Questions on exhaust for grow room

Discussion in 'Grow Room Design/Setup' started by Budsworth, Jan 15, 2010.

  1. I'm still trying to figure exhaust.

    A. Having trouble figuring out a ducting run between lights and intake and exhaust.
    B. How a filter fits in the system and where.
    C. What set up would control odor the best.

    I have some other questions...but lets start with those.

    Some specs on the room:

    Room=13' x 7'6" x 10'
    Closet=2'10" x 6'10" x 10' (ballasts will have to go in place outside room really).
    Window on one side that MUST be sealed (don't want to bother the neighbors with lights or odors).
    Door goes to main living space (I know...only substantial space in house).

    I have figured out the following:

    Minimum needed for 1 to 3 minute rule on air exchange with 5% added for lights, 20% added for filter:


    Was looking at this fan as it is SUPPOSED to be quieter:

    8" Max Fan

    I'm just trying to wrap my brain around some things...and anything you can offer up will help. It will most likely lead to more questions...but it will help.

    I've numbered the lights for ease of telling me how posters think flexible ducting should run.

    Thanks. :wave:


  2. I would put the drying tent close to the intake or run some ducting to a point in the room where you are getting 70F temps consistantly. I would put a 10" fan for exhaust., then i would run 6" ducting from intake to light 1-2-3-then up to a 10"-8"-6" Y.

    Off the 8" side, I would run it up on the celing into the veg room. Then I would poke holes in the duct as needed to regulate temps in the flower room.

    You could have the lighting ventalation seperately on a 6" fan while having the temp/odor control on an 8" fan to provide a more stable environment
  3. #3 Budsworth, Jan 15, 2010
    Last edited by a moderator: Jan 15, 2010

    Okay...working on changing diagram.

    Question. Where does the filter tie in?
  4. Like this? (minus the filter until I know where that goes).

  5. Would I need to cut another exhaust hole? Or just the Y?
  6. are you planning on venting your air that cools your light into you room(not sure by drawing)?
    I would run the air cooling for your lights on seperate fan from exhaust. If you push air thru your hoods you wont have smelly air flowing out and no need to run the lights air thru a scrubber.

    Also try to eliminate bends in venting, it will cause decreased flow from you fans.


  7. If I ran air cooling through the lights...where do I exhaust it? And why don't I need a scrubber if I'm running through the lights?

    And what do I do with the other exhaust for the room? Just leave it with a fan at the exhaust point and no ducting?

    If I can get this straight what you're saying...I'll alter the sketch and make sure I'm thinking what you're 'splainin' lol
  8. well where you exhaust is up to you...I personally on my room vent the air I use for my lights from the hallway thru fan and over lights back into my bedroom(only during the winter months, that way I dont need to heat my room) but once summer hits I just switch a duct to vent out thru the attic.

  9. I don't think I explained myself very well. I'm thoroughly confused.

    So let's see if I've got this right.

    I need TWO ventilation systems. One for lights. On for room.

    So...for lights I INTAKE FROM THE ROOM? Or do I intake from the intake hole to the crawl space? Do I do a ducting run from the intake to the lights?

    For the room...I intake from...whoa. I don't think I understand. Do I put any ducting on the intake hole from the crawl space? Do I leave it open and use it that way for intake for both?

    totally and completely confused.
  10. I think maybe perhaps I'm not understanding the basic principles of how to correctly ventilate a room.

    Does anybody have any links that might explain it to me? I tend to work better by diagram (like my pic). I have a hard time comprehending stuff through just words. Hence why I drew the pic.
  11. #11 VoteYesin2010, Jan 15, 2010
    Last edited by a moderator: Jan 15, 2010
    The main thing is what wattage of lights are you using? Do they need to be air cooled?

    Sorry if you posted this already but I didn't see it anywhere. Put a "Y" on your intake.

    Put a small inline booster fan on the veg light and run the output to the flower room. If the light is big enough to have to cool! If not, don't hook up the "Y" to the light but still use it to vent straight to the flower room. This way you are controlling both rooms somewhat seperately.

    Put a 8"-10" exhaust fan from home depot on the floor between the 2 rooms. May have to make a maze to light proof it. Use a thermostat to control it in the veg room.

    then run ducting from the 2 flower lights to a box that you will make out of MDF or plywood that houses your charcoal filter and fan. Thus creating a vacuum chamber. The fan's outlet will be sticking out the back or top then attach the fan to your outlet. Use a thermostat to control it in your Flower room.

    The vacuum box is the key to filtering all the air in your room by not needing to hook everything up inline

    View attachment 332055
  12. Hey Budsworth,
    I will respond late morning. I saw your PM and didn't want you to think I abandoned you.:D Worked another 14 hour day. Sleepy time now. :wave:
  13. #13 Budsworth, Jan 15, 2010
    Last edited by a moderator: Jan 15, 2010

    This makes sense. And yes. Three big lights (1000w). Thank you for this design. I am assuming the fan between the two rooms would direct air INTO the veg room. Any particular place it should be located? i.e. high, low, middle, towards window like you indicated? I plan on hanging the panda film over a two by four, screwing that to the ceiling...and I could frame out a box and drop it down from the two by four to place the fan wherever I need it.

    And before someone says anything...working on electrical with my electrician right now. Good friend. Been playing in a shitty "hangout in our other buddies garage once a week, get our buzz on, and be loud" band for 5 years (and we have only gotten slightly better lol). Been an electrician for 30 years and knows exactly what this is for.

    on edit: Wait...I see you said put the fan between the two rooms on the floor.
  14. I know how it work days are usually about that long...if not longer. And I have some days coming up like that. Helping a friend all back to house in the evening to size up the entry on that closet (stupid 100 year old house...the opening to that massive closet is on one side and the size of a small doorway...making the closet almost unusable) for supply on Saturday from 10am until probably 2am...Sunday morning cut out the opening in the closet...Monday start working on electrical.

    Very busy. So...don't think I'm ignoring you after you give me your ideas. You'll probably just get a quick thank you for the next few days.

    Thanks for your help everybody.
  15. Budsworth,
    Your diagram shows "exhaust tied into furnace hot water heater exhaust". I would strongly recommend that you NOT do this. There is a delicate static pressure balance that must be maintained so that the furnace and hot water heater combustion gases are properly exhausted. "Teeing" into their exhausts will upset that balance and could result in a backdraft situation that could cause carbon monoxide poisoning. Stay safe, bro!
  16. Using one fan, one intake, and one exhaust is not ideal for your grow space with two rooms and air cooled lights. You should really have a separate sealed air 'circuit' just for your lights. In any case, the diagram below shows a way of using what you've got. Note that the veg room light ends up not being air cooled. Also note that there are no 'parallel' hook ups for air (no tee's). Without proportioning dampers, you can't control how much air goes through each leg - way too complicated. I'll post a pic of a more ideal setup.

    Attached Files:

  17. Below is a diagram showing a separate hood cooling leg with its own fan, intake, and exhaust which is more ideal for your grow op. Since this is a sealed leg (air in this ducting does not come in contact with room air) it does not need to go through a carbon filter. The other fan, intake, and exhaust are ventilating the room and will need to be scrubbed.

    Depending on the size of the room and the fan, you may need to add intake fans instead of just passive intake ducts to boost the flow. The intake cfm's must always be below the exhaust cfm's to ensure negative pressure (slight vacuum) so that smelly room air does not leak out.

    This is one way of doing it. There's plenty more...

    Attached Files:

  18. That seems to be the most simple suggestion so far.

    A couple of quick questions:

    Since the "light leg" is only pulling the air through the lights...does the exhaust fan need to be as large as the one that will be scrubbing and pulling air all the way through the room?

    The vents between the two rooms...located on the floor, ceiling or middle?

    And the exhaust...since you say it would be dangerous to tie into that...can I run one exhaust stack through through the roof and use it for both the light leg and the room leg. In other words...just Y those two into one stack going out the roof?

    Oh....and thank you very much. That idea is very straight forward and easy to understand.
  19. For the light 'leg', a 6" vortex-style would be good since 6" is the most common size used on the hood connectors which just makes hook-up easier.

    Intakes from outside are generally close to the floor since you want to bring in cool air (cold air sinks). For the intakes between the rooms, I think I'd have a couple - one on top, one on the bottom.

    Yeah the exhausts can be tied together into one - The stack must be big enough to accommodate the flow from both legs.

    Good luck bro!

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