Temperature Ventilation Help!

Discussion in 'Grow Room Design/Setup' started by Slypknow, May 9, 2006.

  1. Hey folks,

    I've been working quite a while on perfecting my grow box. I've removed the need to make it stealthy and now am working on getting the temperature down to the perfect level.

    I've attached a picture of my current grow box. Setup is

    400w HPS
    465CFM Squirrel fan exhausting from reflector
    2 large computer fans intaking air into box
    6 plant hydro setup (using 2liter bottles cut in half)
    1 smaller tower fan just circulates air

    Average temp (light on): 84F
    Average temp (ligh off): 78F

    Here's where I'm somewhat lost: How do you guys get your temps down to 78-79 with the light on??? I have so much air blowing through this thing it's like a vacuum. However, in order to get the cold air in the room's temp must be 75 or so. Running my A/C to cool my entire house down to 75 for this single room seems insane.... is this how most of you guys do it?!

    I also considered buying a portable AC unit, but this seems to cause all kinds of other issues like seriously high electric bill, humidity issues, etc.

    My exhaust is being piped into another room, so I dont have that issue, yet the room this box is in heats up regardless. So as the 18hrs continues the temp slowly rises in the room causing the intake air to be higher in temp - you get the idea.

    So how do you guys handle it? I know throwing more CFM's is NOT going to solve the problem - just not sure what would (unless I picked up a portable AC unit or turned my home AC down to like 72F....which is not a great option).


    Attached Files:

  2. exhaust your hot air outside or up into the attic. Any hot air going to another room will eventually lead to higher ambient temps. You could get a thru-wall/window AC unit and run it with the lights. Just get a small one and place it near the intake for your CAB.

    BTW - nice lamp and hood. Sunlight Supply is my favorite.
  3. I also just noticed that there isn't a lot of intake air ports that I could see. What kind of intake do you have for that cab? Just the two computer fans? What is the port opening for each fan? How many CFMs can each intake fan move?
  4. Intake - 2 seperate 3 inch (diameter) holes both with the largest computer fans I could find. This combined with 15 1 inch holes drilled in the bottom (pre-hydro design).

    One odd observation - when I grab on to a leaf (tomato plant) it feels cool even when the light is on. It made me question my thermometer (which is mounted on top with sensor near plants, I read both temps and average).

    I could use the AC option, as mentioned before, but it just doesnt make sense. I have use of an entire home and this is just a small box. If I got rid of the box and just hung the light in the room would that make any difference?! The air in the room would still start around 78F because I just can't believe everyone who grows indoors must have their AC set in their home for 75F.... I just think I must be missing something even though the logic makes sense.
  5. i have my a/c set at 60 but my grow is in a closet and i have a 250 cfm ducting fan piping cold air to my intake ports and my grow box stays at a steady 78 deegrees idahobuds
  6. 1. Temperature cannot be measured accurately in direct light without special equipment. Ordinary temperatures (like the weather report) are always taken in shade. Shade your thermometer with a thick piece of folded printer paper when you want a true reading.

    2. Temperatures to 95 degrees F are acceptable--even beneficial.

    3. Removing humidity will become as big a factor as lowering temperatures when you have a fast-growing biomass under your light. Make sure the exhaust goes outside, somehow.

    4. Intake and exhaust always work as a single unit. Increasing intake increases exhaust effectively, if the room is under sufficient vacuum. If you can sense the air flowing in through the passive intakes with your hand, you should add more intake.

  7. This may make you laugh, but I think you need more intake. Air is cubic and the surface area of a circle is defined by the square of its radius times Pi. For example, ONE 6" hole, is waaaaaaay bigger than TWO 3" holes. Two 3" holes have a surface area of 14.13 square inches. ONE 6" holes has an area of 28.26 square inches. That's twice as big!

    One of the posters above said it correctly. Your intake and exhaust work in conjunctoin. If there's not enough intake, then you're not getting enough exhaust.
  8. yuor temps are fine now, if possible since you said stealth wasnt a problem you could do what im going to do,

    tap into the a/c ducting with a 2'' pvc pipe and run it straight into your growbox,,,, [ at ground level ], :wave:
  9. Well I think I've got quite a bit to solve my issue at this point.

    1: Temps arent accurate in direct light. This makes sense and also explains why all my plants seem to be doing a-ok yet temp is quite high on display. I'll try the folded paper trick, leave it overnight and check in the morning for the average.

    2: MORE INTAKE! Laugh as I did, I tried it. Added 2 additional 3inch diameter holes and also placed 2 fans that were 3inch diameter and let em rip.... box is now a complete whirlwind and temps are showing a solid 82 but it makes sense if taken in direct light the reading would be off.... so I'm sure the temp is lower.

    Thanks everyone for helping me with this nightmare! I have yet to even grow anything but herbs/veggies but atleast I've been eating well.... haha.
  10. Slypknow no advice to give mate, but i noticed your hydro setup, nice:) was it from hydroponicsonline.com. I saw this a while ago and will be giving it a go sometime in the near future, will be interesting to see how it works.Do you have any details on the workings of it?
    Good luck:wave:
  11. this isn't helping the poster but I have a question about intake that i thought i could ask in here. I see you guys talking about intake fans, but I was under the impression that they were not needed because the suction from the exhaust fan/blower would create suction and pull air through an intake hole, instead of needing a fan. Is an intake fan just used to create extra circulation that would not be possible with just holes?

Share This Page