Depends on your rooms size and normal temp range. If you have a wide open space (like a 10x10 bedroom) and the outside temp stays under 70 you shouldn't have any problems, but a closet grow or average outdoor temp ranges in the upper 70's or higher will result in heat issues really quickly. I don't have a cool tube or inline fans, just a 10 x 12 spare bedroom, open windows, and a floor fan, but I only have to worry about temps going over 70 about 4 months of the year, and I can relocate to the basement then. My 600w raises the temp inside the room by about 10-12 degrees, but if it were in a closet or smaller room the temp increase would be higher.