Re: Suspension losses

On 1/15/2025 3:42 PM, Zen Cycle wrote:

On 1/15/2025 1:42 PM, Frank Krygowski wrote:

On 1/15/2025 1:28 PM, Zen Cycle wrote:

On 1/15/2025 1:16 PM, Frank Krygowski wrote:

On 1/15/2025 1:05 PM, Zen Cycle wrote:

On 1/13/2025 11:03 AM, Frank Krygowski wrote:

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It's certainly true that 100% of the electricity consumed by an electric blanket becomes heat.

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No, that isn't true either.

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Please explain. What electrical energy goes elsewhere?

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A very small amount of power is used for the indicator lighting and electronic controls.
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I write "either" because even _if_ it were true that electric heaters are 100% efficient (which isn't true), saying 100% of the electricity consumed by the device become heat is very different than saying it's 100% efficient.

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What's your definition of "efficiency?" As I said earlier, I think a common one used for engineering matters is Desired Output divided by Required Input, or something similar.
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Do you have a different one?

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Nope, it's the notion that every watt of power directly goes into heating the targeted space that I'm stuck on.

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You're moving goalposts. You objected to my statement "It's certainly true that 100% of the electricity consumed by an electric blanket becomes heat."

 Nope, I addressed that point very specifically with "A very small amount of power is used for the indicator lighting and electronic controls."
 What you misinterpreted as 'moving the goalposts' was me taking issue with Jeffs assertion that "electric heaters are all 100% efficient".
 Note that "electric heaters are all 100% efficient" ≠ "It's certainly
true that 100% of the electricity consumed by an electric blanket becomes heat."
 The efficiency of the heater is determined by the energy that is used specifically for generating heat. By that premise, it's logically possible that that the heating element in a heating appliance may be near 100%, but that some energy will be used for the control portion of the system.

You should look at the energy used for the controls and think about what becomes of it. Do that in microcopic detail.

Actually, thermal insulation does not normally prevent heat from leaving a system. It merely reduces the rate at which it leaves. That would be true of, say, some hot component in a blanket controller. More obviously, it's true of the plastic insulation of the heating elements within the blanket, and it's true of the fibers of the blanket itself. Nonetheless, all that heat eventually gets delivered. None goes elsewhere.

 Hmmm....Is that why the water heater in my basement is still cool to the touch 20 years after it was installed? It's been keeping my water at 175 degrees that whole time. By your logic, shouldn't the temperature of the outer surface of the tank be 175 Degrees by now? Or at least much warmer than the surrounding air?

I'm happy to discuss this in great detail if you like.
_IF_ the water heater were enclosed in some big box from which absolutely no heat could possibly escape (understand, that's impossible), the outside of the water heater would eventually reach the temperature of the water.
But in the real world, there is heat being lost continually to the atmosphere, etc. in your basement. ("etc" is because a very small amount is lost by radiation instead of convection, and is absorbed by solid surroundings.) The primary heat loss, by far, is convection to the outside air.
There is a constant flow of heat energy from within the water heater to the air outside. The _rate_ of heat flow depends on the temperature difference (which is analogous to voltage in an electrical circuit) and on the amount of insulation (whose "thermal resistance" is analogous to electrical resistance.)
In practice, the thermal resistance is never infinite. IOW, you can add more and more insulation, but you can never reduce heat flow to zero.
If you were to use absolutely no hot water, and you were to shut off all energy input (gas or electricity or whatever) to your water heater, you would eventually find the water at room temperature. Heat would flow until the temperature difference across the insulation were zero - very analogous to a capacitor sending _some_ current through even a very high resistance, until the capacitor's voltage was zero.

The point is that a direct conversion of energy from electrical wattage into the system to BTU output won't show 100% efficiency.

We disagree. Again, feel free to explain in detail where you think the lost energy would go, if not to heat.
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- Frank Krygowski