Unable to solve heat issue...giving up on growing

Discussion in 'Grow Room Design/Setup' started by thebigdc, Sep 16, 2009.

  1. Well, after many days and alot more $ than i wanted to spend..i have finally decided i am unable to control the heat problem in my grow box. I've already got my seeds from attitude so this is very upsetting that i wont be able to use them.

    I was going to grow in an upright freezer. 6ft tall, 2ft wide, 2ft deep approx.
    I have 2 x 4" intake holes cut on the bottom of the freezer.
    For exhaust i have 2 x 4" exhaust holes cut on the top of the freezer. At first i had 2 x 79cfm exhaust fans....silent but temps stayed about 95.
    i have since put on 2 x 205cfm fans. Temps still stay about 90+, and the noise sounds like i'm running a jet engine. Inside the freezer i have 2 desk fans circulating air and am using 8 x 27w cfl's.

    Unless one of the good people on here can figure out how to lower the temps...i suppose i've wasted a TON of money on the seeds and growing supplies :mad::mad::confused:
  2. unless your pumping cold air in your going to continue having problems, its a freezer.. it was DESIGNED to stay cold and keep cold air in, so reverse that and you have your answer..
  3. Are you using axial (pc) fans?
  4. Replace the lamps with an air cooled system.

    You can use the holes you cut already for stink control or seal the unused ones.
  5. Giggity..yes i am using pc fans.
    I really cant afford to spend much more on this box.
    Right now the top of the box is at 89 and holding...just moved the thermometer to the bottom where the lights and plants are..waiting on a temp..but i'm guessing it will be about 95.
  6. your passive intake(s) should be twice the size of your active exhaust. cut two more intake holes or double the size of the current ones.

    but the more important question is what are the ambient temps where this freezer is located?

    don't quit because of heat issues when summer is about to be over!
  7. Lorenzo...
    i thought i had read somewhere that said the passive intakes should be half the size...that didnt make much sense to me but thats kinda what i was going for. I'll drill some more holes in it tomorrow and see what that does for temps.
    the ambient temps int he room the freezer is in is about 73 at night and probably 80 or a tad lower in the day. You are right with colder temps coming up that air will be much cooler. I'm trying to get an accurate ambient reading in the room now....
  8. sounds good man. you should be able to get those temps down with just cfls. you might even be able to go back to the quieter fans too with the intakes taken care of. good luck brother
  9. #9 toastybiz, Sep 16, 2009
    Last edited by a moderator: Sep 16, 2009
    On the size of intakes, the best answer for heat management is double the size of the exhaust. By having lots of intake available you are allowing the air to flow freely and the exhaust to pull at it maximum ability.

    But, that is not the best odor-control way to manage the pressure in your box. For that some folks recommend the opposite of the above, have the intakes only half the size of the exhaust. That will cause your exhaust fans to work harder, they are having to pull air through relatively small holes (it's like when you drink through a straw). This causes lower pressure inside the box, so any little gap will suck air in (and therefore keeping the odor from escaping those little gaps).

    To the OP, if you're out of money then you're SOL. But if you can build yourself a cooltube for a few dollars that will help a lot -- it will create a separate air ventilation system for the light that keeps most of the heat from ever getting to the plant. You do have to keep in mind that a freezer is heavily insulated and designed to hold a temperature in.

    Oh, and BTW, if you want a hole to be twice the size of another, when dealing with circular holes remember that twice the size (meaning area) does not mean twice the diameter. To double the size of a pair of 4" holes you should make them each about 5 and 3/4" diameter.

  10. Thanks for the info.
    I'm not too concerned about odor control., mostly the heat.
    I dont really have a way to enlarge the 4" intake holes any bigger..i can just drill anohter 4" hole or i have a 1" hole saw as well. what would you recommend for that? I dont think a cooltube would work for my lights...here is a pic of the light setup right now...

    Attached Files:

  11. Build a frame to hold a sheet of tempered glass just below the light. Completely seal in the light/ballast from the rest of the room. Divert one of the computer fans as an exhaust for the new sealed light box (don't forget the inlet too). Now the grow interior can remain at a lower temp while utilizing full advantage of the light through the glass. Hope this helps.
  12. Well i left the setup running all night. It seems to be holding at about 85F with 45 RH. That temp will lower more once the cooler temps get here. For now would 85 work even though its a tad high? I haven't put any new intake holes in her yet, i am gonna drill 1 or 2 1" holes in addition to what i have now..hopefully that helps.

    Also, having 3 internal air circulation fans wont hurt the plant will it? I dont wanna have too much "wind" in htere and break the, etc.....

    I'm gonna start germinating my seeds tonight.

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