Making LED work in a cool basement?

meangreengrowinmachine

Well-Known Member
I think your only issue after nailing the temp will be getting the RH% back up a bit, probably need some sort of humidifier for the tent. sounds doable to me..


I would not get a 4' tall tent if you plan on flowering in it, just IMHO. Unless you are going to dim the leds way down so you can keep them right on top of the canopy you will still need some clearance for top to lights, and training. subtract another 10-12" for the pot height and drainage that leaves you with very little vertical space for your girls.
Yep I use a humidifier and a heater, in a cold basement in the north using leds the heater already will dry out your room and you want higher humidity anyway with leds.
 

PSUAGRO.

Well-Known Member
I mean you could run your basement closet sealed in the winter too....... Just another option to think about.

Like I said ,A WiFi temp/rh logger would help you dial in somewhat with some of these ideas ..

Good luck
 
Last edited:

olegren

Well-Known Member
After all the fantastic advice, I started piecing my equipment together and getting this thing going. In the last week, I've done a few experiments. First, my setup:
  1. HLG QB260W V1
  2. 2x4x6 TopoLite - Cheapie tent but no light leaks and seems to work well
  3. I insulated the floor with 2" of good insulation. Cut custom to fit, got it sitting under the mylar insert in the tent's floor. Also put some carpet under the tent itself so it's not sitting directly on tile.
  4. Grabbed a cloudline T6 fan. More than I need, but will be running a carbon filter and want to be sure it's overpowered for pulling through filter
  5. Set up exhaust w/insulated 6" ducting to bottom of tent and using 3x passive intakes on top of tent. Exhaust is feeding out the tent, through the insulated closet wall and into an unfinished basement room next door. Basically got the tent upside down.

I also grabbed one of the Govee bluetooth loggers for temp/hydro data. This thing was a game changer. I've tested a few different configs and wanted to get some input from you experts.
  • With the aforementioned setup and closet doors closed, I'm sitting around 82 F with lights on and full blast.
  • With the same setup and closet doors opened, I'm sitting around 73 F.
In both cases, I'm getting approximately the same reads on the floor as at canopy (~2-3ft) level. These tests were done overnight - so coldest time of day. The closed door temperature seems upper bound but certainly workable for veg based on what I've read.

I have theories on the large difference. Obviously more cool air is flowing through with the closet doors opened. Ambient temps down here are still around 62. Assuming the tent is acting as a sort of radiator and heating the air immediately around it that eventually gets drawn in through passive intakes. Exhaust is pulled through insulated duct from tent and pushed out to another room, so I know it's not a recirculation issue.

I just typed a lot to pose a relatively simple question: Do you think leaving the closet doors closed is inhibiting airflow in a way that would be detrimental to growth? I'm running my exhaust pretty low, too, so could always try ramping that up. The closet is not sealed tight or anything - basically a folding door type thing, and the tent has a good half its size buffer of open air around it before the closet walls. The room it's joined to is > 300 sq ft and is typically closed off also -- but nowhere near air tight. Beyond that, there's a lot of open and unused square footage that should be providing fresh airflow.

Thanks, as always, for your insights!
-Gren
 

smokeybeard

Well-Known Member
I just typed a lot to pose a relatively simple question: Do you think leaving the closet doors closed is inhibiting airflow in a way that would be detrimental to growth? I'm running my exhaust pretty low, too, so could always try ramping that up. The closet is not sealed tight or anything - basically a folding door type thing, and the tent has a good half its size buffer of open air around it before the closet walls. The room it's joined to is > 300 sq ft and is typically closed off also -- but nowhere near air tight. Beyond that, there's a lot of open and unused square footage that should be providing fresh airflow.

Thanks, as always, for your insights!
-Gren
I don't see this being an issue. Only time my plants suffered was from my not so experienced ass lol. The exhaust fan should be able to pull plenty of air in. My tent had negative pressure and in a closet, if I had the fan all the way up it would take the closet into negative pressure meaning it was tougher to open the door to the closet which I would think would mean its getting plenty of air flow? I am not as experienced as most of these guys so hopefully my input here is correct.
 

olegren

Well-Known Member
I don't see this being an issue. Only time my plants suffered was from my not so experienced ass lol. The exhaust fan should be able to pull plenty of air in. My tent had negative pressure and in a closet, if I had the fan all the way up it would take the closet into negative pressure meaning it was tougher to open the door to the closet which I would think would mean its getting plenty of air flow? I am not as experienced as most of these guys so hopefully my input here is correct.
Thanks. I agree. Logically, I'm thinking air is gonna move where it can. Creating a vacuum should pull from the adjoining room(s) -- I was just worried given the temperature disparity that maybe I was missing something stupid. Appreciate it!
 

olegren

Well-Known Member
@smokeybeard - As a quick follow-up, I was thinking about your remarks and remembered how tight my tent was when I first set the exhaust up. I had since started opening up the 3 rectangular meshed holes up top for additional passive intake. I think this was half my problem. The tent was no longer drawn in so much (if any at all) - at which point I don't think I had enough negative pressure.

It's not quite so cold now as it was last night, but with all those buttoned down (So just passive intake through a single 4" flap) it's nice and drawn up on the lowest setting -- and temps are maxing around 78. Much better. Now if I can just get RH up a bit, I am confident enough to start my seedlings. Then my inexperienced ass can do some real damage.

Thanks again for the thoughts - very helpful in helping me isolate the issue here.
 

smokeybeard

Well-Known Member
@smokeybeard - As a quick follow-up, I was thinking about your remarks and remembered how tight my tent was when I first set the exhaust up. I had since started opening up the 3 rectangular meshed holes up top for additional passive intake. I think this was half my problem. The tent was no longer drawn in so much (if any at all) - at which point I don't think I had enough negative pressure.

It's not quite so cold now as it was last night, but with all those buttoned down (So just passive intake through a single 4" flap) it's nice and drawn up on the lowest setting -- and temps are maxing around 78. Much better. Now if I can just get RH up a bit, I am confident enough to start my seedlings. Then my inexperienced ass can do some real damage.

Thanks again for the thoughts - very helpful in helping me isolate the issue here.
I would keep your temp up in the lower 80's, it makes a HUGE difference with the QBs.
 

2com

Well-Known Member
Im telling ya, an oil drip radiator heater is such a good way to warm up a tent with very little power consumption, safety, and no moving parts.

Oil drip radiator? Must mean oil filled?
The lowest setting is 600w on most of those units. 600 fucking watts of heat, to offset using leds?...it just seems so silly. So running 260w of light, plus 600w of heat...it just seems counter productive. But hey, the heat is needed. I'm looking at similar scenarios with led and temps a little on the lower side of "optimal".

It'd be a good idea, if you (@olegren) decides to use said heater, to track it's usage (on and off time) as well. Calculate how much is spent on heating per day/month.

They're great heaters though, efficient and safe. If it's a "living space", or provide heat to a living space as well, then it could make more sense. I duno. Either way, good luck olegren.
 

2com

Well-Known Member
Thanks. I'm not going to sweat the higher temps if that's the case. How high do you let yours go -- if you don't mind me asking?
82*f is a good minimum in my opinion, if light source is only a white based led. I wouldn't even be concerned unless it was over 88*f maybe? Depending on rh too though. The actual important temperature is the plant itself, right. Not trying to heat air.
Did you mention you bought an IR thermometer. If you have plant(s), check their temps under the light.

Edit: maybe 80*f minimum. And not saying "you won't grow anything and be an utter failure with lesser temp."
 

olegren

Well-Known Member
Thanks, guys. It sounds like my temps are in the right neighborhood. I need to work on RH. Got a humidifier arriving tomorrow that will hopefully help. Basement sits around 40% normally, but when temps are in the range I described it’s usually more like 25% RH in tent — so got some work to do there. Also adding a heat mat to keep roots warmer.

@2com - I ended up not doing the heater. Just flipped intake/exhaust and added some insulation to get temps right. In talking this over with corey and a few others early on I decided I’d just get a CMH if I couldn’t get temps up with LED — rather than add a dedicated heat source. No infrared heater but also no plants yet. Once I get humidity sorted I think I’ll take the plunge and get a couple of these seeds in some soil. Can’t wait.
 

2com

Well-Known Member
Thanks, guys. It sounds like my temps are in the right neighborhood. I need to work on RH. Got a humidifier arriving tomorrow that will hopefully help. Basement sits around 40% normally, but when temps are in the range I described it’s usually more like 25% RH in tent — so got some work to do there. Also adding a heat mat to keep roots warmer.

@2com - I ended up not doing the heater. Just flipped intake/exhaust and added some insulation to get temps right. In talking this over with corey and a few others early on I decided I’d just get a CMH if I couldn’t get temps up with LED — rather than add a dedicated heat source. No infrared heater but also no plants yet. Once I get humidity sorted I think I’ll take the plunge and get a couple of these seeds in some soil. Can’t wait.
Shit, I wish our basement sat at 40% - I'm just talking for human health though, lol. Ain't no growing going on there.

Flipping the intake/exhaust is an interesting idea someone mentioned in another thread as well. I wonder if that method affect co2 at all being that it's "heavier than air". Never mind that though. :)

I was gonna suggest a CMH as well, maybe I did, maybe that was a different thread. I like that idea though. Might as well get some light outta added heat source. Also, it'll directly heat the plants. Right on, man.

Just in case you misunderstood, I was asking about an infrared thermometer, not a heater. These are very useful tools for more than just the garden too. In some trades, they can be used to diagnose equipment even (based on temp); just shoot it at a fan, or a motor, etc, and get instant temp reading. Find an area of poor insulation in a roof/ceiling, making extracts, plant temps, the list goes on. They're less than $20. Sounds like you're on track, with a plan. Good stuff, dude.
1581136020187.png
 

olegren

Well-Known Member
@2com - No idea what it will be like once the heat isn’t running all the time, but hopefully it will stay decent down here. I am sure adding a Humidifier will complicate things.

my bad on the heater. I meant to say thermometer. I want one of those for cooking (of all things, right?) and this gives me another reason to pick one up. Had no idea they were so reasonably priced. I’ll grab one — thanks! This also lends clarity to the whole idea of LED threshold being higher. I knew they didn’t put out the same kind of heat, so I guess that’s why the minimum temps are a bit higher?

thanks for all the info!
 

Airwalker16

Well-Known Member
Shit, I wish our basement sat at 40% - I'm just talking for human health though, lol. Ain't no growing going on there.

Flipping the intake/exhaust is an interesting idea someone mentioned in another thread as well. I wonder if that method affect co2 at all being that it's "heavier than air". Never mind that though. :)

I was gonna suggest a CMH as well, maybe I did, maybe that was a different thread. I like that idea though. Might as well get some light outta added heat source. Also, it'll directly heat the plants. Right on, man.

Just in case you misunderstood, I was asking about an infrared thermometer, not a heater. These are very useful tools for more than just the garden too. In some trades, they can be used to diagnose equipment even (based on temp); just shoot it at a fan, or a motor, etc, and get instant temp reading. Find an area of poor insulation in a roof/ceiling, making extracts, plant temps, the list goes on. They're less than $20. Sounds like you're on track, with a plan. Good stuff, dude.
View attachment 4474296
But MOST importantly, they let you know when your bangers right at 550°F so you can hit it at the perfect temp!! :-P
 

2com

Well-Known Member
I knew they didn’t put out the same kind of heat, so I guess that’s why the minimum temps are a bit higher?
Yea, that's my understanding. They put out hardly any IR, whereas HID emits a substantial amount (at least hps does).
 

Khyber420

Well-Known Member
Here' what I found most effective in my 3x3x6. Basement grow, maybe 20C ambient outside the tent, or less, depending. I've run a dehumidifier outside the tent and that will warm up average temps in the room and bring down the RH across the board. However, what I've found to be more effective is to run a 60W personal heater on an inkbird temp controller and exhaust on an RH controller. That keeps my temps around 23C at night and between 23-28C during lights on and Rh between 45-52% and it uses way less power than the dehumidifier. Running citizen COBS and some jank custom Samsung diodes, the COBS run hot though, if I don't exhaust temps hit over 28C lights on.
 
Top