How much CFM do I need

Discussion in 'Grow Room Design/Setup' started by calimedigrower, Aug 4, 2011.

  1. Looking to do a new indoor grow. I plan on having 8 1000w hps lights with either 6 or 8 inch vents. First question, should I go 6" ducting through the hoods or get 8" hoods and do 8" ducting for that many lights? I am planning on having the room completely sealed and doing co2. I will recirculate the air in the completely sealed room into a secondary room, where I will use charcoal burners to kill smell and dehumidifiers. I will then circulate that same air back into the grow room to conserve on the co2. (no fresh air, only recirculated "cleaned" air). So my question is how many inline/booster fans will I need to circulate in the ducting, and I was going to do a inline/booster fan just connecting from room to room, how much CFM will I need for this?
  2. oh yeah and i forgot to mention the size of the is going to be 8x 1000w, 2 over each 4x8' tray, with walking room in between. so approximately 14x20 with 12' high ceilings
  3. 8 1,000w lights will need a good amount of CFMs...You should be using 8 inch ducting with 450+ CFM fans. Use 8 inch ducting and 8 inch hoods. You can probably get away with using an inline fan for every 2 hoods. So 4 inline fans pulling at least 450 cfms.
    Test temps, if it should be lower, use some boosters.
    Then for air going back into the grow area, you can use another 450 cfm inline.
  4. ok cool thanks for the info. this may sound like a stupid question, but what is the difference between a booster fan and an inline fine? for the 8" ducting on my hoods, will it be an inline fan on both ends?
  5. Air gets sucked in from wherever you want -> hood -> ducting -> hood -> fan -> hood -> ducting -> hood -> fan -> hood -> ducting -> hood -> fan and so on.

    A booster fan is simply a fan to help pull/push air but really couldn't do much on it's own.
  6. ok so lemme know if you think this would successfully vent the hoods. putting an 8 inch 700 cfm inline on one end of the room that pulls air from another room that is connected by ducting 4 feet away. then putting ducting only going a couple of feet, then have a ducting coupler that take the eight inch ducting and switches it to 2x 8 inch ducting (because I will have two rows of lights, 4 lights each row). having ducting connecting all the lights, then having another coupler at the other end of the lights that connects to one eight inch ducting, that has another 700 cfm 8 inch inline at the other end pushing the air into that side room 4 feet away. sound adequate? sorry if this sounds confusing dunno how to say it any better lol
  7. I have no idea...never made a room that big. :eek:
  8. damn didnt think that would work lol how do i upload an image from my computer? i wanna post it so people can look at my layout to see if it would work
  9. you can use imageshack and then paste the "Forum" code.

  10. I think that would work. The only thing I can think of is maybe reducing down to 6" after you tee off for your 2 lines then back to 8" once you reach the inline fan on the other side. Basically what i'm saying is anytime you tee something your going to slow down the flow. But if you reduce to a smaller line it will help prevent that loss of flow.
  11. ooohkk. Cool that makes sense. I will probably try that. Thanks for the info! so what you are saying is you think I should do 2 rows of 6" hoods, that will then t into an 8 inch with 8 inch inline?

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