[tom_poconos]

I have noticed that some LED bulbs produce a lot of heat at their bases. When we compare LEDs to incandescent and halogen, is this heat produced in the circuit board of LEDs accounted for? I realize LEDs are loads more efficient, but was wondering if the comparisons cheat a bit, not accounting for this waste heat production. Frankly some LEDs are as hot as incandescent bulbs when I take them out. Maybe they're faulty or cheap?

 

[Bud9051]

The earlier versions I bought did as you describe. I was shocked to discover later on when I removed a newer 60w led that had been on for several hours that I could take it out with my hands, no burn. I haven't seen this extra heat discussed but both my old hot one and new cool one were both 13.5 w rated.

I agree, strange.
Bud

 

[u2slow]

Watts are watts... doesn't matter if heat or light. Unless they are outright lying in the specs. Light output also diminishes with age/runtime. What you could do is check with an ammeter to verify.

You'll find wattage differences between LED lamps with the same lumen output; or conversely, lumen difference between the same wattages. There, and argument can be made about efficiency or cheapness.

 

[SPS-1]

LED bulbs are supposed to be about 85% to 90% efficient. So a 17 Watt LED bulb, is still making about 2 Watts of heat.

 

[user_12345a]

LED bulbs are designed with heat-sinks so the all the heat is dissipated at a certain part - cfls have it even.

Total heat dissipation is what matters, not surface temperature of a hot part.

 

[3onthetree]

The "cheapness" of LEDs being comparably hot at the base (usually where the driver is) is probably because the lamps "designed" by Chinese manufacturers (versus lamps designed by western companies that are made in China) haven't engineered the proper heat sink required. And no one seems to like to see diffusers/fins for heat sinks on their lamps. LEDs that do not last anywhere near the stated hours are undoubtedly from heat buildup on the electronics.

 

[user_12345a]

Depends on which leds you get.


There can be heatsink/heat dissipation areas without fins - the base is designed to dissipate heat even if it's plastic. The good quality ones have metal or ceramic base.

I bought ge 100w replacement leds with metal base, but the metal is painted white and the bulbs are heavy.

The quality has gone down - 25 000 hours used to be the norm, now most are rated at 15k and the cheapest are at 10k.

 

[bfrabel]

LED bulbs are supposed to be about 85% to 90% efficient. So a 17 Watt LED bulb, is still making about 2 Watts of heat.

Nope. Not true. That's not how it works.

A 17 watt bulb will make 17 watts worth of heat (or 58 btu's per hour to be more specific)

The light produced might be "85% efficient" (whatever that means), but the heat produced will always be "100% percent efficient".

All electric devices (except for refrigeration systems such as heat pumps) produce the exact same amount of heat for a given amount of watts that is consumed. Doesn't matter if it's a LED, or an incandescent, or an ipad charger, or an electric toothbrush. If it uses 17 watts, it's producing 58 btu's worth of heat.

 

[SPS-1]

A 17 watt bulb will make 17 watts worth of heat (or 58 btu's per hour to be more specific)

If that were true, you would have a 17 Watt heater, plus all the light is free energy.

Although eventually it will become heat, but not at the bulb.

15 Watts worth of power is emitted as light, and 2 Watts as heat. That light will eventually be absorbed by walls, furniture. etc., and be converted to heat. But that's not the bulb that is getting 17 Watts worth of heat.

 

[bfrabel]

If that were true, you would have a 17 Watt heater, plus all the light is free energy.

Although eventually it will become heat, but not at the bulb.

15 Watts worth of power is emitted as light, and 2 Watts as heat. That light will eventually be absorbed by walls, furniture. etc., and be converted to heat. But that's not the bulb that is getting 17 Watts worth of heat.

Maybe your laws of electricity and thermal dynamics are different since you're in Canada.

Where I live, if light bulb (or ANY other electrical device that doesn't have a refrigeration compressor) is consuming 17 watts of power, and it's hooked up to 120V, that means that it's drawing about .14 amps AND producing 58 btu's of heat per hour, and it's not from the light that's radiating into the walls, its from the power that is being consumed.

I suspect that your 85% efficiency rating that you are referring to means that it produces 85% more light than an equally rated incandescent bulb would produce at the same wattage, or something like that. I'm not entirely sure.

I do know that it's a fact that 1000 watts worth of light bulbs will produce the same amount of heat as a 1000 watt electric heater. It doesn't matter if those light bulbs are LED or incandescent, or if they were 1000 watts worth of vacuum cleaners or a computer that draws 1000 watts, or a direct short of some wires in your walls that happen to draw 1000 watts. It will all produce the same amount of heat.

(Of course those shorted wires will have the heat super concentrated in one small area, and the LED bulbs will probably spread the heat out over a large area, but over all it's the SAME amount of heat).

 

[SPS-1]

Maybe your laws of electricity and thermal dynamics are different since you're in Canada.

No, we just have smarter people.

 

[SPS-1]

Do an experiment for me please.

Take your 17 Watt light bulb, put a reflector behind it, and put a big photovoltaic solar cell in front of the LED bulb. Now connect the solar cell to a small electric heater, and turn on the light.

In your world, you get 17 Watts of heat from the bulb, plus a few more from the heater hooked up to solar cell. So you get 20 or so Watts of heat while only paying for the consumption of 17 Watts. Neat trick.

In my world, the light that is emitted from the bulb is not radiated as heat from the bulb. The total of bulb, the little electric heater, plus the temperature rise of the solar cell adds up to 17 Watts.

 

[Missouri Bound]

No, we just have smarter people.

Then you better go ask one.
bfrabel is 100% right.

 

[Missouri Bound]

Do an experiment for me please.

Take your 17 Watt light bulb, put a reflector behind it, and put a big photovoltaic solar cell in front of the LED bulb. Now connect the solar cell to a small electric heater, and turn on the light.

One of those "smarter" people wouldn't be comparing apples to oranges like you are.

 

[HotRodx10]

Then you better go ask one.
bfrabel is 100% right.

Maybe you better find one of those smarter people to ask. You and bfrabel are wrong. A 17 Watt, 85% efficient LED bulb produces about 2 Watts of heat. The other 15 Watts is radiant energy (light) that doesn't become heat until it is absorbed by a surface.

 

[tom_poconos]

I do know that it's a fact that 1000 watts worth of light bulbs will produce the same amount of heat as a 1000 watt electric heater.

Aren't light bulbs converting some of the wattage into visible light (LEDs a lot more so than incandescent), and not infrared, therefore they would not produce as many BTUs as an electric heater? Heat is infrared on the EMF spectrum, light is closer to ultra violet. This is as much as I remember from high school physics.

 

[Missouri Bound]

The other 15 Watts is radiant energy (light) that doesn't become heat until it is absorbed by a surface.

Thanks for agreeing.
I'm surprised you don't think radiant energy is heat.
My baseboard heaters are radiant......they must be defective if they are heating.

 

[HotRodx10]

I'm surprised you don't think radiant energy is heat.

As I said, it is converted to heat when it is absorbed by a surface, until then it's light. (which is also what SPS-1 wrote, that bfrabel and then you argued with) If you'll go back to the OP, the question was regarding "...LED bulbs produce a lot of heat at their bases...is this heat produced in the circuit board of LEDs accounted for?"

I was addressing the OP's query about the direct heat at the base of the bulb. Yes, everything becomes heat eventually. I took physics in high school too (and in college, plus thermodynamics).

 

[pawanranta]

Nope. Not true. That's not how it works.

A 17 watt bulb will make 17 watts worth of heat (or 58 btu's per hour to be more specific)

The light produced might be "85% efficient" (whatever that means), but the heat produced will always be "100% percent efficient".

All electric devices (except for refrigeration systems such as heat pumps) produce the exact same amount of heat for a given amount of watts that is consumed. Doesn't matter if it's a LED, or an incandescent, or an ipad charger, or an electric toothbrush. If it uses 17 watts, it's producing 58 btu's worth of heat.

The premise of lighting energy efficiency is producing maximum light for a given watt number. I'm not sure how true it is in the case of LED lights.

Found this article claiming zero heat emission by LED lights.

Why Replace Halogen Downlights & CFLs with LEDs?

Learn how you can cut power bills by 80% & reduce GHGs emissions by replacing Halogens & CFLs with LEDs under the Victorian Government rebate scheme.

www.ecofinsolution.com.au

 

[SPS-1]

That article seems to be written by somebody not very technically educated. I wouldn't take it too literally. LED bulbs do produce heat.

In the winter, I don't worry much about leaving the lights on. All that energy ends up as heat anyways (most after being absorbed by surroundings). Sure, my natural gas heat is somewhat less expensive, but its not a huge cost delta.

On the other hand, in the summer, with any lights on, first you pay for the power to run the light, then for the power to run the AC to pump the heat outdoors. So I am pretty anal about not having lights on unnecessarily. That's where the increased efficiency of LED's really shines --- for any lights that actually are turned on, first they consume far less energy, then your AC has to run less to pump out the heat. Double savings.