So im on try number two, and its not going well. I have a 3'x2'x1.5' box, its split in two chambers, fan and filter on the left, everything else on the right. The fan is a 4" S&P inline that puts out 96cfm, I have 4 lights lights going they are 26 watts a piece. My intake is (2) 4 inch pvc elbows. The intake is on the bottom right, the exhaust is top left. The room temperature the box is in is about 75. My temps are hitting 93 and even 95 around the lights right near the pot, but the top of the box is about 83-85. I had this issue on the last run but it was mid summer and my room itself was 85 degrees. I have tried a ton of different setups Ive redone my box a good 4 times, and I am getting quite frustrated. Ive tried adding pc fans in the box to blow air around but no luck. I feel like I have way more air movement then I need with 96 cfm and a grow space of only 3x1.5x1. I currently dont even have my carbon filter attached so it not like i am slowing down my airflow to much. If I put a piece of paper to my intakes it gets pulled against it. Ive seen setups with more lights and just pcs fans and they were able to get the temps down. The only other thing I can think of is enclosing the lights by adding like plexi glass below the lights, sealing it and then putting a pc fan in the top to pull out the hot air. Anyone know if plexi glass would work, or what I should use for this? Any other suggestions? Edit: I keep thinking that i have plenty of cfm so there must be some sort of issue where in not cooling and im just moving hot air around. Can anyone verify that 2 4" intakes should be sufficient, or could my intake size be off. I dont know Im lost at this point.
If you have more input to you area, than you have output, you are not properly venting. This would explain why your temps up top are lower, than your temps down below, even though common sense says that is strange. You always need to have a negative pressure inside your grow area to vent correctly. I'm guessing you don't have that.
I agree with Do Work... Pull air out, not push air in.. A inline duct fan wont pull or push through a filter anywho.. Those are designed for air exchange, not air filtration..
I do believe that I have negative pressure, because when I hold a piece of paper up to the intakes it gets sucked against them. Maybe I dont have enough though, I will try covering up one of the intakes and see if there is a difference. jamaican, I am pulling air out, I am not pushing air in, I have passive intakes. And as far as the filter my fan should have no problem pushing through my filter, but that isnt an issue at this point because the filter isn't hooked up.
So i just stuffed a pair of shorts in one of the intakes and my temps did drop to 81. When I did my temp runs before germinating the other night I was at 82/83 and that was without cutting off an intake so we will see what happens in the future it seems as if i keep getting fluctuations but for now its looking as if I did not have enough negative pressure. Thanks for the help guys. + rep to you
I must have misread, I thought you said you were using an intake fan. If your passive intake isnt' enough, then you probably need more output. The CFM may be right to simply recycle the air to your plants, and that is what you are thinking, but if you want to use the output to pull the head out of your tent you are going ot need more. Just remember, when most people are talking about CFM for their grow area, they are talking about moving enough air for the plants to properly grow, now about getting heat out of the area. To remove heat, you may need to add intake, and more output, but either way make sure you are keeping negative pressure. You'll get it.
What was killin me was I know I have way more cfm then I need, whether its just to recycle or cool it down, so I didnt tihnk I should be having this issue I couldnt figure out where I was going wrong, but its been running for an hour or so with 1 less intake and im now down to 79 so I should be good, although tomorrow I will probably wake up to it reading 110 heh but we'll see. Thanks again.
NP. I'm glad I could help, even if I didn't really, just glad you got it under control. In my opinion anything under 80 is good, 70-75 is amazing. My temps are always right around 80 at the canopy, and I have had one time where that bit me in the ass with a giant cola the size of your thigh getting infested with internal mold that I never found until shortly before harvest.
so i got a similar problem..although im not using any fans or anything yet, its a very cheap setup. its pretty much an enclosed box that i have draped a blanket over to light proof. i dont have a thermometer but its pretty warm in there, im guessing about 90* using 4 23w cfls for two plants 3 weeks old and 4 inches tall. in a 4x1x1 box. i have turned off the space heater in my room because it gets pretty cold in there without it so i hope that helps the box. i also open it pretty frequently and fan it out. they look healthy and green. so im not sure its a problem...yet??
yep suck out more then ya pull in I have an axial fan (maybe like 10 cfm lol 15) sucking air in and a blower blowing it out my blower in like 110 cfm so a little higher, creatin that negative pressure. Oh yes it is also winter so depending where the box is just open a window and lower the rooms temp enough to lower the inside of the box....then the cool thing with that is ya get cooler night temps and that adds a lot to the beauty of weed, adds color, that is if the strain has color in it genetics...Thats my favorite thing of outdoor is seeing the colors from cool nights and blue skies.