Perception
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Run as much air flow as possible...never too muchJust set up a new grow tent. I've been playing with my light and temperature control. Maybe I'm crazy, but it seems to me that the more negative pressure I have in tent, the better the cooling. On that note, my tent walls are taught like a drum skin when they get sucked in - like... no ripple effect when you tap them.
-LEC 315 light with exposed bulb
-4x4x6.5 tent
-6", 450cfm exhaust fan mounted inside tent
-2x, 6" passive intake ducts (No filter yet)
- Room temp (outside temp) = 71 deg F
- Tent temp (inside) = 77 deg F
If I open up all the passive intake vents in the tent, and there is LESS negative pressure (can tap tent walls and create waves), my temperature difference is 8 degrees. With HIGH negative pressure, my temperature difference is 6 degrees.
My question is:
Can TOO MUCH negative pressure be detrimental to the plants? I'm going to need all the cooling I can get in the summer, and more negative pressure seems to cool better for me.
Run as much air flow as possible...never too much
Install a inline damper so u can control room pressure.
Why?I'm just concerned about how much negative pressure I had in the tent.
Run it till the tent poles bend... they love it... less chance of mold, less heat, more co2I agree, and if things get hotter in summer, I might even up my CFM. I'm just concerned about how much negative pressure I had in the tent.
I'm assuming that the damper would go on the exhaust ducting? At this point, I don't want to reduce airflow/exchange, as I feel like my CFM is "just" enough to keep the tent cool. I tried a smaller fan and it didn't make the cut. Does it hurt anything to have a lot of negative pressure?
Thanks!
the only downside is with a lot of neg pressure your fan is working harder to exchange the air. Which technically could shorten it's service life. Question is by how much? You need to allow more air to be pulled from the tent with your passive ports. The quicker your fan can pull hot air out and bring cooler air in the better. But keep in mind as summer comes your cooling will only be as good as the ambient air temps are from the room that the tent sits in.I agree, and if things get hotter in summer, I might even up my CFM. I'm just concerned about how much negative pressure I had in the tent.
I'm assuming that the damper would go on the exhaust ducting? At this point, I don't want to reduce airflow/exchange, as I feel like my CFM is "just" enough to keep the tent cool. I tried a smaller fan and it didn't make the cut. Does it hurt anything to have a lot of negative pressure?
Thanks!
I'm not omnipotent, but I can't see how that would even make someone think it's an issue. If the airflow is constant, causing a "vacuum" type effect, it's changing the air pressure relative to the outside space. Not the availability of important gases.Ok, sounds good! Thank you.
@Junk I had been googling earlier and saw people posting stuff like, "you want the tent walls sucked in, but not to taught", so I didn't know if it was a real concern or anything. Sounds like it's a non-issue though. Thanks all
the only downside is with a lot of neg pressure your fan is working harder to exchange the air. Which technically could shorten it's service life. Question is by how much? You need to allow more air to be pulled from the tent with your passive ports. The quicker your fan can pull hot air out and bring cooler air in the better. But keep in mind as summer comes your cooling will only be as good as the ambient air temps are from the room that the tent sits in.
I have been able to abuse fans for about 5 years then they crap out... 3 years is a good estimate with any fan and thats runnin 24/7 365the only downside is with a lot of neg pressure your fan is working harder to exchange the air. Which technically could shorten it's service life. Question is by how much? You need to allow more air to be pulled from the tent with your passive ports. The quicker your fan can pull hot air out and bring cooler air in the better. But keep in mind as summer comes your cooling will only be as good as the ambient air temps are from the room that the tent sits in.
What I have done is taken the tent room that no one lives in and I am running a duct
from my AC vent register that will blow the cooled air into the tent during the hottest part of the day when the ac is needed. This will help keep the tent interior cooler.
You have negative pressure cause you're exhausting too hard for the rate of air in. Tweak the inlet higher and the exhaust slower to even it out. Consider going co2 to help with higher Temps and to slow the air exchange rate dramatically since you are injecting co2
I get what you are saying. I think it's me getting stuck on that word...but the only thing you care about is temps/rh etc. The negative pressure you are talking about is relative. This...So I want to be running negative pressure to make my cooling more efficient. I was double checking to see if this could negatively impact plants.
-LEC 315 light with exposed bulb
-4x4x6.5 tent
-6", 450cfm exhaust fan mounted inside tent
-2x, 6" passive intake ducts (No filter yet)
- Room temp (outside temp) = 71 deg F
- Tent temp (inside) = 77 deg F
This is my point, and I realize it's a silly thing to get hung up on, but the above is backwards. You want your cooling to be more efficient. The side effect for your design, is negative pressure.So I want to be running negative pressure to make my cooling more efficient.
It does. Your temps are amazing though, so you are doing something right.@Junk thanks so much for the input. It seems simple, but balancing things just right takes a lot of fine tuning.
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