Home Forums Cannabis Cultivation Ventilation System / Exhaust

last updated by Spin 1 year, 6 months ago
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    • #9429
      Points: 157

      Running a 4×4 setup…..generally speaking Are you guys running your inline exhaust fan 24/7 or only when you need to adjust temp/humidity in the tent?  Problem im having rn is keeping stable temp/humidity range bc it’s cold inside the room my tent is setup in.  Have a heater/humidifier (on timer) inside my tent to try and regulate and keep temps/humidity up but when i run my inline fan , the temp/humidity inside the tent drops too much.

      My plants are currently in seedlings/week 1 veg so I have not been using the ventilation system much trying to keep temp/humidity up in the recommended range.  My gut is telling me to run the inline fan 24/7 but im worried to do that since the room temps are too cold. I’d rather it be hotter than too cold especially in these early stages.   I was reading that it’s good to run the ventilation system 24/7 with a flap opened up at bottom of tent to keep fresh air recycling thru the tent and get rid of stale air but the intake air is just too cold coming in so I’m kind of stuck on what to do.  The temps/humidity are dropping/spiking, especially if I run the inline exhaust fan and im trying to find a happy median to keep my temps/humidity in a stable and comfortable range for my plants

      Room temp is cold (40s-60’s F’) and on really cold days 30s-40s F’

      I know once i get into Veg weeks 2-4 and onward i should run the fans 24/7 but  just wanted to hear your thoughts on this issue and any possible solutions.

      Any suggestions/recommendations would be much appreciated, thanks!


    • #9430
      Points: 691

      I personally run them 24/7 along with intake fans. My other fans just ment to move air I have on same time as lights. In your situation I’d likely do the opposite. It turn intakes and exhaust off and leave other fans going to try and keep as much heat in as possible. You could also stick in 5 gallon buckets full of water if you have room. They will retain heat when lights on and also help keep humidity up. Also try to run light at night when it’s coldest.

    • #9437
      Points: 961

      @BigApple, Buy one of these controllers, and be sure to get at least 20% off or go to close the page and get the Make an Offer.
      Digital Heating and Cooling Professional Thermostat Controller -40-176°F 15A/1875W BN-LINK

      but before you buy one, read my post over here on how to set it up. https://www.thcfarmer.com/threads/how-do-you-control-a-heater-and-exaust-fan-in-your-tent-which-controller.145078/

      In my tents, with a cold intake/outside temp differance of more than about 20-25* between my tents inside temp (75-80*) and the ouside intake air (50-60*), I have issues with condensation on the inside of the tent and humidity getting into the 80% range. Not good. You said your intake air was as low as 30’s*-40’s* and we want our tent in the upper 70’s* to lower 80’s* so yes, you might expect to be needing/running a dehumidifier inside the tent.

      Feel free to ask me any questions about getting it setup and hope that helps.

    • #9476
      Points: 4,165

      I run my exhaust 24/7. I may adjust the power level manually depending on the temps. I’m veg I usually keep a screened vent open to bring in fresh air. With the power on low, not much air is coming in with no vents open. More negative pressure than anything if you as me.
      I have a heat mat in there now covering the floor to keep the root zone from getting too cool/cold. I don’t worry about humidity. I’m as low as 20% in one tent, and 40% in another. “Swings” are what I’ve noticed will mess with a plant more than being out of ideal vpd range. Some may have different results. I tend to get lucky. Seriously lol

    • #9477
      Points: 1,073

      My lung room is usually around 60f. I use a an inkbird temperature controller. An 8 inch fan hooked to the cooling outlet and a 1500 watt oilfilled heater inside the tent hooked to the heating outlet. The heater and fan kick on as needed all while a 4 inch exhaust fan runs 24/7. Not sure if this info helps.

    • #9534
      Points: 255

      Spider Farmer inline fan with controller set your parameters. I have mine set to turn on at 79 and at 65 RH. I change it accordingly to the time of the grow I have 2 tents going right now. 1 5×5 is in flower week 5 and a 4×4 that I have some seedlings going and a mother plant that I have kept for a while. My 5×5 exhaust is goes into my 4×4 because I need the higher humidity and temps in my 4×4 my 4×4 exhaust goes outside through a dryer vent that I installed in a basement window. My circulation fans run 24/7 to keep airflow flowing through


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