years before.

[@Justgoodvids]

Omg I have been thinking about this for months after seeing it go popular on hacker news some years ago when smoke and soot from the fires were overwhelming Californians

[@willemvanriet7160]

Love it! Another way we can bypass big corporations ripping us off

[@lavidren3890]

wonder how quickly does this get destroyed by a pair of house cats compared to an air purifier with a durable plastic shell

[@slackerman9758]

I wonder if putting the Dyson in a corner, where the only path for the air is head on into the fan, is the fairest way to test those units. Maybe you are just discovering that those units should not be crammed into a corner.

[@KimcheeRacing]

I made one of these 20 years ago when the vog was really bad in Hawaii but never got it named after me, lol...

[@TheWebgecko]

Can you please test the kits by Clean Air Kits? Those have multiple smaller fans to be quieter

[@alexherrera3918]

Can you put a funance 4in filter on the walls? that will increase the filter area A LOT.

[@artosbear]

How'd you get to $150 for a box fan and the filters?!

[@princessmiaxo]

Yeah, covid-conscious people figured this out years ago lol

[@leoceoliveira]

Very cool! I wonder how they perform with PC fans!

[@FreeErik]

Gonna build my purifying PC box in 3, 2, 1...

[@tyblackwood]

It looks like a crack house version of my Blueair 211+

[@RotomWash]

especially if pet hair is your main reason for buying a filter, something like this beats all

[@linh8997]

Play make all kinds of fancy, colorful, decorated duct tape

[@jtland4842]

Is it possible to do some sort of noise normal-sized results? Another way to make the a DIY air purifier that is quieter is to use PC fans. It will definitely be more expensive and more complicated but it should be much less noisy even at the same noise level it should perform better especially if you choose high quality fans at the correct size.

[@ObakuZenCenter]

PC fans are tiny and wouldn't move enough air. This is not to cool small parts, it's to clean the air in a larger area.

[@pacioli]

If you stick it in a corner, can you get away with only 2 filters?

[@kkrolik2106]

I Put car cabin filter on to my dehumidifier, Great to clean air

[@CafeaAlba]

I would love to see you test the ones from Xiaomi, they are really popular in Europe

[@adriankoch964]

They are bad (don't cycle a room worth of air often enough to actually remove enough particles and are quite loud at max speed) & the filters are really expensive.

[@silvahawk]

5:13 why don't you want the purifier to be dead center in the room?

[@SirDragonClaw]

What a joke, it's not even base level hepa rated.

[@nopenoperson9118]

oh THAT'S where my Lasko went

[@reddcube]

I surprised you didn’t test the IKEA FÖRNUFTIG. It’s great budget option.

[@dmagik8]

thumbs up for crinacle