[opencl]

I ran a few cheap box fans with filters directly over them for several years and none of them failed, I have heard this claim a lot but it seems overstated. The triangle setup will significantly increase the airflow and thus the effectiveness of filtration though.

[post_break]

I guess it depends on the quality of filter. If you're rocking a high merv filter for smoke the pressure drop can be significant.

[nathancahill]

I've done this too for years and no issues.