Any temp difference MH vs. HPS ?

I'm just curious; is there is a difference in the amount of heat generated by a Metal Halide bulb and a High Pressure Sodium bulb assuming both are of the same wattage?

mc, i found a pdf here that doesn't discuss temperatures directly. but it does state that HPS are much more efficient than MH.

for example:

[align=center]HPS---------Mh[/align]
[align=center]250W-----400W-----250W-----400W[/align]
mean lumens[align=center]26,100-----45,000-----14,100----- 20,500[/align]
avg rate life [align=center]25,000+-----25,000+-----15,000----- 10,000[/align]
(hours)
mecury content [align=center]15-----15----- 81-----38[/align]
(mg)

so if they use the same watts, yet the output is the same then the extra power must be put out as heat. similar to an incandescent bulb, only about 10% of the consumed power is turned into light while the rest is heat.

besides being more efficient, the life of the bulb is better with HPS and they are better of the environment.

hope this helps.

sorry the chart is kinda jacked!



-shake

Thanks shake. I knew there was quite a difference in the lumens between the two. The 2 bulbs I bought are rated at 20,000 for the MH and 30,500 for the HPS.

My concern is the amount of heat actually generated by each. Since, as you already know, I'm running this inside a small grow tent I'm just wondering if I should be thinking about adding a second circulating fan aimed at the reflector, add an insulating blanket like the one hydroinnovations makes or even add a "Y" splitter to the exhaust ducting to pull out hot air from above the reflector. Or......... all of the above.:D

Just trying to plan ahead rather than frantically trying to deal with any additional heat when I switch the bulbs.:D:(:D:D

your question is which would run hotter. correct?

well from what i had gathered (with no expereince of my own) is that a HPS seems to run steady at about 100 lm/W ( lumens per watt) where as the MH ranges anywhere from 65-115 lm/W.

so i would assume (and we both know what can happen here) is that the electricity that is not getting turned into light is getting turned into heat. so depending on how efficient your MH is will depend on which will run hotter.

i wasn't try to tell you which had more lumens, i was just using the chart as a reference to back my hypothesis.

i guess sometimes i just get so excited to help and instead of chiming in i should just sit back and learn.

and keep the ballast outside the room if possible.

hopefully someone will chime in with experience.


-shake

Yup. Which is hotter? Your theory makes sense and I suppose, in time, I'll find out the answer when it comes time to switch bulbs.

The ballast is outside the tent and running cool as a cucumber.:)

I find in my 2 cabinets that the MH runs "hotter" than the HPS bulb. Both are same wattage

In my closet; my 400 watt CMH bulb ran cooler than my 400 watt Hortilux HPS bulb.

I don't know what you can do with this information?..but, ...there it is....:thumbsup:

tinytoon & Dutch Pimp ~ Thank you for your input.

I was just about say basically everything that shake said lol...

energy cannot be created or destroyed - only convereted into different forms... (Law of Conservation of Energy) Conservation of energy - Wikipedia, the free encyclopedia

Wattage is a measure of energy conversion, 1 watt = 1 joule per second. Light bulbs only convert energy into 2 things, lumens and heat. Given 2 bulbs of equal wattage that have different lumen outputs, logic dictates that the one with lower lumens must be generating more heat as that energy must go somewhere, and if its not lumens, it must be heat.


... glad i paid a little bit of attention in physics class! :thumbsup:

syde00 ~ Makes sense to me. Unfortunately, physics and themodynamics are nowhere near my stong suit. :D My youngest son is an expert in those fields but, I can't exactly approach him on the subject.:jointsmile:

What you and shake have said is starting to make sense to me. So, if I've got this correct; the more efficient the lamp is at converting electricity to light, i.e. more lumens per watt, then the less heat it should generate.

So, if a standard 250 watt MH bulb puts out 20,000 lumens

and a standard 250 watt HPS bulb puts out 28,500 lumens

with a Hortilux 250 watt HPS bulb is putting out 30,500 lumens

then both HPS's would generate less heat than the MH and the Hortilux would run slightly cooler than the standard HPS bulb.

Oh no. My brain is starting to feel like it did after reading all the lengthy threads on building the perfect LED lamps.;):D;) Just kidding.;) No offense what-so-ever meant to the participants in those discussions. It just got a bit over my head.:wtf:;) OK. Way over my head.;):);)