running 12k watts vertical lighting in a stadium grow (plants on 3 shelves along the walls).. all the lights are in glass tubes connected with ducts and a fan blowing all the air out of it and new air into it.. I have a fresh air intake fan and carbon filter exhaust fan moving all the air in the room once a minute.. How can I adjust the temperature of the room without messing with the CFM moved or the air pressure? how big an AC would I need? as surely i would need something smaller than whatever is rated for 12,000watts since most of the heat generated leaves the room. also, does a setup like this work with c02 supplementation? or do I need a confined garden with no moving air?
Generally you need at least 3.5 BTU per watt of light. So around 36,000 BTU of A/C but since you are using air cooled tubes for your lights you could get away with probably half of that. Also it seems to be more beneficial to pull the air through the cool tubes than to push air through. Also you would likely need one fan in the middle to keep things moving, you could get a booster fan for this.
Hey Whack I had a question for ya - I'm building a room with slightly less wattage in lights, but is that 3.5btu per watt applicable for sealed rooms? Does that take into account a dehumidifier or a co2 burner? Is there any good resources you know of for how to pick what kind/how much I will need? Also going to have to pick a dehumidifier as I'm in a humid area...never built a room of this size so any help is appreciated and sorry for so many questions
What I've seen is a dedicated vent hood fan with it's own inlet and outlet separate from the room. Then the room needs an exhaust fan and in intake fan. Exhaust fan being at least twice the size in cfm. The fans and ac are on a timer along with the co2. When the co2 comes on for 15 minutes 4 times a day the fans turn off during these time frames to fill the tent with co2 but come back on after 15 or 20 minutes to keep the temps down. The light tube fan stays on because it's on it's own air system separate from the tent. CO2 tank with bleeder solenoid valve. Run 1/8" tubing zip tied to a cage around the top of the plant. Poke holes in the tubing around the plant so it can cascade over it when the solenoid is open. 15 min 4 times a day should be good.
I was more replying to the original poster. The AC is going to probably come with or need a thermostat. That's what will maintain the needed temp. The ac should be connected to your air inlet and come on when the thermostat calls for it. I would say set it at 75-78 or whatever you can maintain economically without running things too hard. Whether the thermostat is remote sensing or senses where it's located you need it sensing the temp at the canopy. An indoor grow room has so much air exchange and microclimates going on under the light that the thermostat location is the difference between a well maintained temp and thinking it's the right temp when it's not. Room temperature should be taken at the canopy level under the light and that's where you want your thermostat for the ac or as close as you can get it. Make sure you buy a cooling thermostat if you buy one not a heating thermostat. Cooling thermostats contacts close on a temp rise heating thermostats open on a temp rise. There are many thermostats that do heating and cooling if this is the case your ac will connect to the cooling circuit. If you buy one you need to know if it needs to be line or low voltage for your ac unit and if line voltage you need to know if the contacts on the stat can handle the amp draw of your ac. If it's low voltage that's no worry it will just be running a contactor inside the ac unit with control voltage.
