7 ms·

The Corsi-Rosenthal box[0] design using a standard box fan and furnace filters has been tested and verified to be very effective (and cheap): [0] https://clean

by breput 3y ago

The Corsi-Rosenthal box[0] design using a standard box fan and furnace filters has been tested and verified to be very effective (and cheap): [0] https://cleanaircrew.org/box-fan-filters/ https://cleanaircrew.org/box-fan-filters/

stinos 3y ago
Also related: https://smartairfilters.com/en/about/our-story/ https://smartairfilters.com/en/about/our-story/
skeaker 3y ago
How does this stack up in terms of noise versus the one in the OP?
- breput 3y ago
  It's constructed using a regular 3 speed box fan, so it isn't going to be significantly louder than that and possibly quieter depending on how it is shrouded and insulated.
- fellowniusmonk 3y ago
  I have a few box fans filters and one cuboid fan, it's not actually the cuboid though, I used a circular hepa filter with the inline duct booster fan. I leave the fan duct fan running on low (right at the midpoint of the speed dial so technically medium I guess) 24/7 in my kitchen out of eye site because it's so quiet. So, in my experience, much quieter, quiet enough that people don't notice it running all the time. I have the dial in reach though so I can crank it all the way if something burns on the stove, clears the air out shockingly fast. I got some sound proof panels and crappily bungee corded them around the fan and it didn't have a noticeable effect. I think if I put more effort into the sound baffles it would reduce the sound, but the whole setup without baffles is quiet enough I haven't bothered.
- deleted 3y ago
  [deleted]
binarymax 3y ago
Indeed, linked in that article is this which I built yesterday and works very very well. 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... -EDIT- I should also mention that you don't need 5 filters for this (MERV 13 is expensive), you can use 4 and a piece of cardboard for the 6th side that is touching the ground.
- lamontcg 3y ago
  Yeah mine has 4 filters with a box fan on top and cardboard that the box fan came in as the base. All taped together with duct tape. Brain dead simple and cheap. Used some more duct tape to fill in the "corners" of the box fan. Mine blows positive pressure into the box, I just saw some designs that suck negative pressure out of the box, I don't know if that matters, but I've got a PM2.5 meter and mine worked fine last year during the smoke days in Seattle.
  - YZF 3y ago
    I would think that you want to keep dust out of your fan motor/bearings etc. so you want the fan to be sucking out of the filter, not the other way around.
    - culopatin 3y ago
      Those fans normally would operate without any filters on either side, so the dust won’t really matter.
      - masukomi 3y ago
        ... they'll still function, but if you've ever had one you'll know that dust does matter. They're a pain to clean and the various crap in your air builds up on every edge. Definitely want it sucking filtered if that's that's an option.
  - Eisenstein 3y ago
    I think it matters because with negative pressure you are causing the box to close and cover the gaps, whereas when you blow you are pushing on the box causing the gaps to expand.
duxup 3y ago
I just built one in preparation for a home remodel. I want to try to clean out any excess dust while we’re living through a remodel. Or even all the excess dust kicked up from a digging out old things we didn’t know he still had…
DeRock 3y ago
I see this all the time, why use multiple 1" thick filters to build a box, when you could just use 1x 4" filter. They are pleated, and the surface area should be equivalent. I documented my setup here before: https://news.ycombinator.com/item?id=28395232 https://news.ycombinator.com/item?id=28395232
- postpawl 3y ago
  Can confirm this works great. I wish there were more options for higher quality 20x20 box fans though. I’ve had Lasko fans that got loud after a few months, and I assume that’s a bearing going bad.
  - bombcar 3y ago
    There are commercial fans but they’re louder and more expensive. If there’s a belt from the motor to the fan you’re in for a good time.
- yumraj 3y ago
  I have the same, without the 1" pre-filter in your case. The air flow is excellent, though it does get a little loud.
- oh_sigh 3y ago
  Having a greater surface area to filter the air through will decrease the static pressure and be nicer on the fan motor. If OP was putting the filters in series, then yes, it should have no effect. But they are putting the filter in parallel.
  - DeRock 3y ago
    My point was that 4x 1" filters assembled into a box is the same surface area as 1x 4" filter, but the latter is much easier to assemble.
    - oh_sigh 3y ago
      Agreed, but it might cause your fan to burn out much quicker, or be less productive if you're using a box fan, since the static pressure differential will be approximately 16x between the two.

by breput 3y ago

stinos 3y ago

Also related: https://smartairfilters.com/en/about/our-story/ https://smartairfilters.com/en/about/our-story/

skeaker 3y ago

How does this stack up in terms of noise versus the one in the OP?

breput 3y ago
It's constructed using a regular 3 speed box fan, so it isn't going to be significantly louder than that and possibly quieter depending on how it is shrouded and insulated.
fellowniusmonk 3y ago
I have a few box fans filters and one cuboid fan, it's not actually the cuboid though, I used a circular hepa filter with the inline duct booster fan. I leave the fan duct fan running on low (right at the midpoint of the speed dial so technically medium I guess) 24/7 in my kitchen out of eye site because it's so quiet. So, in my experience, much quieter, quiet enough that people don't notice it running all the time. I have the dial in reach though so I can crank it all the way if something burns on the stove, clears the air out shockingly fast. I got some sound proof panels and crappily bungee corded them around the fan and it didn't have a noticeable effect. I think if I put more effort into the sound baffles it would reduce the sound, but the whole setup without baffles is quiet enough I haven't bothered.
deleted 3y ago
[deleted]

binarymax 3y ago

Indeed, linked in that article is this which I built yesterday and works very very well. 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... -EDIT- I should also mention that you don't need 5 filters for this (MERV 13 is expensive), you can use 4 and a piece of cardboard for the 6th side that is touching the ground.

lamontcg 3y ago
Yeah mine has 4 filters with a box fan on top and cardboard that the box fan came in as the base. All taped together with duct tape. Brain dead simple and cheap. Used some more duct tape to fill in the "corners" of the box fan. Mine blows positive pressure into the box, I just saw some designs that suck negative pressure out of the box, I don't know if that matters, but I've got a PM2.5 meter and mine worked fine last year during the smoke days in Seattle.
- YZF 3y ago
  I would think that you want to keep dust out of your fan motor/bearings etc. so you want the fan to be sucking out of the filter, not the other way around.
  - culopatin 3y ago
    Those fans normally would operate without any filters on either side, so the dust won’t really matter.
    - masukomi 3y ago
      ... they'll still function, but if you've ever had one you'll know that dust does matter. They're a pain to clean and the various crap in your air builds up on every edge. Definitely want it sucking filtered if that's that's an option.
- Eisenstein 3y ago
  I think it matters because with negative pressure you are causing the box to close and cover the gaps, whereas when you blow you are pushing on the box causing the gaps to expand.

duxup 3y ago

I just built one in preparation for a home remodel. I want to try to clean out any excess dust while we’re living through a remodel. Or even all the excess dust kicked up from a digging out old things we didn’t know he still had…

DeRock 3y ago

I see this all the time, why use multiple 1" thick filters to build a box, when you could just use 1x 4" filter. They are pleated, and the surface area should be equivalent. I documented my setup here before: https://news.ycombinator.com/item?id=28395232 https://news.ycombinator.com/item?id=28395232

postpawl 3y ago
Can confirm this works great. I wish there were more options for higher quality 20x20 box fans though. I’ve had Lasko fans that got loud after a few months, and I assume that’s a bearing going bad.
- bombcar 3y ago
  There are commercial fans but they’re louder and more expensive. If there’s a belt from the motor to the fan you’re in for a good time.
yumraj 3y ago
I have the same, without the 1" pre-filter in your case. The air flow is excellent, though it does get a little loud.
oh_sigh 3y ago
Having a greater surface area to filter the air through will decrease the static pressure and be nicer on the fan motor. If OP was putting the filters in series, then yes, it should have no effect. But they are putting the filter in parallel.
- DeRock 3y ago
  My point was that 4x 1" filters assembled into a box is the same surface area as 1x 4" filter, but the latter is much easier to assemble.
  - oh_sigh 3y ago
    Agreed, but it might cause your fan to burn out much quicker, or be less productive if you're using a box fan, since the static pressure differential will be approximately 16x between the two.