Heat!

Hey all, never had this issue before, but i just set up a new grow tent and
having heat issues. 400w HID/HPS "temp was same with MH as well"

Lighting is Digital ballast with batwing running HPS 400watts
Grow tent is 100x100x120 "4'x4'x6.5'H" (104 sq/ft space)
Exhaust is functioning, and connected in this order.
1) Carbon filter 4"
2) 6inches of 4" Flexi-aluminum duct
3) Can-Fan centrifugal 4" 120v 142cfm(140% airchange / minute) 68watts
4) 12 inches of flexi-aluminum duct in elbow shape to exit flange at back of tent

The exhaust system is about a half foot from the top of the tent
The DIY scrubber is simply 2 layers of activated carbon cloth. not much resistance

Temperatures reach 32*C and will not go down.
Intake is passive at the bottom, 3 flaps, one on each wall about 2" tall and 3 feet long.

Ideas?

Would a 50cfm PC fan as intake fix the heat? im outta ideas here.
my last grow box was wood and never went about 28*C

I thought this was a miami heat thread :/ ?



can u post pics of the setup? i have a similiar sized growtent

whats temps outside of tent?...Are you pulling hot air in through the 3 flaps? Have you tried taping/ tying the flaps open to let more air in?

ur night time or lights out temps r lower arent they? my grow can get up to 92 degrees at times, really it is not that much of a problem. If u r that worried about it, when lights r on, open the tent for more ventilation & u can even have a box fan blowing air in to help control temps.

Intake always helps! Switch to a 6" out and use the 4" as an intake!

Would buying one of those PC fans help. they have 30cfm all pretty cheap on ebay.
i could rig that in at the bottom to force the cooler air in, and would help push the air up too.
I just dont know if 30 CFM would be enough. anyone here try it as intake before?

Ill try to tape open a flap and see if that helps
but when it looks like the sun is caged in my room and beaming out across my floor through the flap, its annoying. i mean HPS is pretty damn orange
and i just dont want that to be my solution.


How much of a CFM loss is that elbow giving me? if its only minor ill leave it, but if im losing half of my CFM
because the duct is turning, ill straighten it. anyone know?

when it comes to batwing setups, you gotta have more airflow than that. With a similar setup (but 600w), I have a 200cfm intake and a 745cfm exhaust. Make sure your exhaust is located at the top of the tent, and the intake at the bottom on the other side of the tent. I have also attached a computer fan to the batwing blowing directly over the bulb at times when its been very hot outside. Also, yes. If you have the ability to straighten that bend in your ducting, do it. a bend is a minimum 30% loss, and can be as much as 50% (esp in lower cfms like the one youre using).

One hundred bucks and some ducting from home depot and your problem is solved. Get a fan like this and use it as your exhaust.

http://www.amazon.com/gp/product/B002JQ14F8/ref=pd_lpo_k2_dp_sr_1?pf_rd_p=486539851&pf_rd_s=lpo-top-stripe-1&pf_rd_t=201&pf_rd_i=B000CRICRY&pf_rd_m=ATVPDKIKX0DER&pf_rd_r=0YZ08PM1WZ8KYBZ8NE7N

Hang it from the top of the tent with bungee cords and the noise will be minimized. Not only will this reduce the temps in your tent, but give your girls more air and CO2 to breathe. Hope this helps.

Buds Mcfadden said:

when it comes to batwing setups, you gotta have more airflow than that. With a similar setup (but 600w), I have a 200cfm intake and a 745cfm exhaust. Make sure your exhaust is located at the top of the tent, and the intake at the bottom on the other side of the tent. I have also attached a computer fan to the batwing blowing directly over the bulb at times when its been very hot outside. Also, yes. If you have the ability to straighten that bend in your ducting, do it. a bend is a minimum 30% loss, and can be as much as 50% (esp in lower cfms like the one youre using).

Click to expand...

ok will change the duct tomorow to a stright run
I can see the force of air inside of it kinda "pushing" at the bend, im probably
closer to that 50% mark.
Not going to have money for awhile, should have went with a 6" to start
but hydro is a fortune already.
If im getting a 30-50% CFM loss in that 45 degree turn though
it may outright fix the problem, as its not that hot no, 31-32.
at 50% i suspect it would drop to 28-29. and ill be happy
TBH as long as its 30 or less ill be all smiles
If not im going to put a 80cfm PC fan as intake, see if that helps.
Wont even duct it, just going to put that shit right on the flap and use
a twist tie to lock it there, and will have to deal with a bit of light leak.

kinda ramblin now, had a bowl of hashberry, time for bed.

thank you all again, will fill ya's in.
wanna get this fixed before i get my new seeds in dirt.

damn ramblin again /gone lol

dankasaurusrex said:

One hundred bucks and some ducting from home depot and your problem is solved. Get a fan like this and use it as your exhaust.

http://www.amazon.com/gp/product/B002JQ14F8/ref=pd_lpo_k2_dp_sr_1?pf_rd_p=486539851&pf_rd_s=lpo-top-stripe-1&pf_rd_t=201&pf_rd_i=B000CRICRY&pf_rd_m=ATVPDKIKX0DER&pf_rd_r=0YZ08PM1WZ8KYBZ8NE7N

Hang it from the top of the tent with bungee cords and the noise will be minimized. Not only will this reduce the temps in your tent, but give your girls more air and CO2 to breathe. Hope this helps.

Click to expand...

no cash for awhile, car needs it. thats how i have my current can-fan though. the bunjie eliminated all noise for me "aside from the sound of air going WOOOOOOSH gendtly out the venting lol.

Made the ducting a straight run, airflow sounds better, and feels like more exiting the area.
Temperature remains unchanged however, it could be that outside the tent (28.2*C) is too hot to cool the interior
through its active intake (32*C)

To cool the inside to the outside, i think i would need an active intake fant of at least half the exhausts CFM.
Didnt realize how hot it was outside the tent I think thats my problem 100%
a 3.8*C difference isnt going to cool inside my tent.
Thanks for the help guys