BobCajun
Well-Known Member
I was using all LED for 3'x1.5'x6' chambers (Walmart portable closets) until recently when a driver burned out for one of the 220w high bays so I had to replace it with a 150w HPS I had, and four 14 LED screw in bulbs. So together it was 206w, and a ratio of about 3w of HPS to 1w of LED. Actually I guess I should add one more 14w led to bring it up to 220w again, just I need to wire up another socket.
So anyway, point being that it seems to be working very nicely, actually looking better than before. I think such a combination may be better than either alone. I know LEDs alone tend to cause bleaching or burning and the potency hasn't really been what I was expecting. HPS alone isn't great either though, because of the spectrum not being ideal. The answer is obvious, a combination with HPS as the majority and enough LED to fill out the spectrum but not enough to cause bleaching. I used 5000k LED to fill out the blue part of the spectrum more.
How did I keep heat from being excessive? There was already a 8" round hole in the top of the chamber for the high bay (reflector removed) so I just covered it with foil and the HPS bulb sits about an inch below it. The foil acts as a reflector and also a heat dissipator. Most of the heat of a HPS bulb rises right above it, so you just need a good heat conductor there. The washroom fan ventilator is sufficient to remove the rest and also from the LED bulbs. The air that comes out is just warm. The rest of the top of the inside is also covered with foil to reflect all light, and I hung pieces of foil at about 45 degrees on each side of the bulb several inches away from it to direct the side light down. Didn't actually need a manufactured reflector. The only actual lamp hardware is the socket and the ballast, which is quite small, like palm size. Both the ballasts and bulbs can be bought at places like Home Depot, as replacement parts for HPS floodlights.
As far as efficency, the HPS is about the same as the high bay and LED bulbs, a little over 100 lm/w, so actually no reduction there. The LED high bays were problematic anyway because that driver burnout was actually the second major problem that developed. The first one was when a few COBs burnt out on the other high bay because the fixture got too hot apparently. Then the driver itself burnt out on the other one. They just seem prone to parts burning out, which obviously can be a big problem when you don't have spares. Sure, the LEDs themselves usually last a long time, with proper heat removal, but the drivers just burn out within a couple years and that's an expensive part to replace. I think I'd rather just replace HPS bulbs regularly. At least when they reach the end of their life they still work, just that they keep cycling on and off, but it's still on most of the time so you could get by until you can get a new bulb. By only using the 14w LED bulbs, when one burns out it's easy to get a new one at any department store, unlike COBs and drivers.
So anyway, point being that it seems to be working very nicely, actually looking better than before. I think such a combination may be better than either alone. I know LEDs alone tend to cause bleaching or burning and the potency hasn't really been what I was expecting. HPS alone isn't great either though, because of the spectrum not being ideal. The answer is obvious, a combination with HPS as the majority and enough LED to fill out the spectrum but not enough to cause bleaching. I used 5000k LED to fill out the blue part of the spectrum more.
How did I keep heat from being excessive? There was already a 8" round hole in the top of the chamber for the high bay (reflector removed) so I just covered it with foil and the HPS bulb sits about an inch below it. The foil acts as a reflector and also a heat dissipator. Most of the heat of a HPS bulb rises right above it, so you just need a good heat conductor there. The washroom fan ventilator is sufficient to remove the rest and also from the LED bulbs. The air that comes out is just warm. The rest of the top of the inside is also covered with foil to reflect all light, and I hung pieces of foil at about 45 degrees on each side of the bulb several inches away from it to direct the side light down. Didn't actually need a manufactured reflector. The only actual lamp hardware is the socket and the ballast, which is quite small, like palm size. Both the ballasts and bulbs can be bought at places like Home Depot, as replacement parts for HPS floodlights.
As far as efficency, the HPS is about the same as the high bay and LED bulbs, a little over 100 lm/w, so actually no reduction there. The LED high bays were problematic anyway because that driver burnout was actually the second major problem that developed. The first one was when a few COBs burnt out on the other high bay because the fixture got too hot apparently. Then the driver itself burnt out on the other one. They just seem prone to parts burning out, which obviously can be a big problem when you don't have spares. Sure, the LEDs themselves usually last a long time, with proper heat removal, but the drivers just burn out within a couple years and that's an expensive part to replace. I think I'd rather just replace HPS bulbs regularly. At least when they reach the end of their life they still work, just that they keep cycling on and off, but it's still on most of the time so you could get by until you can get a new bulb. By only using the 14w LED bulbs, when one burns out it's easy to get a new one at any department store, unlike COBs and drivers.