I just started to flower in a closet that is 6' wide x 2' deep x 8' tall with a 400 watt hps. How many cfm's do I need to vent this? Also, where should I place a thermometer to get the most accurate reading for temperature?
You would put a 6cfm fan? I dunno if those exist.. you would want half the area of your room or more.. depending on heat/rh issues so around 50 cfm should be fine minimum. Altho more, is barely ever worse.
mines 4x2x7 with a 50cfm squirell cage bathroom fan and its struggling to keep temps below 90degrees. i have to keep the door cracked with a box fan blowing cool air in to keep it around 80 degrees. (also using a 400w HPS)
with your 6x2x8 room that gives you 96 cubit feet of space, so a 100 cfm fan would replentish the air supply once every minute.
I have a 3x8x7 room with a 1000 watt hps. For ventilation I use an 8" inline fan ducted to the top of the reflector and a 4" inline for intake. This keeps my temp at about 80f at the highest cala. Thats where my thermometer is at the tallest branch. I don't want those girls getting heat burn now.
I have a 65cfm fan venting now and temps are about 90 degrees with thermometer down next to plant pots. I have one fan blowing towards the light, would it help if I had another fan blowing on the light? I really don't want to put another exhaust fan in but will if I have to. With the door open the temp is about 82 but I want to keep it a little stealthy since I rent
i found that my fan blowing directly on the light actually made my temps go up in the room, cause it was allowing the hot air to blow down to the bottom part of the room.
today on my list of things to do is to move my exhaust fan much closer to the light, right now its just up in the corner of the room, but the temp above the light arent actually all that hot. i think putting it right beside the light or maybe even just a hair below it might help battle my temps a little better.
My fan is up in the ceiling where its not hot either. I didn't know it would be so hard to get the temps down in a closet this big. How people put 400 watt HPS in a closet half this size I don't know. I'm sure I can get the temps down 8 or 10 degrees somehow. Just don't want to have to put in another exhaust fan, but may need to put in another 65 cfm computer fan. They only cost 25 bucks
I'm not sure if a computer exhaust fan will do it. If the temp is near 90 at the base it's way too hot. I never had any luck with blowing the air around with a fan as opposed to cooling. The only thing I noticed was the increase in temp because you are just blowing hot air around. You need to exhaust it some how. Like I said I use a 1000 hps in an are 2x3x7 with temps not getting higher then 81f.
My 8" exhaust fan moves about 800cfm+ and the 4" moves 200cfm
I had the same problem with heat and realized the money that was spent on "cheap" fixes was more then if I just did it right the first time. I