Help!! Its so hot!!!

Discussion in 'Micro Grows' started by Montesquieu, Jul 13, 2010.

  1. ok so i've had my grow room set up for about a week now and finally got my 400w hps going.
    only problem is its 85 F degrees in there! way too hot right? :confused:
    at least it feels to me like it is. i was shooting for 75.

    ive got a 6" inline exhaust in my attic pulling air across the bulb, i also have a passive intake at the bottom (plan on having a small fan there) but thats it for now.

    what can i do to cool it down more? i thought i was doing everything right :(
  2. by the way heres some pictures of the room so you can get an idea of the scale of it.
    5 gallon bucket inside for size reference.

    Attached Files:

  3. :hello:eight five is ok just don't go any higher unless supplementing co2:smoke::smoke::wave:good luck
  4. alright cool, im gonna run the light for a day and see how hot it gets after 18 hours

    once i get that intake fan down in the bottom it should cool down a bit.

    i appreciate the help:smoke:

    i put a 9" high velocity fan at the rooms intake hole and kinda made a little snoot (photography term for you) or funnel out of poster board to make as close to 100% of the fans air flow make it into that hole.

    i left the light on for 12 hours and checked my thermometer and it was 95 F degrees!!!! :eek: thats hotter than it is outside today.

    my thermometer is sitting on the ground so i thought its plastic housing might be getting overly hot since its just sitting beneath the bulb. i made a little shade thing for it out of poster board to see if that changes the temp. then again i wont be putting the plants under shade obviously, so this may been a unnecessary test.

    please post some suggestions!

    ill answer any questions you may have about the room's layout as well.
  6. self bump.

    i still need some help! im at a constant 90 F degrees now.
    i need to know what i can do to cool it down more. or if that isnt possible, what steps i need to take now to make sure the plants survive.

    earlier someone mentioned something about supplementing co2?
  7. Yea Baby - its getten hot out there..

    What is the dimensions of the room.
    You should have a fan large enough to do 5 exchanges per minute.
    Fan should be oriented to SUCK and not BLOW (try pushing a string)
    Fan should be as high as possible.
  8. I have heat issues as well. Check out my thread below and see what I had to do.

  9. I'm a first timer My grow room is 4 feet x 3 1/2 feet by about 8 feet high. Although I had a 4" inline fan sucking over the 400 w light, my temp ran high.

    I broke down and put in a $99 air conditioner that operates in a small room in the attic, in which I suck the AC air into the grow room when the temp gets high.

    This provided a cool 75 degrees with relative humidity running between 40 to 60 (the AC brings humidity down to 40 and when the temp goes to 78degrees the humidity may have reach the 60 mark by the time the AC goes on again). I was running 24 veg hours a day but cut down to 18 hours due to our Cali heat wave (light off during the hottest parts of the day). 

    That's what was necessary for the right temp in my grow room. Never would expect it from the books I've read.

    My question: I have some fuzzy mildew so I need to keep the humidity down during lights out when the AC doesn't run that much. Should I get a Peltier dehumidifier? It would have to be real small. Do they work at all?

    Btu...I sprayed a 10 percent solution of whole milk to water and that seemed to take care of most of the mildew. Can burning suffer work in a micro environment?

  10. hey man i have the same situation, i put in my new 400watt mh/hps (same one as yours:p) about 3 days ago. my plants love it but the temp went up to 85-90! i didnt have the money to buy a new vent system yet so i put in a house fan that sits on the ground and cranked it up to pull air out. its not much but it got my temps down to about 82 :D
  11. It's amazing how much heat builds up in a micro grow room. In all the books and mags I've read no one gave notice on how difficult it is to manage heat without AC. They make it sound like venting the light and room is adequate enough.

    I tried my "room venting system" for heat and humidity. When the AC is on the room venting system (sucking out inline 4" fan - about 280 cfm) turns on (it's set to turn on for 1 min every 15 min for fresh air/co2) the temp goes up along with the humidity. Without the AC I always ran at least 10 degrees hotter that the temp outside the room no matter how much I vented.

    I'm trying the room vent system with the light out to see if I can use it to rid the humidity when the the AC and the light are off.

    I'll let you know what I find.
  12. 1. I don't think this counts as a Micro Grow
    2. If you had a full cool-tube, i'm betting that you'd see much lower temps. Even if you had an open-ended one you would see significantly lower temps. Seems that your light is mounted with an econowing reflector, the air being pulled from the socket end of the bulb. the problem is that you're not actually exhausting the air over the bulb, just pulling l it from the socket area...not a whole lot more effective than simply exhausting from the top o the cab

  13. the dimensions are 4'x4'x6'
    i moved my fan as close to the exhaust as i could get it.
    6" inline supposedly 250 cfm pulling

    i also have an intake thats pushing in air too. i was hoping that would help with the air flow across the bulb

    do you think it is too large for a micro grow or something? i was under the assumption that micro grow applied to closet growing? :confused:

    do you have any suggestions for the setup where i could increase the airflow across the bulb?

    thanks for the help everyone

    edit: i forgot to post pictures before
    the 1st is the 6" exhaust fan pulling air out
    the 2nd is the 9" intake pushing air in

    Attached Files:

  14. Is the 250 CFM venting the room or cooling the bulb?

    4X4X6 = 95 Ft3 X 5 = 480 CFM.
    If the 250 is venting the room it is under-gunned.
  15. #15 Montesquieu, Jul 16, 2010
    Last edited by a moderator: Jul 16, 2010

    kinda both. the starting point of the exhaust is at the socket end of the bulb then i have about 3 feet of ducting that runs to the 250. i figured it was kinda weak and that why i have the 9" pushing at the bottom.

    i have so much airflow into the room that the mylar is ballooning outward.
    from what p_snickers was saying, i dont think my exhaust hole is big enough for that airflow to escape.

    the picture of the "cool tube" i made is below

    Attached Files:

  16. sorry to double post again.

    would adding another duct fan to my exhaust help boost the airflow and get the cfm's i need? or should i look into another cooling method? a small ac unit maybe?
  17. The first thing I notice is that you have a lot of bends in your ducting. Try to make it as straight as possible, as rigid as possible, and as short as possible. Bends in the duct and movement of the duct itself reduce air flow. Stretch the duct as much as you can. This opens it up a bit more and makes it more rigid.

    If your temps went up when you added the intake fan, then it is more of an obstruction than a help.

    Your cool-tube rocks! But obviously something is wrong. What is the ambient temperature outside the grow room? You may need another fan, inline with the existing exhaust fan, to help pull the air. Perhaps this 2nd fan could be placed at the exhaust point in the attic. Or you may need a/c.

    The general rule is that the intake should always be greater than the exhaust, because there are obstructions to airflow (called "static pressure") within the system. So, the diameter of the intake hole should be larger than the diameter of the exhaust fan. People usually say the intake should be 2x the exhaust. So, if you have a 6" diameter exhaust fan, you should have two 6" intake holes. This might be overkill, but it will ensure that you have enough intake.

    Similarly, if you were to have two inline exhaust fans, the first fan (the one closest to the light) should be more powerful than the second. This is because the first fan is acting as "intake" for the second fan. How much more powerful depends on the static pressure between the two fans (ie the length of ducting and the number of bends). The main idea is that you don't want one of the fans to be more of an obstruction than a help. Having said that, I think if you got a similar fan to the one you have and put it in the attic, it would definitely help.

    I just looked at your pics again. You want the first exhaust fan to be as close to the light as possible. Ideally it should be mounted on the tube.
  18. Sorry, Mont, I didn't see your last post. But maybe I answered your question? Whether or not you need an a/c depends on the temp outside the grow room. What is it?

    I would try a second fan before adding a/c because a fan is cheaper to buy and operate, and less noisy. Shortening and straightening your ducting is free (except for your labor!), so do as much of that as you can!
  19. Sorry for so many posts, but I may be wrong about the exhaust rules when it comes to cool tubes. Your intake on the socket end of the tube is obviously smaller than the exhaust, because the socket itself is an obstruction, but maybe this is not a problem -- I've seen other people do it the way you have it.

    Perhaps you could improve temps with a different kind of reflector -- one that has a glass lens on the bottom, and a 6" hole for the intake. It would be less restrictive.

    Another option would be to use 6" ducting and a 6" tube. This would definitely increase airflow.

    But I still think the first thing to try is a 2nd exhaust fan. If you have to upgrade to 6" ducting you can still use the 2nd fan.
  20. thanks for the help vashigopal.

    i think the reason my temperature got hotter after i added the other fan was because before then, i had not run my light for the full 18 hours.

    the only reason my tubing is so bent is cause there's no attic access through my closet. im having to bring it across my bathroom to where the fan there usually is. i bent it up the way it is so i dont have to duck under it all the time to go take a shower. ill see if i cant straighten it a bit though.

    the temperature outside of my grow room is 77 at the moment, but its 75 in my house so that was kinda expected. guess i should knock the thermo down a few notches.

    im looking at getting a 8" 500cfm inline to replace the 6" 250 in the picture. i was thinking of putting the 8" in that same spot, but ill see if i cant attach it straight to the glass tube of the "cool tube". i will then move the 6" back into the attic where it originally was, at the end of the ducting.

    again, thanks for all the help. +rep headed your way :smoke:

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