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/ 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.
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).
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.
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.
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.
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.
I have two. I agree it's quiet on the lowest speed but it's loud on the medium and high speeds so mine are setup to run 24/7 on the lowest speed regardless of the air quality. The air quality in my house is good and they run nearly always at the low speed anyways. Buy them while they are on sale.
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
A deep merv-13 with a lot of pleats can have a very reasonable pressure drop - you just have to shop a little more carefully.
I would stick with merv-13 because you'll get solid performance across a lot of things you might want to remove, from viruses to general pm2.5 and things like volatilized cooking oil. Clean air is awesome and tire dust isn't the only thing that's annoying.
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.
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:
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.
I’m surprised that those little fans can push more air than a box fan while still being quieter. But I guess each of those 5 little fans cost as much as the box fan so maybe my surprise is unwarranted.
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?
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.
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.
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/
25 comments
[ 4.5 ms ] story [ 47.9 ms ] threadhttps://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.
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
embarassing
https://scosman.net/blog/using_in_wall_computer_fans_for_hom...
https://www.amazon.com/dp/B01728NLRG
Quiet, efficient, works super well
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
I would stick with merv-13 because you'll get solid performance across a lot of things you might want to remove, from viruses to general pm2.5 and things like volatilized cooking oil. Clean air is awesome and tire dust isn't the only thing that's annoying.
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.
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
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.
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.
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.
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/