Some tent ventilation help?

Discussion in 'Grow Room Design/Setup' started by dustin27, Sep 30, 2010.

  1. #1 dustin27, Sep 30, 2010
    Last edited by a moderator: Sep 30, 2010
    Hey all. I'm in the process of constructing a new tent. Before I head off to the shop to pick up the new hood and fans ect, I just wanted to double check and make sure my plan is efficient.

    My area is 5x7x7ft. 245cubic feet. I run a 1000w HPS in flowering.

    1. will 6 inch flanges be adequate for a 1000w, or will i need to go to 8?

    I plan on going with a centrifugal fan vortex style, 450ish cfm.
    I have one source telling me that it might be over kill to some but he says keep it at 1cfm per 2watts. However that would leave the tent getting an air exchange almost 2 times a minute. I just dont think any axial or inline fan could cool the lamp enough, even though i dont have to duct very far.

    2. my plan was to go with the 450ish cfm fan and get a variable speed controller with it, instead of working with a smaller fan? yes/no?

    my main concern is keeping a temp range of 75ish in the tent, and the rh around 40. general rh in my area is 20.

    also, how loud are centri fans, what can i expect? security is no issue in case of wondering...

    thanks guys. sorry for my poor punctuation, im workin on an old laptop with half the keys missing.
  2. My tent is 2x4x7, so a total of 56 cubic feet. I run a 400w light and cool it w/ an inline duct fan from htg supply. I exhaust the hottest air, from the top of the tent through a carbon filter w/ a 170 or 190cfm fan and I stay in the mid 70s right at 40% humidity.

    I suck at math, but maybe you can do some calculations and that might help.

    Also, I keep the thermostat in my apartment between 66-68 degrees.

    The inline duct fan is 6 inches, and the carbon filter fan is 4.
  3. thanks for your input! if your fan is pulling through the filter it would cut down the cfm rate at which your air was being exchanged. if not, id imagine it stays near the same.

    ive read that you only need to change the air every 5 minutes, but ive also read, the like the great outdoors, the more fresh air the better.

    my thermostat in my place doesnt work for telling the correct temp. Ill have to pull a thermy out and check my ambient room temps/rh.
  4. bumping!!!!!!!! 250 views over night and not one helpful answer.
  5. I'd use this for exhaust..
    High Tech Garden Supply

    Then use whatever you have to to keep that light cool.
    I use this w/ a cooltube.
    High Tech Garden Supply
    But you might be better off w/ something like this or maybe bigger. That way you wont have to run your a/c constantly or worry about the plants getting fresh air.
    High Tech Garden Supply

  6. 245 cubic feet. x3 for fresh air= 735 CFM rated fan. x2 for air restriction from carbon filter= 1470 CFM rated fan

    yes a carbon filter reduces airflow of a fan. This is why when you build your own carbon filter you have to make sure all activated carbon is the exact same thickness. Or your fan has even a harder time pushing the air
  7. no carbon filter the smell is fine. im dropping the height down to 6ft instead of 7. I think that was too high. 1470 cfm is way to big i think...
  8. 210 cubic feet in your new space

    x3 for air movement= 630 CFM rated fan

    no need to do more math. No carbon filter

  9. Take this guys advice is my opinion. If you can afford it

    first your upset you get no help and then when you get help and you don't like it you just say it's no good. Read some more on venting. If stealth isn't a factor and you live in a super cold area you don't need nearly as much cfms. But with what little info is given. You get maximum numbers spit back at you. Do whatever you like. Apparently you already have the answers. Why ask if you just gonna say" I think that too big".
  10. I've stood in my closet for days at a time in a lab coat w/ a clipboard and 10 thermometers in 10 different places studying this for about 6 months.
  11. thanks for everyones help. i never said anything was no good. i was looking for many opinions. I'm sorry if I got on anyones bad side. Most importantly, I dont want to spend money on the wrong fan.

    it seems like if i dont have to vent but only a foot or so then I would be okay with an inline fan pulling air through my hood?
  12. Use two fans.

    One fan cools only your light and never uses grow space air

    the other fan just pulls fresh air into your grow and pushes it out

    read threw what he suggests. And use a carbon filter. People will be in your business faster than you think without one. Build your own if you have to. 30 bucks for piece of mind
  13. Interesting. Do you feel this is better than leaving one side of the hood open and pulling garden air through the hood?

  14. Both methods are proven with tons of results on GC

    personally. I find it much easier to have just one fan and pull air threw my hood. I also would overcompensate my fan. Just so I could dial it down and make it quieter. I didn't think noise would really matter in the beginning. Try having people over to the crib with a 747 landing in you grow space. It's gonna be that loud. So the trick is getting a giant fan and slowing it down. Saves one headaches as well

    your going to have a 1000W bulb in your closet. How cool are you thinking this is going to run? Take a trip down to a hydro store and ask for a demo. Stick you hand on the bulb and check I out.

    After you get back from the burn unit. Look into using a fan with a large cfm rating to cool that thing down.

    1000W bulbs have to stay something like two feet away from plants. Or it melts them.

    Take some pics of your grow space and give us so
    w temps. Where are you ejecting you air too?
  15. I havent build my new tent yet. I'm aiming for 75 degrees temp wise. I have a 1000w on a open winged reflector, so I know how hot they get.

    I was also leaning towards one fan pulling through the hood.

    Since I havent tried any vent stuff myself, Im trying to get alot of opinions.

    The opinion I seem to be getting the most of is exactly what you said. Basically, go with a bigger cfm and introduce variable speed control.

    It sounds like youre referring to centrifugal fans as the loud ones. Centrifugal style fans seem more economical to me, aside from the noise. However I would be fine with small inline fans venting if it serves the purpose well.

    I will try to get pics of the construction of the tent, I have to do that before I get the fans and hood together. I will most likely have air ejecting straight out of the tent into the room it sits in, with a small possibility of running ducting up into the ceiling, or out the window. I have those panel ceilings you see in schools alot, so I could just move one over.
  16. I was talking about inline fans. I have a four inch. It's super loud. Skip the four and shoot for the six. Much quieter. And If your willing to, Cut a hole threw your drop ceiling. Tiles are easy an cheap to replace. Ana they have a nice R value. So it can easily lock out your grow rooms heat.

    Can't wait to see the pics. Mylar or paint? Stud framing? Does your 1000W ballast use the 120 or 240? Switchable? I'm assuming with the drop ceiling this is an older style split level with a converted basement?
  17. I built the frame out of 1" pvc pipe, and covered it with black plastic, then lined the inside with mylar.



    bad pics but you get the idea. Its large and in charge. At this point I still have to fasten the plastic a bit more, attach the mylar a bit better, rig a door, and double check for light proofness.

    As far as the door goes, I have 2 layers over the side closest in the second pic. The first layer I have cut a line straight down through the plastic, and use that as the opening. Then I have the second layer coming down over it.
    My ideas are: velcro the sides of the second flap, and have pvc pipe attached to the bottom perpendicular to the velcro, then I could roll the flap up around the pvc like a gazebo tent style flap,


    Velcro the straight cut on the first later, and the bottom and as much side as i can of the second layer.

    I may just go with the simpler version and velcro the opening.
  18. i'd use velcro and a tarp zipper... found at lowes... or home depot.. i was at the hydro store today for like three hours... they had them there as well...

    you would just have to have a little more material to cover up your zipper opening...

    keep the pics coming.. and make sure you keep taking them...

    this could be epic

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