greenthumbjudex
Member
Hello what size of passive intake in a 2x2x3 tent with 4" 150cfm as exhaust? to apply negative pressure for odor control
PASSIVE INTAKE SIZE
- Thread starter greenthumbjudex
- Start date
coreywebster
Well-Known Member
There will always be negative pressure with passive intake and active extraction.
Just open whatever lower vents are available.
Just open whatever lower vents are available.
greenthumbjudex
Member
Uhh is opening 2x 4" passive intake a good idea at the btm? is this enoigh to secure the odor wont leak outside?
coreywebster
Well-Known Member
Yep its fine, while you have an extraction fan running, which should be 24/7 , you will have negative pressure.
Air is flowing into any passive intake and can only go in that direction.
Nizza
Well-Known Member
the rule of thumb for passive intake is you want it 2-3 X larger than the area of your exhaust
so 12.56 is the area of a 4" pipe
doubling that is equivalent to 6" (2x larger) or 8" (4x+ larger) would make the fan not have to work as hard.
I agree as long as the extraction fan runs and you have a few passive intakes it will suck a vacuum on the chamber
so 12.56 is the area of a 4" pipe
doubling that is equivalent to 6" (2x larger) or 8" (4x+ larger) would make the fan not have to work as hard.
I agree as long as the extraction fan runs and you have a few passive intakes it will suck a vacuum on the chamber
greenthumbjudex
Member
Okay thanks man.
JoeBlow5823
Well-Known Member
Just open your intake vents at the bottom of the tent. I "upgraded" mine with these "high end" filters.
greenthumbjudex
Member
your intake is 2x the size of your exhaust?
xtsho
Well-Known Member
Make sure you filter those intakes because if you don't you'll be pulling lint, dust, hair, and other crap into your tent and it will stick to the buds and make them nasty.
I run a short length of round metal ducting with one end covered with FPR 8 filter material through 2 4" vents and one 6" vent so I have three open bottom vents. 4 x 4 tent with a 6" 400 CFM fan reduced to about 1/2 with a speed controller. It's quieter to run a larger fan turned down than a smaller one at full power. I had a 4" 200 CFM fan before that ran full power and it made twice the noise as this one turned down.
I went and took a couple pictures of my setup and am glad I did. I need to replace the filters.
I run a short length of round metal ducting with one end covered with FPR 8 filter material through 2 4" vents and one 6" vent so I have three open bottom vents. 4 x 4 tent with a 6" 400 CFM fan reduced to about 1/2 with a speed controller. It's quieter to run a larger fan turned down than a smaller one at full power. I had a 4" 200 CFM fan before that ran full power and it made twice the noise as this one turned down.
I went and took a couple pictures of my setup and am glad I did. I need to replace the filters.
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