UV lights are much more temperature sensitive than the eye would lead you to believe. This is due to the fact that you can't see UV, only visible light, and the visible light output of a lamp is NOT related to the UV output. You can't tell how well the lamp is performing just by looking at it. What you can look at is the ambient air temperature around the lamps, which will give you a very good idea of the UV output.
UV lamps love it when the air around them is between 90°F and 100°F (32°C to 38°C). As the temperature rises above 110°F (43°C), the UV output will start dropping dramatically, and the lamp life will be shorted as well. Running them too cool isn't particularly bad on them, but running below 90°F (32°C) will cause the UV output to drop off moderately, to the point that by the time you get to 70°F (21°C), you've cut the UV by half, and it drops off dramatically from there.
For growers, this isn't much of an issue. For UV curing, it often becomes a design consideration as the UV curing is often happening in a warehouse, factory or other place that might be very cool in the winter time. It may just require running for 5 to 10 minutes to preheat the air around them, but often it means creating a slight shell for them to operate in so they retain the heat, yet don't overheat in the summer. Or something that has removable slats during different times of the year. It doesn't have to be complicated, but you still need to think about it. The image below (not perfectly to scale) gives a rough idea how the relationship works.
Keep in mind that we are talking about the air temperature AROUND the lamp, not the temperature of the lamp itself, which will be higher and is harder to measure. Let the lamps run for 10 minutes, then use any standard thermometer (a meat thermometer works great) and leave it sticking about 2cm to 3cm from the lamps (1 inch) for two or three minutes, you get a pretty good idea. Being a little low is better than a little high, particularly since the lamps will heat up over time.
Back to Support