HELP! Temperature control?

[MrPlow]

Hey everyone first time posting on here. I'm in canada and its winter here right I have a small grow tent 3×3×6 with a 800w Led Cob grow light. I even went over kill with the exhaust fan rated at 375cfm but even on full power with extra fans I can't get the temperature below 28°c in there and I'm in 25days into flower right now with only 2 lady's in the tent. If anyone has any ideas or suggestions on why or how my exhaust isnt cooling things down any help or advice would be much appreciated

[Gingerbeard]

Hey MrPlow . What sort of fans do you have inside your tent? Is your exhaust fan inside or outside your tent? What is the ambient temperature where the tent is drawing it's air from?

[Going2fast]

Well if it's a 3x3 tent and your running true 800 watts that's a little overkill. Plus 28% c is 82%f and that ain't bad. You can get away with 300w in that tent.

[MrPlow]

Its 23°c outside the tent. my exhaust is inside sucking the air out and I have a strong desk type fan inside the tent

[MrPlow]

I don't know how to tell if its a true 800w but I really doubt it, like I also have one of those burple lights that says its 1000w and it definitely isn't.

[Gingerbeard]

Consider moving your exhaust fan outside your tent MrPlow . Any little motor inside will create heat.
I don't know what a strong desk type fan is. Mine is a 3x3x6 tent, as well. I have 1 Hurricane clip on fan for each of my four plants and am planning on another two for the underside of my canopy. I'm saying that a single strong desk fan is not enough. It's also good to split up where the air is coming from. Multiple fans.

[MrPlow]

Would you leave the filter in the tent and the exhaust fan outside I was under the impression having both inside was the bes way to go and its pretty big really thought it would suck more heat out..and Its one of those Honeywell 8inch fans its really strong I know I need more fan but it already is pretty cramped in there

[Gingerbeard]

Fan and filter can go on the outside. It is moving the same amount of air as if it was inside. The Honeywell motor creates heat.

[Going2fast]

Ok I'm confused. You have an 8" fan in a 3x3 tent. Is this feet, yards or meters? I have a 6 " in a 5x12 foot walk in closet.

[MrPlow]

My exhaust has a 6inch fan, my oscillating fan is an 8inch

[Gingerbeard]

Ah! you didn't say it was an oscillating fan. If you have good animation in your leaves, you should be good.

[Going2fast]

You can run the filter either way. To save space you can run it on the exhaust side outside your tent.

[MrPlow]

Do you think that will help pull more heat out? Always thought it was better to pull heat through the filter instead of pushing it out of it

[Gingerbeard]

Sucking or blowing, the fan does the same amount of work.

[MrPlow]

I'm mainly trying to figure out why my big ass exhaust barely reduces any heat in my tent and wondering if putting it outside or switching it up might change that? And I really appreciate the help and insight

[Going2fast]

Or both like gb said.

[Gingerbeard]

My suggestion is to bring your fan outside your tent. Here are some layouts. Yes. There is a preferred method. But there is also practicality.

[MrPlow]

Yea I guess I figured the first one, the preferred method would be the most optimal for reducing heat

[MrPlow]

I have my exhaust and other fan on full blast already and need to be able to get it cooler for the end of flower

[MrPlow]

• • I'm mainly trying to figure out why my big ass exhaust barely reduces any heat in my tent and wondering if putting it outside or switching it up might change that? And I really appreciate the help and insight

[gbauto]

I find that I will usually need at least a 10 degF temp difference in the lung room to keep the grow temps where they need to be.
I use a 6" exhaust fan venting the top of the tent and fresh air coming in from the bottom. I found a nice fan controller that will turn it on if either the temp or humidity exceed my set point.

[MrPlow]

Yes that is exactly what I need can you tell me what the controller is called

[MrPlow]

Should I both vent out and pull in air from outside? and is it okay to use the same window for both

[Smallgrow]

Outside air in/out was suggested to me by my local grow store owner , that’s how my tent is set up. I’m in central Ontario. In winter I add heat during dark period. I still run a CMH315 for heat during light period. I find by about 5-10 c outside temp this works well, it gets tougher from there. I use one small window for both in and out. it can barely fit 2 6” duct boots over/under It’s not ideal that close but it works for me
+1 AC infinity

[UndergroundFarmer]

It should work as long as there is some separation between the exhaust and the intake.

[Jebidiah]

I don’t want to be that guy but your in-line fan is sending its heat load on out with the exhaust they are made to cool themselves…I have 6” variable speed fans and after having the same heat issues with them running on high or low I realized that between the extra equipment (ballasts, power strips, tents) and the tents exhaust pulling my conditioned air from all over the house to the lung room and sending it out the exhaust it caused the temperature of the lung room to raise 2-6 degrees. It can’t be cooler than where it’s pulling air from and it’s just pulling air so any heat introduced from the beginning is picked up.

[MrPlow]

So are you saying your venting into the same room? Or what are you saying your solution was to that exactly?

[DaGreenBlazer]

Yo dude, i think Going2fast is on the right track with the fact that the main issue is the light is likely too large for that tent - if it's 3ft by 3ft than even an 800W CFL would be unnecessary, let alone COBs - if you're struggling to keep it at 28°c with everything blowing then that's an issue - i would suspect that your extract fan is actually removing a load of heat already and if you turned all air systems off the temps would probably hit near 40°c. I can't see on your posts you specifically mention how hot lights are, though from description I'm assuming they are the source of heat issue??

I've never used any LEDs myself though from reading enough of other peoples issues i know COBs run hot as standard & 800W would be designed for use in a much larger area than 3ft x 3ft. Plus, if you bought some MiC special off Amazon, then their non-existent heatsinks & shitty drivers mean thermal output can go uncontrollably high. If it's a proper brand name, quality unit and it's burning hot then it's possibly component failure & needs replacing - It's not a great solution for right now I'm sorry to say, though i would agree different light unit would solve the whole issue going forward.

Secondly, i was just wondering about your room set-up and are you able to just have the window open during lights on period?? Not being a clown, but it did make me chuckle that you're having trouble cooling a room in the middle of a Canadian winter! Is it possible to insulate that room from the rest of the house and just let the temperature drop in that room via the open window? If you could, then it would allow you to just intake & extract into cold room, and naturally cool tent down too.

If not able to do this, and to answer your venting question above, yes you can intake & extract through same window, though try to space them apart from each other as much as possible and, if you can, tilt their opening faces away from each other just to avoid any hot extract air being accidentally sucked back in. Air from outside atm is going to be the coldest so i would say is best bet for combatting heat, though i think overall a new, less powerful/more thermally efficient light would save you even having to mess around with air extraction.

[DeadlyFruit]

Hey there, a fellow Canadian here. I think this was said above but if the air outside your tent is 23 the air inside will always be at least a little warmer without some type of cooling system regardless of the fan setup (a/c or swamp cooler). I think drawing in outside air for the tent in a Canadian winter will reverse your problem so that might not be practical unless you can partly warm it in the process but venting the heated air outside would help if you are not already doing so. If you can’t vent outside then be sure your tents air input and output are not too close and the door to the room is open so some of the heat will dissipate before the air is drawn back in. With that said I have grown in 28 degree heat and it is not impossible although some strains are better suited to it. I use HPS lighting so I probably have more heat to deal with than you do and my solution for three seasons is using the insulated grow room I built in my uninsulated garage (I am in the Toronto area). If you have an insulated garage, room in it for your tent and don’t regularly open the door to outside that might be an option, although given you are using LEDs not HPS you may then have the reverse problem, not enough heat. My room stays the perfect temp for three seasons except when the light is off, at which point the temp slowly drops. During the dark periods I have a low wattage heater on an inkbird temp sensor that will come on when the temp drops enough (similar to some of the other sensors described above). I set it to mimic a cool night which is good for bringing out the colour in plants. If you are not in a position to do any of this you may want to just explore venting your heated air outside, with the 23 degree internal air being drawn into the tent to keep it a little cooler rather than venting the heat into the same room and drawing it back into the tent. Re having a higher powered fan, if you are just drawing in the 23 degree air there is a point where it won’t matter a lot how fast the fan is set to run, and as gingerbeard suggested, the larger fan motor running hard will produce heat that will contribute to the problem - I rarely run my fan on a higher speed. Good luck!

edit: the post above from dagreenblazer has merit - if you can just crack a window to cool the room and leave the door closed to the rest of the house that would be an easy solution although you would have to monitor for snow drifts in your room if you get a good blow coming straight at the window 🙂