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.
[1] https://en.wikipedia.org/wiki/Corsi%E2%80%93Rosenthal_Box
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-fil...
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.
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.
In theory, if you mounted it fan-down and placed some towel or blankets underneath, you could also dampen a fair amount of the noise coming from the fan.
It's probably more effective and cheaper to get thicker filters. A 20x20x5 filter has five times the filter surface area of a 20x20x1 filter, but costs $36 - about 2-3x as much as a 20x20x1. Two 20x20x5 filters would provide twice the filter surface area.
But...these solutions were all intended mostly for emergency situations where purpose-built air filtration units were in really constrained supply. Folks should really just buy a regular air filtration unit that uses much less electricity and is quieter, especially if it auto-adjusts speed depending upon need.
This post is about how one of these made with a ceiling fan can be much quieter than a regular air filtration unit: "Testing my prototype, it has a CADR of ~180 CFM and is only 33dB. By contrast, the Wirecutter's top-recommended air purifier has a CADR of 233 CFM at 54 dB or 110 CFM at 36 dB. With some tweaks it should be able to match the commercial purifier's performance, without being louder."
> especially if it auto-adjusts speed depending upon need
I see how that works for wildfire smoke, but how would it work for covid?
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.
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-...
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.
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.
Consider that they are designed for cooling in a window application, which means they must be able to survive operation 35C in direct sunlight. As an air filter, mine operates at 22C in shade. That easily makes up for the temperature differential due to load conditions.
https://www.epa.gov/indoor-air-quality-iaq/should-you-have-a...
1. https://www.predictiveservices.nifc.gov/outlooks/monthly_sea...
You're trying to reduce the viral load in the air, not build a BSL4 lab.