well i have an ac unit that is about a ft away from the light and blows right on it and i have a duct system hooked to a carbon filter thats running through the lite box i can put my hand about a ft away under the lite and start to feel the heat i would have to put my hand about 4 to 6 inches away to really fell it and i can take the duct off the end by the ac unit and the ac blows right into the hole in the side of the light box when i do that theres like no heat at all my room is 7x7 but i have 3x7 for the light and dwc and then a lil area for the seedlings i have 32 plants veggies i don't think the 400 would be enough or it might be just enough