7 ms·

Great idea. What's worked for me is simply taking a 20"x20"x1" filter and sliding it into the back cover of a standard $25 Lasko box fan. Cheap, easy option for

Great idea. What's worked for me is simply taking a 20"x20"x1" filter and sliding it into the back cover of a standard $25 Lasko box fan. Cheap, easy option for air filtration in the home.

TedDoesntTalk 4y ago
That’s a great idea. What kind of filter do you use?
- newsclues 4y ago
  Standard furnace filters, pick the level of filtration you desire/can afford.
  - bombcar 4y ago
    I've had surprisingly good luck in my area finding brand-new furnace filters at Goodwill for quite cheap. HEPA, too. If you're making your own setup the size doesn't matter as much so that can be a good way to go.
  - azth 4y ago
    I use a furnace filter (3M brand 2200 (merv 13) or even 2800 (merv 14)), and I tape smaller merv 13 filters on the outbound vents in the bedrooms. Those latter ones clearly need changing every couple of months as they become quite dark. So clearly the furnace filter is not sufficient, at least in my case.
- tiahura 4y ago
  https://www.uofmhealth.org/media/19281 https://www.uofmhealth.org/media/19281
- totetsu 4y ago
  Some really good discussion of this has happened on HN last time California was on fire.
  - seanp2k2 4y ago
    Given the wildfire risk for this summer[1], I'd say this article is quite timely. 1. https://www.predictiveservices.nifc.gov/outlooks/monthly_seasonal_outlook.pdf https://www.predictiveservices.nifc.gov/outlooks/monthly_sea...
- jefftk 4y ago
  If you're doing one filter per box fan, I'd go with a MERV-14: https://www.jefftk.com/p/merv-filters-for-covid https://www.jefftk.com/p/merv-filters-for-covid
  - formerkrogemp 4y ago
    This is very similar to what hobbyist mushroom growers use in our setups to inoculate substrate in a 'sterile' environment. Other methods include using sterile, hot oven air, buying very expensive equipment, and making a still air box at home with a plastic tote box. Good times.
    - titanomachy 4y ago
      In college we used to work under a bunsen flame, is that not enough space?
      - formerkrogemp 4y ago
        I think a lot of those options are born out of creativity. Inoculation typically happens from jar to jar or from a jar to a block of substrate for instance. A Bunsen burner would probably work well for many applications in mycology. I only ever used one in cell bio, and only a mini Bunsen in my mushroom hobby.
- TurkishPoptart 4y ago
  Is that enough for allergens, smoke, and pet dander? I don't care about virus filtration (which is not going to happen anyway, if it's something I'm making out of cardboard and duct-tape)
  - tgsovlerkhgsel 4y ago
    You're not getting a "guaranteed certified safe" environment with cardboard and duct tape, but there is no reason why you shouldn't be able to get a significant risk reduction. You're trying to reduce the viral load in the air, not build a BSL4 lab.
  - jjeaff 4y ago
    You would be hard pressed to find much difference between one of the diy jobs and a hospital grade system (although you might need to add a UV light) assuming you use the same filters. The reason is, it's not about having some perfect seal with dirty air going in one side and sterile air coming out the other. It's about recirculating the same air over and over through the filter catching a little bit more particulate matter each time.
sudden_dystopia 4y ago
Can confirm, I have made like a dozen of these at this point. Works great but is loud. Good white noise at night though.
kolencherry 4y ago
Yes! This is the basis for the Corsi-Rosenthal Box [1]. Five 20"x20"x1" filters and a box fan, with duct tape to seal the edges. Not the prettiest, but it's effective. [1] https://en.wikipedia.org/wiki/Corsi%E2%80%93Rosenthal_Box https://en.wikipedia.org/wiki/Corsi%E2%80%93Rosenthal_Box
- alexpw 4y ago
  > An updated design, also known as a Comparetto Cube, [1] uses four filters and a cardboard base that can sit directly on the floor. I never understood the purpose of the bottom filter in the Corsi-Rosenthal Box, so it felt like a waste of a filter, but I'm a big fan of the Comparetto Cube (no put intended). And 4 packs of filters are readily available -- 20x20x2 is suggested for the Comparetto Cube. [edit] Also, thank you. I couldn't recall the Corsi-Rosenthal name/link, but thought of the wiki immediately. [1] https://www.thisoldhouse.com/green-home/22231148/diy-air-filter https://www.thisoldhouse.com/green-home/22231148/diy-air-fil...
  - happyopossum 4y ago
    > I never understood the purpose of the bottom filter in the Corsi-Rosenthal Box It's for when the box fan is not sitting on the floor - either raised up on feet (which many have), sitting in a window, or hung somewhere. That said, you're right - 4 packs are easier to come by and probably work nearly as well in the real world.
  - bredren 4y ago
    I have been focused on HVAC / air purification recently. Its amazing to me that these designs are less than two years old when the tech has been available for decades. One of the biggest problems with the C-R and comparetto is that they are large and hideous to look at. I have been working on a design that makes the C-R or comparetto or a smaller version than the 20" something that can be attractive enough to hang in the corner of a room as both an air purifier and room lighting.
    - donthellbanme 4y ago
hinkley 4y ago
Tends to burn out the motor though. Vornado used to sell an air filter that took two 10x20” house filters. Before I discovered that model I was trying to build my own using computer case fans (my intent was to hide the loud box under furniture). Home Depot used to carry those in the 1500 classification which was great, but those are getting harder to come by too, and even the regional chain that had them doesn’t as much anymore and I have to use the 1200 or once in a while the super basic ones. Or buy them from Amazon and fuck Amazon. Air filters became a rent seeking gambit before the term rent seeking was even invented. We should just be able to use furnace filters. And speaking of furnace filters, if you have central air, do yourself a favor and change the filter religiously. Also helps slow down accumulation of dust in your ductwork, which makes it hard to ever get the house clean, though you can hire someone to come out and vacuum them out. They have something like a softer version of a chimney sweep’s brush with a longer handle. Last place we had them do that on like day 2 to avoid any problems from the previous owners.
- bredren 4y ago
  > Tends to burn out the motor though. Do you have data on this? Adding a fan shroud to the Corsi-R supposedly does not increase energy usage or motor temperature: https://www.texairfilters.com/how-to-improve-the-efficiency-of-the-box-fan-and-merv-13-filter-air-cleaner/ https://www.texairfilters.com/how-to-improve-the-efficiency-... I'm looking for data on the power usage and motor temperature difference from a 20" Hurricane in normal operation, with a 20" merv 14 on the back, a C-R and a Comparetto.
  - hinkley 4y ago
    Same author https://www.texairfilters.com/a-variation-on-the-box-fan-with-merv-13-filter-air-cleaner/ https://www.texairfilters.com/a-variation-on-the-box-fan-wit... chose 4 filters due to higher throughput. He has an addendum at the bottom where they tested the fans and saw no problems with a single filter. I... don't understand how they come to those conclusions based on the charts in the paper. All of the fans were >10ºC hotter and one model went up by 20. 15C is a lot for cheap, planned obsolescence consumer electronics.
sfteus 4y ago
I did this for a cheap dust filter when demoing a ~7 cu ft concrete shower pan in my house. Pretty incredible how much material it pulled out of the air; I ended up running through 3-4 filters total throughout the whole process.
- euroclydon 4y ago
  I prefer to mount a high-power fan in the bathroom window for demolition.
  - sfteus 4y ago
    This bathroom had no window unfortunately, so that was the best solution I could come up without venting it elsewhere in the house.
fady 4y ago
Reminds me of this video that came from University of Michigan during one of California's fire season when many fires were ablaze and air quality was terrible: https://www.youtube.com/watch?v=kH5APw_SLUU https://www.youtube.com/watch?v=kH5APw_SLUU

Great idea. What's worked for me is simply taking a 20"x20"x1" filter and sliding it into the back cover of a standard $25 Lasko box fan. Cheap, easy option for air filtration in the home.

TedDoesntTalk 4y ago

That’s a great idea. What kind of filter do you use?

newsclues 4y ago
Standard furnace filters, pick the level of filtration you desire/can afford.
- bombcar 4y ago
  I've had surprisingly good luck in my area finding brand-new furnace filters at Goodwill for quite cheap. HEPA, too. If you're making your own setup the size doesn't matter as much so that can be a good way to go.
- azth 4y ago
  I use a furnace filter (3M brand 2200 (merv 13) or even 2800 (merv 14)), and I tape smaller merv 13 filters on the outbound vents in the bedrooms. Those latter ones clearly need changing every couple of months as they become quite dark. So clearly the furnace filter is not sufficient, at least in my case.
tiahura 4y ago
https://www.uofmhealth.org/media/19281 https://www.uofmhealth.org/media/19281
totetsu 4y ago
Some really good discussion of this has happened on HN last time California was on fire.
- seanp2k2 4y ago
  Given the wildfire risk for this summer[1], I'd say this article is quite timely. 1. https://www.predictiveservices.nifc.gov/outlooks/monthly_seasonal_outlook.pdf https://www.predictiveservices.nifc.gov/outlooks/monthly_sea...
jefftk 4y ago
If you're doing one filter per box fan, I'd go with a MERV-14: https://www.jefftk.com/p/merv-filters-for-covid https://www.jefftk.com/p/merv-filters-for-covid
- formerkrogemp 4y ago
  This is very similar to what hobbyist mushroom growers use in our setups to inoculate substrate in a 'sterile' environment. Other methods include using sterile, hot oven air, buying very expensive equipment, and making a still air box at home with a plastic tote box. Good times.
  - titanomachy 4y ago
    In college we used to work under a bunsen flame, is that not enough space?
    - formerkrogemp 4y ago
      I think a lot of those options are born out of creativity. Inoculation typically happens from jar to jar or from a jar to a block of substrate for instance. A Bunsen burner would probably work well for many applications in mycology. I only ever used one in cell bio, and only a mini Bunsen in my mushroom hobby.
TurkishPoptart 4y ago
Is that enough for allergens, smoke, and pet dander? I don't care about virus filtration (which is not going to happen anyway, if it's something I'm making out of cardboard and duct-tape)
- tgsovlerkhgsel 4y ago
  You're not getting a "guaranteed certified safe" environment with cardboard and duct tape, but there is no reason why you shouldn't be able to get a significant risk reduction. You're trying to reduce the viral load in the air, not build a BSL4 lab.
- jjeaff 4y ago
  You would be hard pressed to find much difference between one of the diy jobs and a hospital grade system (although you might need to add a UV light) assuming you use the same filters. The reason is, it's not about having some perfect seal with dirty air going in one side and sterile air coming out the other. It's about recirculating the same air over and over through the filter catching a little bit more particulate matter each time.

sudden_dystopia 4y ago

Can confirm, I have made like a dozen of these at this point. Works great but is loud. Good white noise at night though.

kolencherry 4y ago

Yes! This is the basis for the Corsi-Rosenthal Box [1]. Five 20"x20"x1" filters and a box fan, with duct tape to seal the edges. Not the prettiest, but it's effective. [1] https://en.wikipedia.org/wiki/Corsi%E2%80%93Rosenthal_Box https://en.wikipedia.org/wiki/Corsi%E2%80%93Rosenthal_Box

alexpw 4y ago
> An updated design, also known as a Comparetto Cube, [1] uses four filters and a cardboard base that can sit directly on the floor. I never understood the purpose of the bottom filter in the Corsi-Rosenthal Box, so it felt like a waste of a filter, but I'm a big fan of the Comparetto Cube (no put intended). And 4 packs of filters are readily available -- 20x20x2 is suggested for the Comparetto Cube. [edit] Also, thank you. I couldn't recall the Corsi-Rosenthal name/link, but thought of the wiki immediately. [1] https://www.thisoldhouse.com/green-home/22231148/diy-air-filter https://www.thisoldhouse.com/green-home/22231148/diy-air-fil...
- happyopossum 4y ago
  > I never understood the purpose of the bottom filter in the Corsi-Rosenthal Box It's for when the box fan is not sitting on the floor - either raised up on feet (which many have), sitting in a window, or hung somewhere. That said, you're right - 4 packs are easier to come by and probably work nearly as well in the real world.
- bredren 4y ago
  I have been focused on HVAC / air purification recently. Its amazing to me that these designs are less than two years old when the tech has been available for decades. One of the biggest problems with the C-R and comparetto is that they are large and hideous to look at. I have been working on a design that makes the C-R or comparetto or a smaller version than the 20" something that can be attractive enough to hang in the corner of a room as both an air purifier and room lighting.
  - donthellbanme 4y ago

hinkley 4y ago

Tends to burn out the motor though. Vornado used to sell an air filter that took two 10x20” house filters. Before I discovered that model I was trying to build my own using computer case fans (my intent was to hide the loud box under furniture). Home Depot used to carry those in the 1500 classification which was great, but those are getting harder to come by too, and even the regional chain that had them doesn’t as much anymore and I have to use the 1200 or once in a while the super basic ones. Or buy them from Amazon and fuck Amazon. Air filters became a rent seeking gambit before the term rent seeking was even invented. We should just be able to use furnace filters. And speaking of furnace filters, if you have central air, do yourself a favor and change the filter religiously. Also helps slow down accumulation of dust in your ductwork, which makes it hard to ever get the house clean, though you can hire someone to come out and vacuum them out. They have something like a softer version of a chimney sweep’s brush with a longer handle. Last place we had them do that on like day 2 to avoid any problems from the previous owners.

bredren 4y ago
> Tends to burn out the motor though. Do you have data on this? Adding a fan shroud to the Corsi-R supposedly does not increase energy usage or motor temperature: https://www.texairfilters.com/how-to-improve-the-efficiency-of-the-box-fan-and-merv-13-filter-air-cleaner/ https://www.texairfilters.com/how-to-improve-the-efficiency-... I'm looking for data on the power usage and motor temperature difference from a 20" Hurricane in normal operation, with a 20" merv 14 on the back, a C-R and a Comparetto.
- hinkley 4y ago
  Same author https://www.texairfilters.com/a-variation-on-the-box-fan-with-merv-13-filter-air-cleaner/ https://www.texairfilters.com/a-variation-on-the-box-fan-wit... chose 4 filters due to higher throughput. He has an addendum at the bottom where they tested the fans and saw no problems with a single filter. I... don't understand how they come to those conclusions based on the charts in the paper. All of the fans were >10ºC hotter and one model went up by 20. 15C is a lot for cheap, planned obsolescence consumer electronics.

sfteus 4y ago

I did this for a cheap dust filter when demoing a ~7 cu ft concrete shower pan in my house. Pretty incredible how much material it pulled out of the air; I ended up running through 3-4 filters total throughout the whole process.

euroclydon 4y ago
I prefer to mount a high-power fan in the bathroom window for demolition.
- sfteus 4y ago
  This bathroom had no window unfortunately, so that was the best solution I could come up without venting it elsewhere in the house.

fady 4y ago

Reminds me of this video that came from University of Michigan during one of California's fire season when many fires were ablaze and air quality was terrible: https://www.youtube.com/watch?v=kH5APw_SLUU https://www.youtube.com/watch?v=kH5APw_SLUU