question about venting......

can one have too much exhaust.....i am in the process of designing a new small area....the dimensions are 3wx2dx5h...i am going to run a soler palau 6" fan for the exhaust its rated at 293cfm i am going pull from 2 6" vents in the ceiling droping into 1 6" and push through a scrubber about 10 feet away.....for intake im pushing in from the outside through 4 ,4' runs of ducting i was thinking of using a soler palau 4" rated at 101cfm in 2 of the runs to help boost the air......any comments or insite greatly appreciated.....

I'm no expert, but I do know that the more fresh air you supply your plants with, the more they will love you. Seems like your plan is fine.

I'm not sure I understand the logic of the intake setup. Your exhaust cfm would be 3x what your intake is supplying (not accounting for ducting losses on either end).

Why not use all your fan power for exhaust and run passive intakes? Conventional wisdom holds that passive intakes should be twice the size of your exhaust. In other words, if the smallest diameter of your exhaust ducting is 6" you'd want (2) 6" passive intakes.

Is the issue that your fresh air intake is limited to 4" for some reason? Even if that's the situation, I wonder if the 101cfm intake fan will just create more of a problem in terms of obstruction than benefit in terms of air flow. Again, maybe it's better to have that 101cfm pulling out of the space as an exhaust and let the two fans just pull in as much air as possible through that 4" as passive intake. You'd be sure to have plenty of negative pressure in the grow space for containing odor that way.




Regarding the general question of too much exhausting: Within reason, I'm not sure it's really possible in terms of plant health. Having more than necessary may cost you in terms of sound and electrical usage but unless the plants are being wipped around by massive airflow I can't see how it would be harmful. I am not an expert, however.

Better to have too much than not enough, I say.

What Hawk said.

And as long as your ventilation is not affecting any CO2 production you are running you really cannot have enough good fresh air for your plants.

arnt carbon scrubbers more effective when air is pulled through instead of pushing out?

not sure i agree that passive intakes need to be twice the size of the exhaust. i would think that one exactly the same size would be more benificial for circulating the air in the room as the air would be pulled thro at a faster rate. ive used multiple passive intakes that are 1" holes strategically positioned to blow directly onto every single plant (1 hole for each of my 10 plant's) thus there is no need to use a fan inside the cabinet killing two birds with one stone.

Hawk said:

I'm not sure I understand the logic of the intake setup. Your exhaust cfm would be 3x what your intake is supplying (not accounting for ducting losses on either end).

Why not use all your fan power for exhaust and run passive intakes? Conventional wisdom holds that passive intakes should be twice the size of your exhaust. In other words, if the smallest diameter of your exhaust ducting is 6" you'd want (2) 6" passive intakes.

Is the issue that your fresh air intake is limited to 4" for some reason? Even if that's the situation, I wonder if the 101cfm intake fan will just create more of a problem in terms of obstruction than benefit in terms of air flow. Again, maybe it's better to have that 101cfm pulling out of the space as an exhaust and let the two fans just pull in as much air as possible through that 4" as passive intake. You'd be sure to have plenty of negative pressure in the grow space for containing odor that way.




Regarding the general question of too much exhausting: Within reason, I'm not sure it's really possible in terms of plant health. Having more than necessary may cost you in terms of sound and electrical usage but unless the plants are being wipped around by massive airflow I can't see how it would be harmful. I am not an expert, however.

Better to have too much than not enough, I say.

Click to expand...

the logic is that i was loaded when i was writing this.. i want to put in 4 4" intakes...to make in intake of sixteen square inches and an exauhst of twelve square inches..the reason i want to go with 4" intake is to use as little space as possible....if passive would work that would be awesome(save money on fans) but i will be pulling air in from the outdoors about 4-7 feet away(not sure how im going to route ducting yet) i was thinking a fan would help push the fresh air in......