LED panel heat issues

I'm using 2 180w Spectra grow panels from GrowLEDHydro.

I have them both in a 8x3x9 closet, and when they're on the temps go up to 88 in the grow closet.

And thats with 74 degree outside temps.


Is this unusual?? The whole reason I bought LED's was to run a closed, CO2 system.


I'm thinking about switching to the 357 magnum. Their website advertises "virtually zero heat".


Just looking for some opinions out there. Let me know what you think guys. Thanks

I found that out, I gotta run my 4'' inline fan all the time, otherwise it gets too hot... very small space but they are all small lights. 88 degrees is ok for co2 system isnt?

Endur0xX said:

I found that out, I gotta run my 4'' inline fan all the time, otherwise it gets too hot... very small space but they are all small lights. 88 degrees is ok for co2 system isnt?

Click to expand...

I'm trying to aim for 84-85. I run DWC tubs and if the temps get any higher than that, rot explodes in my res's and kills the roots.

I've tried every combination of equipment set ups to discretely and effectively control my grow room temps, but havent found it yet ahaha

I shoot for low 70s

40 degrees Celsius is the peak photosynthetic rate; reason being is more heat = more movement of particles and of the fluids in cells however, above this production degrades sharply.
So that's 104 Fahrenheit.

You can run 88 alright, as long as you can keep it under 100 and the humidity high enough or salt concentration low enough.

As mentioned, 88F ought to be OK.

One thing is that with higher temperatures, the plants transpire more. . .that is, they suck up more water and "exhale" it as water vapor. So you'll be watering more at that temp, and creating more humidity in your grow area, which is something to be careful about.

In terms of heating in general, whether you're using CFLs, regular fluorescents, HPS, MH, or plasma, one thing remains true. **ALL** of those technologies are relatively inefficient in turning energy into light. Even the MOST efficient of them are still going to turn over 70% of energy used into waste heat.

LEDs aren't really all that much more efficient than HPS in terms of light output per watt. The big advantage is that the LED diodes are (in theory) more spectrum tailored to your plants, so less energy is wasted putting out light spectrum your plants can't use. Also, LED diodes themselves don't get all that hot, so you can keep the panel closer to your plants without burning them than you might with, say, HPS. But ultimately, even if your LED successfully substitutes for 400 watts of HPS, if you're running 200-300 watts of LED, you're still putting most of that energy out as waste heat!

A good way to think about it, is if you have a well ventilated HPS system running with temps staying around the optimal 78 degrees and you switch in a close to equal wattage LED you will see slightly lower ambient temps, if not significantly lower temps. Really depends on the set up.

Any space without ventilation will build up heat to an ambient point and some people would argue you should always have some kind of ventilation running just to keep fresh air moving through the grow space. Helps prevent mold and contributes to a plants health in a multitude of ways.

But yea, no ventilation = heat.

thanks for all the replies. I appreciate the input.


I'm going to set up a system that is closed with co2 while the lights are on,
and when the lights are off I'll run an intake and out take fan to cycle fresh air back in the grow room

Make sure your tubing system isn't translucent, meaning any plastic tubes you got if not black are likely translucent which will add to your root rot problems giving the bacteria/algae light for them to grow.

If you're not running compost tea or organics you should go to a hardware store and get a pond uv light for sanitizing your res.

Daemonn789 said:

A good way to think about it, is if you have a well ventilated HPS system running with temps staying around the optimal 78 degrees and you switch in a close to equal wattage LED you will see slightly lower ambient temps, if not significantly lower temps. Really depends on the set up.

Any space without ventilation will build up heat to an ambient point and some people would argue you should always have some kind of ventilation running just to keep fresh air moving through the grow space. Helps prevent mold and contributes to a plants health in a multitude of ways.

But yea, no ventilation = heat.

Click to expand...

Well if you're growing inside a closed cab without ventilation your plants will quickly use up all available CO2.

Unless you're also actively supplementing C02 (and for that you'll still have to vent out some air), your plants will quickly stop growing, and your entire grow won't go anywhere. In short, if you're growing in any small enclosed space you MUST ventilate, even if heat isn't an issue.

In terms of temps, the only reason LEDs put out less heat then HPS on a watt for watt basis is that the nominal watt rating on both is misleading.

Due to the ballast, HPS bulbs generally suck MORE wattage than the number their rated at. My understanding is that a typical "400W" HPS actually draws closer to 475 watts.

In contrast, LEDs generally suck quite a bit less because the diodes themselves are not being driven to their nominal power rating, otherwise they would overheat and greatly reduce their operating life. Actual draw varies between panel and maker, but a nominal "240W" LED panel typically only draws 130 actual watts.

In other words if you're running 400 nominal watts of LED, you're only really using 216 watts, explaining why LEDs run "cooler".
If you want to equal the ACTUAL power draw of one 400 watt HPS lamp, you might have to run a nominal 875 watts of LEDs!

Again, on a true watt-for-watt basis, HPS and LEDs will generate fairly comparable amounts of heat. The difference there (at least in theory) is that because the LED spectrum "ought" to be better tailored to growing plants, the LED should be more efficient on a watt-for-watt basis.