i use exhaust fans to vent hot air but it does control smell also as long as the air being vented is "filtered" or in my case vented outside 3 stories up where noone is around to smell it. i'm a little confused about what you said about using the system for smell and not to vent hot air. you must have an exhaust system in place for venting hot air or your plants aren't gonna live that long. oh yeah, the dementions of my grow space are 2ft deep x 4ft wide x 6ft high. i have 360cfm total from 2 exhaust fans and there is no smell in my house at all even with the door open. hope that helps out a bit.