#crboxes — Public Fediverse posts

An Easy-to-Build #CorsiRosenthalBox Using Modular #PCFan Systems

Jim Rosenthal
October 21, 2023

"The first Corsi-Rosenthal Box was built in August of 2020. It was presented as an #OpenSource' concept so that as many people as possible could have low-cost cleaner, safer indoor air. It is based on sound engineering principles, but it is really very simple. Use 4 (or 5) MERV 13 filters in a 'box' configuration with a box fan. The best thing is – it works! Consequently, many thousands have been made all over the world.

It has also been very enjoyable to see the continuous stream of ingenuity, creativity, and knowledge that has been expended to create a 'better' Corsi-Rosenthal Box. Much of this was out of necessity since many countries in the world do not have the same filters and fans as we have in North America. Many really smart and creative people have developed designs of the CR Box concept that work with the fans and filters available in their countries.

We have also had many people in North America who have contributed to the development of a “better mousetrap” of a DIY air cleaner. For effectiveness and low cost, it is very hard to beat the original box fan and “box” of filters design. But there have been many interesting modifications that have been shown to provide some real benefits. The most interesting of these is the use of PC fans to replace the box fan. The PC fans have the advantages of low noise and low energy usage but are not as economical or as easy to construct.

Here is another alternative – modular PC fan systems. A company by the name of AC Infinity (www.acinfinity.com) makes them. Their primary uses are for audio-visual cabinets and indoor horticulture. However, they provide low noise, high air flow and low power usage. In other words, they should work for Corsi-Rosenthal boxes. My initial tests confirm this conclusion. "

Note: I am not finding the fans on the AC Infinity website. I have found computer fans that can do the job on eBay and Amazon.

Learn more:
https://www.texairfilters.com/an-easy-to-build-corsi-rosenthal-box-using-modular-pc-fan-systems/

#SolarPunkSunday #CleanAir #WildfireSmoke #WildfireHaze #AQI #AirQuality #WildfireSeason #Wildfires #DIY #CRBoxes

An Easy-to-Build #CorsiRosenthalBox Using Modular #PCFan Systems

Jim Rosenthal
October 21, 2023

"The first Corsi-Rosenthal Box was built in August of 2020. It was presented as an #OpenSource' concept so that as many people as possible could have low-cost cleaner, safer indoor air. It is based on sound engineering principles, but it is really very simple. Use 4 (or 5) MERV 13 filters in a 'box' configuration with a box fan. The best thing is – it works! Consequently, many thousands have been made all over the world.

It has also been very enjoyable to see the continuous stream of ingenuity, creativity, and knowledge that has been expended to create a 'better' Corsi-Rosenthal Box. Much of this was out of necessity since many countries in the world do not have the same filters and fans as we have in North America. Many really smart and creative people have developed designs of the CR Box concept that work with the fans and filters available in their countries.

We have also had many people in North America who have contributed to the development of a “better mousetrap” of a DIY air cleaner. For effectiveness and low cost, it is very hard to beat the original box fan and “box” of filters design. But there have been many interesting modifications that have been shown to provide some real benefits. The most interesting of these is the use of PC fans to replace the box fan. The PC fans have the advantages of low noise and low energy usage but are not as economical or as easy to construct.

Here is another alternative – modular PC fan systems. A company by the name of AC Infinity (www.acinfinity.com) makes them. Their primary uses are for audio-visual cabinets and indoor horticulture. However, they provide low noise, high air flow and low power usage. In other words, they should work for Corsi-Rosenthal boxes. My initial tests confirm this conclusion. "

Note: I am not finding the fans on the AC Infinity website. I have found computer fans that can do the job on eBay and Amazon.

Learn more:
https://www.texairfilters.com/an-easy-to-build-corsi-rosenthal-box-using-modular-pc-fan-systems/

#SolarPunkSunday #CleanAir #WildfireSmoke #WildfireHaze #AQI #AirQuality #WildfireSeason #Wildfires #DIY #CRBoxes

@tinker Timely post! I'll be posting about #CRBoxes for this week's #SolarPunkSunday!

@tinker Timely post! I'll be posting about #CRBoxes for this week's #SolarPunkSunday!

RE: https://social.ridetrans.it/@Andres4NY/116931466428900883

Tagging this thread for #SolarPunkSunday... Discussions about building one's own #CorsiRosenthalBox from folks who have built them. These ones use computer fans, which are a lot quieter than the box fans recommended in the original instructions by Corsi.

#DIY #CRBoxes #AirCleaners

RE: https://social.ridetrans.it/@Andres4NY/116931466428900883

Tagging this thread for #SolarPunkSunday... Discussions about building one's own #CorsiRosenthalBox from folks who have built them. These ones use computer fans, which are a lot quieter than the box fans recommended in the original instructions by Corsi.

#DIY #CRBoxes #AirCleaners

Scientists Tested a DIY Air Cleaner – And It Beat Expensive Filters

By American Chemical Society, March 24, 2025

Excerpt: "As Corsi highlights during his presentation, he and his colleagues recently tested the durability and performance of #CRBoxes by installing units in four locations across the UC Davis campus. They ran them for 2,500 hours — the equivalent of two K-12 school years.

"The CR Box filters performed as well or better than comparable #HEPAFilters. The #DIY system was also more effective at clearing particles 1-3 micrometers in diameter than particles 0.35-1 micrometers. For a sense of scale, typical smoke particles are smaller than 1 micrometer, whereas dust and pollen are 0.5-3 micrometers.

"Although HEPA filters are more efficient at removing particles in a single pass than the HVAC filters used in the DIY system, Corsi explains, much more air passes through the CR Boxes, leading to more particles being removed from the air. Although the CR Boxes’ effectiveness diminished over time, they still performed better than new and more expensive HEPA air filters for the larger particle size and performed competitively with HEPA for smaller particles over the extended study period."

Read more:
https://scitechdaily.com/scientists-tested-a-diy-air-cleaner-and-it-beat-expensive-filters/

#DIYAirCleaner #CorsiRosenthalBox #CorsiRosenthalBox #AirCleaners #AirFilters #DIY #WildfireSmoke

Scientists Tested a DIY Air Cleaner – And It Beat Expensive Filters

By American Chemical Society, March 24, 2025

Excerpt: "As Corsi highlights during his presentation, he and his colleagues recently tested the durability and performance of #CRBoxes by installing units in four locations across the UC Davis campus. They ran them for 2,500 hours — the equivalent of two K-12 school years.

"The CR Box filters performed as well or better than comparable #HEPAFilters. The #DIY system was also more effective at clearing particles 1-3 micrometers in diameter than particles 0.35-1 micrometers. For a sense of scale, typical smoke particles are smaller than 1 micrometer, whereas dust and pollen are 0.5-3 micrometers.

"Although HEPA filters are more efficient at removing particles in a single pass than the HVAC filters used in the DIY system, Corsi explains, much more air passes through the CR Boxes, leading to more particles being removed from the air. Although the CR Boxes’ effectiveness diminished over time, they still performed better than new and more expensive HEPA air filters for the larger particle size and performed competitively with HEPA for smaller particles over the extended study period."

Read more:
https://scitechdaily.com/scientists-tested-a-diy-air-cleaner-and-it-beat-expensive-filters/

#DIYAirCleaner #CorsiRosenthalBox #CorsiRosenthalBox #AirCleaners #AirFilters #DIY #WildfireSmoke

@cdarwin

wearing an N95 :n95: when there's wildfire smoke 🔥💨 cuts between 19/20 and 999/1000 of dangerous PM2.5

fine particulate matter (PM2.5) pollution released by wildfires is even more toxic [...]

neurotoxic particles [...] including heavy metals [...]

These particles can reach the brain via the olfactory nerve and pass through the blood–brain barrier

And indoors, where PM2.5 from wildfire smoke does still reach, air purifiers are also highly effective!

https://www.theguardian.com/wellness/article/2024/aug/07/how-wildfires-affect-mental-health

#maskUp #cleanAir #CleanTheAir #CRBoxes

@cdarwin

wearing an N95 :n95: when there's wildfire smoke 🔥💨 cuts between 19/20 and 999/1000 of dangerous PM2.5

fine particulate matter (PM2.5) pollution released by wildfires is even more toxic [...]

neurotoxic particles [...] including heavy metals [...]

These particles can reach the brain via the olfactory nerve and pass through the blood–brain barrier

And indoors, where PM2.5 from wildfire smoke does still reach, air purifiers are also highly effective!

https://www.theguardian.com/wellness/article/2024/aug/07/how-wildfires-affect-mental-health

#maskUp #cleanAir #CleanTheAir #CRBoxes

In other news, the cat (who turns 1yo today) broke one of the #CRBoxes by playing with the fan.

20" box fan. I don't know how he did it, but I heard him forcing the fan blades to stop. Now it doesn't turn on any more!

In other news, the cat (who turns 1yo today) broke one of the #CRBoxes by playing with the fan.

20" box fan. I don't know how he did it, but I heard him forcing the fan blades to stop. Now it doesn't turn on any more!

@IcooIey @eniko It is significant and important that a statewide government, CT, is implementing this relatively inexpensive technology instead of spending the budget “studying” the issue and deciding the high cost solution is beyond the schools’ means.
#CRboxes #ventilation #airfilters #AirFiltersInSchools #respiratoryvirus #respiratorydiseases #covid #COVID19 #SeattleCentral

Filter sales for your #CRBoxes - if you're a costco member, you can get 20x20x1 MERV-14 filtrete filters for $12.50 each (4 for $50): https://www.costco.com/3m-2500-series-filtrete-1%22-filter%2c-4-pack.product.4000181409.html

I've never used MERV-14 (filtrete) filters in a #CRBox before, so I'm curious about others' experience with them.

Otherwise, here's MERV-12 filtrete filters for $13.79 each (6 for $83): https://www.walmart.com/ip/Filtrete-20x20x1-Air-Filter-MPR-1500-MERV-12-Advanced-Allergen-Reduction-6-Filters/615381943

Filter sales for your #CRBoxes - if you're a costco member, you can get 20x20x1 MERV-14 filtrete filters for $12.50 each (4 for $50): https://www.costco.com/3m-2500-series-filtrete-1%22-filter%2c-4-pack.product.4000181409.html

I've never used MERV-14 (filtrete) filters in a #CRBox before, so I'm curious about others' experience with them.

Otherwise, here's MERV-12 filtrete filters for $13.79 each (6 for $83): https://www.walmart.com/ip/Filtrete-20x20x1-Air-Filter-MPR-1500-MERV-12-Advanced-Allergen-Reduction-6-Filters/615381943

"How well do the PC fan #CRBoxes work", you ask?

Normally my AQI monitor sits at 1 with windows closed. With windows open, as outdoor AQI has been around 30-40 recently, the indoor monitor has been around 5.

I had a number of windows open earlier today, and had to close most of them when outdoor AQI spiked up to 60 in the past ~4 hours. Now I have one window open, and while the AQI outdoors is 73, the indoor AQI monitor next to it shows 11.

"How well do the PC fan #CRBoxes work", you ask?

Normally my AQI monitor sits at 1 with windows closed. With windows open, as outdoor AQI has been around 30-40 recently, the indoor monitor has been around 5.

I had a number of windows open earlier today, and had to close most of them when outdoor AQI spiked up to 60 in the past ~4 hours. Now I have one window open, and while the AQI outdoors is 73, the indoor AQI monitor next to it shows 11.

Hi, John! Nice to meet you. You post good stuff, thanks.

In Colorado, US, where I live, we have lots of bad indoor air from viruses and wildfire smoke. I'm starting to fiddle with portable, replaceable-filter #CRBoxes.

#Physics #Science #PublicHealth #HEPAMilitant #CRBoxes https://mstdn.ca/@johncormier/109378108308929895

Hi, John! Nice to meet you. You post good stuff, thanks.

In Colorado, US, where I live, we have lots of bad indoor air from viruses and wildfire smoke. I'm starting to fiddle with portable, replaceable-filter #CRBoxes.

#Physics #Science #PublicHealth #HEPAMilitant #CRBoxes https://mstdn.ca/@johncormier/109378108308929895

Turns out my #bced wife had been sending sick kids home all last week. So it’s clear that parents have been sending their covid sick kids to school, unmasked in a pandemic.

Unfortunately no amount of self bought #crboxes and #masks can combat that kind of callousness.

It’s almost as if the general population is convinced that the pandemic is truly over. So many are delusional, living a 2019 mentality oblivious to the damage they are causing families.

People are losing their health, jobs and livelihood to “you do you” normal seekers who couldn’t care less because thats the low bar their gutless govt has set.

Turns out my #bced wife had been sending sick kids home all last week. So it’s clear that parents have been sending their covid sick kids to school, unmasked in a pandemic.

Unfortunately no amount of self bought #crboxes and #masks can combat that kind of callousness.

It’s almost as if the general population is convinced that the pandemic is truly over. So many are delusional, living a 2019 mentality oblivious to the damage they are causing families.

People are losing their health, jobs and livelihood to “you do you” normal seekers who couldn’t care less because thats the low bar their gutless govt has set.

@kkarhan

Sure would! Keep kids home when they are sick, let kids who are immunocompromised do school remotely!

Ventilation and filtration… there hints people are starting to get it?

But not nearly enough.

#cleanair #cleanaircrew #crboxes

@kkarhan

Sure would! Keep kids home when they are sick, let kids who are immunocompromised do school remotely!

Ventilation and filtration… there hints people are starting to get it?

But not nearly enough.

#cleanair #cleanaircrew #crboxes

Them: Get covid everyone, it’s fine🤡

Covid: literally decreasing your brain functions if it doesn’t murder you 🦠

Them: now... believe me this minority is out to get you, there’s no such thing as faxts [insert new conspiracy here]

...repeat until???

I actually find the facts kinda helpful 🙃
#CorsiRosenthal
#CRboxes
#airfiltrationworks
#MasksSaveLives
#CovidIsNotOver #CovidBrainDamage #COVIDisAirborne

Them: Get covid everyone, it’s fine🤡

Covid: literally decreasing your brain functions if it doesn’t murder you 🦠

Them: now... believe me this minority is out to get you, there’s no such thing as faxts [insert new conspiracy here]

...repeat until???

I actually find the facts kinda helpful 🙃
#CorsiRosenthal
#CRboxes
#airfiltrationworks
#MasksSaveLives
#CovidIsNotOver #CovidBrainDamage #COVIDisAirborne

I've wired the fans together. I used some segments of cat 5 cable and pushed the wire into the existing plug and then connected all the positives and grounds.

I've cut the material for sides. I've gone back to using cardboard because it's light and fast to cut and it will tape well to the filters. Taping things gives a better air seal. Don't @ me on this design choice until you've built a couple #CRboxes.

I've also dug up a vintage Brown light switch for the power. I'll mount that on the side of the box.

7/n We had a blast, safely, today. Everyone masked. #CRBoxes placed in rooms where we ate and drank, i.e.: unmasked. No more than 8 people at one time. I continuously monitored #CO2; it varied between 500 and 800 throughout.

Our guests enjoyed going through our hundreds of #Ornaments collected over three decades. There are even some heirloom family ornaments from the #1960s.

This group is more recent, befitting a #Queer / #Gay household.

https://flic.kr/p/2o6ARaB

#ChristmasTree #SolsticeTree

7/n We had a blast, safely, today. Everyone masked. #CRBoxes placed in rooms where we ate and drank, i.e.: unmasked. No more than 8 people at one time. I continuously monitored #CO2; it varied between 500 and 800 throughout.

Our guests enjoyed going through our hundreds of #Ornaments collected over three decades. There are even some heirloom family ornaments from the #1960s.

This group is more recent, befitting a #Queer / #Gay household.

https://flic.kr/p/2o6ARaB

#ChristmasTree #SolsticeTree

@erictopol

Yet again, it's clear we need to stop the spread using Non-Pharmaceutical Interventions, specifically #P100 and #N95 masks and #HEPA filters and #CRBoxes.

Treatment & vaccine development is slower than viral evolution. HEPA filters and P100 masks are variant-proof.

#CovidIsNotOver #CovidIsAirborne

@erictopol

Yet again, it's clear we need to stop the spread using Non-Pharmaceutical Interventions, specifically #P100 and #N95 masks and #HEPA filters and #CRBoxes.

Treatment & vaccine development is slower than viral evolution. HEPA filters and P100 masks are variant-proof.

#CovidIsNotOver #CovidIsAirborne

@sonyah @catsalad I do both, and my personal life is just fine, thank you.

I wish people would start wearing their #P100 masks and using #HEPA filters and #CRboxes though. I'm going to survive this pandemic but I'm tired of watching people be reckless.

@sonyah @catsalad I do both, and my personal life is just fine, thank you.

I wish people would start wearing their #P100 masks and using #HEPA filters and #CRboxes though. I'm going to survive this pandemic but I'm tired of watching people be reckless.

@GregCirillo @Mathlover @Spacedad @yaneerbaryam

Naomi Wu is practically tearing her hair out right now because even the Chinese government refuses to promote #HEPA filters, #CRboxes, #P100 masks, #N95 or #KN95 masks, or all the other things which work really well.

Lockdowns were a tool for back when we didn't know how Covid spreads. But we know now! We can stop it with masks and air filters! Why is no government even TRYING?

#BringBackMasks #CleanTheAir

@GregCirillo @yaneerbaryam Ability to assess the relative risks is important. Covid is the highest risk. Car wrecks are still a serious risk.

Then you apply protection: wear your seatbelt, drive sober, etc.

#P100 masks are EXTREMELY effective against Covid, #N95 masks very protective too. So go to the party but keep your mask on. #BringBackMasks

#HEPA filters are EXTREMELY effective, #CRboxes quite effective too. So put those in the room with the party. #CleanTheAir

@GregCirillo @yaneerbaryam Ability to assess the relative risks is important. Covid is the highest risk. Car wrecks are still a serious risk.

Then you apply protection: wear your seatbelt, drive sober, etc.

#P100 masks are EXTREMELY effective against Covid, #N95 masks very protective too. So go to the party but keep your mask on. #BringBackMasks

#HEPA filters are EXTREMELY effective, #CRboxes quite effective too. So put those in the room with the party. #CleanTheAir

Hello everyone, finally sharing my #introduction with you all. If you read this, please say hello! Some fun facts about me:
- I’ve enjoyed a very rewarding career as an #inventor and #founder of #DeepTech #startups. Nowadays I help other entrepreneurs do great things.
- I was called a #HEPAMilitant and blocked by NB’s education minister, for offering to build #CRBoxes for classrooms.
- I’m a big music fan and was at the Horseshoe Tavern in #Toronto when the Stones played a secret gig there.

Hello everyone, finally sharing my #introduction with you all. If you read this, please say hello! Some fun facts about me:
- I’ve enjoyed a very rewarding career as an #inventor and #founder of #DeepTech #startups. Nowadays I help other entrepreneurs do great things.
- I was called a #HEPAMilitant and blocked by NB’s education minister, for offering to build #CRBoxes for classrooms.
- I’m a big music fan and was at the Horseshoe Tavern in #Toronto when the Stones played a secret gig there.

@erictopol Professors of evolutionary biology predicted that something like this would happen. With uncontrolled spread, virus evolves to evade antibodies.

#P100 and #N95 masks, #HEPA filters and #CRBoxes work against all variants. Virus cannot evolve to fully evade them (it is not physically possible).

#BringBackMasks #MaskUp #CleanTheAir #CovidIsAirborne

@erictopol Professors of evolutionary biology predicted that something like this would happen. With uncontrolled spread, virus evolves to evade antibodies.

#P100 and #N95 masks, #HEPA filters and #CRBoxes work against all variants. Virus cannot evolve to fully evade them (it is not physically possible).

#BringBackMasks #MaskUp #CleanTheAir #CovidIsAirborne

@MozzieBytes @DavidElfstrom

#HEPA filters and #CRboxes #CleanTheAir; #masks (#p100, #n95, etc) also clean the air (immediately before you breathe it).

The evidence says that enough filters + enough masks *will* end the pandemic. Ask Apricot Tree Cafe or Abrome Ed -- or see the Cambridge hospital study of HEPA filters.

https://www.medrxiv.org/content/10.1101/2021.09.16.21263684v1.full.pdf