Fans, To push or to pull

Enigma said:

No, sir. You are wrong. That analogy wouldn't hold a water balloon.

Different design = different placement

For example:

Squirrel Cage fans = PUSH

In-line fans = PULL



E

Click to expand...

well if your putting a duct on the both ends of both fan your going to loose cfm. I dont care who you think you are, its physics. Your making the fan work harder

I voted for pulling. My reasoning when setting up was that even with an oscillating fan circulating air in the room, the hot air is going to make its way upward. So, having a pulling fan up near the ceiling will more efficiently remove the hot air. I haven't had a fan burn out yet, so I'm not worried bout that. Also, like someone mentioned, if you're trying to hide smell, it's better to pull air into any random leak spots rather than push air out of them.

Thinking about it, I can see reasons for either way, but that was my thinking at the time.

Enigma said:

What style fan are you using?




Those are pretty weak fans bro, so it would make sense you would need two of them. Using one powerful 6" in-line fan would do the work of those two, but that would cost ya.

+rep for working out a cost-efficient solution to your problem.



E

Click to expand...

hey and thank you for the rep my friend im still kind of on a budget for now until this harvest so i had to improvise just a little..when i upgrade to a larger hps ill definately go with the best fan possible..Peace Pot Prosperity..

I use both, since fresh air is just as important as light in the garden according to Jorge Cerevantes.

I also exhaust directly to the outdoors. The grow room is in the basement, so the room is supplied w/ basement air which is between 55F in the winter and 65F in the summer.

Enigma said:

No, sir. You are wrong. That analogy wouldn't hold a water balloon.

Different design = different placement

For example:

Squirrel Cage fans = PUSH

In-line fans = PULL



E

Click to expand...

That is not correct.

Both the squirrel cage and in line fans are capable of pulling and pushing air. The difference is the amount of static pressure, or suction, the fan develops.

The in-line fan is an axial blade design. Such a design is great at moving a lot of CFM, but very poor in developing static pressure, or suction. Static pressure overcomes resistance to flow, as in the case of ductwork: the squirrel cage fan will operate more efficiently, i.e. closer to the advertised CFM rating of the fan, with ductwork attached more than the in line fan.

Squirrel cage fans have a centrifugal blade design. They develop a LOT more static pressure/suction than the in line fan.

The difference? Take two fans, both drawing 300 CFMs. One is centrifugal blade design, the other axial blade design. Hook six feet of ductwork to the intake of each fan. The centrifugal fan will clearly outperform the axial blade fan in both suction power and total CFMs moved.

Remember, with ANY fan, best performance will be achieved with minimal ductwork on both intake and exhaust ends.

Best fans of the market today are the Can Max brand fans. They are the only fan I could find with performance information published by the manufacturer and with ratings according to AMCA, the ventilation industry professional organization that publishes fan testing standards and practices, among other things:

http://www.canfilters.com/max_fan_6.html

http://www.amca.org/

My little computer case fans are made to pull air not push.Also pulling air creates a negative pressure for me so it helps to keep removing the stale air and removing smell.