wathe Posted December 19, 2021 Share Posted December 19, 2021 (edited) (Dec 31/22 ETA: fancy update in new post.) We made one. More about them here. Box fan from big-box store $30 High filtration furnace filters (MERV 13 equivalent) $40 Some packing tape Cardboard from the fan box, and one extra piece 17x17 inch for the bottom We used 16x25 inch furnace filters instead of the recommended 20x20 inch because: 1) I can re-use them in the furnace when we are done with the thing (if I can get the tape off) and I can get a four pack at Costco for less than half the price of four 20 inch filters purchased individually elsewhere. I adapted by putting a cardboard shroud on both sides of the fan to block leaks. The cardboard shrouds on the fan are to prevent backdraft through the corners (which we tested with a piece of thread - yes, there is a back draft, and the shroud eliminates it) The popsicle stick is hiding our family name, which puns will with covid - my kids have a strange sense of humour. Edited December 31, 2022 by wathe 12 4 Quote Link to comment Share on other sites More sharing options...
Catwoman Posted December 19, 2021 Share Posted December 19, 2021 Very cool!!! Thanks for the link to the instructions! Quote Link to comment Share on other sites More sharing options...
J-rap Posted December 19, 2021 Share Posted December 19, 2021 Neat! I'd never heard of these until Thanksgiving, when my BIL had built one for the occasion. It seems so simple, yet I hear they're very effective. Quote Link to comment Share on other sites More sharing options...
crazyforlatin Posted December 19, 2021 Share Posted December 19, 2021 I’m going to have Dd and Dh work on this during the break! Quote Link to comment Share on other sites More sharing options...
saraha Posted December 19, 2021 Share Posted December 19, 2021 Someone had suggested this a few months ago when I asked about recommendations for a filter for ds21’s apartment. Smoke filters into his apartment from the apartment below him and it made everything stink. He decided he didn’t have room for the whole 4 sided box in his little apartment so set up the box fan with one filter on the back of it and it works like a charm! No smoke smell at all even though you can smell it outside his door on the stairwell, and it cost him $25 dollars total with $10 every so often for a new m13 filter 2 Quote Link to comment Share on other sites More sharing options...
MEmama Posted December 19, 2021 Share Posted December 19, 2021 Can I ask, why not just use a HEPA air purifier? Quote Link to comment Share on other sites More sharing options...
KSera Posted December 19, 2021 Share Posted December 19, 2021 (edited) 2 hours ago, MEmama said: Can I ask, why not just use a HEPA air purifier? It costs nearly $1000 to get an air purifier that can move as much air and filter as efficiently as this DIY version can do for $80-120 (depending where you live). There are a lot of even expensive Hepa purifiers being sold that do indeed remove virus from the air, but they do it so slowly that it’s almost useless (in an occupied room, it’s useless if the device isn’t even removing it as fast as new virus is being added to the air by an infected person breathing). That’s not to say there aren’t good options for people if they want to buy an off the shelf version. Somewhere is a good chart I will try to find. eta chart from Edited December 19, 2021 by KSera Added chart 3 Quote Link to comment Share on other sites More sharing options...
Halftime Hope Posted December 19, 2021 Share Posted December 19, 2021 13 hours ago, wathe said: We made one. More about them here. Box fan from big-box store $30 High filtration furnace filters (MERV 13 equivalent) $40 Some packing tape Cardboard from the fan box, and one extra piece 17x17 inch for the bottom We used 16x25 inch furnace filters instead of the recommended 20x20 inch because: 1) I can re-use them in the furnace when we are done with the thing (if I can get the tape off) and I can get a four pack at Costco for less than half the price of four 20 inch filters purchased individually elsewhere. I adapted by putting a cardboard shroud on both sides of the fan to block leaks. The cardboard shrouds on the fan are to prevent backdraft through the corners (which we tested with a piece of thread - yes, there is a back draft, and the shroud eliminates it) The popsicle stick is hiding our family name, which puns will with covid - my kids have a strange sense of humour. This is awesome. @wathe could you post the underside view? I'd like to see how you seal the back side of the fan to the filters. Thanks! 1 Quote Link to comment Share on other sites More sharing options...
wathe Posted December 19, 2021 Author Share Posted December 19, 2021 1 hour ago, Halftime Hope said: This is awesome. @wathe could you post the underside view? I'd like to see how you seal the back side of the fan to the filters. Thanks! Backside of the fan has a cardboard shroud just like the top. Seal the edges shroud to fan with tape, seal the edges filter box to shroud with tape. 2 Quote Link to comment Share on other sites More sharing options...
wathe Posted December 19, 2021 Author Share Posted December 19, 2021 5 hours ago, MEmama said: Can I ask, why not just use a HEPA air purifier? What @KSera said: value for money. The graph she posted was for a single filter version. The four filter version that we built apparently rivals the very best home HEPA units, at a small fraction of the cost. Components were very easy to source. We'll also be able to re-use the components. The filters are the same size that my furnace takes, so can re-use if there is life left in them. The box fan can be just a box fan. And it's a homeschool science lesson that really engaged my kids - priceless!! One silver linings of this pandemic (if such a terrible thing can be said to have silver linings) for me has been the endless opportunities to schoolify it in a very authentic/engaging way - physiology, virology, epidemiology, immunology, statistics, exponential vs linear growth, how to read a graph, public heatlh policy, social justice, international affairs, politics, psychology, critical appraisal of news and scientific publications, critical appraisal of media and social media, and now physics and aerosol science 4 Quote Link to comment Share on other sites More sharing options...
ktgrok Posted December 19, 2021 Share Posted December 19, 2021 Maybe a dumb question - but how does using this compare to running Central AC, with fan turned to "on", with a Merv 13 filter? Like, how much air is moved/cleaned with one of these versus a typical AC with Fan on all the time, I wonder? 1 Quote Link to comment Share on other sites More sharing options...
wathe Posted December 19, 2021 Author Share Posted December 19, 2021 45 minutes ago, ktgrok said: Maybe a dumb question - but how does using this compare to running Central AC, with fan turned to "on", with a Merv 13 filter? Like, how much air is moved/cleaned with one of these versus a typical AC with Fan on all the time, I wonder? I don't know. My completely subjective opinion: The CR box moves A LOT of air. Subjectively way, way more than my furnace fan. Quote Link to comment Share on other sites More sharing options...
Halftime Hope Posted December 19, 2021 Share Posted December 19, 2021 4 hours ago, wathe said: Backside of the fan has a cardboard shroud just like the top. Seal the edges shroud to fan with tape, seal the edges filter box to shroud with tape. Thanks! that makes sense, and I should have thought of it. :-) Quote Link to comment Share on other sites More sharing options...
Clarita Posted December 19, 2021 Share Posted December 19, 2021 This is what we used last fire season. It doesn't look fancy but it works, better than any expensive filter. It comes out of the physics; this video has a great explanation. We do put the hefty filter on our central air unit, but when it gets bad this configuration is what we have to use. 1 Quote Link to comment Share on other sites More sharing options...
wathe Posted December 25, 2021 Author Share Posted December 25, 2021 Frivolous update: Not only does it clean the air, it provides engaging Christmas entertainment for all ages: This thing levitates balloons like nobody's business. The same balloon has been suspended in space for 2 hours now. No strings attached 🙂 Also fun to attach streamers. Levitate ping pong balls. Creative use of ping pong balls and toilet roll tubes, and bits of cardboard, and balloons with various coins stuffed in them to add weight.... And all the whack-the-other-guys-balloon-while-defending-your-own sort of nonsense you can imagine...... 2 1 7 Quote Link to comment Share on other sites More sharing options...
wathe Posted December 25, 2021 Author Share Posted December 25, 2021 I anticipate that wrapping paper and ribbons will only add to the fun tomorrow. 1 Quote Link to comment Share on other sites More sharing options...
Clarita Posted December 25, 2021 Share Posted December 25, 2021 3 hours ago, wathe said: Also fun to attach streamers. Levitate ping pong balls. Creative use of ping pong balls and toilet roll tubes, and bits of cardboard, and balloons with various coins stuffed in them to add weight.... I need to do this if we have to utilize ours again! Quote Link to comment Share on other sites More sharing options...
Debbirie Posted October 26, 2022 Share Posted October 26, 2022 (edited) On 12/25/2021 at 5:02 AM, wathe said: Frivolous update: Not only does it clean the air, it provides engaging Christmas entertainment for all ages: This thing levitates balloons like nobody's business. The same balloon has been suspended in space for 2 hours now. No strings attached 🙂 Also fun to attach streamers. Levitate ping pong balls. Creative use of these ping pong balls and toilet roll tubes, and bits of cardboard, and balloons with various coins stuffed in them to add weight.... And all the whack-the-other-guys-balloon-while-defending-your-own sort of nonsense you can imagine...... Sounds very interesting! I don't have much of an imagination and I would never have thought of that 😄 Edited October 28, 2022 by Debbirie Quote Link to comment Share on other sites More sharing options...
Bambam Posted October 26, 2022 Share Posted October 26, 2022 We attached some ribbons to our HEPA filter - the cat loved it. 1 Quote Link to comment Share on other sites More sharing options...
wathe Posted October 26, 2022 Author Share Posted October 26, 2022 Since this thread has been resuscitated, I might as well update: The CR box is still going strong. We use it whenever we have anyone in the house who doesn't live with us, and when any of us is feeling under the weather. We also cart it along to my parents when we visit. It still floats balloons beautifully. Worth every cent of the approx $80 we spent on it. 5 Quote Link to comment Share on other sites More sharing options...
wathe Posted December 31, 2022 Author Share Posted December 31, 2022 Fancied up the CR box for the holidays!. I put a string of LED lights inside it. The blur above the fan is a streamer dancing in the clean exhaust air. 8 2 Quote Link to comment Share on other sites More sharing options...
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