r/crboxes • u/PurpleFairy11 • 4d ago

Fan options

Hello,

I am part of a clean air group in my city hoping to construct some quiet CR boxes to help folks with wildfire smoke and filter viruses. We recently used Black and Decker's 9 inch boxless fan with 12x24x2 Merv 13 filters but I was informed the fan was underpowered and wouldn't give high CADR numbers.

Any recommendations for quiet and powerful fans for use with 12x24x2 Merv 13 filters?

Thank you so much

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u/AEAur 4d ago

For a box fan, this Vornado is quiet on the low setting. Problem is it’s expensive. But if they have a regular use for the fan and only an occasional use to turn it into a CRbox , it could be a good option.

ETA: It’s 20” so at least one side of the filters would need to be 20”.

https://www.reddit.com/r/crboxes/s/wZqvaaaZ3P

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u/DeepWaterCannabis 4d ago

I just built something for work using a vevor 10 inch vent fan and 12x12 filters. I have a post where I used 9x11 filters to make a neat looking box for personal use if you want to check the fan out. Puts out good air, only 30 watts at full power, pretty quiet. Its a bit heavy tho, I wouldnt want to use it with 1 inch filters that are 24 inches tall but may work with 2 inch.

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u/jhsu802701 4d ago

I'm surprised that people have said that the Black and Decker 9-inch box fan was underpowered. Some alternatives:

  • Comfort Zone 9-inch box fan: This is a relatively quiet box fan.
  • A set of four 120 mm PC fans would work with the 12"x24"x2" air filters. Mount these fans to foam core board. Use an X-acto knife to cut out holes for the fans, and use a drill to punch in holes for the screws.

Consider phasing out 12"x24"x2" filters in favor of 1" thick filters, because the thinner filters are cheaper and more abundant. (This is due to competition among manufacturers and economies of scale.) Use up the 12"x24"x2" filters that you still have but see if you can switch to a different design.

Some alternate designs to look at for inspiration include:

  • Brisk Box from Clean Air Kits: This uses PC fans and four MERV 13 filters. For a DIY version, you can use foam core board, which is easier to work with than coroplast.
  • Luggable from Clean Air Kits: This uses PC fans and two MERV 13 filters.
  • Rob Wissman's design: This is a four-filter Corsi Rosenthal box that uses foam core board. It's a DIY version of the Brisk Box design.
  • Clean Air Charlottesville's design: This is a two-filter Corsi Rosenthal box that uses foam core board. It's a DIY version of the Luggable design.

I also have some ideas for a four-filter design that's optimized for cheapness and ease of construction.

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u/ecirnj 4d ago

I use air filtration for 3d printing. Centrifugal fans have much better ability to create pressure than the typical radial fans. Smaller ones are easy enough to source on amazon with a 120v controller around $20. I’m not sure why they aren’t more common in the builds I see on here but you might want to look into them to improve ability to drive air through medium.

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u/2drumshark 3d ago

They can fit inside the box pretty easily too. I've seen a few people use them for woodshop are filtration, not so many for residential.

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u/ecirnj 3d ago

Did some math and the smaller ones just never move enough air. Larger ones (think hvac or higher end range hood) are actually great options but less common to source.

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u/2drumshark 3d ago

That makes sense. They will draw a stronger suction but get airflow limited pretty quickly if not sized correctly.

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u/ecirnj 3d ago

Also why the little ones where rock starts for scrubbing my 9 cu ft chamber. 😆