Comment by mfkp
14 hours ago
One of the best air purifiers you can get (linked in the above writeup) uses PC fans and a custom controller where you can control the speed/volume: https://housefresh.com/best-air-purifiers-we-tested/#2-best-...
14 hours ago
One of the best air purifiers you can get (linked in the above writeup) uses PC fans and a custom controller where you can control the speed/volume: https://housefresh.com/best-air-purifiers-we-tested/#2-best-...
Why is this so expensive? It's literally 4 PC fans and some plastic trays? I presume you bring your own filters.
You can make your own to save money, I made this project for example. I paired it with an Air-1 sensor and home assistant to ramp up and down the downs in real time according to the live air quality readings.
https://makerworld.com/en/models/2470181-nukit-tempest-euro-...
Filters are included, as well as high quality fans, AC/DC converter and speed controller, and the portable/collapsible enclosure. It's really not that expensive vs trying to put together the parts yourself, and it's tested to work very well compared to other more expensive filters.
Those fans will not have sufficient static pressure to be useful. These makeshift purifiers may be great in a pinch (wildfire season and stores are all out), but far from the best.
This is indeed the "conventional wisdom," but if you do the math it turns out this is incorrect.
The trick is to use high-airflow MERV 13 filters (ideally 3M 1900, which has high pleat count and low resistance) instead of high-resistance HEPA filters, so axial PC fans can generate enough pressure.
At that point, you’re not doing any actual air filtering. Just use them as fans instead.
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The linked PC-fan purifier has been tested and shown to purify air faster than the conventional alternatives, and are not makeshift, so I'm not sure what you are referring to.
From the specs it looks like they are probably closer to higher-static-pressure server fans, the CADR is a few hundred CFM and it pulls 30+ watts. And as with many of these designs, you can compensate for low pressure performance by increasing filter surface area... the greater the surface area the lower the pressure drop. Of course, the problem with this is you are just spending more money on filters, which is the expensive part.
The filter cost for the AirFanta 3 doesn't seem particularly high? In fact it seems cheaper than competitors.
All the purifier companies realized they make more money selling overpriced filters, so $60+ for the OEM filters is common nowadays. Despite it just being a standard HEPA filter cut to a specific size.
Airfanta 3 Pro filters (four) - $57
Coway Mighty Filter - $60
Coway Mighty2 Filter - $70-$80
I'd be concerned about the availability of filters after a few years. Some of these companies have been changing their models and filter type every year to add some nebulous feature. Others just go out of business.
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There's an Open Source tool for building your own that does all the calculations for you: https://filterboxbuilder.com
For up-front cost, this is true.
For cost over time, twice the filters means twice the replacement interval, so the additional filter cost cancels out.
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