I think 2x4 are prone to this problem if you live in high temp areas. Exact same problem with mine and I have a 6in exhaust. Still can’t achieve negative pressure unless I want to let Temps jump up into the 80s. 7 weeks into flower and I don’t want that high of temps. I’ll deal with the smell from the positive pressure pushing the odor out the tent into the room. This is what I rigged up to get the temp down and it has a dehumidifier that works well too. Old houses don’t help holding ac in a room.
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I also run lights off 7am-7pm. Helps a lot
I run a 2 x 4 x 7 foot tall tent Running 616w mixed lighting (HID + T5s)
Sealed air cooled hood, sadly LED fixtures dont allow this.
What I have found is The small Cool mist humidifiers Will reduce the
heat by 1 to 3 degs EACH, at times I need to run 6 to keep the temp mid
to high 70s. Yes the humidity goes up but stays within VPD range.
Higher humidity when seedling or early veg is good. I start in July and by
the time I hit flower the outside temps start to cool down and I can turn
off the humidifiers since I dont want them during flower anyway.
Its a challenge running a small tent and have not been able to
find a way to use LED Fixtures without the HEAT ISSUE, wish they
would build one that can evacuate the heat like a sealed HID Hood.
1w of HID Light is the same heat as 1w of LED light so if your pulling
600w from the wall thats the same heat as a 600w HID but with the HID
you have options to remove the heat
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Interesting on the heat comparison. @dbrn32. Would you agree on heat being the same LED vs. HID if pulling the same at the wall?
In terms of btu, yes. But that was horrible example because most of waste heat on a passively cooled led doesn’t make canopy either.
Heat in the tent is HEAT in the tent Weather it makes it to the canopy or not
Lol ok. I suppose leaf surface temperature doesn’t have anything to do with transpiration either?
If Heat is generated and dissipated into the environment it was there
and any cooling that has been absorbed into the ambient temp has caused
an increase in OVERALL temp, Does not matter were you take the temp once
its generated it effects the overall temp in the tent
Now if we want to talk about whats more efficient or has a better penetration
that different BUT Heat is Heat and does not magically disperse without some effect
I should add the advantage of the NEWER LED lights is the fact
you dont need as much Watt to achieve great results, so less
Watts = Less Heat but if you put 1000w from the wall of LEDs
in a 2 x 4 tent you may have issues
I respectfully disagree with most of your comment. A properly designed grow room will either have intake near bottom and exhaust out of top, or be sealed with cooling and supplemental co2. It’s not a vacuum, which is what your explanation would need to be true. Since the natural movement of heat is up and away from the heatsink, and it’s assisted by a properly setup exhaust, then removed from space with very little interaction with plant canopy. It’s actually very similar to cooling an hid light with a fan, something you said couldn’t be done.
I do agree that your method is way less efficient. You take a moderately efficient light like 400-1000 hps that runs 1-1.6 umol per joule and then use an additional 100-200 watts to remove all of the waste heat. On a 600 that’s a 15-30% drop in light per watt consumed. As opposed to a decent led fixture running over 2 umol per joule and using the exhaust fan already needed for co2 replenishment in the space to accomplish the same thing.
In addition, there’s an added benefit in temperature compensation with leds. Due to lack of ir wavelengths, the canopy temp actually needs to be run higher in order to maintain proper transpiration rates.
In terms of thermodynamics, sure a watt is a watt. You can put your finger on a 150 watt quantum board and hold it there for a reasonable amount time without issue. But you’ll burn the piss out of your finger trying to do the same with a 150 watt hps bulb. Every other explanation should fall into place from there.
OK
Did not know we were talking Grow ROOM I thought we were talking
2 x 4 foot TENT and How it would effect that space. NOT a well designed
grow room
Tent, room, box, or anything else would all still require the same stuff right? Being in a tent or a room doesn’t nullify the need for air exchange. That is all I meant by “well designed”.
interesting thought hmm… you think it is a good idea to put the carbon filter on the other side of the exhaust on the outside instead the inside to get more warm air out?
Most people don’t do that because the filters are said to be less effective that way. I would say if you’re not moving enough air through your space that you need to take a look at the ratings of your filter and fan. Taking a look at duct, bends, and stuff like that a good idea too.
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