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2 x 300 Watt LED Grow Tent In Closet - Heat Issues

amillergreen

New Member
So I have done days of researching before ordering all my parts. I put it all together and the Temps are horrible!

Setup:
2'x4'5 Grow Tent
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2 300watt LED
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a 4" 100 CFM inline duct fan
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a 6" 220 CFM inline duct fan
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a 4" carbon fliter
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The 100 CFM fan is used as an active intake (it is pushing through a mesh window because the grow tent had no low access holes.). The 220 CFM fan is used as the exhaust. I started with just the 100CFM so all my ducting is 4" but with just the 100 I was getting low 90s for temp so I ordered the 220. I thought it would make a big difference but it didn't.
With both lights on I am getting temps of 86-88 F
With just one on I get 84-86 F
I don't know why the temps are so bad. Ambient air here has been around 75 F. And it is only going to go up as summer gets hotter, so my temps will probably hit the 90s in no time. Also I cant seem to get negative pressure in the tent. because the tent walls don't buckle in, even slightly. I feel like a 220 CFM should be able to do that no problem.

I think one of my problems is i am exhausting through my dryer vent that is only 3". could this be causing the weak suction problems? My 6' fan is connected to a 4" carbon filter and 4 "ducting that funnels int my 3" dryer exhaust. cool all the small pipes be constraining the usefulness of the fan? I do not have any other options of exhaust vent then the 3" dryer pipe. So if I cant do this grow tent then so be it. But I want to know before I run out of return time! I don't think that's the case as I have seen people grow in closets while exhausting into the closet! I am at least getting it out my building! 3" pipe or not I feel like that has to be better.

Another problem I have noticed is the suction around my carbon filter is so weak it cant even hold onto a tissue! 220CFM is literally less than a foot away! But I also ran the system with the carbon filter off, and after running one light for an hours the temp was....... 86.... the same that it was with the damn carbon filter on! Also put a dual window fan in there to stir up the air more and the temp was still 86.

Another weird quirk of my messed up system is I did a temp test without any lights and the temp went from 77 (everything off all night) to 79 after 30mins of just intake and exhaust running. So my fans are actually heating up my tent... Not sure what that is telling. But I am guessing something is messed up! I did the incense smoke test to verify that all air flow was going the right way

Please help cause I am running out of ideas! I attached pics of my setup,

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madscientist9

New Member
You need to tie into your ac duct or find a way to get some cold air blowing in there if you plan on flowering in the summer months if not you can just veg and pay the penalty of slower growth from heat issues but every single thing you plug in is going to produce heat so you need a way to cool the air temps stand infront of your ac vent that air is well below the 77 ambient that you have and you are just pushing around 77 degree air.
 

amillergreen

New Member
You need to tie into your ac duct or find a way to get some cold air blowing in there if you plan on flowering in the summer months if not you can just veg and pay the penalty of slower growth from heat issues but every single thing you plug in is going to produce heat so you need a way to cool the air temps stand infront of your ac vent that air is well below the 77 ambient that you have and you are just pushing around 77 degree air.

Do you have any explanation for why, with the 220CFM fan attached the Carbon filter does not have enough suction to hold a tissue to it?

I was thinking the high ambient temp could be an issue but was not sure the tent temp would go up that much with that all the ventilation. Well this is less than ideal as there is no window close to the tent to have an ac window unit. I already have 2 window AC units thats why I am suggesting that. There is no way I can spend a few hundred on a floor ac unit. I might look into some DIY AC, but I dont know how effective they are. Sigh. I might just have to not grow in the summer time. :(
 

Sephiroth420

New Member
I have the same tent with different lights but same total watts. My temps dropped after I moved it to a room with ac and stepped the fan down to ~50% speed. I use passive intake for negative pressure and now my temps are 68-81depending on outside heat and the setting for the ac. In that tent you will need ac for summer.
 

madscientist9

New Member
look into adding an icebox to your fans check em out just google it and you can run it from a tub you keep chilled using 2L bottles more work but will knock your temps down and make sure you are starting your light cycle 2 hours after it is dark outside. Lower temps to begin with
 

FloridaSunset

New Member
I'm having similar probs with my tent (2x2x4) with one MarsHydro 300w + 100CFM 4" inline exhaust fan ducted out of the top of the tent and passive intake via a 4" duct vent on the bottom side of the tent. The inside temp with everything buttoned up was in the low 90s and with two of the screened windows (on bottom sides of the tent) open to allow additional intake of outside air (a/c room at 75f) only dropped it to the mid 80s.

I'v ordered a 6" (220CFM) inline fan for add'l exhaust, but it's not arrived yet so I can't speak as to how that will impact things.

I have been in touch with the light manufacturer and have been advised that a temp in the mid-80s would be common for that light in a small grow tent and the only option(s) to lower the temp are the ones that have already been suggested by other growers here - more vent, a/c, etc., etc., etc.

So, at this point I've retired the LED until the 6" fan gets here and have replaced it with a CFL system. Temps are still in the lower to mid-80s with everything buttoned up, but I guess I'm just going to have to live with that for the time being and hope the add'l ventilation from the 6" fan will do the trick...
 
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