I'm glad you sked that question, because the single thing that bugs me the most about people trying to build a sealed room is when they try to cool their HID lighting directly, and wonder why they then need HUGE AC capacity, and spend HUGE amounts of money running it! And if that weren't enough, they spend a lot of time dealing with indirect effects of such overcapacity, like hot and cold spots, low humidity and electrical problems.
I run an aircooled setup to cool my lights; the air comes from outside the growroom, is ducted to each light (in this case two rows of four Ochos each), PULLED through the hoods, and then sucked out of the room. The fan that pulls the air through the hoods is sited as close to the exit as possible, as this drastically reduces heat buildup. There is no active cooling other than air to cool the lights, and none is needed because this air never mixes with the sealed room environment. Even if the air leaves the room at 120 degrees it's okay since... well, since it's leaving, right?
The working air in the room is then cooled by 2 maxfans each blowing through its own Ice Box, which removes residual heat from the hoods, radiant heat (the part the plants actually use), heat from fans, electronics, dehuey, CO2 burner, etc. These units are taped together and hung from the ceiling, so they just suck air in at one end and blow it back out into the room. I aim them down somewhat so they can blow cooled air down towards the plants and create a nice breeze while they run. Again, these fans are thrmostatically controlled by my environmental controller and run about half time when all the gear is on full blast. That warmed water then mixes with warmed water from my RDWC units and continues on to my chiller, where the heat is removed. My chiller is set for 52 with an 8 degree rise before it kicks on. Keeping the relative humidity in the growroom below 60% prevents condensation issues on waterlines and Ice Boxes.
When I asked you about sizing cooling capacity for this room originally, I remember your calculations were based on 8kW of unvented lighting in the room and you suggested that a 2 ton chiller might or might not quite keep up, but it would be close. With the aircooling, the chiller runs about half time, and it's cooling all the other loads I mentioned above as well. Therefore, it works, and it works very well.
The reason I asked the question I did is so that I can quantify how much cooling I'm gaining with this aircooled helper setup. Just telling people they will save an unspecified but 'large' amount of power isn't as convincing as saying something specific , such as they're looking at saving some 2/3 of their total bulb cooling requirement. As it stands, two-thirds is my best guess on how much heat the aircooled system removes from the lights. Combined with other energy saving strategies I'm working on, as discussed elsewhere in these forums, I'm trying to reduce a given grow's energy consumption footprint by a solid 50% per unit of output produced over currently practiced methods.
