confused about what kind of fan/neg air pressure

[vindiesel]

first grow coming up. been researching for awhile. will be a stealth grow 2X2 box 3' high. 150W HPS maybe a few CFL. will have an intake hole and thinking of 1 or 2 4" axial fans, 105cfm each. i keep reading about neg air pressure and blowers and whatnot..... i'm looking for a simple but effective setup. can u guys give me some ideas in regards to my setup and fans. and what neg air pressure is...box will be in a closet in basement. closet is cinderblock, dark, about 12X4. picure and l shaped closed, at end it makes a 90 degree turn, that L part is about 12X1. it's what is in back of bar. the end of that is open to laundery roo. about a 8X1 vertical opening. thanks.

 

[hurricane]

Neg air pressure, is where there is enough air exiting your cab through the fan that air is sucked in through every single crack and crevice possible, all air flows into the room and to the fan. For this to happen your fan must also have the ability to create a decent ammount of pressure.The important thing here is when you have negative pressure the smell of the plants will always go through the fan, and whatever is in the fans ventilation circuit, usually a carbon scrubber.

As for fans to get neg pressure in a space like that, computer style(thats axial right?) wont likely be able to build the pressure you want. For a really quiet fan(remember that noise is a large part of stealth) the smallest panasonic whisperline fan will be plenty.
Froogle it and find prices a bit over $100, not bad for what it does.

Another thing to remember is you don't need too much neg pressure. When i built my first C24 cab w/ a 6" Elicent inline fan i would literally have to pull on the doors to get them to open. Adding a little more intake space made the doors still suction shut when i closed it, but allowed more air to pass through the cab and put less stress on the fan.
Hurricane

 

[vindiesel]

thanks man for that fan link. i'll look into that too. i will not b using a computer tower. will be using a rubbermaid, or rubbermaid material cabinet. 36WX30HX20D. here it is:
http://www.target.com/Suncast-2-Doo...ref=bxgy_cc_img_b_3673081/602-6045249-9818215

 

[Guest]

Neg air pressure, is where there is enough air exiting your cab through the fan that air is sucked in through every single crack and crevice possible, all air flows into the room and to the fan. For this to happen your fan must also have the ability to create a decent ammount of pressure.The important thing here is when you have negative pressure the smell of the plants will always go through the fan, and whatever is in the fans ventilation circuit, usually a carbon scrubber.

As for fans to get neg pressure in a space like that, computer style(thats axial right?) wont likely be able to build the pressure you want. For a really quiet fan(remember that noise is a large part of stealth) the smallest panasonic whisperline fan will be plenty.
Froogle it and find prices a bit over $100, not bad for what it does.

Another thing to remember is you don't need too much neg pressure. When i built my first C24 cab w/ a 6" Elicent inline fan i would literally have to pull on the doors to get them to open. Adding a little more intake space made the doors still suction shut when i closed it, but allowed more air to pass through the cab and put less stress on the fan.
Hurricane

Will the following fan and scrubber http://www.wormsway.com/detail.asp?sku=CC0633 create enough neg. air pressure in a homebox xl?

 

[hurricane]

Definatly. The fans that create pressure are like the one you pictured, with a large fan blade in the middle, but it doesn't look anything like the fan blade in your computers or your window fans on the inside. The fan blade that looks like a window or box fan is the kind that dont work, the kind you pictured is great Do remember that that style of fan can put out a bit of noise. My growroom is in my bedroom, and my 6" elicent (similar design style) was just too loud. I'm now using a stanley blower, which at least for me has brought the noise level to acceptable levels. Its quieter in the room with the grow, than the other room with computer & aquarium

Hurricane

 

[smokey.mcpot]

what about computer fans with 110cfm or more?

 

[hurricane]

what about computer fans with 110cfm or more?

While i've not used computer fans for this application, and i have read of people using computer fans pushing carbon in a small drying chamber, i dont believe the computer fans have the right fin design to create actual pressure.

The fans that create pressure spin a fan that looks nothing like a regular countertop, box, or computer fan. My elicent for example has a flat disc that rotates, heres a pic of the blade in my 6" elicent. This is not the only blade design there are others, but shows you how different it is from your standard computer fan.

Hurricane