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Does Exhaust Fan Need To Run 24/7

  • Thread starter Thread starter Irietime
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Does Exhaust Fan Need To Run 24/7

Irietime 25 Replies 103,732 Views
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Irietime

Irietime

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#1
greetings farmers! Just had a question about exhaust fans, wondering if I need to keep it running all the time or if I could put it on a timer and run it an hour on, hour off? Any feed back is greatly appreciated. Thanks
 
#3
Like @Homesteader mentioned it really depends on your setup and just what your peak temps will be during that hour its off. You most certainly will want to run it with a idler control at lights out as this is when your RH and such will spike. But during lights on would depend on your maximum temps are. Keep a close eye as you could fry your plants depending on your lighting setup.
 
#4
exhaust fans are often used for two different purposes. some rooms utilize them to control temperature. depending on location and time of year, some growers use them to cool good-sized rooms. others use them on a smaller scale to cool a tent.
the other purpose is for air exchange. many of us who run sealed rooms have inline fans on timers and dampers on the ducts so that at lights off the dampers open up, the fans come on, and all the CO2-laden air is sucked out of the room and fresh air is brought in. after the required length of time the fans go off and the dampers close and the dehumidifiers come on for the dark cycle.
 
#5
Thanks for responses guys! I just finished expanding my grow area by a little more than double. Room was 2.5x5x6. All I was working with was a occilating fan, a clip on fan down below canopy where the air intake was and a couple cheap leds. One was 600w and the other a 300w. Grow room is inside a shed so I would just leave the grow room door cracked to exhaust into shed. Bare bones style. It worked fine, did four rounds and grew some dank. The humidity was a bit out of hand though, lost a couple tops to mold, nothing to crazy.
So now my room is 5x7x6ft tall and I added another 600w led. I may be getting it all wrong, but I was hoping the 4" hurricane inline fan and phresh carbon filter will suck up that warm humid air and ditch it outside, in turn keeping my humidity a little more in check? Am I wrong? Not sure if the fan will suck to much air out leaving the plants gasping for air. Ill have a clip on fan set up in front of my intake sucking in fresh air 24/7, but this hurricane fan does work!
I guess I'll just have to see what my temps do with the three lights running. It's a bigger space and these leds run cool so I might not have the same issues as I did in the smaller room.
Thanks for the feed back, I got high hopes for this new room. Peace
 
#6
you needn't worry about your plants "gasping for air."

every room/environment is different. get a thermometer/hygrometer if you don't already have one. less than $10 on amazon. put it into your room and record some data. lights on, lights off, fan on, fan off, etc. try to keep your room close to a VPD chart.

good luck!
 
#7
Thanks @Papa. I've got the thermometer/hydrometer. My plan is to grow as I did before and use the exhaust fan every two hours, for an hour to clear out room and see how that goes, and adjust accordingly. Thanks again for the response. Peace. If you want to check in on how things are going my thread is "irietimes bare bones grows"
 
#8
Hey, Irietime keep an eye on the RH, I was thinking as you do and cycled my fan (exhaust) off/on every hour, wasn't even thinking humidity. Got PM, had to scrap entire harvest. I'm running exhaust fan 24/7 on every grow after that, learned a painful lesson.
After last grow figured the electrical costs of everything and the exhaust fan run at 24/7 through bloom especially (10 weeks) didn't amount to much, maybe $10.
 
#10
I would get a short cycle timer and run it. I do mine every 45 min for 5 minutes
 
#11
My clone/pre veg and veg rooms all run intake/exhaust fans 24/7. My sealed flower room never gets air exchanged.
 
#13
DemonTrich said:
My clone/pre veg and veg rooms all run intake/exhaust fans 24/7. My sealed flower room never gets air exchanged.
Click to expand...
Hey D can you explain the flowering with no air exchange ? 1st time if heard of it. .
 
#14
I run a fully sealed room with co2. The only time any air gets exchanged is when I open or close my flower room door. My co2 is 1000-1200ppm from flip to day 56, day 57-64 I drop it to 550ppm.
 
#16
Got even sized intake/extract on a GSE Temp, humidity and negative pressure controller. Takes away the guesswork.

Environment is absolutely everything.
 
#18
I have an intake and exhaust fan on speed controllers, plugged into a thermostat set at 74*. When the tent temp gets above 75*, fans come on at about 30% speed. Temp drops below 72*, fans turn off. Works perfectly, costs about $30 for the thermostat. I got the 2 inline hurricane fans and 2 controllers off Craigslist for $70.
 
#19
I turn mine off so they can sleep in peace, this is only my opinion but I think plants do most of there growing at night. SNOLEPERD
 
#20
DemonTrich said:
I run a fully sealed room with co2. The only time any air gets exchanged is when I open or close my flower room door. My co2 is 1000-1200ppm from flip to day 56, day 57-64 I drop it to 550ppm.
Click to expand...

I run a fully sealed room as well. What are your nighttime c02 levels? Do you notice they have a relationship with daytime co2 levels or if yours always fall down? My nighttime c02 ranges from 500-800.

How come I never never read or hear about actual oxygen levels in grow rooms?

Do you know what would happen if you had a sealed room c02 lights on but ran an air out when lights off? I think that could help if you were having a hard time with humidity levels.
 
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