Originally Posted by
Vapor
Stacking fans does increase CFM as well as decrease CFM-loss due to restriction.
e.g., a 100CFM fan on a radiator may only push (or pull) 75CFM through the radiator. That's a 25% loss.
Stacking two ideal (ignoring rotational direction for now) 100CFM fans may increase throughput to 125CFM. When this is put on a radiator, the fannage 'unit' can usually push nearly 105CFM through the radiator. This is only a 16% loss AND a higher 0-point. It does have a slight disadvantage when it comes to air dispersion patterns however.
Where this is useful is both in increasing performance and/or decreasing noise. For instance, if your goal is to have 75CFM pushed through your radiator, you can use a single loud 100CFM fan or two medium-noise 72-ish CFM fans. Two medium-noise fans are usually quieter and emit a lower-pitch sound as well.
DISCLAIMER: don't quote me on those figures, it GREATLY depends on the fans used and what I used is the best-case scenario I've seen. The way most people do push-pull doesn't give 105% efficiency (closer to 98% or so I'd estimate) since almost nobody does counter-rotation and even a radiator separating two fans doesn't reduce all rotational airflow patterns that counter-rotating fans do.
Posting Permissions
Reply With Quote
Bookmarks