indoor a question about heat in a grow tent

cotfessi · Dec 6, 2013

so i have a grow tent: a 2'x4'x84" setup and a 6 tube 4' T5 setup with 6500K bulbs that's going to kick off 30,000 lumens. I have seeds in a root shooter in the tent right now along side a temp monitor and the temp currently hovers around 72 or so. Before I put the seeds in, I tested out the the lights and with the tent sealed, the temp reached about 95 degrees... as far as I can tell, that's way too high to grow peppers. I have a little 6" oscillating fan I was planning to use to strength the plants... I thought the air movement from that fan and maybe an open flap at the bottom of the tent might be enough? But i'm wondering should i open up one of the top vents of the tent to let out some more heat?
I thought about putting one of those elbow joints for duct work in one of the top vents of the tent? I was hoping it could act like a chimney and just provide a way for the heat to escape? I understand my situation would be different if I was rocking a larger HID type light, but for my purposes is this enough?

has anyone grown in a setup like I have? Or does anyone with more experience growing indoors have any other ideas?

thanks in advance...

MeatHead1313 · Dec 6, 2013

I'd say try the little fan and opening one of the bottom vents and seeing what the temps run then. If it's still too high, open a top vent as well and try again.

rebelgrower3 · Dec 6, 2013

Put the fan in the top vent and open the bottom flap. Heat rises so you want to exhaust through the top and draw intake air from the bottom.
I use a 4" ventec fan in my 4×4 tent with a 600 watt metal halide in it and my temps stay around 80°. I bought it off amazon for around $50.

cotfessi · Dec 7, 2013

rebelgrower3 said:
Put the fan in the top vent and open the bottom flap. Heat rises so you want to exhaust through the top and draw intake air from the bottom.
I use a 4" ventec fan in my 4×4 tent with a 600 watt metal halide in it and my temps stay around 80°. I bought it off amazon for around $50.

thanks for the advice... i forget to look at amazon sometimes... I'm going to check it out...

Ignite · Dec 7, 2013

Here's the one I bought from Amazon for my homemade grow box / rack. It works well and moves a lot of air.

VenTech 6" Inline

This one is much cheaper but I don't know how well it works

8" Inline Fan

willard3 · Dec 8, 2013

Both fans posted are approx 400 cfm. If you use this fan on the space the OP proposed, it would change the air 500 times per hour.....more or less a hurricane.

Hot air rises and will provide its own power.....make an adjustable opening in the top and bottom.

Jetchuka · Dec 10, 2013

Agreed with Willard.

Before spending money, sucking up more electricity, and creating noise, try using natural convection first.

Open up a flap up top and down bottom, and watch the temps drop 10 degrees

cotfessi · Dec 11, 2013

Jetchuka said:
Agreed with Willard.

Before spending money, sucking up more electricity, and creating noise, try using natural convection first.

Open up a flap up top and down bottom, and watch the temps drop 10 degrees

willard3 said:
Both fans posted are approx 400 cfm. If you use this fan on the space the OP proposed, it would change the air 500 times per hour.....more or less a hurricane.

Hot air rises and will provide its own power.....make an adjustable opening in the top and bottom.

thanks so much for all the posts... yesterday i had all 6 tubes on from 3am... when i got up at 7, the temp was near 90 degrees... i even had an extra 4" dryer vent that a friend had lying around and i placed it in one of the upper vents and turned the end up so the heat would escape

I ended up biting the bullet and buying an inline duct fan... the cool thing is, the power strip in my tent has 2 plugs that are controlled via a wireless key fob, sort of like my car... i work from home, in the same room as my tent and i have the digital thermometer on my desk (and the remote, outdoor sensor is placed in the tent) so I can see when the heat is getting too high and i activate the fan without opening the tent - i figure i can turn on the fan for a few minutes and release some of the heat... i'm going to give it a try.. I'll post back when i've got a handle on this!

thanks again!

defeyter · Jan 4, 2014

I noticed that even placing a cold air misting humidifier helps cool down the air, as long as two bottom vents are open.

willard3 · Jan 5, 2014

The dryer vent has a backdraft damper that won't let air out; wrong thing to use.

megahurts · Jan 16, 2014

Passive cooling from bottom to top will usually do the trick if your ambient air outside the tent is much cooler, otherwise, there wont be movement. Its important to state what that air temp is too. As the overall humidity increases, it will make it more difficult to cool. Get an inline duct fan at one of the big box stores used to boost your house vents. You may have to add your own power plug but many sites sell them. The centrifugal fan is designed to operate with resistance for pulling air through a filter...for other things. Its often WAY too powerful, especially in a 2x4 setup. Its going to try to collapse the sides. I got one in a kit and I'm thinking about using it to vent my entire 2 car garage.