i've now read the most of the grow room setup thread, thanks :thumbsup:

ok a couple more observations...

when i computed the cubic feet and air movement, i used a 90 cfm computer fan as my base. i have done a little research today and have found that i can get a computer fan with cfm ratings that are much lower. so let's just use 25 cfm as my base. so now let me do some re-calculations.

setup:
-3'x5'x8' sealed room with one active exhaust (computer fan, 25 cfm sucking the air from the room through a carbon scrubber)
-passive intake (except when heat/air are running. i need to find out what the output cfm is for my HVAC)
-120 cubic feet in the room (roughy 15,000 cubic feet in my house)
-LED's and CFL's for lighting so heat will be very minimal.

assuming the HVAC output in cfm doesn't over do the computer fan i can maintain negative pressure in the room.

so with the lower cfm fan i can reduce how much air i am actually pulling out of my home and exhausting into the attic. if my re-calculations are correct it would take 10 hours to suck all the air from house. of course where i live the A/C is running frequently, so i think the loss of cool/heated air would be minimal...

a question for some of you who might know; what kind of output in cfm does a 3.5 ton HVAC unit put out? What i don't want to do is create positive pressure in the room... on a side note, i could create a passive output as well with another carbon scrubber for when the A/C is running. That way i could prevent any positive pressure issues....

as far as returning the scrubbed air to the room, i think that would cause positive pressure issues also, so i am scraping that idea.


anyone else have comments/questions/advice?

thanks :jointsmile: