6 ms·

I made a quieter air purifier

131 points by crescit_eundo 11mo ago

runariot 11mo ago
Why do computer fans blow air inside?
- brtv 11mo ago
  I think this done to create a slight overpressure which helps keep the dust out.
- pixl97 11mo ago
  Your question isn't very clear... Is it why do they use computer fans? (My guess is that is what they had). Or is it why do you blow instead of suck?
- chr-s 11mo ago
  You want to suck air through the filters rather than blow into them. For one, this keeps the fans cleaner but also it's more efficient, reducing turbulence inside the box. https://old.reddit.com/r/crboxes/ https://old.reddit.com/r/crboxes/ is a good resource if you're looking to make your own. There's been a general shift from large box fans to PC fans because their performance/noise ratio is better.
- nbf_1995 11mo ago
  I think it's because there are no grills on the outside. If the fans were sucking air out of the box, dust would build up on the outside, and bumping it would dislodge dust back into the environment. With the fans blowing in, all the dust is on the inside of the box (and on the fans). The box fan version also blows air into the box
calvinmorrison 11mo ago
Corsi-Rosenthal... they taped some filters to a fan, something the poor folk have been doing forever and academia acts like they invented fire. It's caveman technology with a fancy name. embarassing
- pkd 11mo ago
  It didn't really come out of academia in that way. It was an innovation borne out of necessity during Covid. I don't think I've seen anybody using a box design for it. If you have a source, I'll be happy to be corrected. Regardless technology is often named after people who made it popular, especially when original inventors are unknown or too diffuse.
  - tguvot 11mo ago
    not that much of innovation. i build one like this back in 2018 during california fires. used it mostly in garage for filtering air when i work on "things". decommissioned it last week. i guess i am not the only one who came up with this idea prior to covid as this is pretty obvious
    - tehjoker 11mo ago
      i did think the 4-sided design using the cardboard box as a base was very efficient. one of the contributions here was Corsi and Rosenthal did this in a lab and reported particulate counts, flow rates, and energy usage. So there was some kind of intellectual contribution to broaden adoption by giving it more of an imprimatur of quality other refinements were using a shroud to prevent back flow
      - tguvot 11mo ago
        back in 2018, during fires, when air filters were unobtanium, on bayarea subreddits (and probably here) were floating a lot of posts of DIY filter made from box fan + hvac filters. plenty of people also posted particulate count reduction charts. you don't need a lab to figure out that replacing 1" filter with 4" filter and even better arranging multiple filters in a box will improve flow rates and filtration (especially for box fans that not really designed for static pressure) corsi&rosental work, imho, is equivalent to lab work reporting that you can move more water through 10" pipe than through 1" pipe.
        11mo ago
scosman 11mo ago
I had the same insight for in-home air movement. Purpose built inter-room fans from broan/etc are 3x louder and several times more expensive than computer fans at the same CFM. I've been very happy with them. https://scosman.net/blog/using_in_wall_computer_fans_for_home_air_movement https://scosman.net/blog/using_in_wall_computer_fans_for_hom...
- lozenge 11mo ago
  There are continuous extraction fans, they're called dMEV systems. Eg https://www.epicair.co.uk/products/vent-axia-lo-carbon-revive-5-selv https://www.epicair.co.uk/products/vent-axia-lo-carbon-reviv... There's also systems which can move air both ways through the whole house - https://www.ventilation-alnor.co.uk/index/support/alnor-knowledge-base/heat-recovery/mvhr-guide.html https://www.ventilation-alnor.co.uk/index/support/alnor-know... Your DIY solution looks a lot cheaper though.
- ortusdux 11mo ago
  Vevor makes drop-in floor/wall register fans in the $35-40 price range. The 'proper' solution is inline booster fans in each leg of the ducts, but retrofitting can be expensive depending on access.
  - scosman 10mo ago
    Houses with rads don’t have ducts or registers. There’s a whole other class of solutions for these houses.
- tguvot 11mo ago
  if you have house (with attic), jump ducts are nicer solution
- rao-v 11mo ago
  The general rule about computer fans is that the bigger they are the the quieter they are (i.e. 140mm > 120mm etc.) It's a wierd market gap that large "commercial" air moving fans are so loud.
erwincoumans 11mo ago
I wonder if they used silent computer fans? I love the quiet Noctua fans, and replace all noisy fans with them: fans in pc, wifi router, playstation 5, mister fpga, robots, jetson orin etc.
- ruralfam 11mo ago
  I use a bank of eight Noctuas to vent from the rooom with our wood stove to the main hall. Then use more units with two sets of Noctuas ganged to move from the hall to various remote rooms. Been using them for more years than I can remember. Silent, never failed yet. It has been great vs. using house fans (my initial approach). BTW: Our local thrift store has a huge amount of various DC power supplies from donations. I sift thru them to find the right volts/amp combo needed for the ganged units, and generally spend about a dollar per supply. HTH, RF.
tyre 11mo ago
My favorite DIY air purifier setup is buying this Conway, myself: https://www.amazon.com/dp/B01728NLRG https://www.amazon.com/dp/B01728NLRG Quiet, efficient, works super well
- deleted 11mo ago
  [deleted]
- notatoad 11mo ago
  yeah, i get why people were doing the DIY air purifier thing during covid when air purifiers were hard to come by, and the box fan version at least has cost-effectiveness going for it. but 5x arctic cooling PC fans is ~$100. the commercial versions are easily available, more effective, no more expensive, and don't look like a box of furnace filters taped together.
  - blargey 11mo ago
    Huh? 5x Arctic P12 is $24 on Amazon right now, no sale going on. And the whole Corsi-Rosenthal trend started specifically because consumer air purifiers were tested to be both noisier and less effective at their job. But I'd honestly pay a premium for a commercial air purifier that just has a bunch of 120mm/140mm fan mounts instead of their "maybe tolerable at Very Low" integrated box-fan equivalent. In general, all I've learned from online reviews of "quiet" appliances is that different people have very different definitions / criteria for "quiet".
    - tguvot 11mo ago
      conway filter posted above, you can't really hear it from 10ft when it runs on low speed (it has sensor and he autoadjusts ). i also have iqair which according to reviews is quiet at low speed. in my experience this quiet sounds like airplane (i got it replaced once. apparently it's just the way it is).
      - Implicated 11mo ago
        I think you're missing his point entirely. The problem with these retail purifiers is that you either get quiet or effective. You don't get both. Sure, you can't hear it from 10ft away - but how much air is it moving at that setting? I have various configurations of these PC fan setups and the Arctic P14 Pro that you can get 5 for $32 on amazon are honestly wildly effective and designed for applications with some static pressure (radiators and such). So we're back to; effective or quiet, you're only going to get both with the PC fans, for now.
xnx 11mo ago
Are those 200mm fans?
- jsheard 11mo ago
  They're from Arctic Cooling, so 140mm at most. They don't make anything bigger than that.
ruralfam 11mo ago
Appreciate any thoughts you all have re: this post. For years I have been using Noctua NF-P14 fans to circulate air in house to distribute heat in the winter from our wood stove. E.g. cut holes in the walls, and circulate remote rooms using the fans. Has worked great, and the Noctuas have been rock solid. Recently a daughter moved into a really nice apartment close to a major university/freeway where she will live for the number of years it takes to get a Phd. I got concerned about tire dust. So I am about to start building a really nice air DIY air filter using eight Noctua NF-P14s (about 1000 cfm). XMas present. I really wanted to use merv-13, but got quite worried about air flow restrictions, plus cost to replace (assume monthly). Instead I went with two 12x24 Carter reusable electrostatic merv-8 filters. I use Carter filters on my house blower, and really like them (just washed them... scary how much junk is in household air). Also, I got the 12x24 direct from Carter for a very low price as they were returns. Note: This is NOT a low cost project, but I just got scared re: merv-13 so went with what I know. Anyway, the final product will NOT be like this guy's DIY. I will use my somewhat decent woodworking skills to fashion a good looking standing "lamp like" appliance that should look good in most living rooms. I am thinking of going with knotless cedar as I really like working with cedar, and there are some mills here in NW WA where one can go to get such wood (not a HomeDepot specialty). My question is whether an electrostatic merv-8 filter would do well with tire dust. I am not looking to create "clean room" conditions in the apartment. Just get rid of some of the bad stuff. I am very weak re: understanding filters, mervs, etc. APPRECIATE any insights. Thx, RF
- tim333 11mo ago
  I recently bought one of these. It's pretty quiet (on the low setting) - you quite likely wouldn't hear it near a freeway https://www.amazon.co.uk/gp/aw/d/B071SLZRRV https://www.amazon.co.uk/gp/aw/d/B071SLZRRV vid of the noise levels https://youtu.be/wOc0TM1ErYA?t=195 https://youtu.be/wOc0TM1ErYA?t=195
- bsilvereagle 11mo ago
  Check out the plot in the header, and find the particulate size you care the most about: https://www.frdmtoplay.com/nagivating-air-purification/ https://www.frdmtoplay.com/nagivating-air-purification/
dpark 11mo ago
If these 5 little fans do the job as well as a full size box fan, I have to wonder: 1. Are box fans just really terrible? I would expect the amount of airflow from a box fan to absolutely demolish these little case fans. 2. Does airflow not actually matter that much? Assuming the box fan really does move far more air, that would imply that air filtration is somehow not driven by air flow. Or else the testing methodology is flawed.
- hollerith 11mo ago
  Box fans are a fire hazard when used continuously to pull air through filtration media. They are not designed for that. Computer cooling fans also might not have been designed to handle that much "load", but in the case of the box fan, we have an actual report of someone who almost burned down the house: https://news.ycombinator.com/item?id=21382994 https://news.ycombinator.com/item?id=21382994
  - SoftTalker 11mo ago
    One report? You can find one report of anything. It might even be true.
    - QuercusMax 11mo ago
      Yeah, it's just as likely they had it plugged in improperly or the wires were fraying or something. Might as well say it was spontaneous combustion. I had a dishwasher catch fire because the installers didn't properly connect the power cable. That doesn't mean dishwashers are inherently a fire hazard.
- unregistereddev 11mo ago
  The 5 little fans are on high while the box fan is on low. The box fan is capable of much higher airflow, but the objection is noise. The PC case fans have been specifically designed to be as quiet as possible. The Lasko box fan ... well, these are cheap fans. They're designed to be manufactured at the lowest price possible while still meeting the low quality bar of "It's acceptable considering I got the cheapest option that WalMart carries". But in general yes, box fans are terrible.
skhameneh 11mo ago
At first glance, it appears to have lower negative pressure and a much higher filter surface area than most air purifiers. AFAIK PC fans are designed to move air at low pressure while quality air purifiers are designed to handle more pressure. Other than that, it’s a neat writeup. Would like to see a follow-up with static pressure considerations.
DCKP 11mo ago
With a multi-fan set-up, would it help to vary the individual fan RPMs, to spread the noise over a broader range of frequencies? Would a 9-fan grid at slightly lower RPMs improve this further?
codemac 11mo ago
I've bought a few of these, and love them: https://www.cleanairkits.com/ https://www.cleanairkits.com/
Night_Thastus 11mo ago
Good PC case fans are incredibly quiet, move a lot of air and last forever. That's the nice thing about having some many companies competing over optimizing them for so long. I have a similar setup, just premade from CleanAirKits. Allergies are gone, house has far less dust and cat hair floating around. Can't do anything for wood smoke though, that would need carbon filters - which run out quite quickly.
globular-toast 11mo ago
This is something that's annoyed me for ages. Why are extractor fans so loud and horrible sounding when PC fans are almost silent? I'm surprised someone like Noctua doesn't go into house fans. But maybe the market isn't there as they're more difficult to fit and people seem to keep them for decades. Or perhaps they just wouldn't work as well outside of that nice cosy PC case.
LTL_FTC 11mo ago
Oh, boy. During the great California fire of 2020, I went down a very deep rabbit hole looking to air purification. I studied what is out there. I compared their characteristics with regard to filter media quality, air cycles, PM2.5 performance, VOC's, energy consumption, and so on, but my goal was to have performance and near silence. I learned about static pressure and how important it is to choose the right blower for the job (impeller and blower vs fan; and yes, a blower creates vastly more static pressure than these fans). I looked into what quantities of charcoal actually deliver meaningful VOC reduction and how often they must be replaced (you need lbs of it; that single filter on the front of most purification units does nothing but act as a pre-filter). I really should have written all my research and discovery down but if you are serious about it, I came to the following conclusions: 1. A furniture company that decides to integrate a purification system into their offerings can hit it big. Imagine a big, heavy dresser in your bedroom that sucks in air from the bottom and pushes up to the top or a TV stand that where different compartments are filter media. The mass of these reduces noise and vibration and allow for larger, slower spinning blowers and larger surface area of filter media (less static pressure, longer replacement intervals, easily hold pounds of activated charcoal). 2. One needs to pump in oxygen from the outside and exchange the indoor air with the outside air. Circulating and cleaning the air in the home, especially with modern doors and windows, will become unpleasant in a short while, especially during wildfire season. The positive pressure this creates also helps pollutants stay out, if done correctly. I would absolutely go the diy route using large filters, activated carbon, housed in a wooden box with a blower and implement something like AC Infinity's in-line filtration systems to pull outside air in through a window, with a large carbon filter on one end. Or if a homeowner, set up a more permanent solution. https://acinfinity.com/inline-fan-systems/ https://acinfinity.com/inline-fan-systems/

131 points by crescit_eundo 11mo ago

runariot 11mo ago

Why do computer fans blow air inside?

brtv 11mo ago
I think this done to create a slight overpressure which helps keep the dust out.
pixl97 11mo ago
Your question isn't very clear... Is it why do they use computer fans? (My guess is that is what they had). Or is it why do you blow instead of suck?
chr-s 11mo ago
You want to suck air through the filters rather than blow into them. For one, this keeps the fans cleaner but also it's more efficient, reducing turbulence inside the box. https://old.reddit.com/r/crboxes/ https://old.reddit.com/r/crboxes/ is a good resource if you're looking to make your own. There's been a general shift from large box fans to PC fans because their performance/noise ratio is better.
nbf_1995 11mo ago
I think it's because there are no grills on the outside. If the fans were sucking air out of the box, dust would build up on the outside, and bumping it would dislodge dust back into the environment. With the fans blowing in, all the dust is on the inside of the box (and on the fans). The box fan version also blows air into the box

calvinmorrison 11mo ago

Corsi-Rosenthal... they taped some filters to a fan, something the poor folk have been doing forever and academia acts like they invented fire. It's caveman technology with a fancy name. embarassing

pkd 11mo ago
It didn't really come out of academia in that way. It was an innovation borne out of necessity during Covid. I don't think I've seen anybody using a box design for it. If you have a source, I'll be happy to be corrected. Regardless technology is often named after people who made it popular, especially when original inventors are unknown or too diffuse.
- tguvot 11mo ago
  not that much of innovation. i build one like this back in 2018 during california fires. used it mostly in garage for filtering air when i work on "things". decommissioned it last week. i guess i am not the only one who came up with this idea prior to covid as this is pretty obvious
  - tehjoker 11mo ago
    i did think the 4-sided design using the cardboard box as a base was very efficient. one of the contributions here was Corsi and Rosenthal did this in a lab and reported particulate counts, flow rates, and energy usage. So there was some kind of intellectual contribution to broaden adoption by giving it more of an imprimatur of quality other refinements were using a shroud to prevent back flow
    - tguvot 11mo ago
      back in 2018, during fires, when air filters were unobtanium, on bayarea subreddits (and probably here) were floating a lot of posts of DIY filter made from box fan + hvac filters. plenty of people also posted particulate count reduction charts. you don't need a lab to figure out that replacing 1" filter with 4" filter and even better arranging multiple filters in a box will improve flow rates and filtration (especially for box fans that not really designed for static pressure) corsi&rosental work, imho, is equivalent to lab work reporting that you can move more water through 10" pipe than through 1" pipe.
      - 11mo ago

scosman 11mo ago

I had the same insight for in-home air movement. Purpose built inter-room fans from broan/etc are 3x louder and several times more expensive than computer fans at the same CFM. I've been very happy with them. https://scosman.net/blog/using_in_wall_computer_fans_for_home_air_movement https://scosman.net/blog/using_in_wall_computer_fans_for_hom...

lozenge 11mo ago
There are continuous extraction fans, they're called dMEV systems. Eg https://www.epicair.co.uk/products/vent-axia-lo-carbon-revive-5-selv https://www.epicair.co.uk/products/vent-axia-lo-carbon-reviv... There's also systems which can move air both ways through the whole house - https://www.ventilation-alnor.co.uk/index/support/alnor-knowledge-base/heat-recovery/mvhr-guide.html https://www.ventilation-alnor.co.uk/index/support/alnor-know... Your DIY solution looks a lot cheaper though.
ortusdux 11mo ago
Vevor makes drop-in floor/wall register fans in the $35-40 price range. The 'proper' solution is inline booster fans in each leg of the ducts, but retrofitting can be expensive depending on access.
- scosman 10mo ago
  Houses with rads don’t have ducts or registers. There’s a whole other class of solutions for these houses.
tguvot 11mo ago
if you have house (with attic), jump ducts are nicer solution
rao-v 11mo ago
The general rule about computer fans is that the bigger they are the the quieter they are (i.e. 140mm > 120mm etc.) It's a wierd market gap that large "commercial" air moving fans are so loud.

erwincoumans 11mo ago

I wonder if they used silent computer fans? I love the quiet Noctua fans, and replace all noisy fans with them: fans in pc, wifi router, playstation 5, mister fpga, robots, jetson orin etc.

ruralfam 11mo ago
I use a bank of eight Noctuas to vent from the rooom with our wood stove to the main hall. Then use more units with two sets of Noctuas ganged to move from the hall to various remote rooms. Been using them for more years than I can remember. Silent, never failed yet. It has been great vs. using house fans (my initial approach). BTW: Our local thrift store has a huge amount of various DC power supplies from donations. I sift thru them to find the right volts/amp combo needed for the ganged units, and generally spend about a dollar per supply. HTH, RF.

tyre 11mo ago

My favorite DIY air purifier setup is buying this Conway, myself: https://www.amazon.com/dp/B01728NLRG https://www.amazon.com/dp/B01728NLRG Quiet, efficient, works super well

deleted 11mo ago
[deleted]
notatoad 11mo ago
yeah, i get why people were doing the DIY air purifier thing during covid when air purifiers were hard to come by, and the box fan version at least has cost-effectiveness going for it. but 5x arctic cooling PC fans is ~$100. the commercial versions are easily available, more effective, no more expensive, and don't look like a box of furnace filters taped together.
- blargey 11mo ago
  Huh? 5x Arctic P12 is $24 on Amazon right now, no sale going on. And the whole Corsi-Rosenthal trend started specifically because consumer air purifiers were tested to be both noisier and less effective at their job. But I'd honestly pay a premium for a commercial air purifier that just has a bunch of 120mm/140mm fan mounts instead of their "maybe tolerable at Very Low" integrated box-fan equivalent. In general, all I've learned from online reviews of "quiet" appliances is that different people have very different definitions / criteria for "quiet".
  - tguvot 11mo ago
    conway filter posted above, you can't really hear it from 10ft when it runs on low speed (it has sensor and he autoadjusts ). i also have iqair which according to reviews is quiet at low speed. in my experience this quiet sounds like airplane (i got it replaced once. apparently it's just the way it is).
    - Implicated 11mo ago
      I think you're missing his point entirely. The problem with these retail purifiers is that you either get quiet or effective. You don't get both. Sure, you can't hear it from 10ft away - but how much air is it moving at that setting? I have various configurations of these PC fan setups and the Arctic P14 Pro that you can get 5 for $32 on amazon are honestly wildly effective and designed for applications with some static pressure (radiators and such). So we're back to; effective or quiet, you're only going to get both with the PC fans, for now.

xnx 11mo ago

Are those 200mm fans?

jsheard 11mo ago
They're from Arctic Cooling, so 140mm at most. They don't make anything bigger than that.

ruralfam 11mo ago

Appreciate any thoughts you all have re: this post. For years I have been using Noctua NF-P14 fans to circulate air in house to distribute heat in the winter from our wood stove. E.g. cut holes in the walls, and circulate remote rooms using the fans. Has worked great, and the Noctuas have been rock solid. Recently a daughter moved into a really nice apartment close to a major university/freeway where she will live for the number of years it takes to get a Phd. I got concerned about tire dust. So I am about to start building a really nice air DIY air filter using eight Noctua NF-P14s (about 1000 cfm). XMas present. I really wanted to use merv-13, but got quite worried about air flow restrictions, plus cost to replace (assume monthly). Instead I went with two 12x24 Carter reusable electrostatic merv-8 filters. I use Carter filters on my house blower, and really like them (just washed them... scary how much junk is in household air). Also, I got the 12x24 direct from Carter for a very low price as they were returns. Note: This is NOT a low cost project, but I just got scared re: merv-13 so went with what I know. Anyway, the final product will NOT be like this guy's DIY. I will use my somewhat decent woodworking skills to fashion a good looking standing "lamp like" appliance that should look good in most living rooms. I am thinking of going with knotless cedar as I really like working with cedar, and there are some mills here in NW WA where one can go to get such wood (not a HomeDepot specialty). My question is whether an electrostatic merv-8 filter would do well with tire dust. I am not looking to create "clean room" conditions in the apartment. Just get rid of some of the bad stuff. I am very weak re: understanding filters, mervs, etc. APPRECIATE any insights. Thx, RF

tim333 11mo ago
I recently bought one of these. It's pretty quiet (on the low setting) - you quite likely wouldn't hear it near a freeway https://www.amazon.co.uk/gp/aw/d/B071SLZRRV https://www.amazon.co.uk/gp/aw/d/B071SLZRRV vid of the noise levels https://youtu.be/wOc0TM1ErYA?t=195 https://youtu.be/wOc0TM1ErYA?t=195
bsilvereagle 11mo ago
Check out the plot in the header, and find the particulate size you care the most about: https://www.frdmtoplay.com/nagivating-air-purification/ https://www.frdmtoplay.com/nagivating-air-purification/

dpark 11mo ago

If these 5 little fans do the job as well as a full size box fan, I have to wonder: 1. Are box fans just really terrible? I would expect the amount of airflow from a box fan to absolutely demolish these little case fans. 2. Does airflow not actually matter that much? Assuming the box fan really does move far more air, that would imply that air filtration is somehow not driven by air flow. Or else the testing methodology is flawed.

hollerith 11mo ago
Box fans are a fire hazard when used continuously to pull air through filtration media. They are not designed for that. Computer cooling fans also might not have been designed to handle that much "load", but in the case of the box fan, we have an actual report of someone who almost burned down the house: https://news.ycombinator.com/item?id=21382994 https://news.ycombinator.com/item?id=21382994
- SoftTalker 11mo ago
  One report? You can find one report of anything. It might even be true.
  - QuercusMax 11mo ago
    Yeah, it's just as likely they had it plugged in improperly or the wires were fraying or something. Might as well say it was spontaneous combustion. I had a dishwasher catch fire because the installers didn't properly connect the power cable. That doesn't mean dishwashers are inherently a fire hazard.
unregistereddev 11mo ago
The 5 little fans are on high while the box fan is on low. The box fan is capable of much higher airflow, but the objection is noise. The PC case fans have been specifically designed to be as quiet as possible. The Lasko box fan ... well, these are cheap fans. They're designed to be manufactured at the lowest price possible while still meeting the low quality bar of "It's acceptable considering I got the cheapest option that WalMart carries". But in general yes, box fans are terrible.

skhameneh 11mo ago

At first glance, it appears to have lower negative pressure and a much higher filter surface area than most air purifiers. AFAIK PC fans are designed to move air at low pressure while quality air purifiers are designed to handle more pressure. Other than that, it’s a neat writeup. Would like to see a follow-up with static pressure considerations.

DCKP 11mo ago

With a multi-fan set-up, would it help to vary the individual fan RPMs, to spread the noise over a broader range of frequencies? Would a 9-fan grid at slightly lower RPMs improve this further?

codemac 11mo ago

I've bought a few of these, and love them: https://www.cleanairkits.com/ https://www.cleanairkits.com/

Night_Thastus 11mo ago

Good PC case fans are incredibly quiet, move a lot of air and last forever. That's the nice thing about having some many companies competing over optimizing them for so long. I have a similar setup, just premade from CleanAirKits. Allergies are gone, house has far less dust and cat hair floating around. Can't do anything for wood smoke though, that would need carbon filters - which run out quite quickly.

globular-toast 11mo ago

This is something that's annoyed me for ages. Why are extractor fans so loud and horrible sounding when PC fans are almost silent? I'm surprised someone like Noctua doesn't go into house fans. But maybe the market isn't there as they're more difficult to fit and people seem to keep them for decades. Or perhaps they just wouldn't work as well outside of that nice cosy PC case.

LTL_FTC 11mo ago

Oh, boy. During the great California fire of 2020, I went down a very deep rabbit hole looking to air purification. I studied what is out there. I compared their characteristics with regard to filter media quality, air cycles, PM2.5 performance, VOC's, energy consumption, and so on, but my goal was to have performance and near silence. I learned about static pressure and how important it is to choose the right blower for the job (impeller and blower vs fan; and yes, a blower creates vastly more static pressure than these fans). I looked into what quantities of charcoal actually deliver meaningful VOC reduction and how often they must be replaced (you need lbs of it; that single filter on the front of most purification units does nothing but act as a pre-filter). I really should have written all my research and discovery down but if you are serious about it, I came to the following conclusions: 1. A furniture company that decides to integrate a purification system into their offerings can hit it big. Imagine a big, heavy dresser in your bedroom that sucks in air from the bottom and pushes up to the top or a TV stand that where different compartments are filter media. The mass of these reduces noise and vibration and allow for larger, slower spinning blowers and larger surface area of filter media (less static pressure, longer replacement intervals, easily hold pounds of activated charcoal). 2. One needs to pump in oxygen from the outside and exchange the indoor air with the outside air. Circulating and cleaning the air in the home, especially with modern doors and windows, will become unpleasant in a short while, especially during wildfire season. The positive pressure this creates also helps pollutants stay out, if done correctly. I would absolutely go the diy route using large filters, activated carbon, housed in a wooden box with a blower and implement something like AC Infinity's in-line filtration systems to pull outside air in through a window, with a large carbon filter on one end. Or if a homeowner, set up a more permanent solution. https://acinfinity.com/inline-fan-systems/ https://acinfinity.com/inline-fan-systems/