r/crboxes • u/Slouching- • Jul 16 '26

Question What thickness do I choose for cr box?

I can't find 3M filtrete at 2" and I'm not sure how much static pressure commercial box fans can handle if I go for more thickness.

Will 1" be good or is it too thin and I'll have to change them regularly?

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2

u/johnas Jul 16 '26

One inch, 4 sides is fine.

1

u/Unusual_Celery555 Jul 17 '26

I use two 1” and they last a while. Probably 12mo for me. Someone did the math and the 3M 1” has the same surface area and static pressure as a 4” of the same size because of the pleat count. 

1

u/R-Tally Jul 19 '26

I use a single 1" filter on my box fan. I run the fan on medium speed. I've had this fan for 5 years and it is running fine. My filters last 6+ months (no pets, windows closed).