is the hps in a cool tube? I would assume that is where the majority of the heat is coming from. I use an old furnace blower fan for exhaust. with these 2 items combined you should be able to control the temps provided the temps where you get your fresh air from are reasonable.
If you move enough fresh air thru the room it won't have enough time to heat up.
McDanger Reviewed by McDanger on . Heating Problem I've recently expanded my grow closet's lighting. I now have three banks of 10 24 watt CFL that output 1600 lumens (48,000 lumens) as well as a 400 watt hps that outputs 55,000 lumens. This is for a space roughly 1 1/2 x 3 feet, holding six plants. The problem is, its basically turning into an oven. If I close the closet door the temperature at the top of the plants can top out at about 110 degrees (I haven't let it stay that way long enough to hurt the plants). I decoupled the fan Rating: 5