Closet grow w/ 315cmh, opinions?

I'm in a closet (32×72×96) and dont have an air cooled hood. But before i go through VEG, (closet is in a room running at 76 degrees). Im worried about my temps/environment, I'm running a 315cmh. Can someone direct me to a helpful or similar link?? Was thinking about running 2 carbon filters at the top and venting into the attic w/ 2 intake fans on the bottom. I do have a portable AC but would rather not use it.

I would think that as long as you're able to exhaust waste heat out of your space and replace it with your conditioned room air it should work. Also, your light will flower about 1/2 of your space.

Depends on intake air temperature. You can't cool a room with warm air.

Also I should mention, venting warm humid air into your cold attic is a BIG no no. The warm humid air will condense and cause black mold up there. Terrible health situation that is extremely expensive to repair.

Renfro said:

Also I should mention, venting warm humid air into your cold attic is a BIG no no. The warm humid air will condense and cause black mold up there. Terrible health situation that is extremely expensive to repair.

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My location is on the hotter side, dont know if it matters with the mold issue, would it be more efficient to run exhaust into the attic and out of the house VIA clothes dryer access. Does anyone know a company that makes a dual/tri exhaust port? My issue, is getting the already cooled air into the closet , without light leak problems. Anyone have an idea that will work in a well-organized competent way?

If you vent into the attic your half way to getting it out the house, just install a few roof or soffit vents.

If you use intake fans you shouldn't have light leaks.

If your ambient air temp is less than your desired grow room air temp then its just a case of more airflow to maintain less degree rise.

What if you add co2? You want 80-85f with co2.

Phat J said:

What if you add co2? You want 80-85f with co2.

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I'm used to a 400 watt hps/mh / 600 during flower, seems like they put out almost dbl the heat a cmh does... but this is speculation, a new location and I've never used a cmh before... so sort of uncharted territory....

Phat J said:

What if you add co2? You want 80-85f with co2.

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GBAUTO said:

I would think that as long as you're able to exhaust waste heat out of your space and replace it with your conditioned room air it should work. Also, your light will flower about 1/2 of your space.

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You think I should run 2, 315 cmh's (@$150 a light) for my space during flower??.... I think the 400 watt hps i have, generates too much heat for the 4 plant site in coco mix... I figured the single 315 would work out better than throwing 2 heat performing lights in the closet and praying my exhaust/intake fans can keep up....

I have no experience with cmh, so I don't want to give bad advice. My input of adding co2 was just trying to think outside the box. Using co2 you could use higher temps temps to your advantage.

You have a total of 16 sq ft of area to illuminate. For a CMH rig, I would shoot for approx. 40w/sq ft, so that comes to 640w for the room. a single will only give you a 20w/sqft density-not enough intensity for good flowering.

build a box around the light with a glass bottom, then duct outside air in, then out of the lamps box. No smell leaves your room. Cold air stays in. Hot air goes out.

Its how I have mine. Winter is a problem tho, you don't want cold air going into your light. It will condense.

Very similar setup except my closet ceiling slopes down abt 3' into it and is a foot taller. Running a single vert 315 and it's good for 3 plants, 4 max. Not able to use all floor space but it's a walk in and I can move around in there. Plants on casters to facilitate.

To maintain temp, I do have an intake "hatch" from an unconditioned exterior void space at floor level on one end, 6" inline fan exhausting to attic on the other.

Setup seems ideal temp wise right now (midwest) but I'd need a/c or to just leave the closet door open when its warmer. If you're in a warmer place, I'd rely on your adjacent room to maintain, perhaps a high cfm single would work.