Re: Suspension losses

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.

 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.
If Jeff had written "Electric heaters are all _nearly_ 100% efficient" I wouldn't have commented.

 

There are other losses in the cabling and plug interface which - while realized as heat - do not contribute the heating of the targeted space. The heat generated by the plug and cord are rather well insulated.

 But it's still heat, delivered into the room. It's not lost elsewhere.

I differ with "delivered to the room". It's held within the insulation, not delivered to the room (see more below).

 

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You may have experienced unplugging an electric appliance and felt the plug to be hot. What's happening is that the resistance of the plug/ socket interface generates heat. In those cases you were able to touch the actual metal contacts inside the plug, it's likely it would leave a blister. The fact that it doesn't shows the insulation is preventing the heat from leaving the system - IOW, not 100% efficiency.

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

 

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