passive intake with neg pressure???

[hippie hill]

i have 3 2 1/2" holes in the bottom of the door with a piec of carbon fiber over it and a 4" squirrel cage fan sucking the air out of the top of the box and going threw a dyi carbon filter when the fan is on it holds the door shut and once you open the door u hear more air rush threw the fan when u close the door and it gets within 1/2" if your not ready for it it will pop out of your hand the box is 3' w x 2' d x 3' h

can you have negative pressure with a passive intake or do i not have enoug intake?

 

[FreezerBoy]

What you're describing is negative pressure. The pressure inside is less than outside. This makes all air in the vicinity try to enter the box which is why the door self closes. With negative pressure, the only way out is through the exhaust fan which allows us to control odors.

Positive pressure is like a balloon. All air is trying to escape which would cause your door to self open rather that self close.

You did good.

 

[hippie hill]

ok so with neg pressure that makes it so bugs and mold dont like it?
is there and affect on the growth of the plant with a neg pressure?

 

[1G12]

Neg. pressure won't affect bugs or your plants unless you have too much neg. pressure. Then you are not maximizing your air flow & may be making your fan work extra hard. My bet is that you could have at least one more intake hole. More air flow will help prevent mold (along with a small circulation fan).

 

[Whatever]

Then you are not maximizing your air flow & may be making your fan work extra hard. My bet is that you could have at least one more intake hole.

Basically yes. I've always tried to dial things in so I have decent but not excessive negative pressure. You only really need a little. I've had situations where doors suck them selves shut and not necessary. Sometimes I've used a lit stick of incense to make sure I've got negative pressure.