cooling needed with 3590 cobs

linky

linky

Well-Known Member
Hey all, I am curious for cooling requirements when using led/cobs. With HPS bulbs each 1k unvented bulb you should have approx 6k btu of cooling.. does this translate the same with cobs? If I were to have 1k of cobs, no venting, sealed room would you want 6k btu per 1k watts of cobs? I am trying to determine the correct cooling I am needing. thanks all
 
linky

linky

Well-Known Member
churchhaze said:
You will need the same cooling for 1kW of HPS and 1kW of cobs, enough to handle 1kW of heat production.
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I was not sure if it were the same or not, since with 1k hps you are losing like ~65 percent to heat, with 1k cobs you are losing only ~40 percent of that to heat I believe.
 
JorgeGonzales

JorgeGonzales

Well-Known Member
linky said:
I was not sure if it were the same or not, since with 1k hps you are losing like ~65 percent to heat, with 1k cobs you are losing only ~40 percent of that to heat I believe.
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It (mostly) all ends up as heat. Some light is obviously used in photosynthesis, but that's a surprisingly small fraction. The vast majority bounces off something and is converted into heat energy.
 
B

BlackD.O.G

Active Member
JorgeGonzales said:
It (mostly) all ends up as heat. Some light is obviously used in photosynthesis, but that's a surprisingly small fraction. The vast majority bounces off something and is converted into heat energy.
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Are you sure? I thought that cobs are far more efficient and generate less heat watt per watt.
 
qballizhere

qballizhere

Well-Known Member
Jungle time put it best here I believe https://www.rollitup.org/t/can-someone-dumb-down-cbx3590s.912731/
JungleTime said:
To replace 2;1000w hps lights you need roughly 1000-1200w of leds.

To properly light up a 4x8 tray you need 2; 1,000 watt lights or 1,000-1200 watts of leds. We'll go with 1,000 watts of led to make the math work out a lil better.

Hps = 1000w being 35% efficient
Heat = 650w of heat energy
750w x 2 = 1300w of heat energy.

Led = 1000w being 56% efficient
Heat = 440w of heat energy

Air cooled lights generally remove half the heat that is produced, unless of course you have multiple 1000's on the same inline fan.

So.. final numbers.
Air cooled Hps = 1300w / 2 = 750w of heat energy
Led = 440w of heat energy

So you can see we save on 32% on heat moving to led.
.
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Atulip

Atulip

Well-Known Member
How does the added IR of HPS add to heat/temperature?

I always see the equal heat thing posted, but anecdotal evidence tells me otherwise. I replaced hps with less efficient led(400w(never measured wall) hps to 450w(wall) of epi panels) with the same cooling and space and saw lower overall canopy temperatures.
 
BOBBY_G

BOBBY_G

Well-Known Member
while IR is notorious for heating up surfaces, ALL wavelengths of light have radiant heat component

in HPS case the large amount of IR is in a poor absorbance spectrum and is wasted light essentially

in your example canopy temps =/= room temps and without an at the wall measurement there is no basis as "total watts" of cheap led fixtures is almost always exaggerated
 
JorgeGonzales

JorgeGonzales

Well-Known Member
Atulip said:
How does the added IR of HPS add to heat/temperature?

I always see the equal heat thing posted, but anecdotal evidence tells me otherwise. I replaced hps with less efficient led(400w(never measured wall) hps to 450w(wall) of epi panels) with the same cooling and space and saw lower overall canopy temperatures.
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You know, this is a good question, but not the question the OP asked. He said a sealed unvented room. But I think your point sometimes gets lost in the glib "watts is watts" answer people love to give here.

An LED will keep canopy temps lower in a well-ventilated room with intake on the bottom, outtake at the top. IR will heat up the canopy directly, whereas an LED is dumping it's wasted energy into a heat sink, which promply gets blown the hell out of the room/tent by a big ol' fan.
 
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Atulip

Atulip

Well-Known Member
@JorgeGonzales Thank you. I've was thinking IR had something to do with it. My issue became summer temps, where the intake temps may hit 80℉+ some days. The canopy under hps had always been +8-10℉ higher than intake temps, with led, just a few degrees higher than intake.

@BOBBY_G I stated the at the wall of the epi panels(450w), but I never bothered to check the 400w hps.
 
optzulu

optzulu

Well-Known Member
Can we agree that when you using 1000w of cxb3590 @1400ma and 1000w of cxb3590 @700ma you need the same cooling power for the space ?
 
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