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Does cold air in air-cooled hoods DIM the light?

samba

samba

Active member
Does cold air in air-cooled hoods DIM the light?
http://www.youtube.com/user/MonsterGardens#p/u/13/TUPlaKadogc
@ 1 minute
The man is selling non air-cooled hood, so...
But I do remember seeing a setup sucking -20C / -4F air from outside in the winter and pushing it strait in to the hoods and the lights were dimmer, if I remember correctly, it was years ago I visited that grow room.

I also heard on a gavita video, cant find it now, that the cord between the ballast and bulb reduces the light,the longer the more. Anyone have info on this?
 
messn'n'gommin'

messn'n'gommin'

ember
Veteran
I believe that spectral graphs from a particular lamp are taken in a company lab with particular equipment, a particular environment, a particular set of parameters, etc. and averaged. Lamps are designed to operate at particular temps, frequencies, position, and so on. Altering the parameters more than likely affects performance and I do know that cooling a lamp below its optimal temps can cause it to shift its color. I suppose dimming and a color shift would go hand in hand, but I don't know for that certain.

hth
 
C

chefro420

Have done it down to 15 F or there abouts . Biggest problem for me was condensation , no noticeable loss as far as intensity is concerned . Street lights and sports arenas are HID ? But Im also no lighting engineer.....
 
whazzup

whazzup

Member
Veteran
Yes I do have info on that. There are specific HPS lamps that are very sensitive to operating temperature. Cooling those down can actually cost you a lot of light. A good example are the highly efficient philips 400V 1000W electronic lamps. They have a very small arc tube and a very small quartz outer balloon and are gas filled instead of vacuum. Some of the earlier luminaries designed for this lamp even had lamp warmers. They lose a lot of light when you cool them below the operating temperature. But operating temperature is important for all HPS lamps. Some will be influenced a bit more than others. I think most growers pump way too much air through their systems.

Now the gentleman in the video talks about 10% loss in air cooled shielded systems. A clean, well designed air cooled reflector will give losses, if only through the use of the glass. Whether that is just 5% glass losses in a well designed system or 10% in those crappy internal reflector cool tubes depends on the system. He is European and has the cool tubes as a reference. In Europe they use cooltubes as a last resort if they can't do it with an open reflector. Air cooled shades are very rare in the low lands.

Combining glass losses and losses due to a lamp running too cool (which will happen with some lamps) can cost you a lot of light. Don't trust your eyes, they suck for determining light intensity :D

It's easy to test btw. Run a lamp in reflector with shade and cooling and then without shade and cooling and measure the difference. Do allow the lamp to run for at least half an hour. Keep the light meter fixed at a steady spot, not directly under the lamp.

About the leads to your lamp: Most electronic ballast manufacturers recommend to keep them short. Long leads will cause small losses yes, so cable quality and length is important. Also to prevent EMI I would personally keep the leads as short as possible. The remote ballast is a hobby invention anyways, almost nobody in professional horticulture uses remote ballast systems. Modern high efficiency electronic ballasts only dissipate 32W (600W) up to 60W (1000W) of heat and that is not a lot of extra heat. When using a more efficient lamp you can expect to have less heat: energy is converted to heat and light. There is no need anymore to take the ballast out of the grow room.

So you see grows in Europe with 5x 1000W open reflectors (complete fixtures) on 7,5 square meters with an opticlimate (heats/cools/dehumidifies, water cooled) with CO2 in a completely closed room, about 55-60 cm from the crop, yielding almost 7 kg. It's a different approach to growing I guess.
 
samba

samba

Active member
whazzup said:
Yes I do have info on that. There are specific HPS lamps that are very sensitive to operating temperature. Cooling those down can actually cost you a lot of light. A good example are the highly efficient philips 400V 1000W electronic lamps. They have a very small arc tube and a very small quartz outer balloon and are gas filled instead of vacuum. Some of the earlier luminaries designed for this lamp even had lamp warmers. They lose a lot of light when you cool them below the operating temperature. But operating temperature is important for all HPS lamps. Some will be influenced a bit more than others. I think most growers pump way too much air through their systems.

Now the gentleman in the video talks about 10% loss in air cooled shielded systems. A clean, well designed air cooled reflector will give losses, if only through the use of the glass. Whether that is just 5% glass losses in a well designed system or 10% in those crappy internal reflector cool tubes depends on the system. He is European and has the cool tubes as a reference. In Europe they use cooltubes as a last resort if they can't do it with an open reflector. Air cooled shades are very rare in the low lands.

Combining glass losses and losses due to a lamp running too cool (which will happen with some lamps) can cost you a lot of light. Don't trust your eyes, they suck for determining light intensity :D

It's easy to test btw. Run a lamp in reflector with shade and cooling and then without shade and cooling and measure the difference. Do allow the lamp to run for at least half an hour. Keep the light meter fixed at a steady spot, not directly under the lamp.

About the leads to your lamp: Most electronic ballast manufacturers recommend to keep them short. Long leads will cause small losses yes, so cable quality and length is important. Also to prevent EMI I would personally keep the leads as short as possible. The remote ballast is a hobby invention anyways, almost nobody in professional horticulture uses remote ballast systems. Modern high efficiency electronic ballasts only dissipate 32W (600W) up to 60W (1000W) of heat and that is not a lot of extra heat. When using a more efficient lamp you can expect to have less heat: energy is converted to heat and light. There is no need anymore to take the ballast out of the grow room.

So you see grows in Europe with 5x 1000W open reflectors (complete fixtures) on 7,5 square meters with an opticlimate (heats/cools/dehumidifies, water cooled) with CO2 in a completely closed room, about 55-60 cm from the crop, yielding almost 7 kg. It's a different approach to growing I guess.
Click to expand...

THANK YOU!
You seem to know what your talking about. And I'm actually European, from the north. Running cooltubes, but upgrading to the high end U.S. reflectors. Waiting for them to arrive. Can get them here in the EU now!!!
About cable length, your talking about digital? I'm running magnetic, old style, should of mentioned that...
 
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