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Old 11-22-2009, 04:41 PM  
kok328
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Default CFL Floods

I wanted to conserve energy and replace a regular 65W flood light bulb with a 65W CFL flood light bulb.

The box indicated that regular floods were 650 lumens and that the CFL was 750 lumens.

After I changed out the first flood, I noticed that the CFL was not even as bright as the 650 lumen, 65W regular flood.

I also have noticed when replacing incandescent bulbs through out the home but, it really showed a difference when it came to the floods.

What watt CFL is equivalent to a regular 65w flood?
What part am I missing here in the lumens ratings?



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Old 11-22-2009, 06:44 PM  
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Could it be the temperature? I have CFLs in my garage and it takes them a couple of minutes to get to full brightness when it is cold outside.



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Old 11-23-2009, 12:09 AM  
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It's admittedly a guess, but it's my best guess.

I think the problem you're running into here is that an incandescent flood light would inherantly work better than a CFL flood light simply because the incandescent floodlight's filament is much closer to a "point source" than that of a CFL tube. And, for exactly the same reason, a Xenon bulb would work better in a spot light or a flood light than an incandescent bulb simply because the source of the light is much smaller in a Xenon bulb than an incandescent bulb. The smaller the source of light, the more you can count on a parabolic reflector to convert that point source of light into a spot light, and the better spot light you have, the better flood light you can design.

If you look at a spot light, you'll notice that it uses a parabolic reflector. The point source of the light is located right at the focal point of that parabola so that the light comes out of the spot light in almost a straight line. (Think "flashlight")

Flood lights work in a similar way, but they have a light diffusing cover that spreads that straight beam of light outwards so that you illuminate a much larger area. You can also get much the same effect by moving the source of light so it's not right at the focal point of the parabola, or changing the shape of the parabola so that it no longer creates a straight spotlight, but a spread out flood light.

Deck Floodlight Technology - Hella marine

(Notice that in the above link, only the first diagram shows the reflector as being a true parabola. The "free form" shape of the reflector they're talking about means that it's not a true parabola as evidenced by the fact that light doesn't bounce off the reflector to form a true "spot light" but bounces off the reflector at an angle so that it's really the non-parabolic shape of the reflector that results in the floodlight, not the diffuser cover.)

The problem is that a CFL doesn't have a filiment like an incandescent bulb, and so the source of the light isn't a point source, and so that makes it impossible to design a reasonably sized parabolic reflector that will create a spotlight for the diffuser to work with. About the only way you can use a CFL with a parabolic reflector to create a spotlight would be to have a reflector the size of a radio telescope. Then you could get a CFL to produce a very weak, very large "spot light".

A parabolic reflector around a CFL won't work properly and will scatter light all over the place, and so the diffuser on the front of the floodlight won't work properly either and will scatter the light even more. The result is that you'll get your 750 lumens out of the sucker, but it'll be going in every direction, not into the area you want to illuminate. So, the CFL floodlight will seem much dimmer when you're in the area you want illuminated and much brighter when you're outside the area that's supposed to be illuminated.

My guess is that the CFL floodlight you're buying has a reflector on it that's intended for an incandescent bulb, but the company is just putting a CFL bulb into it cuz that's what people are asking for. It might not work worth a crap, but if they sell and don't come back, then the company doesn't care. Most people buying the darn thing don't know what to expect from it, so if it's a piece of crap, they're unaware of it cuz they don't know how well it should work.

You might want to switch to a floodlight that uses a Xenon bulb instead. You'll have a much smaller "point source" of light that a parabola can work with, and the light output from a Xenon bulb is much higher per watt than that of an incandescent bulb.

That is, I think that the idea of using a CFL as the source of light for either a spot light or flood light is inherantly flawed cuz the thing is just too big to be a "point source", and without a point source you can't use a parabolic reflector to create a spot light, and without that straight spot light, you can't design a diffuser to spread that spot light out to make a decent flood light.

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Old 11-23-2009, 08:36 AM  
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Hi Nestor, I agree with your dissertation ane as I was looking at the bulb the same thoughts came to mind. However, I wouldn't think this would be the case with the plain non-flood CFL's that I used to replace the incandescent bulbs in the bedrooms. I would also think that with all the technology out there that the manufacturers would have realized this and figured out a way to make a CFL's as bright as the incandescents that they replace.
In the course of my research, I also became aware that they now make 3-way CFL's and dimmable CFL's but, I hesitate on replacement because a CFL (no matter what type) just isn't as bright as incandescents. I'm thinking that you would have to buy a CFL with wattage far greater than the bulb your attempting to replace thus, leaving you with a zero net savings in energy.

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Old 11-23-2009, 08:59 AM  
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Quote:
Originally Posted by kok328 View Post
.................... I'm thinking that you would have to buy a CFL with wattage far greater than the bulb your attempting to replace thus, leaving you with a zero net savings in energy.
This is exactly what I do - I replace a 60 watt incandescent bulb with a 100 watt equivalent bulb. But the "60 watt" CFL only uses an actual 13 to 15 watts and the "100 watt" CFL uses 23 to 30 actual watts, so there is still a substantial electricity saving. The bulbs also dim somewhat as they age and I move old ones to closets and utility rooms, etc.

Compact fluorescent lamp - Wikipedia, the free encyclopedia
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Old 11-23-2009, 11:00 AM  
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Quote:
Originally Posted by kok328 View Post
However, I wouldn't think this would be the case with the plain non-flood CFL's that I used to replace the incandescent bulbs in the bedrooms. I would also think that with all the technology out there that the manufacturers would have realized this and figured out a way to make a CFL's as bright as the incandescents that they replace.
I dunno. I find that CFL's might not be as intensely bright at the center of the bulb as an incandescent bulb, but they seem to throw as much light. That is, the room is as well illuminated with two 13 watt CFL's in the light fixture as with two 60W incandescents. You need to give the CFL bulbs a minute or so to reach full intensity tho.

Quote:
I'm thinking that you would have to buy a CFL with wattage far greater than the bulb your attempting to replace thus, leaving you with a zero net savings in energy.
Oh, heck no. Incandescent bulbs are so inefficient because the light they produce is really just a byproduct of what they really do. As you know, an incandescent bulb is really just a heating element, like the one in a stove or in a toaster. The only difference is that the heating element in a light bulb is designed to get SO hot, that it produces a lot of light. So, MOST of the 60 Watts you put into an incandescent bulb is converted to heat, and only about 10 percent gets converted to light. With a CFL, MOST of the 13 watts gets converted to light, and only a very small percentage gets converted to heat.

But, I think the bottom line is that the source of light in a CFL just doesn't lend itself to making spot lights or flood lights which depend on reflecting the light from a point source in a particular geometric way. If you're gonna use a CFL, then you're wasting your money buying a parabolic reflector for it. You'd be just as well off putting a mirror behind a 13W CFL to send the light in one general direction instead of both directions, and call that your flood light.
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Old 11-23-2009, 02:40 PM  
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LED lights are brighter and save even more energy. Kichler makes some great LED flood/spot lighting

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Old 11-24-2009, 03:11 AM  
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I'm finishing a basement, and have installed a bunch of 5" recessed lighting. My intention was to use compact fluorescent floods (in the appropriate shape), so I could save a little on electricity. I have heard, that CFLs (especially the floods) have miserable lifetime in recessed fixtures. The heat just bakes the ballast. This is a little disappointing: after all, why manufacture CFL-floodlights, if not for use in recessed fixtures. Any recent lifetime improvements? Are some brands better than others? Any thoughts? Thanks

Regards,



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