Large Grow Room - ventilation & CO2 questions

Okay, I have a number of questions about ventilation, heat issues, and CO2 regulation related to a grow room that I'm constructing. First off, here are the stats:

20ft X 10ft X 7ft room (1400 cubic feet) in an insulated basement which has concrete walls and is sealed really well
1 window at each end of the room
1 secret entrance that can be sealed as well
the veg area takes up 1/3 of the room and has two 1000w MH
the flowering area takes up the remaining and had six 1000w HPS
Can-filter 100 with a 10" Max-fan
the entire room is covered with Permaflect
ebb and flow bucket systems with numerous 55 gallon drum reservoirs in the room
electric and water supply is all set

Presently, none of the HPS lights are on because I'm not that far yet but the metal halides are already cooking the place. Under the lights, it's about 85F and ambient temps are mid 70s. I currently have the door to the room propped open with a fan blowing in air from the rest of the house, and an opening in one of the windows about 8 inches in diameter that is passively letting in cold air from outside (currently in the 20s and 30s). There is no active exhaust of the room yet.

The lights are aligned in such a way that I'm running two lines of 6" ducting, each going thru 4 light hoods (1 in veg and 3 in flower) across the entire room. I want to have two vortex fans pulling the air across the room through all eight lights and exhaust it. The can-filter isn't running yet but I have it suspended horizontally in the flower area. I plan on having it scrub the air and exhaust it down a long, enclosed shelf which will house all my ballasts and then push all this heat outside (actually, I'm going to pipe this air back into my house to heat it). Not sure if I will need another fan here or not, or maybe I'll feed it right into the ducting for the lights right near one of the vortex fans. Essentially, the room would be sealed at this point. I plan on adding a CO2 generator and a ppm controller that will run off the natural gas. I need to know what to do to keep the temperature down in the room. Do I need to also bring fresh air into the room to keep the temp down?

Here are my questions:

1. How many exhaust fans should I have for the light and can-filter? Vortex? How many CFMs (the ducting runs approx 20 ft each with 4 lights inline and the can-filter ducting is approx 20 ft as well)? Will this solve my heat issue?
2. What should I do to pull the air from outside into the ducting for the lights? Do I need inline boosters between the veg and flower areas of ducting? I'm open to suggestions including changing my plan for the can-filter and ballasts.
3. Will I need to bring fresh air in for the room and exhaust any of the CO2 produced or just let it leak out? If so, how? I'd like to use motorized dampers in this case so I can hook up the CO2, the can-filter and any fans.
4. Size of the CO2 generator for this 1400 cubic foot room? Will this add significantly to the heat already present?

Sorry for the length, and thank you for your help on any of the questions.

buttsnake said:

Okay, I have a number of questions about ventilation, heat issues, and CO2 regulation related to a grow room that I'm constructing. First off, here are the stats:

20ft X 10ft X 7ft room (1400 cubic feet) in an insulated basement which has concrete walls and is sealed really well
1 window at each end of the room
1 secret entrance that can be sealed as well
the veg area takes up 1/3 of the room and has two 1000w MH
the flowering area takes up the remaining and had six 1000w HPS
Can-filter 100 with a 10" Max-fan
the entire room is covered with Permaflect
ebb and flow bucket systems with numerous 55 gallon drum reservoirs in the room
electric and water supply is all set

Presently, none of the HPS lights are on because I'm not that far yet but the metal halides are already cooking the place. Under the lights, it's about 85F and ambient temps are mid 70s. I currently have the door to the room propped open with a fan blowing in air from the rest of the house, and an opening in one of the windows about 8 inches in diameter that is passively letting in cold air from outside (currently in the 20s and 30s). There is no active exhaust of the room yet.

The lights are aligned in such a way that I'm running two lines of 6" ducting, each going thru 4 light hoods (1 in veg and 3 in flower) across the entire room. I want to have two vortex fans pulling the air across the room through all eight lights and exhaust it. The can-filter isn't running yet but I have it suspended horizontally in the flower area. I plan on having it scrub the air and exhaust it down a long, enclosed shelf which will house all my ballasts and then push all this heat outside (actually, I'm going to pipe this air back into my house to heat it). Not sure if I will need another fan here or not, or maybe I'll feed it right into the ducting for the lights right near one of the vortex fans. Essentially, the room would be sealed at this point. I plan on adding a CO2 generator and a ppm controller that will run off the natural gas. I need to know what to do to keep the temperature down in the room. Do I need to also bring fresh air into the room to keep the temp down?

Here are my questions:

1. How many exhaust fans should I have for the light and can-filter? Vortex? How many CFMs (the ducting runs approx 20 ft each with 4 lights inline and the can-filter ducting is approx 20 ft as well)? Will this solve my heat issue?
2. What should I do to pull the air from outside into the ducting for the lights? Do I need inline boosters between the veg and flower areas of ducting? I'm open to suggestions including changing my plan for the can-filter and ballasts.
3. Will I need to bring fresh air in for the room and exhaust any of the CO2 produced or just let it leak out? If so, how? I'd like to use motorized dampers in this case so I can hook up the CO2, the can-filter and any fans.
4. Size of the CO2 generator for this 1400 cubic foot room? Will this add significantly to the heat already present?

Sorry for the length, and thank you for your help on any of the questions.

Click to expand...

hey man, this post is a bit too long for most ppl to read.. but ill speak for myself and say i could prob help u with most of ur questions here but i cant be bothered reading soo much..
Um try breaking it up or researching alot of it urself and then just ask wot u cant find anywhere..
anyways someone might help so BUMP

With co2 you want to seal your room, that means no exhaust so that way your not going to let out the co2 produced by the co2 generator. Propane co2 generators ususally raise the temp about 10 degrees from what ive read, don't remember the size of the room that was used though. Bottled is definately the way to go if ur worried about temps.

You definately need to seal the room for Co2. I'm going through the same thing right now. If I were you, I would pick up some AC's for your room.

The AC's need to be dual hose portable systems (if you want full stealth) or single zone split AC's (considerably more expensive and require an HVAC person.) If you don't get a dual hose system, you'll be exhausting your Co2 out of your room.

I just picked up one of these http://www.overstock.com/Home-Garden/EdgeStar-Extreme-Cool-14-000-BTU-Dual-hose-AC-Heater/3879155/product.html?cid=123620&fp=F&ci_src=14110944&ci_sku=11927316 that is currently being shipped to me and that will work to cool my 3400 watts that I'm not exhausting.

For the amount of power that your using, you'll need 2-3 of them depending upon whether you were using fans to exhaust the reflectors (I'm running my lights vertically and will not be using any type of reflector so I'll maintain higher ambient temps but I won't have the hotspots.)

I believe the typical rule of thumb here is 3k btu's per 1k watts of exhausted light and 4k btu's per 1k of unexausted light.

Another problem you're likely going to have is maintaining appropriate temps in your rez's. Hopefully it won't get too hot but it's something to consider before firing her up.

I would seriously look into running your lights vertically and growing fewer plants larger. Look up some of the stuff this guy has done. http://www.thcfarmer.com/forums/f131/

He's a canadian medical grower that's literally pulled 42 lbs off of 10 plants using between 9k and 12k watts (12k when temps would allow) and he did this with only 3 weeks veg.

Personally, I'm going to be using the CAP E&G system with 12 pots and 3400watts. 4- 600 watts and 1- 1k watt in this configuration:

..X X
XoXoX
XOX
XoXoX
..X X

X's are plants and the O's are light. Little o's are 600's and the O is the 1k. My goal is 5 lb's with 4 weeks veg but I'm hoping for 1g/w for 7.5 lbs.

I'm not sure what to tell you about the other ???'s as that's a little bit beyond my knowledge.

Hope some of this helps and hit me back up. Happy growing.