Quote Originally Posted by oldman
MH lights run hotter then HPS lights. I've measured the difference in 600w HPS vs MH and the MH bulb produces much more direct heat then an HPS. The reason is as Irydyum stated, for 600w energy in the MH bulb produces about 40,000 lumens of light, while the HPS converts 600w into 90,000 lumens. What does not get converted into lumens goes to extra heat. If you want to consider secondary heat generation, then the HPS will heat an object greater because it has more then twice the radiant energy then the MH. But the greater radiant heat produced is a product of simply more light energy then spectrial differences.
Well, you are wrong dude, IF the pure MH bulb is hotter it's due to the kelvin difference in the light, hence the "color temperature" and kelvin scale. Even Wikipedia and the known laws of physics state the blue light has the most photons or really "Photon Flux Density", thus produces more radiant heat as it has more total energy. The extra heat is not from an inefficient ballast although that does produce heat due to electrical losses in all HID set-ups and that is nothing new, we all know that. PLUS the heat is outside the tent in this conversation so we are talking about light produced in the tent and the radiant heat energy it creates based on it's Photon Flux Density. The HPS light just has less photons per lumen and thus more lumens per watt produced by the light. (along with alot of infared which is very very hot, hotter than blue) The HPS has far more infared light than the MH, hence it ultimately is hotter. Then consider most HPS users run the hortilux bulbs with the blue added to the spectrum and you have a very hot light creating alot of ambient heat just like the sun that heats the earth does through light energy and infared heat, etc.


Quote Originally Posted by oldfart
This can be seen better with say a T5 fluro tube. If you measure the heat output from an actinic white @ 420nm or abt 12,000K, a 6500K daylight tube and a 2,700K bloom tube, they all produce the same heat output even tho they are way different in Kelvin temps. According to FreeDaHerb this can not be, the 12,000K should be much hotter then the 2,700K tube. But in the real world it is not.
Well, again missing the simple stuff but I guess it's all too easy with a simple mind and worrying about falling off that soon to break & very thin branch.

The lights in fact are all very different temperature kelvin wise to begin with due to their obvious color differences, blue light having more photons / light energy and red having less photons per lumen. Because of their revelant spectrums they produce varying amounts of lumens or actual light in that range per watt burned, so yes they all do produce similiar heat levels most likely but from very different total lumens of light, i.e. some light is hotter, some is cooler based on the total amount of light being produced and their spectrum. Pure Blue light is much hotter energy wise in equal amounts of light than say 660 nm Red.

Plus, my original statement clearly states it's the radiant/ambient heat too.

I mean it say's it right there in Wikipedia, maybe you should argue with them.

Don't confuse yourself again. :jointsmile: :thumbsup: