I did something very similiar. I had floor HVAC vent/duct in the bedroom...so I used 6 inch dryer vent flex hose running from the floor vent to the area between the canopy of the plants and my 400 watt HPS light. This maintained a temp of 78-82 degrees at the top of the canopy and less than 50% humidity...near ideal...:thumbsup:...and I left the fan running constantly.

Bottomline: the temps would be whatever I set the thermostat at....heat or cooling.