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Heat, at wits end...

The duct at top of photo is exhaust fan intake. The duct running down the side and out of grow space is the exhaust. My issue is top of space is 10 degrees cooler than bottom.
 
Yes small space does not help but.. Air out must equal air in think of it as water. Basically if you outtake 100cfm and your intake is blowing in 100cfm and say have 50cubic feet of air space. You will be replacing all the air in the tent 2 times every minute. so all that humidity and hot air will be completely sucked out and fresh cooler air should be put in its place but if you are just putting in warm room air with normal humidity then to cool it you will have to have something in the tent cooling the air inside the easiest way is to pump a/c cooled dry into the grow room and suck out all the hot humid air. Doing it this will always keep fresh in the tent or grow room. Think of the grow room as its own box and the air like water. You have to exhaust your hot air outside of the tent/room or else your just cycling warm air and heating it up over and over.
 
Try using the inline fan (exhaust) to suck air from the bottom and blow out the top. Pretty much opposite of what you currently have.
 
My intake is at the bottom and exhaust at top. The exhaust duct from fan runs towards the bottom so I can exhaust under some shelves in tool room next door. Stealth is key in my illegal state...
 
Yeah D.A.A.S.69, It's all you and Greene's fault!! 😉 Plus local hydro store had a 315 set up and I was amazed how little heat it put out. I really wonder if my grow area is too small for 315 but I see others here with similar set up and no heat issues... gonna take Insights suggestion to relocate fans.
 
That's what has me stumped... grow space is 75 cubic feet, exhaust fan rated at 340 cfm. Should be exchanging air better than 4 times a minute. Air at top is 10 degrees cooler than at floor.
 
I grow autos and leave my tent open most all the time, except when people are coming over and might open the door to that room. I adjust my lights' height when I have an issue with too much heat, I've found that if they aren't staggered in height, they produce way too much heat, and use a small fan to circulate the air and have a ceiling fan on at all times. When we are here alone the door to the grow room is open. I know not everyone can be this lax in a non-legal state but we never have visitors and if someone knocks on the door the door is closed before we answer the knock.
I hope you figure it out.
 
If it's within your means, you could switch to autocobs. They give off very little heat, almost nothing compared to hps and others. I have 4 in my 3*3*6, one over each plant.

Whatever you decide to do, I hope it works! Heat problems can be a bummer!
 
I do just what BlueCanoe does, except it's the door to my grow box instead of a tent. After last fall's harvest with nanners and some seeds, I realized that the stressor had been the heat during flowering inside of the box (HPS 400w bulb). Leaving the door open during lights on has taken care of that problem, although I'm going to time my next grow so that the end of flowering is during cooler weather.
 
Ok Purv, just a thought here,the temp. at the top is is taken in a shaded area, radiant heat causes the higher reading. at your canopy. Put a thermometer in the sun on a 60 degree day and it aint gonna read 60.
 
I went back and forth between cob or 315 before light upgrade, finally decided on 315 after looking at a display at local hydro store. Got too much invested in new set up to give up just yet... 😂
 
PRIMO, that appears to be exactly what I got going on but my thought is that I still need temps at canopy, directly below light, to be ideally in the upper 70's. Mine is at 81 which is fine during veg but would like to get it a bit lower during flower. Gonna play around with fan locations to see if that will help.
 
I would think it should exchange but if you don’t have the corruclation and have a few spots with stale pockets of air. Sounds like if the top is cooler then it is exhausting air cuz it’s sucking the air out with a passive intake I assume makes it hard. I have 112 cubic feet and at the rate of 440 cfm I still have issues it came down to air circulation. Also try to move you exhaust pipe around like where it pulls from the room move it down low on the side etc see if you can get better air moment a fan ripping at 340 should tearing that room up. Do one hung for me turn fan on low feel it turn fan on high feel it. Now stand in the room and close the door turn the game on high and feel it does it feel like it’s running at 340 or not because if only 100 cfm is coming in then it will only exhaust at 100 cfm my suggestion do a regular inline fan intake and get rid of passive.
 
ALso remove your fans pointing down you wan them moving air to the exhaust not away. Put them low and have hem point up get rid of the hot lower air you low air in the tent is trapped I can almost guarantee it. As in having the same issue my self. Another edited in thought get rid of the ballist if it uses energy aka electricity it is making btu s aka heat put it outside of room or whatever but that makes heat. That is what I would try and let t even out for a day and see. With environmental stuff sometimes I leave it for 2 days after changing something just to see if it will all settle out and check it regularly.
 
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I wondered if I had created an environment that trapped hot air lower in the room. That was my reasoning for small fans pointed down, to help move cool, moist air at top of room to circulate downward and help air movement. If I do add a fan for intake should it match cfm of exhaust fan? Seems to me if it doesn't I would restrict air intake. Make sense?? I added another passive intake when I upgraded to 6" exhaust fan (80 sq inches total) to help 340 cfm exhaust fan hit it's full potential, or so I thought.Current fan locations is creating so much air movement that light is swaying slightly! My current temps at canopy are acceptable for veg (81 degrees) but I worry about flower when I install carbon filter, which will decrease cfm of exhaust fan, currently running full speed.
 
I think with the way your air flow is right now is trapping the air. Adding a intake fan would make sense and I would usually just buy two of the same fan. Also you can turn them down the recommended air exchange rate in a marijuana grow room is exchange there 1 every 3 minutes which you could dump 4 times a minute almost. Tour trapping your hot air at the bottom your not moving cool air low because your outtake fan is so much stronger than those two fans and It wins pulling the air around those two fans right out of the room so those two fans are not moving cold air there keeping the hot air trapped down there because the hot air can’t rise because you keep forcing it down. Your basically cycling hot air down and it won’t let it get to the exhaust if that makes sense to you. Your hot air rises and the gets pulled over the top of ur fan by ur exhaust and on the way up your fans pointing down suck the hot air being forced up and blow it right back down just like a circle.
 
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Move you fans pointing down just barely below your canopy point them up. So that they make a cross of air flow from the bottom of the canopy pointing up that will push the hot trapped above and in the canopy and force it up towards the outtake fan
 
PuravidaC, I am the wife! And I love the smell so I don't care if my house smells like a grow room, as long as nobody is coming over.
 
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