Originally published at: How does a $1 furnace filter compare to a $50 one? | Boing Boing
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…Dude is so good, he hypnotized me into watching him compare furnace filters for quite a long time, before I snapped out of it. If you can make this kind of thing interesting, the world missed out on an academic schoolteacher ^^’ .
Mmm, them’s good science.
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The tl;dw summary: “permanent” filters aren’t very good, and you get what you pay for so don’t cheap out on filters.
That being said I agree with @Bozobub - this was fascinating and I don’t even have a furnace.
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That really was fascinating. It was good to see the breakdown like that. I live in an area that gets a lot of airborne allergens like pollen and smoke and my wife is asthmatic, so we need a good filter.
Now I need to check my filter to see what I bought last time. Fingers crossed it was one of the ones that ranked well.
Update: My filter desperately needs to be replaced. But at least it’s one of the good ones.
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I turn to Project Farm nowadays when I get lonely for Mythbusters.
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Project farm is awesome!
I use a 3m 1800 here, so It’s great to see that despite it being expensive, it’s is presumably doing nearly as good a job as the 1900 he tested.
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So what’s the tl:dr verdict? Which one is the best?
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After careful mathematical calculations, the answer is somewhere in the neighborhood of $49.00 US, that’s the difference.
You’re welcome.
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speaking of, I still need to get some 20" filters before fire season this summer (to strap to a box fan)
edit: I need to find a video comparing those standalone purifiers - they seem overpriced for a a fan with a filter-holding housing
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I went from the washable ones to the 3M 600s to the 3M 1500s. Consumer Reports led me down the same path this guy does.
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My takeaway was that more pleats is better. Also it was surprising how similar most were in terms of pressure differential. I wish he did better summaries; would have been great to see a graph of particles vs cost. And loaded pressure vs particles.
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Kinda bummed that the washable one didn’t do better. Seems like there’s an opportunity there to make a really good reusable filter.
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He either prepares extensively or edits extremely well, or probably both.
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would have been great to see a graph of particles vs cost
You know, I was thinking the very same thing @bolamig! 
Below are the 1-inch MERV-8 (blue) and Merv-11+ (orange) filters tested. Both non-rated and thicker filters are excluded:
My tl;dr takeaway from the video is that thicker filters (not graphed) are better – but failing that, more material (i.e. more pleats, as @bolemig deduced) seems to make for better performance – with correspondingly increased cost!
Overall, the 3M filters (perhaps excepting the 3M Basic) appear to be the consistent best performers of the brands tested.
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I’d love to see an electrostatic filter review vs standard.
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The instant he said he’d gauge the upstream static pressure, that told me he knew what he was doing. My chest swelled with confidence! 
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I was told my HVAC service person that if I use a cheap filter the manufacturer might not cover my unit under warrantee. Your manual might require standards of filters.
I had a whole house filter installed for each of my HVAC units (2 zone house). This are multilayer filters where for each sheet smaller particles are allowed through than the previous, allowing them to last longer and filter better. Now I want to watch this video and see if it covers whole house filters.
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I can’t remember the context (if any?) as far as fire safety goes, but someone from the fire department said the disposable ones were better than the reusable/washable ones. FWIW.
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I wish he was less frantic and more clear in his conclusions.
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