If i had a passive intake system (holes all long the bottom, on the opposite side of the exhaust fan) in a space of 4' height x 2.5' width x 2' depth with 250w hps and ~100 watts of fluros/cfls what would be the best fan for this situation? I will also have a fan blowing towards the holes to help with intake. Would a passive intake be good enough or would i need intake? Sorry if this doesnt make much sense im fuckin faded... Im looking at a 160cfm 6" inline for $40, has a max boosted cfm of 240-250, what does this mean? also i calculated my cubic feet and its 25, and ive read u need 2 to 3x cfm. Would having 160cfm fan be overkill?
also, would having the fan on the top instead of the side better? Lots of questions, i want to do this right... and not waste $$$
The top is best as heat rises and you want to remove the hottest air. If it a variable speed fan then you can adjust it to suit you, I doubt it will be to much fan even at full speed. You really don't need an intake with the above mention fan it will suck plenty in.
well, it depends. when i first got my cab running (4' wide x 6' tall x 30" deep) i only had one 6" inline exhaust fan and passive intakes. also one 8" ossilating fan inside and that wasn't enough. temps went into the 90's. but that was also with 400w hps and no floros. with a 250w and floros you should be ok. i'd leave your design open to allow change if you need to add an intake fan. oh, and i think the "max boosted cfm" means if you have two inline fans on the same duct blowing in unison, you won't get more then 250cfm total? not too sure on that though.
oh, and homedepot has inline fans under the brand name "inductor" for cheaper then any you'll find at a hydro shop/or hort supply website. check these out, i use the 6"ers. http://www.homedepot.com/prel80/HDU...ID=ccfiaddjlejfificgelceffdfgidgio.0&MID=9876
i can't get that link to work for some reason. just search "inline fan" at the website and you'll see them.
thanks guys, guess i shouldve looked at homedepot before i ordered off the internet (no big deal tho, paid $40 with free shipping, but it already comes wired or comes with a kit or something, ordered from a trusted company) i will definitely go to home depot if i need an intake fan... "same day delivery" lol
You ask if passive intake will be "good enough" -- that depends on what you want to achieve. For fresh air circulation almost certainly yes it is good enough. For temp management you are the only one who can judge that, in your own particular conditions. Make sure the area of your intakes is at least twice the area of your exhaust. For example, if you have a 6 inch diameter exhaust (assuming it's round), that hole has an area of 28.3 square inches (remember ∏r²). Note that twice the area of a 6" circle is not a 12" circle, that would be fine but more than necessary. Easiest way to figure it out is to just make two intake holes of the same size, but you can figure the formula backwards for any number of holes of any size. Exhaust is best on the top but OK if at the top of a side wall. As for fan, I continue to maintain that nothing beats a Stanley blower, I think it's rated at over 1200 cfm on low. However, you need the space and some ingenuity to rig it up inline.
Yes I think i will be fine on temp management with this, i have a/c or heat to control temps outside of the box, only problem is going to be making the 6 inch hole for the fan...