Radiant heat vs overall temp?

[VincenzioVonHook]

Hey, just curious as to how you guys control radiant heat from the underside of LEDs, or if I should even worry...I'm in a room now that is at 21c. If I check the temp at floor level it is 20c due to cement floor, at mid canopy level it is 24c. If I move the temp sensors to 12" from the quantum boards, the temp shows 35c, but I'm not sure if it's from radiant heat, or the sensor heating up due to black plastic casing. If I take 15 readings from the tent at varying locations, it averages 26c, but I'm just a bit worried about the 35c hot pocket under the lights.

If I hold my hand 12" away it gets very hot after a minute, but the plants seem fine. The lights don't get that hot too touch, and it sits around 28c at the very top of the tent. Is it normal to have such a hot pocket (10c over average) under the lights when there is adequate exhaust and intake, plus two 150mm fans inside a 2x4?

 

[MustGro]

I take my temps at canopy level. Try to keep them under 30C but it's better at 25-26c. You say quantum board so it's a bright LED. I run my 240 watt LEDs at least 24 inches above my canopy and the fans get pretty done by the end of flower.

 

[VincenzioVonHook]

Sadly I'm just stuck for space now. I've got the quantum board 8" away and dimmed lol. These two autos are massive. Didn't expect indica based autos to stretch so much. I removed one of the 100w quantum boards as the heat was just insane 8" away from 340w. I'm at 240w now and. I'm screwed lol.



At pot level it's 21c. At canopy level its 31c. Hopefully they hang in there.. worst comes to worst I'll remove the roof and add a canopy extension to get at least another foot out of it...the coverage is very focused 8" away as you can imagine.

 

[curious2garden]

Sadly I'm just stuck for space now. I've got the quantum board 8" away and dimmed lol. These two autos are massive. Didn't expect indica based autos to stretch so much. I removed one of the 100w quantum boards as the heat was just insane 8" away from 340w. I'm at 240w now and. I'm screwed lol.

View attachment 4940246

At pot level it's 21c. At canopy level its 31c. Hopefully they hang in there.. worst comes to worst I'll remove the roof and add a canopy extension to get at least another foot out of it...the coverage is very focused 8" away as you can imagine.

If you can add that extension I would and wow

 

[VincenzioVonHook]

If you can add that extension I would and wow

I'm going down the hardware store tomorrow to get a few lengths of inch by inch shs and some particle board to make a frame. I'm lucky I did not take the advice of running four to six in the 2x4 from the breeder. Apparently these GDP autos don't get much bigger than 2.5 foot lol.

Planning on cutting the roof out and adding Velcro strips if I ever need to put the original roof on. Should have paid the extra $20 for a tall tent for sure. 160cm doesn't cut it.

 

[VincenzioVonHook]

Do you guys think it would be worth it to open the tent up here and there and throw some side lighting at it? There is basically zero light getting through that canopy. Half way down it's almost darkness.

 

[curious2garden]

I'm going down the hardware store tomorrow to get a few lengths of inch by inch shs and some particle board to make a frame. I'm lucky I take the advice of running four to six in the 2x4 from the breeder. Apparently these GDP autos don't get much bigger than 2.5 foot lol.

Planning on cutting the roof out and adding Velcro strips if I ever need to put the original roof on. Should have paid the extra $20 for a tall tent for sure. 160cm doesn't cut it.

I was going to suggest super cropping and then I took a close look

 

[VincenzioVonHook]

I was going to suggest super cropping and then I took a close look

Yep...they bounced back after two days...fully doubled over to erect in two days.

 

[curious2garden]

Do you guys think it would be worth it to open the tent up here and there and throw some side lighting at it? There is basically zero light getting through that canopy. Half way down it's almost darkness.

If you can add side light now's the time. I'd also trim and clean up where you can't get light. You can also harvest tops and then allow some undergrowth to mature.

 

[curious2garden]

Yep...they bounced back after two days...fully doubled over to erect in two days.

I've had to super crop more than once and you can use tie downs, bend and hold them in place.

Be careful you don't burn a cola you can get botrytis or other mold issues from the tissue damage.

 

[Skunkbudz]

Yep...they bounced back after two days...fully doubled over to erect in two days.

Bend them again then tie them down.

 

[GrowingAbroad]

How are you measuring the temp exactly?
As far as i know and always do is measure the temp in between the plant just onder the top and "always" in the shadow so not in the direct light and this has always worked for me. Also, how are the top leaves compared to the lower leaves? As long as their the same and not curling upwards or getting dry i wouldn't worry to much.

 

[GrowingAbroad]

You should be careful for light stress and bleaching at that distance of course.

 

[VincenzioVonHook]

You should be careful for light stress and bleaching at that distance of course.

They are a bit lighter than the lower leaves, but not pulling taco or anything. No curling, browning or bleaching of the tips yet apart from a bit of overfed tip burn . I've dimmed it down to 3.2a at 48v ATM so it's not too bad.

These are around 8"-9" away ATM.


I'll be adding another foot of height tomorrow which should do the trick. I'm too lazy to tie them down. Plus I love a good project. Added bonus is being able to add the other 100w QB in there to even up the coverage when I have adequate space..

 

[VincenzioVonHook]

How are you measuring the temp exactly?
As far as i know and always do is measure the temp in between the plant just onder the top and "always" in the shadow so not in the direct light and this has always worked for me. Also, how are the top leaves compared to the lower leaves? As long as their the same and not curling upwards or getting dry i wouldn't worry to much.

I figured it might be an issue with radiant light heating up the black plastic casing...I measure about 5 differing spots in the tent...lower is always around 21-23c, middle is around 25c and the tops with heaps of radiant light hits 31c. Out of the coverage in the top corner it is only 26c, so if I average it all out it's not too bad, probably just heating up from light exposure being black plastic.

 

[curious2garden]

I figured it might be an issue with radiant light heating up the black plastic casing...I measure about 5 differing spots in the tent...lower is always around 21-23c, middle is around 25c and the tops with heaps of radiant light hits 31c. Out of the coverage in the top corner it is only 26c, so if I average it all out it's not too bad, probably just heating up from light exposure being black plastic.

Keep fans moving everything so heat doesn't build in one spot.

 

[VincenzioVonHook]

Keep fans moving everything so heat doesn't build in one spot.

More fans are on the list for today. I had two 15cm fans in there, but didn't realise one stopped working at one stage, so there's only one at light height right now, the other barely turns. I'm surprised nothing has burnt out and set my house on fire.

Going to pick up another two now. Throw one down under the canopy to blow the cooler air up, and the other up top to cool the light. The driver is getting damned hot touching the top of the tent. The mylar is insulation lol.

 

[1212ham]

I'd put something over the sensor to shade it.

 

[GrowingAbroad]

I'd put something over the sensor to shade it.

Yeah just like a said. Taking the temperature in direct light/sunlight is misleading. As long as your shade temp is ok and the upper leaves don't turn dry or start curling on the sides you're basically ok.

 

[Star Dog]

I don't find any absolute I've seen canopy temperature equal to the ambient, I've seen it 1.5/2c higher and 1.5/2c lower, it can't just be me that's seen this?

For the sake of being thorough I put a naked thermometer on the canopy 1.5 hrs ago... 540w 20"

Room temperature

Canopy temperature

Hot spot

Environment controller.

???