8 ms·

This is a really cool project but frankly you can do it a lot cheaper. Find the cheapest box fan you can find, and find the cheapest HEPA filter you can, and st

by kn100 7y ago

This is a really cool project but frankly you can do it a lot cheaper. Find the cheapest box fan you can find, and find the cheapest HEPA filter you can, and strap the HEPA filter to the front. To improve air purification even futher, slap an activated carbon filter on the front too, and your air purifier now filters VoCs! For cheap Activated Carbon Filters, look into the kind used for Aquarium filters. They'll work just as well for air as far as I know. In China there is a whole company founded on doing just this, although they've since pivoted into selling specific air purification hardware at a significant discount. See: https://smartairfilters.com/cn/en/product/diy-1-1-air-purifier/ https://smartairfilters.com/cn/en/product/diy-1-1-air-purifi...

mhd 7y ago
I don't know why, but I love the fact that someone is selling filters strapped to fans on a reasonably glossy and well-made page.
- OJFord 7y ago
  It does kind of look like a joke doesn't it? A demo/how-to masquerading as a shop page.
dandare 7y ago
I came here to post the very same link :D
thehesiod 7y ago
know a way to get them to US reasonably? cost is like 10x when shipping to US :(
- insensible 7y ago
  In the US, grab a basic 20" box fan and toss on a 20x20x1 furnace filter like this one: https://www.homedepot.com/p/Honeywell-20-in-x-20-in-x-1-in-Allergen-Plus-Pleated-FPR-7-Air-Filter-90701-012020/203145810 https://www.homedepot.com/p/Honeywell-20-in-x-20-in-x-1-in-A... For extra flow, set up a triangle with the fan on one side and 2 of these filters on the intake end as the other two sides, and duct tape some cardboard to seal the top and bottom.
marcinzm 7y ago
This may or may not work, cheap box fans aren't designed to push/pull air through obstructions (ie: low static pressure) and HEPA filters are giant obstructions. So instead of the air going through the filter it'll go through gaps, around the edges of the blades, etc. I used a cheap box fan for some DIY ventilation and the loss in airflow is massive after filter and ducting.
- Spooks 7y ago
  couldn't you easily test this by sticking your hand (wet it first) in the middle section of the filter and see if you feel any air coming through
  - dunkelan 7y ago
    You could, but I think the goal would be to make sure the design will work before going through the effort of making it. If you already have all the parts though definitely worth a try.
- jakeogh 7y ago
  I have a box fan on low 24x7 with a 12 on the input and a 7 on the output. That's not a HEPA rated filter set, but it's fantastic. Allergy season just went away (while in my room) when I started using it a few years ago. I also tried a 3 on the output, and that worked as well, but the flow was noticeably lower. The fan is cheap, $20. I change the filters every few months, and it always looks like I waited too long.
- UnFleshedOne 7y ago
  I used a cheap box fan and a furnace filter held simply by pressure differential. Flow drops a lot, but it still works. Filter was dirty after some time. It was hilariously undersized for my purpose (serious belt-sander action leveling sub-floors), but air does move.
fareesh 7y ago
Would something like this this work sufficiently well to capture airborne fur/dander from a tabby cat? Or will there be a vastly different outcome from an expensive one?
- kevinconroy 7y ago
  Yes! We have two box fans with HEPA filters in our bedroom to combat the cat fur/dander. It's made a world of difference. You can see it working as the filter captures everything. Have to change them monthly... but so worth it. #YMMV #YouCatsMayVary
  - apta 7y ago
    Do you strap them to the front or the rear of the fan? Doesn't having them on the front (i.e. where the air blows out) mean that the fan will get dirty since it's sucking the air in?
    - Nexxxeh 7y ago
      You may wish to use a cheap thin washable pre-filter either way. It will catch a lot of the hair before it hits the fine filtration, which you can then just wash off the pre-filter, making it easier and cheaper to maintain.
      - fareesh 7y ago
        Do you have a link to one of the cheap thin washable pre-filters that I can look at as a reference for what to buy?
        wang_li 7y ago
        Get some window screen from your local home improvement big box store.
post_break 7y ago
If you want this to actually work, you take a box fan, and 2 filters. You make a triangle and then some cardboard on the top and bottom to fill the gap. This increases surface area and reduces the stress on the fan due to pressure drop. Slapping a filter directly on to the box fan is going to kill the fan very quickly. https://i.imgur.com/SX1RloH.jpg https://i.imgur.com/SX1RloH.jpg
- opencl 7y ago
  I ran a few cheap box fans with filters directly over them for several years and none of them failed, I have heard this claim a lot but it seems overstated. The triangle setup will significantly increase the airflow and thus the effectiveness of filtration though.
  - post_break 7y ago
    I guess it depends on the quality of filter. If you're rocking a high merv filter for smoke the pressure drop can be significant.
  - nathancahill 7y ago
    I've done this too for years and no issues.
- yjftsjthsd-h 7y ago
  Clarification: triangle goes on the in or out side of the fan?
  - post_break 7y ago
    Doesn't really matter as long as the filters are in the correct orientation. However it would be beneficial if the air is clean before it goes through the fan.
  - spookthesunset 7y ago
    Put it on the intake. It will keep the fan clean.
cosmolev 7y ago
I have smartairfilter's Cannon purifier. As all those standalone purifiers it works only with windows completely closed. I went for ventilation systems that take air from outside, filter it and then bring it inside the room. Namely Xiaomi MJXFJ-300-G1: https://www.xiaomitoday.com/xiaomi-mijia-air-purifier-mjxfj-300-g1-intelligent-household-filter-at-1040/ https://www.xiaomitoday.com/xiaomi-mijia-air-purifier-mjxfj-... I've installed one in every bedroom.
- driverdan 7y ago
  That seems quite expensive for what it is. For that price I'd expect it to have an efficient heat exchanger.
asah 7y ago
Can confirm: did this when the wildfires hit SF a couple years ago, and it really worked!! My "measurement" was my lungs when working from home: coughing before, no coughing after. Filters turned black.
dublinben 7y ago
Here's a video from the University of Michigan showing just how effective these cheap DIY air filters can be: https://www.youtube.com/watch?v=kH5APw_SLUU https://www.youtube.com/watch?v=kH5APw_SLUU

by kn100 7y ago

mhd 7y ago

I don't know why, but I love the fact that someone is selling filters strapped to fans on a reasonably glossy and well-made page.

OJFord 7y ago
It does kind of look like a joke doesn't it? A demo/how-to masquerading as a shop page.

dandare 7y ago

I came here to post the very same link :D

thehesiod 7y ago

know a way to get them to US reasonably? cost is like 10x when shipping to US :(

insensible 7y ago
In the US, grab a basic 20" box fan and toss on a 20x20x1 furnace filter like this one: https://www.homedepot.com/p/Honeywell-20-in-x-20-in-x-1-in-Allergen-Plus-Pleated-FPR-7-Air-Filter-90701-012020/203145810 https://www.homedepot.com/p/Honeywell-20-in-x-20-in-x-1-in-A... For extra flow, set up a triangle with the fan on one side and 2 of these filters on the intake end as the other two sides, and duct tape some cardboard to seal the top and bottom.

marcinzm 7y ago

This may or may not work, cheap box fans aren't designed to push/pull air through obstructions (ie: low static pressure) and HEPA filters are giant obstructions. So instead of the air going through the filter it'll go through gaps, around the edges of the blades, etc. I used a cheap box fan for some DIY ventilation and the loss in airflow is massive after filter and ducting.

Spooks 7y ago
couldn't you easily test this by sticking your hand (wet it first) in the middle section of the filter and see if you feel any air coming through
- dunkelan 7y ago
  You could, but I think the goal would be to make sure the design will work before going through the effort of making it. If you already have all the parts though definitely worth a try.
jakeogh 7y ago
I have a box fan on low 24x7 with a 12 on the input and a 7 on the output. That's not a HEPA rated filter set, but it's fantastic. Allergy season just went away (while in my room) when I started using it a few years ago. I also tried a 3 on the output, and that worked as well, but the flow was noticeably lower. The fan is cheap, $20. I change the filters every few months, and it always looks like I waited too long.
UnFleshedOne 7y ago
I used a cheap box fan and a furnace filter held simply by pressure differential. Flow drops a lot, but it still works. Filter was dirty after some time. It was hilariously undersized for my purpose (serious belt-sander action leveling sub-floors), but air does move.

fareesh 7y ago

Would something like this this work sufficiently well to capture airborne fur/dander from a tabby cat? Or will there be a vastly different outcome from an expensive one?

kevinconroy 7y ago
Yes! We have two box fans with HEPA filters in our bedroom to combat the cat fur/dander. It's made a world of difference. You can see it working as the filter captures everything. Have to change them monthly... but so worth it. #YMMV #YouCatsMayVary
- apta 7y ago
  Do you strap them to the front or the rear of the fan? Doesn't having them on the front (i.e. where the air blows out) mean that the fan will get dirty since it's sucking the air in?
  - Nexxxeh 7y ago
    You may wish to use a cheap thin washable pre-filter either way. It will catch a lot of the hair before it hits the fine filtration, which you can then just wash off the pre-filter, making it easier and cheaper to maintain.
    - fareesh 7y ago
      Do you have a link to one of the cheap thin washable pre-filters that I can look at as a reference for what to buy?
      - wang_li 7y ago
        Get some window screen from your local home improvement big box store.

post_break 7y ago

If you want this to actually work, you take a box fan, and 2 filters. You make a triangle and then some cardboard on the top and bottom to fill the gap. This increases surface area and reduces the stress on the fan due to pressure drop. Slapping a filter directly on to the box fan is going to kill the fan very quickly. https://i.imgur.com/SX1RloH.jpg https://i.imgur.com/SX1RloH.jpg

opencl 7y ago
I ran a few cheap box fans with filters directly over them for several years and none of them failed, I have heard this claim a lot but it seems overstated. The triangle setup will significantly increase the airflow and thus the effectiveness of filtration though.
- post_break 7y ago
  I guess it depends on the quality of filter. If you're rocking a high merv filter for smoke the pressure drop can be significant.
- nathancahill 7y ago
  I've done this too for years and no issues.
yjftsjthsd-h 7y ago
Clarification: triangle goes on the in or out side of the fan?
- post_break 7y ago
  Doesn't really matter as long as the filters are in the correct orientation. However it would be beneficial if the air is clean before it goes through the fan.
- spookthesunset 7y ago
  Put it on the intake. It will keep the fan clean.

cosmolev 7y ago

I have smartairfilter's Cannon purifier. As all those standalone purifiers it works only with windows completely closed. I went for ventilation systems that take air from outside, filter it and then bring it inside the room. Namely Xiaomi MJXFJ-300-G1: https://www.xiaomitoday.com/xiaomi-mijia-air-purifier-mjxfj-300-g1-intelligent-household-filter-at-1040/ https://www.xiaomitoday.com/xiaomi-mijia-air-purifier-mjxfj-... I've installed one in every bedroom.

driverdan 7y ago
That seems quite expensive for what it is. For that price I'd expect it to have an efficient heat exchanger.

asah 7y ago

Can confirm: did this when the wildfires hit SF a couple years ago, and it really worked!! My "measurement" was my lungs when working from home: coughing before, no coughing after. Filters turned black.

dublinben 7y ago

Here's a video from the University of Michigan showing just how effective these cheap DIY air filters can be: https://www.youtube.com/watch?v=kH5APw_SLUU https://www.youtube.com/watch?v=kH5APw_SLUU