Please help me solve my heat issues?

Discussion in 'Grow Room Design/Setup' started by InterWorks, May 10, 2011.

  1. #1 InterWorks, May 10, 2011
    Last edited by a moderator: May 10, 2011
    I have a cabinet built, and here are the basic specifications of it:

    18" Wide x 18" Long x 20" Tall
    2 - 26 watt 65k CFLs
    1 - 26 watt 27k CFL
    (Both plugged into a power strip via plug in sockets)

    Now, the power strip and the CFL's are mounted in the top of the cabinet, facing out, with their sides facing down towards the floor to present the most light to the plants. They are separated from the grow area by 1/4" plexiglas in a space 4" tall.
    This slice of space I have airtight except for a 1/2" slit going down into the growing area and a venting shaft I made which is pulling air over the bulbs and out using a single 12v computer case fan rated for 60 CFM.

    Air is being sucked from the cabinet, past the bulbs, through the vent, and is expelled out the back of the cabinet. I'm not using an intake, I'm letting the box draw air from the spaces in the door, and that air gets drawn through the slit near the front in the plexiglas.

    Now for the problem:

    In my dry runs (Without plants or seedlings) I get a temperature of somewhere between 80 - 85 F and from what I'm reading, that's too hot, by about seven degrees.

    Am I right in thinking that? And how can I solve this?

    My first thought was putting a passive intake (Just a light proof, filtered hole) in the section that's plexiglassed off for the lights, to draw fresh air through that part.


    Make an active intake for the plexiglas section.

    Any help is appreciated!



  2. You need an intake.....same size as the exhaust, maybe 1.5 the exhaust size...this is just a hole (light trapped)

    Try using cardboard over the door with varying hole sizes to see if it solves the problem....all holes at the bottom of the cabinet

    Report back
  3. Seal the room and add Co2...
    Problem solved...
    With Co2, temps can be in the mid to upper 80s...

    Or make a HillBilly A/C Unit to cool the chamber...
    [ame=""]HillBilly A/C Unit[/ame]
  4. You're suggesting co2 installation for a 18"x18"x20"? Come on man really?

    His problem is exactly what Tihspeed said, He needs a intake.

    You can't exhaust and move air properly without a dedicated intake fan or passive intake holes. Get a intake installed, and then the issue will be solved.
  5. #6 InterWorks, May 10, 2011
    Last edited by a moderator: May 10, 2011
    First off, thanks for all the responses guys! It's really nice to get some help instead of lurking for the answer.

    I left one of the doors open which is roughly 8 times the size of the outtake fan hole (like Tihspeed recommended) Hoping that it would increase the air flow over the bulbs and solve some temperature issues.

    The temperature dropped by around five degrees, which is spectacular, but still leaves me with a temperature of 80 - 81 F

    Another thing I've noticed that I hadn't before is that the temp in the room where the cab is, is higher than the rest of the house. (Derp, should have checked that...)

    For those who grow in standalone cabinets, what's the temperature of your room that you've got the cabinet in?

    What I think I'm going to do is:

    Drill a passive intake in the bottom part of the cab, light proof, and filter it.
    Maybe move the cabinet to a room/closet that's more temperate?

    There's a possibility of me being able to make a CO2 generator in there, because of its small size, could I get away with letting my wine burp into the room via a long overflow tube and a water filter, dispersing CO2 into it?

    This is what I'm talking about:
    [ame=""]YouTube - Setting Up An Overflow Tube[/ame]

    I think that's a good solution as well if I can't get the temps down, as it would let one of my hobbies feed the other.
  6. 80 - 81 degrees isn't bad at all. If your ambient room temperature is 75 or 80 expect that your grow box will be 83 - 85, usually a couple degrees hotter then the actually room temperature the box is in. Your box is only going to be as cool as your room.

    You shouldn't need a co2 generator for that small of a grow operation and that little bit of light, You just need proper ventilation.
  7. So, what you're saying is, if I can drop the temps to 80 - 81 F using a passive intake it would be perfectly fine to grow in?
  8. 85-90 is disaster zone. If you can keep a solid 80 you would be fine as long as your humidity doesn't get out of control. But I mean if really thing you want to go head and do that co2 thing anyways more power to you. Just sounds like your trying to get around actually fixing a ventilation problem.
  9. Not in the least.

    I'm going to make the intake. I've just read that the ideal temps are around 75 - 78 F
    I'm trying to work to make a usable cab, and I've got a lot of time invested in this one which makes me reluctant to scrap it and start over if it's an issue that can't be worked around.

    I doubt it's unworkable, but I'm trying to assess all my options.
  10. Grow bible says temperatures about 75 are good, up to 85 are great, but over that is too much.
  11. Perfect.

    What version are you using?
    I've got "Marijuana Horticulture The IndoorOutdoor Medical Growers Bible"
  12. Greg Green

    I have read that one you have mentioned as well, very solid read.
  13. Thanks man. +Rep for all your help.

  14. DIY Co2 costs about 5 bucks, would work in that small size and would solve his problem...

    So ya, for 5 fucking bucks to fix my issue, I would, but I guess you wouldn't huh...
  15. If you say so. To each his own.

  16. Honestly, if you can increase the grow rate and solve the heat problem for like 5 or 6 bucks, you would not do that??? :confused::confused:

    Ya, I guess options are like assholes... ;)
    Everybody has one... :smoke:

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