Excess Heat In Grow Area

Discussion in 'First Time Marijuana Growers' started by jonb, Aug 24, 2008.

  1. I have 10 jiffy pots in a small enclosed area with two compact fluorescent lights. Each has a newly planted seed in it. 5 of them have started to show plant material and I'm still waiting on the other 5. I have found that its very hard to keep the temperature in the area down at 75F even with the door open and a whole bunch of fans pointed at it. It gets to 86 sometimes... I know this is way too hot for the plants but I don't know what to do to cool the room. I have an exhaust fan (small one, "computer fan") at the top left attached to a carbon filter and another small fan which is used as intake at the bottom right. I can't really be leaving the door open as a permanent thing so I need to find a solution to the heat problem. Can anyone suggest something I can try to tackle the heat? At what is the maximum temparature the plants can stand?
  2. well then theres an obvious solution, more fans.
  3. Okay, so if I just put a floor fan on the shelf above the plants near the exhaust, would that help circulation and temperature.
  4. fans blowing on your lights always helps cool thelights down, thus dropping temps.
  5. #5 Mr. MJ, Aug 24, 2008
    Last edited by a moderator: Aug 24, 2008
    How are 2 small CFL's causing that much heat for you? I've got a 400MH in a 2x4' space, and even without ventilation I rarely had heat problems. Then again, I don't really consider 85-86 degrees to be a significant heat problem, just a little out of the "ideal" range.

    Either way, simply adding more fans won't necessarily bring temps down... you could end up just blowing hot air all over the place. Fan placement is just as - if not more - important... but it sounds like you have an intake/exhaust system in place already, which should be helping. I would recommend a few things maybe.

    1.) Look info 'regular' flouros rather than CFL's. They emit less heat in my experience.

    2.) Get BIGGER, more powerful fans, and find somewhere to send the heat - like outside, or a cooler area of the house. If possible you want to completely exchange the air in there every few minutes.

    3.) If things don't improve, you might need to look into a window a/c unit for your room during this time of year.

    4.) Move the grow to a cooler area of the house... like a basement, for example - if this is possible.

    ...that's about all I can suggest without actually seeing your setup.
  6. yea thats shocking there must be something else going on there to get that much heat off of 2 CFL's. That small computer fan is probably way too weak though...
  7. I am in an apartment so I am very limited as to access to outside air and moving to other areas. I think the heat problem is directly related to being in an apartment as the whole apartment gets pretty hot during the day. I believe it is around 73F without the lights on in the room. But I have been doing some reading and realize that 80-85 range is not super bad unless the plants aren't getting the water they need. The problem is with the door closed it gets way hotter than the 80-85. Waiting for summer to end so this isn't such a problem.
  8. Yeah, summer can present a whole bunch of problems... heat and bugs have been relentless for me - I started in the winter, when temp control was as simple as cracking a window, and bugs were nowhere to be found.

    ...but now you know what to expect next year. ;)

    Since you can't move the grow - and getting cool, fresh air in seems to be a challenge, I would recommend getting a larger, more powerful fan. Since your grow space is small, a small inline fan from www.htgsupply.com should help. They have some rated @ 80 cfm for about $20 USD.
  9. Okay I tried leaving the door closed for an hour to see how hot it actually gets, it reached 97F. I am currently on the 24 hour cycle. I think I will switch to 18/6 with the 6 hours being during the afternoon (when it is hottest). I read something in this forum:
    that was an idea to have a hole in the reflectors to pull the heat away from the lightbulbs and straight to the exhaust. Would this help in my situation? I will post pictures later tonight so you can have an idea of what I am dealing with.
  10. Okay here are the pictures.

    Grow area:

    Exhaust fan:

    Carbon filter which exhaust goes to:

    Intake fan:

    Intake pipe:

    At the moment I have the door open with a regular standing fan pointed in and a regular floor fan pointing at the intake pipe to get more air in just to keep the temperature at 80-85. I can't really keep up the sitation because I need to be discrete about this as I am in an apartment building.

    Any suggestions would be appreciated.
  11. Ah shit those pictures came up so huge. My bad.
  12. a fan on the intake pipe maybe
  13. Dumb question, but I thought 90F was the limit. 86 is warm, but not deathly.
  14. Yes 90F is the limit and with my door open and a fan blowing in I can keep it below this. THe problem is its not really possible for me to use this is a permanent solution: You can see the lights from the outside if the landlord ever wants to come in, etc.
  15. Oooooh, you're using the BIG cfl's... that explains the heat probs. I was thinking a small cfl grow, like with 23w bulbs. lol! :cool:

    Your best bet is a fan powerful enough to exchange the air in your grow space several times per minute. Find your cubic footage, and buy a fan rated for the CFM you need. For example, if your veg space is around 32 cubic feet (2'x4'x4'), a fan that moves 80 cfm or more would be sufficient... 140 CFM or more would be even better.
  16. Okay I removed the shelf and all the stuff that was on it as this was probably blocking alot of the circulation. Left the door closed from 1:30AM - 8AM and temperature reached 89F, so a little bit better. And now I have they have dark from 12:30PM to 6:30PM so that will help as well. Am probably just going to replace the two fans with stronger ones and I should be gold. Will post pics when I am done incase anyone is curious.
  17. 89 is fine. my cabinet gets to 91 but the plants are thriving. just make sure to have plenty of fresh air coming in and lots of air circulating and blowing on the plants, and you'll be fine. $.02
  18. The problem with my set up is that I don't have access to outside air. So the air needs to be exchanged alot more for it to be fresh. Anyways I got two fans with a much higher CFM rating. The temperature is alot better, it stays around 79 at night with the door closed (previously 97 then down to 89 with ventilation).

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