i second what justaseed just said. I just put a 4inch exhaust fan in my closet (rvk fan- closet about 130cm-60cm-210cm). It does make a bit of difference but not much, i still cant close doors fully even with the fan running. Well not if i want my 400 watt light about 8 inches from my tips. temps with door closed gets over 30c which is bad. looks like i must buy another fan too.