Temps from hell!!!!

I am growing in a 4x4 x11 plywood box. I am 8 weeks into my grow....day 23 of flowering. Plants look good overall......a little deficiency but corrected I think. My trouble now is heat. I have been okay with tewmps thus far...but I am sitting at 90 all day during the light cycle (9 am to 9pm). I have 3 oscillating fans in there, plus am running two 4" cage fans...one exhaust & one intake....nada....still having temps in high 80's/low 90's.....any suggestions on cooling the room without having to buy a portable AC??
Also, anyone who would like to help check my P or K post in plant problems and advise.
Thanks all!

Would evaporative cooling work in your set-up?

what size light are you using?
is the box in a room that is warm all the time?
i have my setup in a basement where it is cool it helps with the heat problems also i bring air in from an outside vent on the north side of my house where it is cooler
think "outside the box"

something else you might want to consider is reversing that light schedule... run the lights at night when the outside temp is cooler and keep it dark during the day when it is hotter.

as i cram my little grow area full of CFL's the temps were starting to get outrageous in there... but i added a fan powered exhaust duct that pulls from the top of my tank (just above the lights) and an equally sized (4") intake duct diagonally across from the exhaust at the bottom of the tank and knocked 10 degrees off the temp. i had an exhaust before, but it wasnt setup clean and the intake was way too small.

switch your light schedule and make your intake/exhaust "just so" and things should get better.

as i reread your initial question and notice again the plywood, i have to wonder how the inside of the grow area is treated. a plastic lining would not transfer the heat to the wood where it would be stored, but force it to stay in the air and thus be drawn out by your exhaust.

if it was me, i would make two exhausts (since you have too much heat and two fans) and would use those to pull the air through the chamber from two equally sized passive (no fans) intakes and make sure there are no other air leaks. this will ensure proper negative pressure in the grow area... and also, fans do NOT cool air, they move air but they actually raise the temperature... so, by having an electric fan in your intake you are actually making it blow hot air in instead of drawing cool air.

i have been awake for far too many hours, i hope that made sense. where's my bong, that will help!

i agree with bfq. i was doing passive intakes then added a 4inch fan to the intake and couldn't figure out why my temps rose. the fan inside the cab was "i guess" circulating the air thus raising the overall temp.. in effect the active exhaust/passive intake i learned in the growfaq always-if done properly-pulls air up, never letting the hottest air go back down. i will do awat with my oscillating fans in the hottest parts of the month and see how it goes.

. . . .oh yeah in the growfaq he says that the intake has to be larger than the exhaust so as not to stress the fan, plus limit the bend in your circulation/ventilation, straight and easy if you can.

. . . .since you're in 12/12 keep with your schedule unless you want to do a 24 dark period then transfer to night lighting-just a thought.

the reason the fans raise the temperature is because they are electric motors... electric motors are inefficient and part of the power they use gets turned directly into heat. the cheaper the fan, the more heat it actually produces.

always listen to the grow faq rather than some nutter typing in a thread... but the reason i use matched intakes or even smaller intakes is because the faster the air flows through the intakes the cooler it will be... big honkin exhaust and equally sized or smaller intakes and things will be cooler than if you have a bigger intake than exhaust.

fuck my exhaust fan, when it dies i will buy a new one

as for if you decide to reverse your light schedule, if it is early in the flowering stage i would just give it a 24 hour dark period and go at it... if it is later in the flower period (after the first 3-4 weeks) i would probably use gradual shifting to avoid stress.... but really, i think 90 degrees is FAR more stress on the plants than shifting the lights... i do reserve the right to be totally wrong on that though.

I have been using active intake and exhaust.......so I guess I am just recirculating stale air....makes sense.......I can vent to below my house......and will be trying that tonight....I just wonder if I sould bring cool air in or take hot air out......seems to be hot air out wins. I am day 22 into flowering...but do not want to switch light cycle unless 100% necessary due to my work schedule. I am going to look into evap cooling as well. I have overcome far greater obstacles than these. The plywood grow box is painted with reflective elastomerand was a quick fix after a hydrohut nightmare. I am preparing an internal closet for next grow.
Overall plants look decent. Short and stout. I have one that is a tall gangly freak but she will yield a little. Loose buds and small...but hey....the other three look damn good for a first grow with a few major issues early on.
Anyway...thanks to everyone. I will research exhaust and see what I want to do....I can easily bring cool air in but getting the hot air out will require more work than I want to expend on a temp grow area.
Peace all!

Get a small AC.

Hank.

Well, I ran a vent tube from my intake to an AC register to put cool air into the grow area for now....will look more into active exhaust as well....it just was super easy to make the intake pull cool air in.......quick fix until long term can be reached....in the time it has taken me to post, I have dropped 2.3 degrees!

er, cool

be sure to put some sort of a filter on that intake line though, you would be disgusted if you knew the amount of mold and crap that can live in HVAC ductwork! (all our intakes should be filtered anyway.)

Hot air out, yes, as the person way above was saying. S/He is correct about the intake vs. exhaust issues.

I put a hepa filter out of an ionizer in it........thanks for the ups....also am getting the hot air out now too.....it goes into a carbon filter in an adjacent area......will run it into attic when more ductwork obtained........so cool air in.....hot air out......temps still linger in the high 80's.........adjusted light angle because noted the reflector was very hot......reflector cooled.......changed batteries in the thermo.....still 89.6.....humidity climbed to 60% when it has been around 45% before modifications......lights out in 30 minutes, so will start again tomorrow........at least I corected my yellowing and dying problem (more food)...but now I am getting singed leaf tips on the upper parts of the plant.....too hot....light is 24" away.......WTF.....oh well......tomorrow I WILL solve this

That HEPA will seriously slow down the air flow, and unless it's actually doing something besides removing particulate matter (HEPA is nothing but mechanical filtration) then I'd take it off.

Man.. I miss my HEPA filter. When the pollen got really bad, like it is now, I used to just lock myself up in my bedroom (this was when I was still single) and I'd crank on that ionizing filter with the HEPA, and just chill out. No more itchy, watery, goopy eyes! No more sneezing! No more itchy lips or insides of ears! No more! Now..? Now I'm not single and I haven't got a HEPA. Waahh.

Well fuck. I came out this AM as soon as the lights came on....temp 81, humidity 62%....god damn. I am running 3 fans to circulate air in the closet......on 4" fan intake cool air from under my house.....one 4" fan taking hot air out intoi another room......the grow room feels coolish.......but my temps are still high. After 1 hour 40 of light, temps are already 88 with humidity at 67%. I put a dehumidifier in, but it isn't doing shit. I figured my my hygrometer was broken. Took it inside to AC'ed house. Temp 70........right on.....humidity 73%....I doubt my house is that humid. There is no condensation on anything. So...I am off to Wally World this AM to buy a new unit. Maybe that was my problem. Anyway...we'll see......

P.S. Took the HEPA off per Seamaiden......what other filter might I use??

platypusmann said:

Well fuck. I came out this AM as soon as the lights came on....temp 81, humidity 62%....

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I can't remember who suggested switching the light cycle, but it's a really good idea.

god damn. I am running 3 fans to circulate air in the closet......on 4" fan intake cool air from under my house.....one 4" fan taking hot air out intoi another room......the grow room feels coolish.......but my temps are still high.

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Dedicate BOTH those fans to PULLING the hot air out. The cool air, as long as it's unobstructed, will follow. Make sure the cool's being pulled in from low and the hot's being pulled from high, given the laws of thermodynamics and all.

After 1 hour 40 of light, temps are already 88 with humidity at 67%. I put a dehumidifier in, but it isn't doing shit. I figured my my hygrometer was broken. Took it inside to AC'ed house. Temp 70........right on.....humidity 73%....I doubt my house is that humid. There is no condensation on anything. So...I am off to Wally World this AM to buy a new unit. Maybe that was my problem. Anyway...we'll see......

P.S. Took the HEPA off per Seamaiden......what other filter might I use??

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If all you're worried about is scent control, then carbon filtration would be the ticket.

Here's what I would do in your situation, presuming the box isn't being heated via solar energy:
1) Take BOTH 4" exhaust fans and put them next to each other near the top to pull out the hot air, you want to pull as much volume as possible.
2) Double the INTAKE hole size for each fan you're using. Pulling that cool air in from under the house would be your best bet, but remember, that air is likely to be more humid. For each 4" fan, if you have an 8" intake hole that's pulling in cooler air then the fan won't have to "work" so hard (and generate more heat) to pull the hot air out. Does that make sense?

I believe that once you have your air movement problems solved your humidity issue will be solved as well, accuracy of the meter itself notwithstanding.

I think panhead made a really good, and cheap, homemade carbon filtration unit. If you're slapping one of those on, then you may need to add another fan as that will also obstruct air flow and cause the fans to work harder. It shouldn't be as bad as a HEPA filter, unless the carbon is really packed in their tightly.

OH JESUS! I can't believe I never thought of this. Can you run a duct from your exhaust to tie into the roof vents (the ones topped with those turban-shaped fans) of your house? If so, then you maybe don't even NEED to worry about odor control.

Seamaiden said:

OH JESUS! I can't believe I never thought of this. Can you run a duct from your exhaust to tie into the roof vents (the ones topped with those turban-shaped fans) of your house? If so, then you maybe don't even NEED to worry about odor control.

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I hope so because i have found that homemade carbon filters...lick my balls as far as removing the odor goes...

Did you see panhead's design? He said it works pretty well, and I think he started a thread on it. Pictures and everything. It might be easier for you to tie into the household duct-work, though.

Seamaiden said:

OH JESUS! I can't believe I never thought of this. Can you run a duct from your exhaust to tie into the roof vents (the ones topped with those turban-shaped fans) of your house? If so, then you maybe don't even NEED to worry about odor control.

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this does work good ,i run mine out to a sealed bulk head in my basement and the smell has gone away inside. i do get a hint of skunky outside near the thing but i'm 200 feet off the road. venting up out of roof vents would definatly work well

overfiend said:

this does work good ,i run mine out to a sealed bulk head in my basement and the smell has gone away inside. i do get a hint of skunky outside near the thing but i'm 200 feet off the road. venting up out of roof vents would definatly work well

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VERY cool! And, I figure that if there's a decent breeze (most folks have some sort of air movement around their houses) then it would carry the scent to different areas, making it much harder to tell where it's come from.