Intake fan for small room - what size exhaust vent?

[gualapa]

I'm making a small part of my 11.5X9.5 flower room into a veg room for mothers & clones. I'm using a 6" 240 cfm intake duct booster fan for the small room. What size should the exhaust vent be? 6"?

I ask because in the main room I have an exhaust fan and I know the intake vent should be twice the area of the exhaust fan diameter. What I'm wondering is how big should an exhaust vent be when there's an intake fan in place, which is the opposite of exhaust fan/intake vent.

 

[LEDfoot]

I'd think a passive exhaust port would follow the same rules as a passive intake: at least twice the area of the powered vent. Otherwise, the fan is going to be working harder. So I'm guessing an 8" exhaust would be good. (My calculations show 8.5" diameter is twice the area of a 6" diameter circle.)

 

[gualapa]

Yeah, I think you're right, except your calculations a little off. It should be: sqrt(2*(9*3.14)) = 7.5", not 8.5". The 9 is the radius squared (3^2).

Or instead of a 7.5x7.5 vent, I could use a 9" pvc pipe (also use as a light catcher), but add a 1/2" of duct tape on the entrance of the vent to slow down amount of air because: 7.5X7.5 = 56.25 & area of 9" circle = 63.62. an 8.5" circle = 56.75, so a tiny bit of duct tape can adjust how much air is coming thru.

this is all assuming that I need twice as much area as the intake fan diameter.

 

[LEDfoot]

I don't care about the neg rep and I know it's not you, gualapa, but for the benefit of any interested third parties:

Area of circle = 3.1416 * r^2 (In words, pi times the squared radius)

I stand by my original post--I did not know you wanted the dimensions of a square port.

 

[gualapa]

whoops you're the one that's right. I automatically assumed you meant for a square port, then I provided the calculations for both square & circle, and got the same for the circle. srry for the confusion. don't know why someone would neg rep you tho, that's usually for people that are out of line, not wrong, which you actually weren't.

 

[LEDfoot]

Off topic: that's the second unhelpful rating I've had and neither shows up on the My IC listing. I assume it's a malcontent that gets banned repeatedly. I've seen a lot of random "unhelpful" votes recently.

 

[gualapa]

that's odd. you should try messaging a moderator or admin, they might be able to sort out what's going on or provide an explanation.