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Comment by julianlam | Hacker News Reader

After watching this segment, I immediately bought a 20" box fan, a 20x20 MERV 11 filter, and put one together.

It kicks the pants off of air purifiers twice the price and it moves a lot of air through. Best investment ever.

CBC was testing CADR, which is one metric among others, but an important one if you're looking to clean a room's air, fast.

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I've used a box fan with a 20x20 filter for years when I'm doing woodworking, but it's a little too clunky of a solution to use in my primary living space.

I love the fact that Lasko has decided to own this concept with box fan designed specifically for this setup. It looks much better than a filter taped to the outside of the fan. Maybe this would help with your decor vs cleaner air conundrum?

https://www.amazon.com/Lasko-FF305-20-inch-Purifier-Purifyin...

They are great for reacting to bad air quality (like wildfires), but are way too loud for normal use.

I have an Awair and did that dance of turning on the box fan filter when levels were higher than normal, then turning it back off once in normal range.

Now I much prefer keeping a quieter (less performant unit) on continuously to keep the levels low.

I've had one of these for years with MERV10-12 (depending on availability) filters. This is in addition to the 20x25 filter in the central unit. Judging by how dirty the filter on the box fan gets, it is amazing how the central unit is just unable to do an adequate job.

Does your central air also use a merv 10 filter? A lot of people use the cheap fiberglass ones which are not very effective

I am an EU resident (Netherlands) and have wanted to make a DIY air filter for myself for several years. Unfortunately, I simply can’t find any flat box fans on the market. Would someone else in the EU be willing to point me in the right direction?

I'm not Dutch so I used Google translate and searched for "vierkante ventilator" (no ideas if it is correct but it worked). Look at image results for a quick overview. I also got interested and found this one:

https://www.biltema.dk/en-dk/construction/fans/floor-fans/fl...

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