Heat Issue

[Bubba88]

I have 400w hps in a 3x3x78 grow tent that's in the closet. I have a 500cfm fan blowing air out into the attic and yet I can't get the temperature down. With an added oscillating fan and without I couldn't get the temperature below 85 while the house temperature is 74. Any ideas?

[WashougalWonder]

Is the tent closed tight or ? Sounds like you are not getting enough fresh source air.

[Greenthing]

Is the tent closed tight or ? Sounds like you are not getting enough fresh source air.
Yeah i agree with that,:hippy: you need fresh cool air

[Bubba88]

It's pretty closed off, there are vents in the bottom and top, but I think the tight fit keeps them from being effective. What would yall suggest? I was thinking maybe cutting a hole in the top of the tent which would then be open to the attic, but that's also where I'm venting the hot air out, so would that be ok to do?

[Greenthing]

I was thinking maybe cutting a hole in the top of the tent which would then be open to the attic, but that's also where I'm venting the hot air out, so would that be ok to do?
you have all the warm air from your house rising up to your attic as well as the warm air that you vent up there also the sun on your roof will make it hot as well, so i recon its not a good idea, growing in the loft or attic in summer there is always going to be heat problems in my opinion
Cool air is found at ground level in shaded places.:hippy:

[rikb631]

portable ac?? i noticed this is an old post why was it at the top?

portable air conditioner - Google Search (http://www.google.com/search?q=portable+air+conditioner&sourceid=ie7&rls=com.microsoft:en-us:IE-SearchBox&ie=&oe=&rlz=1I7ADRA_en)

[Bubba88]

Well I'm not sure what I should do, the closet is a pretty tight fit and I had to cut a hole in the roof to run the duct work. I was thinking maybe running duct from my home ac unit to the room via one of the other openings, but I'm thinking that would be a lot of trouble. Thanks for the info guys I really do appreciate it.

[mahavatar]

In tight locations like that it would be better using CFL's than HPS.. Maybe you should change the HPS for a couple high-watt CFL's instead as they don't run hot at all (gets "warm" but far from "hot", can touch a 100w CFL without burning your fingers).

[THContent]

Before making any hasty decisions, you might wanna give the home made cool tube a try, it is in my sig, everything will cost about $35. I currently have a 600W HPS in my 2 x 3 x 8 closet, temps are right around 75-80 with cooltube. And of course, good constant air flow.

It will most likely be the cheapest option for you. I have an extra bake a around if you need, $20 shipped. I am paypal business verified :)

Just putting that out there, you will be happy with the results of HPS over CFL, hands down.

[WashougalWonder]

How about a simple experiment like

LEAVE THE DOOR ON THE CLOSET open and see what happens. Crap, all this spendy stuff????

The temp of the roots is what is important, if you are going to cool anything, cool them to the mid 60-70 range.

The air flow is necessary to remove humidity, oxygen, and heat. You get better of both if you can leave that door open an inch or so, you will have to experiment to find out how much.

[Rusty Trichome]

WW has you on the right track.

Have you looked at the link in my signature regarding dealing with heat issues?

[Bubba88]

I'm going to experiment with that tonight, just haven't had the time with work and school, but thanks guys it's greatly appreciated. Rusty I am about to check it out.

[Bubba88]

Rusty in your post you mention that the 80 degree temperature is just a guideline to go by for beginners. My thing is I have a fan and an exhaust fan, when I put my head in there while it shows 84 it feels fairly cool inside, much cooler than outside here and nowhere near "hot". So I was curious as to your thoughts on this, is it something that I shouldn't worry too much about?

[Rusty Trichome]

Takes a couple days of plant acclimation and the gardener fretting, but they get used to the warmer temps. I'd never recommend a newbie go overboard, but a few degrees will not kill the plant.

Keep them hydrated, and keep the stale air and heat vented out as much as possible. I give my ladies a gentle "mercy misting" once a month to wash-off dust and lint. Other than that, they never get misted, especially when growroom is hot.

[Bubba88]

I've gotta be doing something wrong, it doesn't cool the room at all when the light is off and the oscillating fan and exhaust fan were running.

[THContent]

It wouldn't hurt to get some ducting and an inline fan to bring fresh air from outside, get circulation, and most likely lower temps by at least a degree or two. Small price to pay to get the outcome you desire.


Outside wall > 4-6 inch ducting > inline fan (blowing in) > ducting to near plants > oscillating fan to blow from ducting to plant area. I guarantee this brings temps down, while giving you good co2 level, plus good airflow.

No matter what, you are going to need to vent the hot stale air to the attic, or out the window, especially if you wanna lower the temps and keep a good fresh air ratio.

400W is going to give off heat, in an enclosed area like that, cooltube is really all you can do to really bring it down.

[THContent]

Here is my setup with a 600W HPS, and I still hit 79 when the AC is off, I am waiting for my inline fan. But so far, my setup works great for a closet grow, that's why I know it will work for you too.

Here are a few shots for you to check out.

http://img30.imageshack.us/img30/9049/dscf7810h.jpg

http://img3.imageshack.us/img3/1554/dscf7811o.jpg

http://img514.imageshack.us/img514/7864/dscf7812.jpg

http://img22.imageshack.us/img22/1894/dscf7815.jpg

http://img28.imageshack.us/img28/6055/dscf7816m.jpg

[WashougalWonder]

I've gotta be doing something wrong, it doesn't cool the room at all when the light is off and the oscillating fan and exhaust fan were running.

Was the closet door open at this point?

[Rusty Trichome]

Heat does not linger for hours, if it's being vented-out. Is there a way to open both, the growroom door and the tent flaps at night without exposing to light leaks? You'll want to come up with an arrangement that allows the fresh air overnight every night.

Either you aren't venting enough, or you have a heat source providing extra heat.

Are you fan-forcing the heat out, or just using the 'heat rises' technique?
Fan forcing the heat out makes a negative air pressure in the growroom, which forces fresh (cooler) air into the growspace.
If you are only fan-forcing the fresh air in, you lose that control over the heat, and overclock the ability of the vent to remove the heat. (mixed air gets vented out, rather than the heat) But regardless, the heat shouldn't remain for more than an hour after lights-off.

Is your growroom above the oven...?
Is your growtent in the water heater closet...? (had to ask...ya never know. :jointsmile: )

[WashougalWonder]

Is your growtent in the water heater closet...? (had to ask...ya never know. :jointsmile: )

good point, Well all of them were actually, but I had not considered an alternate source of heat.

[seventhchild]

how are you measuring temperature ? what kind of monitor and its location ? the light from your blub should not shine directly on it.why are you using a tent in a closet ?what is the size of the closet [not the tent]?