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How many 120mm PC fans would it take to offset the exchange of a 260CFM squirrel fan

HiTech-Hate

New Member
Ok, so I have a 260CFM squirrel cage fan from a past failed grow attempt.

The difference this time is that I will be growing in a dresser, dimensions 39"x39"x16" and it has to be ultra stealth lol

How many 120mm PC fans would it take to offset the exchange of a 260CFM squirrel fan (I will have a small oscillating fan inside as well)?

I'm assuming its best to use the more powerful squirrel fan for exhaust instead of intake?

Would a passive intake be enough to skip the PC fans altogether, or would I be creating so much negative pressure from the exhaust fan?

Also, how detrimental is it to place the exhaust fan at the bottom? I'm kinda stuck in that placing any fans near the top of my dresser on either side, or the back would be CLEARLY obvious to anybody walking by.

Thanks in advance
 

TorturedSoul

Member of the Month: May 2009, Oct 2010, Sept 2017
Re: How many 120mm PC fans would it take to offset the exchange of a 260CFM squirrel

Would a passive intake be enough to skip the PC fans altogether, or would I be creating so much negative pressure from the exhaust fan?
You're not going to implode your dresser;).

Seriously, though... Passive intakes are fine. Just don't undersize them. Seems like there are formulas around here somewhere (I don't remember offhand what they are) that would help. But basically, you want a little negative pressure in your GR/box so that all heat/smell exits the correct place. Not enough to strain your blower but a little.

Worst comes to worst, I suppose you could build a "test area" out of plastic sheeting, add your blower, and cut a LARGE opening in the far lower corner. Then keep covering more and more of the opening until you see signs of negative pressure. Probably not the correct way to figure it out, lol, but...
 

HiTech-Hate

New Member
Re: How many 120mm PC fans would it take to offset the exchange of a 260CFM squirrel

You're not going to implode your dresser;).

Seriously, though... Passive intakes are fine. Just don't undersize them. Seems like there are formulas around here somewhere (I don't remember offhand what they are) that would help. But basically, you want a little negative pressure in your GR/box so that all heat/smell exits the correct place. Not enough to strain your blower but a little.

Worst comes to worst, I suppose you could build a "test area" out of plastic sheeting, add your blower, and cut a LARGE opening in the far lower corner. Then keep covering more and more of the opening until you see signs of negative pressure. Probably not the correct way to figure it out, lol, but...
Thanks tortured.

Implosions are fun though :p

I've been hunting around these forums for some kind of 'formula', these forums are just so VAST that even with the search function its hard as hell to find very specific stuff lol. I went to show my friend a grow journal I read on here (420fied's 1200W NFT SCROG), and couldn't find the damn thing for 10 minutes, even know i knew what it was lol !!
 

ronbowe63

New Member
Re: How many 120mm PC fans would it take to offset the exchange of a 260CFM squirrel

Hi-Tech,.I learned from the overgrow days it is one and one half times the exhaust,which worked awesome on my first cab.4'' exhaust with a six inch intake.But now people will tell you at least twice the exhaust.6'' exhaust = 12'' intake.
 
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