Yesterday I was watching a BRS video on T5HO lighting, towards the end of the video he was talking about bulb efficiency and the effect fan speed can have on the bulb's output. Fast forward to 23m36s.
[video]https://youtu.be/C61DTnWKGjc?t=23m36s[/video]
I was curious and PAR tested my 4x24w ATI Sunpower at all available fan voltages (3, 4.5, 6, 7.5, 9, and 12) with and without the splashguard. The PAR readings were taken 3 minutes after voltage changes to ensure the temperature would have time to settle. Room temperature was measured at 74F.
Everything I have read tends to suggest that there is an optimal "lamp cold spot" temperature in which the bulbs are most efficient, and that once you exceed that temperature the efficiency begins to drop again. For all of the fan settings, 3V gave the highest PAR readings, possibly a slower fan would have produced an even higher PAR number. I did also test both with and without the shield with the fans off to see if the shield transparency was cause for the nearly 10% gain in PAR numbers at all voltages, but it was the same at 108. This would suggest that the wall temps of the bulbs are also a factor just like in the BRS video.
Page two of the following PDF suggests the optimal operating temp for the cold spot to be 118F.
http://lumenoptix.com/uploads/HowtoDesignBetter_lowres.pdf
[video]https://youtu.be/C61DTnWKGjc?t=23m36s[/video]
I was curious and PAR tested my 4x24w ATI Sunpower at all available fan voltages (3, 4.5, 6, 7.5, 9, and 12) with and without the splashguard. The PAR readings were taken 3 minutes after voltage changes to ensure the temperature would have time to settle. Room temperature was measured at 74F.
Everything I have read tends to suggest that there is an optimal "lamp cold spot" temperature in which the bulbs are most efficient, and that once you exceed that temperature the efficiency begins to drop again. For all of the fan settings, 3V gave the highest PAR readings, possibly a slower fan would have produced an even higher PAR number. I did also test both with and without the shield with the fans off to see if the shield transparency was cause for the nearly 10% gain in PAR numbers at all voltages, but it was the same at 108. This would suggest that the wall temps of the bulbs are also a factor just like in the BRS video.
Page two of the following PDF suggests the optimal operating temp for the cold spot to be 118F.
http://lumenoptix.com/uploads/HowtoDesignBetter_lowres.pdf
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