It's over 90 degrees in here?!

I have read responses on heat issues and I thought I had addressed my problem but it appears not.
Here is a little about my setup:

This is my second time using a computer cabinet that I have modified. It is 1.5 x 2.5 x 4 feet (=15 cubic feet).
I am running CFLs (2-65 watts, 4-42 watts, 2-23 watts).
I used to have those reflective thermo sheets up for reflective-ness but I thought that might be contributing to my heat problem so I took that down and painted the interior white.
I have a 4 inch fan that is supposed to move 230 cfm. It is attached to ~3 feet of ducting with on ~100 degree bend. I have it blowing through 2 sheets of carbon filters.
There is a considerable amount of wind being blown out so I know there is good airflow.

I did a test run overnight with all the lights on, fan running, and doors closed and when I got up it was 97 degrees!! The temperature in the house is a steady 75. Also, I have a little personal fan blowing on the lights. If I hold my hand between the light and thermometer, it feels fine.

What am I doing wrong?! Below are some pics to give you a better idea of setup:
Empty, painted cabinet. Holes on bottom are for intake
Ducting from light to fan to filter.
Thin carbon filter air is passing thru.
Light setup and arrangement.

Please help!

Do you have any thing pulling fresh air in?

M4sT3rM1nD said:

Do you have any thing pulling fresh air in?

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Just the holes in the bottom for passive intake.

You're probably not getting good air flow. From what I see it looks like the vent holes are on the bottom. Is there a gap at the bottom of the cabinet for air to move through?

M4sT3rM1nD said:

You're probably not getting good air flow. From what I see it looks like the vent holes are on the bottom. Is there a gap at the bottom of the cabinet for air to move through?

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Yep. I have the whole thing on a flat dolly that raises it a good 4-5 inches off the ground. I put my hand under there when the doors are closed and the fan is running and I can tell air is getting pulled in but it doesn't seem like its creating a vacuum. The doors aren't hard to open or anything.

Do you think cutting additional intake holes would help?

run the lights at night when the temps are lower in your home. Pulling in 75 degree air u are going to have temp issues, get it down to like 65-70 ill make a huge difference.

Not sure I have the full picture, but I would not be venting directly in the light housing but would just put ducting sucking air out of the very top of the cabinet...because it looks like any heat that gets above your lights, not sucked by your ducting, is just going to build up, up there. Make sure your thermometer is in the shade.

purplehays1 said:

run the lights at night when the temps are lower in your home. Pulling in 75 degree air u are going to have temp issues, get it down to like 65-70 ill make a huge difference.

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I did my temp test at night

bravedave said:

Not sure I have the full picture, but I would not be venting directly in the light housing but would just put ducting sucking air out of the very top of the cabinet...because it looks like any heat that gets above your lights, not sucked by your ducting, is just going to build up, up there. Make sure your thermometer is in the shade.

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I will try this. Thanks! I had the thermometer right up next to the lights, about 2 inches away because I figured that is where my plants would be. I will move it down. When I put my hand next to the light, it kind of feels cool with the fans blowing. Maybe it got that hot because it sat in constant light over night?

You could consider putting severel cpu fans or even a small high velocity fan at the top for exhaust ( as heat rises) this additional fan will allow alot of negative air pressure so like what was mentioned aboge you can use passive intakes. I ran into a similar problem running 450 watts of cfl, used a 9in. Fan as exhaust plust 2 cpu fan intakes and 5 3in. Hole passive intakes and it dropped it to highs of 88 for an hour at the hottest part of the day typically running at 81-82°F.

bravedave said:

Not sure I have the full picture, but I would not be venting directly in the light housing but would just put ducting sucking air out of the very top of the cabinet...because it looks like any heat that gets above your lights, not sucked by your ducting, is just going to build up, up there. Make sure your thermometer is in the shade.

Click to expand...

I removed the duct from the lights so that all air can be removed. I also moved the thermometer a little lower and it got up to 100 degrees over night!

eLinc420 said:

You could consider putting severel cpu fans or even a small high velocity fan at the top for exhaust ( as heat rises) this additional fan will allow alot of negative air pressure so like what was mentioned aboge you can use passive intakes. I ran into a similar problem running 450 watts of cfl, used a 9in. Fan as exhaust plust 2 cpu fan intakes and 5 3in. Hole passive intakes and it dropped it to highs of 88 for an hour at the hottest part of the day typically running at 81-82°F.

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I don't really want to make holes in the top of my cabinet, but I can put more passive intake holes on the bottom. I am concerned about putting too make because I thought there needed to be negative pressure in the cabinet to ensure smell wouldn't escape. Please correct me if I'm wrong! I suppose there will be no smell to worry about unless I get my temps under control.

that CFL rig you have is just going to be hot. also a fire hazzard made out of kiln dried 2x4 (or whatever lumber it is you used)

bottom line is if you done have a much cooler place (basements work well) to draw cool air from your going to have heat issues. the cash you dropped on that CFL rig you could have got a nice little 400w HPS with cooled reflector and been much better off.

http://www.amazon.com/Apollo-Horticulture-GLK400CT24E-Digital-Dimmable/dp/B00547I5I8/ref=sr_1_4?ie=UTF8&qid=1407253937&sr=8-4&keywords=400w+apollo

not sure how your funding is but this light would be a great investment for you.

3 year warranty, i have 2 of them and my 1k watter shit the bed 2 years 8 months after i bought it, 20 bucks for return shipping and i had a new one within 4 business days.

if you think a HID will be hotter i would like to argue that theory, with an air cooled hood they stay pretty cool. and the balast dosent have to be inside the room.

each of them CFL you are running are individually ballasted so essentially you have 8 seperate ballast inside your grow area generating heat with no real way to cool the room except passive intake.

sorry for the multiple posts

RetiredMatthebrute said:

http://www.amazon.com/Apollo-Horticulture-GLK400CT24E-Digital-Dimmable/dp/B00547I5I8/ref=sr_1_4?ie=UTF8&qid=1407253937&sr=8-4&keywords=400w apollo

not sure how your funding is but this light would be a great investment for you.

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So it's the ballast that creates the most heat, not the bulb? The whole reason I started with CFLs was because a ton of people said they are not as hot. Heat was a constant issue with my first grow. Is the "cool tube" necessary or can I get a "gull wing" type with a fan blowing on the bulb? Like this one:

http://www.ebay.com/itm/Apollo-Horticulture-400-Watt-MH-HPS-Grow-Light-System-Set-Kit-for-Plant-Growing-/191055700117?pt=US_Hydroponics&var=&hash=item2c7bcea095

Its also a little cheaper.
Another reason I was using CFLs is my limited height. I only have 4 feet of space TOTAL, and these lights can't get too close to the plants, right? So with that light set up and distance from the light I can only have a MAX of 3 feet of plant. I will also have it in a 5 gal container so that shortens more to 2 feet of plant. I had height problems before because I let her veg for 2 months (didn't know what I was doing) and she was out of control. I had to do some major LST but we made it through.

No worries about multiple post....I need all the help I can get!

you really want something with a cool tube. this keep any heat from the bulb out of the room then you only have the ambient heat the light creates.

the cool tube will take up around 6 inch, you need to reconsider using different types of pots to lower your pot height, you dont need a 5 gal container for that big of a room, 3 gal nursery pots like these

http://www.amazon.com/Plastic-Nursery-Gallon-Actual-Volume/dp/B0058E4388/ref=sr_1_5?ie=UTF8&qid=1407258585&sr=8-5&keywords=3gal+nursery

are great for smaller spots, also look into training and maybe a ScROG so you can keep you canopy height nice and even.

bottom line though is its the CFL you are using that are creating the heat, or you can always go T5 panel like this

http://www.amazon.com/Hydrofarm-FLT24-4-Tube-Commercial-System/dp/B002JQBQZQ/ref=sr_1_2?ie=UTF8&qid=1407258699&sr=8-2&keywords=t5+HO

this is a bit cheaper and will run cooler than the arrangement you have now, but you still have the issue with having a ballast in the grow tent/cab,

its amazon so maybe order the T5 fixture, try it and if it dosent work return it and try the HID if that dosent work return it as well lol. i really think with a HID and cool tube with a good fan for exaust your temps will drop.

also you can put some ducting on your passive intake and run it somewhere cooler like the basement, you will draw that cool in when the exause fan is on, you will want your exaust on at all times the light is on anyways.

also your carbon filter is not going to do anything...

check this out



also heat rises naturally so your almost doing more harm than good by having that ducting and fan run through the top of that CFL fixture, before you but anything try just venting straight from the top of the cab, having it the way you have it is essentially creating a wind tunnel to the bottom of the cab. try hooking it up like the image below and see if that helps before buying anything.

I put the exhaust through the back at the very top for the rising hot air. I put the exhaust holes at the bottom to bring in cool air. I do not have a basement. What I thought I was doing is diagrammed below. I still don't understand why this can't work.


I can put a tray of ice near the intake holes and see if that helps. I turned off the two giant bulbs and my temp is holding at 86F.

well 86 isnt too bad a little high but manaegable. but you lost 2 lights.

looks like you had the ducting from the exaust fan run into the light hood.

i really think your problem is all the CFL but maybe wait for someone else to chime in. i built a hood similar to yours and had so much heat issues it was redicules. i had 8x 26w bulbs in mine.

if your not interested in spending money on aother light maybe a bigger fan. i just think with a 400w HID and cool tube you wont only increase broduction but will decrease heat. and like i said earlier worst case it dosent work out for you and you just return it.

RetiredMatthebrute said:

well 86 isnt too bad a little high but manaegable. but you lost 2 lights.

looks like you had the ducting from the exaust fan run into the light hood.

i really think your problem is all the CFL but maybe wait for someone else to chime in. i built a hood similar to yours and had so much heat issues it was redicules. i had 8x 26w bulbs in mine.

if your not interested in spending money on aother light maybe a bigger fan. i just think with a 400w HID and cool tube you wont only increase broduction but will decrease heat. and like i said earlier worst case it dosent work out for you and you just return it.

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I did have ducting running from the light to the exhaust but removed it and did a test run again but the temps still got up to 100. I think I can get away without having those 65-watters.

I am seriously considering a HPS light....maybe I could get away with a 250 watt unit? I only have 3.75 sq feet. My girlfriend is unhappy with any more money going into my "hobby".