Cant keep my temps down

[Yeti1]

This is my first real grow, so Im still learning what things work for me and what things dont. I built my growbox out of some thrift store purchases. Its roughly 30"Lx25"Wx26"H. Im running 12 mixed spectrum 23w CFLs, for a total of around 300 actual watts of CFL lighting. I have 4 girls growing, all from bagseed, and they are 25 days into flowering.

Now, my problem. Ive had a constant problem with exhaust and keeping temps down. I started with a 4" duct booster for size reasons, and it wasnt enough. So I got a 6" duct booster, and it was working fine with ~100-150w of CFL. Now into flowering, I purchased a 87cfm computer fan. Trimming the edges off, I wedged it into the 6" ducting, putting it "in front" of the duct booster, and didnt notice much difference. I'd really like to run a carbon filter, but upon installing mine, i was running temps above 100*F.

I have a passive 6" intake, and 2 desk fans in the box for circulation. What could I do to help myself with these temps?

 

[catman]

What is your room temperature? You can't get lower then it!

 

[ourcee]

I dont know where you're exhausting to but make sure it isnt anywhere near your intake. As obvious as that sounds I've wanted to throw someone infront of a train for this before. (it wasnt a micro grow )

 

[messn'n'gommin']

Hope this helps.

“Understanding Air Flow,” by Hoosierdaddy
http://www.icmag.com/ic/showthread.php?t=100823

Namaste, mess

 

[Yeti1]

My intake and exhaust are on opposite corners, and my temps are 87-92* with duct and comp fan, and 95-100*+ with a carbon filter on. I know I should have a little bigger of an intake, but Im weary of making the hole much bigger. Would 2 6" holes be overkill? For that matter, would 3 6" holes be even better than 2?

my room temps are 69-75*

 

[Cozy Amnesia]

At least one link in your ventilation system isn't enough. . How big are your intake holes? When you put your hand up to it do you feel the air rushing through?

 

[Yeti1]

At least one link in your ventilation system isn't enough. . How big are your intake holes? When you put your hand up to it do you feel the air rushing through?

I have 1 6" passive intake

 

[Styr]

you need your passive intake to be twice the area your exhaust is. so, since you have a 6" exhaust (if i read correctly) and one 6" passive intake, you need to add in another 6" intake.

 

[Mr_Puffanpass]

It other way around styr... You need your exhaust to be twice your intake - negative pressure, odors stay in, better airflow...

Maybe another vent/fan to blow beneath your lamps to better move the air in box?

 

[FreezerBoy]

It other way around styr... You need your exhaust to be twice your intake - negative pressure, odors stay in, better airflow...

Incorrect. Styr is right. Intake should be double the exhaust. Intake is the bottle neck on cool air. Restricting cool air restricts cooling. More intakes means more cool air. More cool air means, well, more cool air.

I started with a 150 using a 76 CFM axial and two 4" holes. One for intake one for exhaust. When I upgraded to 250 my cab became an oven. Yes, doubling CFM with an inline cooled me down but, blew my stealth to hell and back. Adding a second 4" intake allowed me to dump the inline and return to the axial. Failure to provide two intakes cost me $300 in unnecessary equipment, not to mention time.

Added bonus, with two intakes, fan stress and noise is greatly reduced. My fan still ramps up every time I close the door. I could easily use triple intakes and still maintain negative pressure.

Go to Home Depot and get the hole saw of your choice. Punch 3 holes in your cab. One at top, two at bottom. Attach fan to top. If that doesn't cure your problem, you have the wrong fan or your ambient room temps are too high.

 

[bigd21]

I think you need to add another intake, and also remove the fans inside the box..........if you have intake and exhaust correct you should have air moving inside your box, everytime I put a fan inside my box my temps shoot up 5 degrees or more............

 

[Nugz]

Well, I find variation even within the "room temperature" outside my grow. If you pull the intake air near the floor it will be a few degrees C lower than if you pull the air from higher up. Also exhausting from the top of the room provides better efficiency.

You should also look into getting a stronger outtake fan, maybe look into a small high-pressure centrifugal fan and adding a small house fan for better air circulation. This should help get the air moving and maybe even reduce your noise level as I'm not sure how much noise those 2 fans make in comparison with one efficient centrifugal fan.

Good luck.

Nugz

 

[spliffmaster]

pictures!!!

pictures!!!

we want piccieesssss!!!!!!!!!! lol

 

[Pig-Pen]

1:1 for an active exhaust/passive intake is plenty sufficient IME.

2 desk fans = overkill. Try running the cab without any "circulation" fans and see where temps are.

Where are you taking temps? At the bulb, the wall, plant top, exhaust ducting......?????

Is the cab air-tight save the intake and exhaust?

What is the general (or better yet, specific) layout of your lights, and ventilation ports and apparatus?

What is the temp of the intake air?

Does your intake port hold a piece of paper with vacuum alone?

Are your exhaust fan(s) actually sealed to your exhaust port or just loosely set into place?

Double-fanning (two fans in series) is largely ineffective and often counter-produtive IME.

 

[GrizzleB]

Double-fanning (two fans in series) is largely ineffective and often counter-produtive IME.

So your saying if u exhausted with a 4" fan, putting another right before the carbon filter wouldnt work well? Ive got 2 micro boxes which both run about 80 degrees with PC fans for the exhaust and im trying to figure out how I can setup a filter.

 

[Pig-Pen]

So your saying if u exhausted with a 4" fan, putting another right before the carbon filter wouldnt work well? Ive got 2 micro boxes which both run about 80 degrees with PC fans for the exhaust and im trying to figure out how I can setup a filter.

Not sure what you mean by putting another right before the CF?

I just mean that stacking 2 fans doesn't increase airflow and can actually decrease it, IME.

As far as using two fans to push/pull a CF (I think might be what you were asking); if the push fan is pushing more than the pull fan is pulling, you'll get back pressure and the CF will lose effectiveness. But, if the pull fan is pulling more than what the push fan is pushing, the push fan can actually be creating more resistance for the pull fan, slowing it and thereby decreasing airflow and overall efficiency and using twice the electricity in the meantime.

As with most things most of the time: the simpler, the more efficient.

 

[Yeti1]

1:1 for an active exhaust/passive intake is plenty sufficient IME.

2 desk fans = overkill. Try running the cab without any "circulation" fans and see where temps are.

Where are you taking temps? At the bulb, the wall, plant top, exhaust ducting......?????

Is the cab air-tight save the intake and exhaust?

What is the general (or better yet, specific) layout of your lights, and ventilation ports and apparatus?

What is the temp of the intake air?

Does your intake port hold a piece of paper with vacuum alone?

Are your exhaust fan(s) actually sealed to your exhaust port or just loosely set into place?

Double-fanning (two fans in series) is largely ineffective and often counter-produtive IME.

Cab has slight openings around the front doors, but I keep 2 blankets over the front half (not covering the intake or exhaust), so I figure this keeps the air in pretty well.

Intake are is 70-75*

I have a desk fan in front of it, so yes.

exhaust is wedged in pretty tight, but not caulked, because I wanted a good setup before I made it permanent.

Heres a pic of my cab. 25 days into flowering

 

[Pig-Pen]

Cab has slight openings around the front doors, but I keep 2 blankets over the front half (not covering the intake or exhaust), so I figure this keeps the air in pretty well.

Intake are is 70-75*

I have a desk fan in front of it, so yes.

exhaust is wedged in pretty tight, but not caulked, because I wanted a good setup before I made it permanent.

Heres a pic of my cab. 25 days into flowering

The reflector is not helping anything. It's a heat trap and it's not reflecting any usable light that far above the lights. Just let 'em hang free, it makes a HUGE difference with CFL heat.

The desk fan is working against your exhaust fan in that it's blowing away from it. You need to think of how the air will flow through the cab and create as much of a smooth airstream as you can, which means having it well sealed so that air can only go in and out through your ports.

Any leaks, especially with the exhaust port/fan will allow air to come in through the leaks rather than through the cab. Air will go the path of least resistance.

Where are you taking your temps in the cab?

 

[Yeti1]

The reflector is not helping anything. It's a heat trap and it's not reflecting any usable light that far above the lights. Just let 'em hang free, it makes a HUGE difference with CFL heat.

The desk fan is working against your exhaust fan in that it's blowing away from it. You need to think of how the air will flow through the cab and create as much of a smooth airstream as you can, which means having it well sealed so that air can only go in and out through your ports.

Any leaks, especially with the exhaust port/fan will allow air to come in through the leaks rather than through the cab. Air will go the path of least resistance.

Where are you taking your temps in the cab?

The reflector is usually lower than in that pic, and on the back side, it was actually touching the other lights. Im worried that because of my cab having such unused space up top, that alot of light was getting lost.

The desk fan has been turned off. I did have the exhaust going straight through from the side where it exits, so the fan WAS blowing in its direction, but I decided to angle the exhaust to keep light from leaking out. Ive read that its good to keep the plants in a little breeze, thats why I had the extra fans in there.

Temps have been taken from the ground level and from the canopy. There is approx a 5 degree difference. Ground level is 80-85*, canopy has been 85-90*.

 

[highallthetime]

Try one of these

Try one of these

Holds up too 6 - 42watt cfl bulbs. 250 watts max



There are more in my photo gallery. If you would like more let me know.
Air Cooled made simple..

I am using 3 fans. Massive intake fan. 1 on my light for its exhaust and one in the top of the cab. temps 64 night 76 day.