LED Grow Light heat

Edward84

Edward84

Active Member
I was wondering if anyone knew of a good light that don't produce a lot of heat. My biggest issue is is keeping my tent cool. I'm running the KS3000 and my temps reach 85 in my 3x3. My room temperature is always at 73 degrees. If anyone has any tips on keeping the LED temps down I would appreciate it. I currently run the 4" AC infinity .
 
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Delps8

Well-Known Member
I've never seen a discussion about heat given off by a given LED grow light vs another. Perhaps that's because, compared to gas discharge, LED's generate so little heat.

The driver for your light can be dismounted so that will help get that heat source out of the tent. If the wires on the light are not long enough, you could patch in your own extension cord. I've added 10' to the wire for my Mars SP 3000.

Re. temps - the Chandra paper "Photosynthetic response of Cannabis sativa L. to variations in photosynthetic photon flux densities, temperature and CO2 conditions" demonstrates how the rate of photosynthesis increases as ambient temp increases, up to 30°C. That's in a CO2-enhanced environment but the underlying processes are the same at 420 PPM.

Per the graphic below, net photosynthesis increases from 13±µmols/m2 to 18±µmols/m2 when the temperature goes from 77° to 86° which is pretty much the same bump as going from 500µmols of light to 1000µmols. You might find that 86° is too warm for your liking but, if you can keep control your RH, you should be able to get increased yield at the higher temps rather than at 73°.


1672391055724.png
 
coreywebster

coreywebster

Well-Known Member
Edward84 said:
I was wondering if anyone knew of a good light that don't produce a lot of heat. My biggest issue is is keeping my tent cool. I'm running the KS3000 and my temps reach 85 in my 3x3. My room temperature is always at 73 degrees. If anyone has any tips on keeping the LED temps down I would appreciate it. I currently run the 4" AC infinity .
Click to expand...
Are you venting back into the same room?

The temp of your tent is directly related to your ambient room tent and the wattage and the airflow.

Though some fans do a better Job because some aren't up to the task in the first place.

As an example I'm able to vent 2x 400w mh with a 4" box fan.
Plus 1200w of flowering LEDs with a 6".

Because both are vented up a chimney.


The difference between a 300w led and another is in its ability to remove heat into the air from the diodes, the one with the better heat sink will feel cooler but its still putting the Same heat into the tent.

One thing though, 85f is not a problem.
But if your getting such a temp rise either your fans not good with resistance( unlikely) or, more likely, your extraction set up is not set up right, ie out of a window ect
 
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Delps8

Well-Known Member
Horselover fat said:
The less power your light uses the less heat it produces. A 400w led is going to produce 400w worth of heat. Doesn't matter which 400w led it is. The heat is also the same as a 400w HPS, or 400w of incandescent bulbs.
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Good point.

My thinking was heating the plant not the total amount of heat generated.
 
Edward84

Edward84

Active Member
Delps8 said:
I've never seen a discussion about heat given off by a given LED grow light vs another. Perhaps that's because, compared to gas discharge, LED's generate so little heat.

The driver for your light can be dismounted so that will help get that heat source out of the tent. If the wires on the light are not long enough, you could patch in your own extension cord. I've added 10' to the wire for my Mars SP 3000.

Re. temps - the Chandra paper "Photosynthetic response of Cannabis sativa L. to variations in photosynthetic photon flux densities, temperature and CO2 conditions" demonstrates how the rate of photosynthesis increases as ambient temp increases, up to 30°C. That's in a CO2-enhanced environment but the underlying processes are the same at 420 PPM.

Per the graphic below, net photosynthesis increases from 13±µmols/m2 to 18±µmols/m2 when the temperature goes from 77° to 86° which is pretty much the same bump as going from 500µmols of light to 1000µmols. You might find that 86° is too warm for your liking but, if you can keep control your RH, you should be able to get increased yield at the higher temps rather than at 73°.


View attachment 5243116
Click to expand...
Thank you for the reply. I was under the impression that the high 70's is where it needed to be. But everything has changed in the last 8 years. I am still used to the old MH/HPS. I will let the temperatures sit where they are and maybe add another fan to move the air.
 
Edward84

Edward84

Active Member
Horselover fat said:
The less power your light uses the less heat it produces. A 400w led is going to produce 400w worth of heat. Doesn't matter which 400w led it is. The heat is also the same as a 400w HPS, or 400w of incandescent bulbs.
Click to expand...
The whole energy can't be created or destroyed thing, understood. Thank you for getting back to me.
 
ProPheT 216

ProPheT 216

Well-Known Member
That light should be optimized for that space. Maybe you need to up your cfm of air exchange. Also 82 to 85 is where I want my leaf temp to be in the tent anyways

Put a thermometer in your exhaust vent and see what your air coming out actually is. Way lower than you think probably

Surface temp and air temp are different
 
Edward84

Edward84

Active Member
coreywebster said:
Are you venting back into the same room?

The temp of your tent is directly related to your ambient room tent and the wattage and the airflow.

Though some fans do a better Job because some aren't up to the task in the first place.

As an example I'm able to vent 2x 400w mh with a 4" box fan.
Plus 1200w of flowering LEDs with a 6".

Because both are vented up a chimney.


The difference between a 300w led and another is in its ability to remove heat into the air from the diodes, the one with the better heat sink will feel cooler but its still putting the Same heat into the tent.

One thing though, 85f is not a problem.
But if your getting such a temp rise either your fans not good with resistance( unlikely) or, more likely, your extraction set up is not set up right, ie out of a window ect
Click to expand...
Im not venting back into the room, but I am venting out of a window. Is this something that needs to be changed? Is there a reason you are still using MH? Is there an advantage using them during part of your cycle? Better penetration maybe?
 
coreywebster

coreywebster

Well-Known Member
Edward84 said:
Im not venting back into the room, but I am venting out of a window. Is this something that needs to be changed? Is there a reason you are still using MH? Is there an advantage using them during part of your cycle? Better penetration maybe?
Click to expand...
I like a chimney but I'm lucky to have had working ones in every house I've grown in.
Nothing wrong with a window.

I like Metal halide for veg because generally plants are happier in the low 70s , where under LED they are happier and grow faster high 70s to low 80s.
It's just easier for me to manage environment without paying to heat the area this way.
Everyone's environment is different.
I also vent my veg tent to my flower tent normally so that saves me heating that when lights are off in flower tent.
I also always flower with LED though.
 
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coreywebster

coreywebster

Well-Known Member
So given your not Recirculating air in the same room and venting out the house as you should.

That leaves a couple of things.

1. Do you have a lot of bends and restrictions in your ducting? Long lengths of duct?
2. Are you measuring air temp out of direct light? Because light can throw off the readings.
3. Are you mixing your air properly by way of circulation fans so that it's as even as possible and not all the heat up top and all the cool air at the bottom ?
 
Edward84

Edward84

Active Member
coreywebster said:
I like a chimney but I'm lucky to have had working ones in every house I've grown in.
Nothing wrong with a window.

I like Metal halide for veg because generally plants are happier in the low 70s , where under LED they are happier and grow faster high 70s to low 80s.
It's just easier for me to manage environment without paying to heat the area this way.
Everyone's environment is different.
I also vent my veg ten to my flower tent normally so that saves me heating that when lights are off in flower tent.
I also ways flower with LED though.
Click to expand...
That is some nest level stuff right there. Im glad that the window isn't a problem. It's my only option that won't require putting a hole in the ceiling.
 
Edward84

Edward84

Active Member
coreywebster said:
So given your not Recirculating air in the same room and venting out the house as you should.

That leaves a couple of things.

1. Do you have a lot of bends and restrictions in your ducting?
2. Are you measuring air temp out of direct light? Because light can throw off the readings.
3. Are you mixing your air properly by way of circulation fans so that it's as even as possible and not all the heat up top and all the cool air at the bottom ?
Click to expand...
I have been measuring in direct light, yes. I might need to get another fan, no lie. I will place an order after work. This thread helped a lot, I really appreciate you guys.
 
coreywebster

coreywebster

Well-Known Member
Edward84 said:
I have been measuring in direct light, yes. I might need to get another fan, no lie. I will place an order after work. This thread helped a lot, I really appreciate you guys.
Click to expand...
If you Google a Stevenson screen, you'll see those that give world weather reading at weather stations deliberately measure in shade because the IR from the sun heats the measuring equipment.

Now we don't have masses of IR with LED, we have a lot with HPS , not close to the sun levels though. But non the less , it gives a false reading.

So you can hang a thermometer above the light line or you can simple shade it with white card.

That would be my first move.

Point is your temps may be a few degrees lower than you think.

Regardless, 85f is fine, it's nothing to worry about.
 
Boatguy

Boatguy

Well-Known Member
Edward84 said:
I have been measuring in direct light, yes. I might need to get another fan, no lie. I will place an order after work. This thread helped a lot, I really appreciate you guys.
Click to expand...
Your current fan should be more than adequate for a tent that size in a 73 degree room even if you are exhausting into it.
Do you have your intake flaps open?

Im in a 3x3 with 300w and it literally takes a minute of the fan running to get temps back down. I had to dial my temps down to 79 because at 81 the fan didnt run enough to control humidity.
 
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