cfm needed to cool 400 watt HPS in air cooled hood - GreenPassion.org - Dedicated to Medicinal Cannabis Cultivation and Education

GreenPunter · #1 09-11-2009, 07:16 PM

i have a 400 watt hps in a sealed air cooled hood. it's got 6" openings for ducting and i'm wondering if i should use my Eco Plus 4" 140cfm fan (with an adaptor) or my Eco Plus 6" 440cfm fan for cooling my bulb. if i can get away with the smaller fan, i'll save electricity but if i need the bigger one to cool, then i'd rather pay a little more for electricity and not have my plants burn up. thanks.

gP

Zigzagman · #2 09-12-2009, 09:27 AM

If the hood is going to be the only thing drawing, the 4" will do the job. Save the 6" for venting the room itself. Peace.

GreenPunter · #3 09-13-2009, 12:13 AM

great! that's what i was hoping to do since i can just dedicate the 4" to the hood only. hopefully this will also save some money on electricity. thanks for the input.

gP

Hatch · #4 09-13-2009, 01:15 AM

If You Already Have The Smaller One, Try It, If It's Not Enough You Can Always Go Get The Bigger One, There Really Wouldn't Be That Much Difference Between The Two On The Electric Bill.

GreenPunter · #5 09-16-2009, 03:27 AM

well, i set up the 4" fan and the air coming out of the hood feels really weak, almost the same pressure as someone just blowing air lightly through their mouth. since i have heat problems consistently, i think i should probably switch and use my 6" fan to cool my hood. that means i'll be using my 4" 170 cfm fan to cool my mother clone area. the area is 2.25'x3.58'x5' which is 40 cubic feet. if i remember correctly, i'm supposed to multiply that by 4 or 5 to get the proper cfm. that is either 160 or 201, leaving me 10 extra cfm or 31 cfm short of target. I'm still going to go with the 4" fan to ventilate but i wanted a second opinion since i often make the wrong choice. thanks.

gP

Hatch · #6 09-16-2009, 03:38 AM

Bro, All I Can Add Is Set It, Let It Run For 2 Or More Hours & Check Your Temp's..Some Times It Will Surprise You. But Trial & Error Are The Best Answer..

theOMINOUS_BOTANIST · #7 11-22-2009, 03:18 PM

hell yea bro i was runnin 404watts of cfl an jus switched lastnight to my 400w hps w cool tube in my cab 3ftwidex2ftdeepx4-1/2fttall .. i was worried,, hehe

but

all seems to be well!! i was worried cuz im only using a 4in blower 100cfm to suck clean air through passive intakes than through the cool tube than through the homemade carbon scrubber.. i wasnt sure it was gna b enough..

but with my window cracked during lights on im keepin the temp rite @77f. steady @ about 50% humidity,,,
so i feel good an i hope things stay cool.. hehehe..... peace lemme how that works ya,,, peace

the ominous botanist...