Cooling in small spaces

A wooden box with dimensions 36"x20"x60" (25 cubic feet) sits inside a closed space measuring 37"x61"x93" (121 cubic feet). The closed space is used for storage and so actually has less room than that available. Is it possible to use a 400 watt HPS light with hood inside the wooden box and still maintain optimal temperatures? Preliminary tests suggest that temperatures easily exceed 100°F within the box, using 2-3 80mm fans each on intakes and outtakes.

The light itself generates most of the heat. Would larger, higher CFM fans cool the box sufficiently? Would adding more 80mm fans (computer case fans) help lower temperatures? Would a large grid of 80mm fans work (4x4 80mm fans, 5x5, etc)? Would some sort of glass enclosure/screen around/below the light work, given the space constraints? Would a homemade cool tube fit (like this one)?

Or is a 400 watt HPS just too much for such a small space?

Whatz up WaZ?! :)

Nice wording... I thought I was taking a high-school physics test reading the first two sentences... :p


HPS bulbs put out a LOT of heat... as opposed to MH bulbs. (same wattage being considered)

I suggest you build a cool tube like the one you linked to. In addition to the hurricane glass MellowMan used, you can eBay "Bake-A-Round". Those kick ass, without a doubt.

I used to cool my 400W MH Bake-A-Round cool tube, with ONE 45CFM fart fan. Ducting and all.
Once, the fan's relay did not turn on... and the temps never went above 90ish. Amazing.

You definitely need to step up your fans. The small ones you are using will not help... even if you put them up 8 in a row... even if you do a wall of 16x16 of them. They just are not designed for such tasks.

(1) Fans
(2) Cooltube
(3) Testing

Depending on how much ductwork (how many feet of ducts, both intake and exhaust, upstream and downstream of the fan), you are going to have to adjust your fan size.

If you want to go all loco and stuff, buy a Fantech... those fans will suck dust out of wall switch covers, and they will bend doors with the vacuum, I kid you not. They are expensive.

Alternately, try out a few setups. Maybe a 45CFM fart fan pushing air IN, then after the cool tube, another 45CFM fart fan pulling the air out.

Let us know how it goes!! :)

Best,

-turtle420 :cool:
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using any hid lighting i would recommend getting a good inline fan, being a 400 watt i would use atleast a 4" fan maybe a 6" depending on temps. good fans are fantech, vortex, can fan, ect. i would also recommend trying to exhaust the light to a complete other room than your grow box is in. you will be circulating the hotter air with the cool air

the best thing about using quality inline fans is you can also hook up aircooled hoods and carbon filters to the same fan(knockout most security and ventilation problems with 1 major purchase)

The 80mm fans I mentioned are ~50 CFM each. It would be preferable to keep all cooling necessities (ducting, etc) inside the wooden box. Could something like a Peltier on intake cool the air inside the box sufficiently to negate the heat buildup from exhaust outside the box? How about a U piece of duct with water at the bottom so that the hot air is pulled through, perhaps with a system to cycle the water?

Thanks for the replies so far. :)

The other day i saw a water cooled light. It was running at an even 70 deg. w/ out a chiller. You would need a space for a 50 gal. drum though. I herd you can run these babies as cold as you want w chiller as long as you stay above your dew point. I gotta say i was unsure about them until i saw it in person. Now I can't wait to get one. xxx.westcoastgrowers.xxx

sorry. I mean xxx.bestcoastgrowers.xxx:)

Quote:

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Originally Posted by WaZ

The 80mm fans I mentioned are ~50 CFM each.

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Fancy schmanzy computer fans?

Ohh... nice. Pretty.
No.

Again, they are not designed for that.
Do as you please from now on.

Quote:

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Originally Posted by WaZ

Could something like a Peltier on intake cool the air inside the box sufficiently to negate the heat buildup from exhaust outside the box?

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Ok, dude... computer hardware has very limited use on cannabis growing.
Peltier thingies will do jack-crap against 400 watts of High INTENSITY Discharge bulbs.

In addition... I do not understand your question.
Will it cool the intake air?
Sure.
Enough?
No.
Negate the heat build-up from exhaust outside the box?
What?
Ummm... what?

I fail to comprehend this setup.

Quote:

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Originally Posted by WaZ

How about a U piece of duct with water at the bottom so that the hot air is pulled through, perhaps with a system to cycle the water?

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You know, I would say 'no', but... go for it.
I doubt it will work... but hey, there is only one way to find out. :)

In this second idea of yours, I also fail to comprehend it.
What's the point of the water/U-duct?
What's the point of the water cycling?
Like a radiator?
Get a radiator then. They have been around for over 200 years. They are pretty much nailed down by now.

Best of luck to you buddy,

-turtle420 :cool:
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Hey WaZ,

I wanted to comment on your positive attitude towards trying new things.
I know I said 'no'... but, dude, experiment. Go for it. :)

The great thing about this hobby, is that there isn't "a right way" to do things.
I have seen some wierd, wierd, wiiiieerrrrdddd things.

Best,

-turtle420 :cool:
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Sorry about the confusion. Obviously, I am not so knowledgeable about heat management in closed systems.

Didn't know what a "45CFM fart fan" was (before Googling), so mentioned the ~50 CFM of the fans I had in mind.

Though I'm not very familiar with Peltier devices, they can be had up to and probably above 226 watt ratings. My idea was to expel the heat from the bulb through ducting directly to the outside of the wooden box, then have some sort of cooling device working on the air coming into the box so that the temperature outside the box becomes less important and thus less harmful to maintaining cool temperatures. I don't care how hot it gets outside the wooden box.

I realized after posting that I was basically trying to reinvent a refrigeration/cooling system. In the interest of saving money, I am trying to find cheap means of cooling.

Essentially, I am trying to cool everything inside this wooden box as cheaply as possible. It's not that I'm disregarding suggestions, but throwing more out there to find a good (cheap) solution. Probably should have mentioned that earlier.

I've got a cabinet I built that measures 36"x36"x72". I am using just 2 Lasko Box fans. Temps at the top of the canopy, which is 8 inches away, under a 400 watt HPS is at a steady 77 degrees.

I JUST NOW built a tray style carbon scrubber to go over the exhaust box fan. Air flow has come to a crawl but I'm willing to bet it still pushes about 300CFM.

Lasko rates this fan at slightly higher than 3200 CFM at it's highest setting.

The problem is that they velocity at which the air moves is not very fast.

I'm about to go check on my temps in my cabinet in about an hour or so. I'll let you know what the temps are with the carbon scrubber on.

btw.. box fans cost me 10 bucks a piece at Target.

update.

After about an Hour my temps rose up to 82 degrees and have stayed there steadily.

This is with 2 box fans.

The intake is pushing through a fiberglass air cleaner (the kind you use for your house a/c.)

The exhaust is pushing through some wire, A/C filter and 2 inches of activated carbon (10lbs total) across a 20x20 space.

I can't say as of yet if the carbon filter is working, but I think it is. I'm having a friend come by later and test it with his nose.

I can definitely say this. When I open the cab door the smell hits me hard. When the door is closed I don't smell anything. Previously I had a hard time smelling the plants when I opened the door because I Was used to smelling them slightly all day long. So it looks like something is working. We'll see though.

on a side note.. I'm pissed. When I went to go check my temps I spilled like 3/4 of a container of Sweet. UGH!!!!! I haven't even used it yet, I'm not sure how the cap was off/loose.

Heat always was a issue for me till I stepped up and got a water cooled light a little more work in the beginning but so worthit my yeild is steady and not stressed I bought it from bestcoastgrowers.com they were super helpful I saw my buddys garden and I was convinced

Quote:

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Originally Posted by greencloset

Heat always was a issue for me till I stepped up and got a water cooled light a little more work in the beginning but so worthit my yeild is steady and not stressed I bought it from bestcoastgrowers.com they were super helpful I saw my buddys garden and I was convinced

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sure are expensive though. too much in my opinion for a personal grow. you can air cool your lights for much cheaper.

Take a hundred or so bucks and invest in inline fan 365 cfm should be enough.
Install all your fans that you have now at the top to exhaust the hot air and create a passive intake.
Last but not least option, install an A/C 75 bucks...

Quote:

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Originally Posted by Forwhat420

Take a hundred or so bucks and invest in inline fan 365 cfm should be enough.
Install all your fans that you have now at the top to exhaust the hot air and create a passive intake.
Last but not least option, install an A/C 75 bucks...

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you my sir, have got the right idea.