Grow light efficiency and heat

Sellardore

Sellardore

Member
Hello all!

I’ve searched for a while and couldn’t find a definitive answer on efficiency and heat so I’m hopeful some of you could help me out.

Generally speaking the more efficient the grow light the less heat it produces given the same wattage. Although, this isn’t always true, example;

8 tube T5HO (432w) = 540 umols output
VS
400w HPS-SE = 725 umols output

HPS is more efficient than T5HO in producing more usable light for plants with equal wattage, but it produces far more heat. I’m curious why this is? I understand the most of grow lightning except for a solid understanding of why and how much heat is produced.

I brought this question up because I was eyeing the new 1000w CMH DE fixtures/bulbs, although they are rated less umols output compared to the HPS DE fixtures/bulbs (2100 umols HPS DE compared to 1650 umols CMH DE). CMH produces about 20% less heat than HPS, but that’s for the 315s and 630s because they’re more efficient so I’m wondering if these new 1000w CMH fixtures/bulbs given that they’re less efficient, will they produce more heat or less than the HPS?

Thanks a ton in advance!
 
ThatBoyZooted

ThatBoyZooted

Well-Known Member
Sellardore said:
Hello all!

I’ve searched for a while and couldn’t find a definitive answer on efficiency and heat so I’m hopeful some of you could help me out.

Generally speaking the more efficient the grow light the less heat it produces given the same wattage. Although, this isn’t always true, example;

8 tube T5HO (432w) = 540 umols output
VS
400w HPS-SE = 725 umols output

HPS is more efficient than T5HO in producing more usable light for plants with equal wattage, but it produces far more heat. I’m curious why this is? I understand the most of grow lightning except for a solid understanding of why and how much heat is produced.

I brought this question up because I was eyeing the new 1000w CMH DE fixtures/bulbs, although they are rated less umols output compared to the HPS DE fixtures/bulbs (2100 umols HPS DE compared to 1650 umols CMH DE). CMH produces about 20% less heat than HPS, but that’s for the 315s and 630s because they’re more efficient so I’m wondering if these new 1000w CMH fixtures/bulbs given that they’re less efficient, will they produce more heat or less than the HPS?

Thanks a ton in advance!
Click to expand...
From what ive read and understand, CMH might be the new frontrunner in HID . Its similar efficiency to HPS , but like you said doesnt run nearly as hot as the HPS does . My friend has a sun system 630 with 2 smaller 600w mars hydro LEDs and his tent has gotten well over 120 degrees at times . Without proper ventilation that is one of the bigger concerns with HPS. CMH on the other hand doesnt run nearly as hot and puts out an even better light spectrum (more usable light) than HPS.
 
S

spek9

Well-Known Member
ThatBoyZooted said:
CMH on the other hand doesnt run nearly as hot and puts out an even better light spectrum (more usable light) than HPS
Click to expand...
Do you have any citings that refer to the fact that CMH has a "better light spectrum (more usable light)" than HPS?

And as far as heat output, are you comparing equal wattage lamps, or are you comparing a 600W HPS to a 300W CMH?
 
nurrgle

nurrgle

Well-Known Member
They would or should put out close to the same heat. For my math I always assume a watt is going to produce the same amount of heat inside a closed grow room

Spectrum has a huge impact I recently switched out some HPS for 315’s.

6 x 1000w hps = 6000w and a shit ton of heat
15 x 315 cmh = 4725 w and a shit ton of heat

I found the heat load on the room decreased proportionately to the decrease in wattage. I am not an engineer but I would suspect those 1000w with attached ballasts will run the same Btu’s as a 1000w gravita.

If your pushing for the highest yield, hps is king for now.
 
Corso312

Corso312

Well-Known Member
nurrgle said:
They would or should put out close to the same heat. For my math I always assume a watt is going to produce the same amount of heat inside a closed grow room

Spectrum has a huge impact I recently switched out some HPS for 315’s.

6 x 1000w hps = 6000w and a shit ton of heat
15 x 315 cmh = 4725 w and a shit ton of heat

I found the heat load on the room decreased proportionately to the decrease in wattage. I am not an engineer but I would suspect those 1000w with attached ballasts will run the same Btu’s as a 1000w gravita.

If your pushing for the highest yield, hps is king for now.
Click to expand...
Hps hasn't been King for several years.
 
JoeBlow5823

JoeBlow5823

Well-Known Member
nurrgle said:
I’d wager 1000de with good environmental controls are still tops for yield per sqft.
Click to expand...
Id wager your right. For my 5x5 that I only run during winter, the 1000 DE is perfect. 1000w DE is still what you will find in almost every commercial growers setup. Light output per watt is right there with the best LEDsIMG_4158.JPG
 
Renfro

Renfro

Well-Known Member
JoeBlow5823 said:
Light output per watt is right there with the best LEDs
Click to expand...
With HPS you want around 50 - 60 watts per sqft.

With quality LED you want about 30 - 35 watts per sqft

Quality LED will blow HPS away. In time it's what everyone will be running.

HPS can still grow weed, it just costs more to do so. I also got better quality off LED. So just saying, LED is taking over. HPS is old news. CMH is a tweener that I consider neat and all but LED is where it's at now.
 
JoeBlow5823

JoeBlow5823

Well-Known Member
Renfro said:
With HPS you want around 50 - 60 watts per sqft.

With quality LED you want about 30 - 35 watts per sqft

Quality LED will blow HPS away. In time it's what everyone will be running.

HPS can still grow weed, it just costs more to do so. I also got better quality off LED. So just saying, LED is taking over. HPS is old news. CMH is a tweener that I consider neat and all but LED is where it's at now.
Click to expand...
"With HPS you want around 50 - 60 watts per sqft." is a very broad statement and applies more to old fashioned single ended bulbs, double ended bulbs are putting out about 30% more light than single enders.
 
Sellardore

Sellardore

Member
Renfro said:
With HPS you want around 50 - 60 watts per sqft.

With quality LED you want about 30 - 35 watts per sqft

Quality LED will blow HPS away. In time it's what everyone will be running.

HPS can still grow weed, it just costs more to do so. I also got better quality off LED. So just saying, LED is taking over. HPS is old news. CMH is a tweener that I consider neat and all but LED is where it's at now.
Click to expand...
LEDs are definitely something I plan on upgrading to eventually. The minimal heat and efficiency is extremely attractive. There are great LEDs and there are also plenty of crappy ones too. Although, spectrum and upfront costs are the prohibiting factor. CMH still has the second best spectrum next to the sun though.

As for efficiency a quality HPS DE is actually quite on par with the majority of LEDs (beats many) with an average PPFD/watt of 1.5 with the exception of some recent new (and pricey) LEDs that I’ve seen as high as 2.0 - 2.4. Besides, unless you’re running CO2, the plants are basically maxed with the amount of light they can utilize and going higher than 1000 PPFD is usually detrimental without it.
The real reason to run the super efficient LEDs is if you’re trying to grow your plants in hyperdrive and getting up to 1500+ PPFD while running CO2 which you really can’t do with HPS because the heat would be too hard to manage.
 
You must log in or register to reply here.
Top