Can't keep temps down.

Discussion in 'Grow Room Design/Setup' started by dazeeman, Jun 2, 2019.

  1. #1 dazeeman, Jun 2, 2019
    Last edited: Jun 2, 2019
    Having trouble with my friend's 8' x 8' x8' grow area. It is built inside stand alone garage. First grow went ok through the cool months. This grow vegged ok with temps peaking mid 80's .Flipped last weekend and Now we are struggling keeping it under 90°F. We started with 2 bestva led lights, using the same lights and settings used through veg.Ambient outside has been in high 90's this past week.
    Temps in the grow area peaked over 100°F. Portabe 700 BTU ac unit just goes into thermal mid day. I took out one of the lights to see if that was it,no better. I tried helping ac exhaust out with another 6" inline with little change. My inline filtered exhaust is on lowest setting.
    I even tried blocking off fresh inlet to see if that was to hot but
    No luck.
    All 6 " ductwork leaves the room and passes through the attic. The Attic gets freaking hot.
    Exhaust ducts go straight to the roof peak vent,intake comes in from the Soffit.
    Here is the layout with specs. Let me know if anyone sees any problems. 20190602_115816.jpg 20190602_115822.jpg
  2. What's the CFM rating of the fan you have pulling air out of the room? Also, it's a centrifuge fan, not a booster, correct?
  3. 390 cfm inline centrifuge
  4. Hey dazeeman, have you tried taking off the filter temporarily to see if the resistance caused by it is the issue? if it keeps it cool with the filter off temporarily, then you know you need a more powerful (600cfm or so) fan. Or do like I did and time your lights to turn on during the cool hours (mine come on at 7pm) of the day and off (1pm because I'm vegging) during the hottest time of day. I even bought an A/C unit to cool it down, but haven't needed it since I adjusted my times. Your lights don't have to be on during the day. The plants don't know the difference. Just as long as you have them on the proper light schedule for the growth cycle. Hope this helps you man. Keep us posted and good luck!

    Sent from my LG-LS997 using Grasscity Forum mobile app
  5. Oh, also try taking the filter out of the fresh air in box to see if that might help. I've also used nylon netting on the inlet to decrease the resistance and allow more fresh air in. Basically, take off both filters and see if it cools. Then adjust fan power and filtration accordingly. That's it.

    Sent from my LG-LS997 using Grasscity Forum mobile app
  6. We ended up making it a closed system. No intake from outside the room and we are just scrubbing the air not exhausting out. We added a fan to exhaust the heat out of the attic.Our temps are manageable just at or under 90F at the canapy with both lights.We do have lots of airflow now. Plants are doing good. They also got some serious lollipoping. 20190615_123753.jpg
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  7. Right on man! Those ladies are looking mighty purdy!

    What strain/strains you got there and how far along are they? Week 3, 4? The setup looks great! Keep those lights as close as possible without burning to promote short node growth and more dense buds! I have to remind myself to keep checking that shit especially during the initial stretch.

    Great job man!!

    Sent from my LG-LS997 using Grasscity Forum mobile app
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  8. Well the strain was unknown bagweed. Best guess was Blue Dream . Atleast thats what the flowers were supposed to be. There were different phenotypes that came from the original 6 seeds we found. That grow pictured had atleast 2 different phenotypes that looked the same til about week 4 in flower. 1 pheno stacked heavier, the other way more resin production ,little less yield.
    That was week 3-4.
    The bad news......
    My buddies ac overloaded the gfi that controlled them,the lights and exhaust.
    The problem was the gfi was hidden behind his toolbox.He had no idea it was there. He thought he burned up the circuit ,so........he chopped them all and started drying them. Needless to say he was pretty pissed when he found it only a needed the gfi reset.
    He was just so upset with the heat issues that he was tired of fighting.
    On the plus side. I took 10 cuttings from them to my tent when we flipped them.
    We suspect that the temp problems were coming from hot air from the exhaust that was backfeeding into the ac exhaust. Sounds crazy,but it must have been some sort of pressure differential from the room vs outside air. We closed off air inlets from the soffit to room and exhausted ac directly to the attic. Our inline carbon filter is now just scrubbing,not exhausting.
    Now room temps are way lower.
    We'll have clones ready to go in flower in about a week.
    If that was my room ,I would have fixed the problem being only a few weeks from harvest. But I have more patience than him. He may have crossed things up in the attic ,causing the ac units to overheat. Also i never run lights and cooling on the same circuit.
    Hope he learned a lesson.
  9. Way too low. That size of an area you probably need an 8"
    • Agree Agree x 1
  10. Yep, I agree . His space so....he sometimes(most of the time) does what he want's ,not what I suggest. He bitched about how expensive the 8" was so he went with a cheap 6".
    • Agree Agree x 1

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