Help! Temperature issues in large grow room

Hello all, I am having some heat issues in my grow room that I have not been able to resolve on my own.

Room Details:

8x8x20' (shipping container)
8-Ultra Grow 6" Cool Tubes (four in a string on each side)
2- 12" 1060 CFM Fans, reduced to 6" cooling lights
2- 15,000 BTU RV Style Rooftop air conditioners
CO2 Enrichment with Atlas 1 and a 50lb bottle
1- 10" 780 CFM Exhaust fan which is on all night and comes on every 2 hr for 10 minutes when the lights are on.

I currently have temperatures averaging 90 to 95* during the day, I'm struggling to believe that 30,000 BTU's of cooling power can't keep up with eight lights.

Where have I gone wrong? The room is 100% sealed and the air conditioners are putting out conditioned air that is 20-25* cooler than the return air, so they are working properly.

I have my light cooling fans sucking air from outside the unit, blowing through 4 lights a piece then they go into a T and exit the roof with a 6" vent cap.

Are my CFM's dropping significantly since i have the fans reduced from 12" to 6"? I know that when you reduce ducting size, you increase velocity of the air being pushed through the duct but do you lose CFM as well?

Please give any insight you may have.

What is the temp outside of the shipping container. Bad thing about them is they aren't insulated AT ALL so if its hot out during the day you can try allll you want but that things like an oven in the sun.

It sounds to me as if you are trying to draw and exit too large a volume of hot air through too narrow a chamber.

How hot are the cool-tubes when you touch them?

The container is in our building so it doesn't get TOO hot during the day, during the dead heat of the summer it averages 85* F inside the building.

The cool tubes are hot to the touch, I can hold my hand on them for 30 seconds or so before they start to burn.

Have you tried running your light cycle at night???.........I would move all the ballast outside of the grow room......those thing throw off plenty of heat

IKON said:

The container is in our building so it doesn't get TOO hot during the day, during the dead heat of the summer it averages 85* F inside the building.

The cool tubes are hot to the touch, I can hold my hand on them for 30 seconds or so before they start to burn.

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A 12" fan is huge. You need more than 6" to draw the heat from 4 lights, imo. You also have two 12" fans trying to exhaust out of a 6" hole.

Easy fix......... Mount those ballasts by the A/C unit outside of the container......... That should drop temps quite a bit. Or, be less greedy and turn a light or two off.

im a certified rv tech and i can tell you right now that the ac units are your problem. it doesnt matter if its a dometic or a coleman they both suck. in a unit that is 32 ft and up they put 2 of these ac units to cool the rv and thats with no grow lights. they are only designed to reduce ambient temps about 20 degrees max. you cant count the btu`s on the ac units as a measure to be honest. they are very compairable to the portable acs vs the window units. even though both rated at 10k btu the window unit produces twice the cold air. i hate to be the guy to piss in your cherrios but you need to upgrade to more ac units. if you live in so cal i can actually install the ac unit for you if you cant find someone you can trust.

I am going to return the rooftop air conditioners and purchase a 24,500 BTU wall mount unit from Home Depot. Not only should it cool better but is much cheaper and I should get a decent amount of money back.

I had an idea on the light cooling fans; If i change the setup so it draws in trough a 12" duct then splits to two 6" ducts which cool to lights a piece solve the issue of stuffing too much air into a duct which is too small?

If this doesn't solve the issue, I will move the ballasts outside the unit, I would prefer them inside however for security and so the unit just looks like a shipping container from the outside.

If your going to do that just get a split ac unit, much more efficient

I looked into the split A/C systems, but they were all a bit more than I wanted to spend. I did a total heat input calculation and came up with 36,431 BTU/hr with the ballasts in the room. If I remove the ballasts it should drop to around 22,000 BTU/hr.

Today I installed a 24,000 BTU/hr wall mount air conditioner and temperatures have already dropped 7-10*. Tomorrow I plan on moving the ballasts outside the unit and redoing my ducting for the hoods.

Hopefully, with these two changes I can get my temperatures where they need to be.

Will update again tomorrow, thanks for everyones input.

what kind of bud do you have? strain name...is it indica or sativa? and how long are the cola's?

Just my advice for what it's worth, I would put a 6 inch fan on a 2 light run into your 12 inch duct meaning make 4 duct runs into one. I personally think there is just too much heat in your ducts to deal with because your running 4 lights in a row. I would look into moving more cooler air over your lights because it may save you even more money in keeping your temps down.
Your setup looks killer though and I am sure once you get your temps down you will be in business. Good luck and happy growing.
KnB

Moved the ballasts outside the container on Friday. After the weekend my high temp as 83* F. If I get the lights ducted properly will I get down the 5-10* F that I need?

IKON said:

........1- 10" 780 CFM Exhaust fan which is on all night and comes on every 2 hr for 10 minutes when the lights are on..

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I know a sealed room w/ CO2 still needs some air turnover but that seems like a lot to me. wont that waste alot of AC and CO2?
how much fresh air do you need during the day in a sealed room?

The lights properly ducted will reduce it a lot, hopefully within the point that they feel like they are room temperature. Should be good Ikon!

Your only problem is your ducting. When you reduce 12" to 6" is won't work. You probably have blow back coming from your 12" fans. Its too much of a drop. You need to split your fan gradually. use y connectors. Your light can still be in a line but your ducting would look more like this 12 x 8 x 8 y on your fan each 8 goes too 2 lights reduced to 6". that will fix the issue with your cool tubes being too hot. BUT you need a way larger exhaust hole. 6" exhaust only allows a max of 450cfm (somewhere around there) no matter how much cfm you blow into it. Honestly 2 12" exhausts would maximize what your doing

mrmadcow said:

I know a sealed room w/ CO2 still needs some air turnover but that seems like a lot to me. wont that waste alot of AC and CO2?
how much fresh air do you need during the day in a sealed room?

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This is where my research has fooled me...Ive spoken to people who exchange the air once per day with co2 and I've seen people with a constant exchange with co2. What does the rollitup community suggest?

researchkitty said:

The lights properly ducted will reduce it a lot, hopefully within the point that they feel like they are room temperature. Should be good Ikon!

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Spoke to a mech engineer buddy. He explained that in order to maintain cfm I would need to split my 12" ducting to 4 6" ducts. We decided against this however.

What we ended up doing was taking my 12" fan and using a 12" intake, then splitting to two 6" ducts and cooling two lights per 6" then out. The other half of the room is a mirror image. So each 12" fan cools 4 lights. My temperatures have dropped to a steady 75-78* F and the lights are maybe 85*, warm to the touch but not hot.

I appreciate everyones input and will post some pictures when flower time hits.

Pretty rad setup ya got going there. Should keep your hands full I'd imagine.
I'm running 25k btu for 6k watts and dehumidifiers in a 1k sf room for what its worth.
As far as Co2 enrichment is concerned. I've never read/heard conclusive evidence that a fresh air exchange is necessary in a co2 enriched environment, so long as all other factors are within reasonable levels i.e. temp, humid, etc. Some may argue that the roots need a small amount of oxygen, I have not read nor would believe that the roots need more than what is available even in a co2 enriched environment. I've never run into any asphyxiation issues in my room nor have heard of any.