Vent/Heat/Air Questions

Discussion in 'Grow Room Design/Setup' started by Kushqt, May 8, 2011.

  1. #1 Kushqt, May 8, 2011
    Last edited by a moderator: May 8, 2011
    Hi GC,

    I am having trouble keeping the temperature below 82 degrees in my flowering room. I just had two rooms built and I am using a passive intake system. I have a passive cold air return in the veg room which I am keeping fine temps in. There is also another cold air return going from the veg room to the flowering room. I have a carbon air filter connected to flex duct running through the 1000w hps with an exhaust fan putting the hot air outside. The carbon air filter is mounted high up to take out hot air. Also, I have another cold air return in the flowering room, but the temperatures have still not gone down enough. Any suggestions would be great. I could get a window air conditioner but then my security is weakened.



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  2. bumparooo
  3. 82 really isnt that bad. If air is moving inside, sub to high 80s still isnt detrimental. Easiest suggestion would be upgrade the exit fan. And tighten up all that ducting. Flex ducting causes turbulence when draped like that. The light is also heating up the ducting.

    Otherwise, I wouldnt be stressed about ac, with lights on, 1k, and 82 degrees. Its pretty low if u ask me.
  4. Thanks for the suggestion Pentax. The only reason I don't want to upgrade the fan is because what if that doesn't fix it. Then I'll still have to get an AC. I was also thinking I could just upgrade the fan and put an exhaust in both the veg and flowering room and seal the cold air intake between the two rooms. At 1k, my room is getting up to the mid to high 80s with a low humidity (20%-40% depending on watering). Definitely going to tighten up the connections with the flex duct.
  5. A bigger fan will definately change the temps, assuming its an upgrade. Are you using a 4" fan now? A 6" would make a world of diff. An exh in each room is best. Then you dont force one fan to do all the cooling. Efficiency in what you have will change temps.
  6. I'm using a 6'' exhaust fan I believe. I could just put that one in the veg room venting out, and get a stronger exhaust fan for the flowering room.
  7. 82-86F is fine with Co2...
    So add Co2 to the chamber and problem solved....
  8. Its 82-86 at 600w. At 1000w I was hitting 85 degrees within an hour of the lights turning on. I could have easily pushed into 90 degrees if I left that on. I've also noticed that when I run my osc fan the temps go up since it must be mixing all the air in the room together.

  9. Ya, that is a little high and way to fast...

    You want to separate your chamber cooling and your lamp cooling..
    What I would do is run a 6" inline duct booster fan for the lamp cooling..
    [ame=""]You can get them for like $35 bucks[/ame]..

    The reason I separate the lamp and chamber cooling is because it will make your carbon filter last longer... You do not need to clean the lamp's air if it is sealed off from the chamber...
  10. Where does the 6'' inline duct booster fan go? I have air coming in from the passive cold air intakes>>Carbon Filter>>flex duct>>light chamber>>flex duct>>exhaust fan.


  11. Like this...

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  12. I think I'm going to put another smaller exhaust fan in the veg room. Seal off between the veg and flower room. Then put a portable 12000 btu air conditioner in the flower room and vent the exhaust out. Sound good?
  13. The duct booster fan wont move the amount of air he needs through a filter. A propeller fan does not create static pressure. It must be an inline or a squirrel cage for that set up.

    A bigger fan moving more CFM will certainly help. You said you fresh air return was from the outside correct? Is there anyway to pull indoor air? (slightly cooler)

    The AC unit will also dehumidify for you. A 12000 BTU portable air conditioner will definitely help. If you vent with 4" round pipe (26g dryer venting), you could insulate it and keep the condenser from throwing heat back in your grow room.

  14. You did NOT read what I posted....
    I NEVER said use a duct fan on a filter!
    Not once :rolleyes:
    You must be :smoke:
  15. Your absolutely right I apologize. Im a little high so I did skim through a bit.
    Pentak gave good advice straighten up those flex runs, that will help.
    At any point when you do get the temp down your RH will increase.

    Im still a little confused on your setup.
    You have two separate cold air supplies to your veg and flowering room? How big?

    Your veg and flowering room are connected by a duct, and you only have one exhaust fan in the flower room? They are in entirely separate rooms correct?
  16. Yes they are entirely separate rooms. With the help of some bud all day I have figured out the plan. I'm going to do what someone said above and seal off the two rooms. Get another small exhaust fan for the veg room, and get a 400 cfm intake fan for the flowering room. I already have a passive cold air intake from an indoor area that stays 65ish degrees or lower all year in both flower and veg room. I have also started talking to a guy about a cheap portable lg ac. I might go grab that too just to make sure I'm set.

    I went in there and straightened up the flex duct and it lowered temps 2 degrees in both rooms. Woot.
  17. Yeah thats good, always try to keep as many kinks and bends out of your ducting as you can it really improves air flow when you do. :cool:
  18. I got all of the vent/air problems fixed for the time being. After 9 hours of light in the flowering room at 1000w I'm at 81 degrees which is pretty good. Low humidity though (30%) in the flowering room. In the veg room with the new vent its sticking around 70-77 and 50-60 percent humidity at all times. To fix I put in a 400 cfm fan in the veg room which is 320 cf and sealed off the ventilation between the flowering and veg room. I also added a 165 cfm intake fan to the flowering room to bring in cold air.

    Thanks for all the help GC! :smoke:
  19. If you dedicate a fan soley for exhausting hot air from the cooltube you can lower even more. Going thru a scrubber you lose about 60% efficiency not taking into account the length and bends of vent pipe that effect static pressure..;)
    Bringing in fresh air from floor level is cooler air....
  20. Yes I know the air from lower is cooler but the guy that I was working with said that too much light would get through.

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