Too much negative pressure?

renyman

renyman

Active Member
Is there such a thing? If i zip everything up my tent walls get sucked in as far as they possibly can. Im not only worried about the tent but also my girls. Im running two 400cfm with one attached to a carbon filter and the other attached to an intake hose. Two sealed hoods. My temps are perfect. I guess i should make sure every connection is sealed up good but i believe they are. Do you guys use tape along with a clamp when attaching ducting? Seriously, i can barely pull the walls back if everything is zipped up. Thanks.
 
Shrubs First

Shrubs First

Well-Known Member
Hmm, some people say a negative pressure is good, some people say a positive, I find I can get better airflow in a slightly positively pressured environment. I'm not quite sure why you would be getting a negative pressure, the only reason that would happen would be if either your outtake was extraordinarily stronger than your intake. Maybe there are some large kinks in the ducting of your intake causing your outtake to be much more efficient? with equal fans and your outtake being slightly hindered by the carbon filter I feel you should be getting a positive pressure... My outtake is 2x as strong as my intake and I have a positive pressure... strange.
 
D

dgk4life

Well-Known Member
neg pressure is a good thing it means your exhaust is putting out just a bit more then your taking in.. which is good.. i use a passive intake system and the air in my room gets exchanged 2x a min in my main flower room and 4x a min in my tent . u want negative pressure.. its a good thing
 
renyman

renyman

Active Member
Shrubs First said:
Hmm, some people say a negative pressure is good, some people say a positive, I find I can get better airflow in a slightly positively pressured environment. I'm not quite sure why you would be getting a negative pressure, the only reason that would happen would be if either your outtake was extraordinarily stronger than your intake. Maybe there are some large kinks in the ducting of your intake causing your outtake to be much more efficient? with equal fans and your outtake being slightly hindered by the carbon filter I feel you should be getting a positive pressure... My outtake is 2x as strong as my intake and I have a positive pressure... strange.
Click to expand...

na dude, i really dont have an actual intake because the intake i referred to only blows cool air through a sealed hood. i know for a fact that im getting way too much suction which is negative intake, right? So my options, i believe, are to either get a fan speed controler or redesign everything so i have an actual intake.

I just upgraded my Stanley blowers to inline fans and i didnt realize they were that much more powerful. What a waste of time and money those stanleys were. Just buy the good shit from the get is my advice to noobs. Ayways, I was able to drop my temps by about 8 degrees but now i have a new problem.
 
renyman

renyman

Active Member
Shrubs First said:
Hmm, some people say a negative pressure is good, some people say a positive, I find I can get better airflow in a slightly positively pressured environment. I'm not quite sure why you would be getting a negative pressure, the only reason that would happen would be if either your outtake was extraordinarily stronger than your intake. Maybe there are some large kinks in the ducting of your intake causing your outtake to be much more efficient? with equal fans and your outtake being slightly hindered by the carbon filter I feel you should be getting a positive pressure... My outtake is 2x as strong as my intake and I have a positive pressure... strange.
Click to expand...

na dude, i really dont have an actual intake because the intake i referred to only blows cool air through a sealed hood. i know for a fact that im getting way too much suction which is negative intake, right? So my options, i believe, are to either get a fan speed controler or redesign everything so i have an actual intake.

I just upgraded my Stanley blowers to inline fans and i didnt realize they were that much more powerful. What a waste of time and money those stanleys were. Just buy the good shit from the get is my advice to noobs. Ayways, I was able to drop my temps by about 8 degrees but now i have a new problem.
 
Shrubs First

Shrubs First

Well-Known Member
yes you have a major negative pressure because of so much outtake and not enough passive intake, get a fan about 1/4 to 1/2 the strength of your outtake and make that your intake, that will even it out much better... and better efficiency on both ends.
 
renyman

renyman

Active Member
Shrubs First said:
Hmm, some people say a negative pressure is good, some people say a positive, I find I can get better airflow in a slightly positively pressured environment. I'm not quite sure why you would be getting a negative pressure, the only reason that would happen would be if either your outtake was extraordinarily stronger than your intake. Maybe there are some large kinks in the ducting of your intake causing your outtake to be much more efficient? with equal fans and your outtake being slightly hindered by the carbon filter I feel you should be getting a positive pressure... My outtake is 2x as strong as my intake and I have a positive pressure... strange.
Click to expand...

na dude, i really dont have an actual intake because the intake i referred to only blows cool air through a sealed hood. i know for a fact that im getting way too much suction which is negative intake, right? So my options, i believe, are to either get a fan speed controler or redesign everything so i have an actual intake.

I just upgraded my Stanley blowers to inline fans and i didnt realize they were that much more powerful. What a waste of time and money those stanleys were. Just buy the good shit from the get is my advice to noobs. Ayways, I was able to drop my temps by about 8 degrees but now i have a new problem.
 
Shrubs First

Shrubs First

Well-Known Member
Depends, that means that the air coming in is on a direct course out of the outtake, I have mine so that it has time to be blown around a little bit.. It's all preference man, one persons way might be different that someone else, in nature it is perfectly random there will be positive pressure and negative pressure.
 
SmokeyMcChokey

SmokeyMcChokey

Well-Known Member
^^^ true true. i usually keep a very slight neg pressure but when im in my room the tent is unzipped so its all fine but im only using like 100cfm fan. works fine for me no heat probs.
 
D

dgk4life

Well-Known Member
i would say put your filter and fan in the back of your room directly diagonal across the room for your intake.. this will draw fresh air across your plants clean the hot smelly air and expell good fresh air.. no one will know. also u def want neg pressure because that way your sure that smell is not leaking out .. does that make sence? sorry im reall sick and on a bunch of pills .. i hope that clears things up for u
 
Shrubs First

Shrubs First

Well-Known Member
Ahhh yes, if you are worried about smell a negative pressure would make sense... Gotta love boulder, it's pretty natural to be growin the herb here, aint gotta worry about my smell.
 
renyman

renyman

Active Member
dgk4life said:
i would say put your filter and fan in the back of your room directly diagonal across the room for your intake.. this will draw fresh air across your plants clean the hot smelly air and expell good fresh air.. no one will know. also u def want neg pressure because that way your sure that smell is not leaking out .. does that make sence? sorry im reall sick and on a bunch of pills .. i hope that clears things up for u
Click to expand...

My filter is my only outtake/exhaust. Im thinking my fan is too powerful so i think ill buy a fan speed controller and go from there. Im wondering if its possible to pull air too fast through your carbon filter making it less effective?
 
Shrubs First

Shrubs First

Well-Known Member
renyman said:
My filter is my only outtake/exhaust. Im thinking my fan is too powerful so i think ill buy a fan speed controller and go from there. Im wondering if its possible to pull air too fast through your carbon filter making it less effective?
Click to expand...
Of course it is lol, your filter says what the maximum fan CFM should be....
 
D

dgk4life

Well-Known Member
renyman said:
My filter is my only outtake/exhaust. Im thinking my fan is too powerful so i think ill buy a fan speed controller and go from there. Im wondering if its possible to pull air too fast through your carbon filter making it less effective?
Click to expand...
your fans cfm should be less then what your filters cfm is........ so it dont get overloaded and not work properly.. neg pressure is good i would not worry about a fan speed control i would concentrate on makin sure my fan is not too powerful for the filter
 
the church man

the church man

Well-Known Member
a negative pressure means that the pressure within your system is less than the pressure of the environment. high pressure flows to low, so any and all air leaks will be leaking into your system. this is optimal for smell control. so basically: environment>>leaks and intake>>system>>filter>>blower>>environment

i have a passive intake, so a negative pressure is naturally maintained.

i'd say you done a good thing!
 
brainwarp

brainwarp

Active Member
Your exhaust far exceeds your intake, and its trying to find places to suck air from.

Just take a length of flexible aluminum tubing. Make an "S" shape or a loop, so light can't come in or out. Start with a 4". You may need to add more, if the diameter is not big enough. Seal the end coming into your tent with (duct) tape. Some filter material in the intake end will keep out dust, etc.
 
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