How to Properly Ventilate Racks
By Frank Federman
Should rack fans blow in cool air or push out hot air? Should some fans in a rack be pushing while others are pulling?

Is it better to push cool air into a cabinet or pull the hot air out? Should all rack fans push or pull, or should you use half for each function?

There are a couple of fundamentals to remember when you’re planning to ventilate a cabinet, closet, video projector enclosure, etc.



Check Air Movement
In a situation where air can move freely with little or no resistance, multiple fans should either all be used for intake of fresh air or exhaust of hot air. If air can move freely, ventilation probably isn’t much of a problem.

This is called placing the fans “in parallel.” In the real world, you’d probably use all of the fans to exhaust hot air high and out the rear of the cabinet, but they would work just as well pushing fresh air in low in the front of the cabinet.

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