this post was submitted on 17 Feb 2024

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If a machine is never 100% efficient transforming energy into work because part of the energy is converted into heat, does it mean an electric heater is 100% efficient? [@[email protected]](h (social.graves.cl)

submitted 7 months ago by [email protected] to c/[email protected]

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If a machine is never 100% efficient transforming energy into work because part of the energy is converted into heat, does it mean an electric heater is 100% efficient? @[email protected]

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[–] [email protected] 37 points 7 months ago (1 children)

Yes, except a heat pump is capable of being more than 100% efficient because the using the power to move heat around is more efficient than converting power directly to heat

[–] [email protected] 7 points 7 months ago (1 children)

but but muh thermodynamics

[–] [email protected] 7 points 7 months ago

I get you are joking, but incase someone doesn't see the /s. As the top comment said it's easier to move heat around than creating it. Regardless if it's warmer or colder outside there's still energy there that we can use.

It's easier to move your clothes from the laundry basket to the wardrobe, than to go out and buy new clothes (or is it?).

[+] [email protected] -17 points 7 months ago (2 children)

No by your logic it'd zero percent.

Efficiency is against a goal. You can't change goal post and make argument. Good try.

[–] [email protected] 4 points 7 months ago (1 children)

This is discussed in many places, but you are here, so let's do it... A heater that consists of a resistance element is turning nearly all of the electricity into heat. Around 100% efficiency. But if it has an LED and fan, then maybe 5% (or less?) of that electricity is used for those, so it's easy only 95% (or more?) efficient.

That is how those terms are defined in this context. How much heat is produced by a resistance heater using one watt? That's a known quantity, and we use it to compare against other heating sources.

And it makes sense to use this number if you are comparing to wood or gas or coal or oil heat, where some goes out the chimney, or to heat pumps, where things are a lot more complicated.

[–] [email protected] 1 points 7 months ago (1 children)

it has an LED and fan

If you can't see the light or hear the fan from outside the room you are using the heater in, that energy has also become heat.

[–] [email protected] 1 points 7 months ago (1 children)

Yeah, but than, does it really makes a sound?

[–] [email protected] 2 points 7 months ago (1 children)

At the expense of ruining the joke, yes it does. Anyone inside the room would be able to hear the sound.

And if no one is in the room to hear if there is a sound or not, you might want to turn the heater off to conserve energy.

[–] [email protected] 1 points 7 months ago

Oh I didn't think of it!

[–] [email protected] 2 points 7 months ago

Do you even math bro?

[–] [email protected] 100 points 7 months ago (1 children)

Not quite. Some is lost in magnetic flux and mechanical deformation. But that is a VERY small about.

[–] [email protected] 17 points 7 months ago (1 children)

Do those not end up as heat later down the line as well?

[–] [email protected] 27 points 7 months ago (1 children)

Yes, but magnetic flux causes radio waves and there isn't a guarantee these will turn into heat in the space you are heating.

[–] [email protected] 2 points 7 months ago

That's an interesting point about radio emissions leaving the heated space.

[–] [email protected] 70 points 7 months ago* (last edited 7 months ago) (1 children)

Yes, but, it is also possible to achieve greater than 100% efficiency in using electrical energy for heat. You can use electricity to move heat from where you don't need it to where you want it. The amount of heat energy you move can be greater than the amount of electrical energy put into the system, so it's greater than 100% electrically efficient. It's well below 100% thermal efficiency, of course.

[–] [email protected] 61 points 7 months ago (4 children)

(he's talking about heat pumps)

https://youtu.be/7J52mDjZzto?si=i57lMtNvpoLUxKGK

[–] [email protected] 14 points 7 months ago (1 children)

Same link with site tracking removed: https://youtu.be/7J52mDjZzto

I am not a bot, and this action was performed manually.

[–] [email protected] 7 points 7 months ago

Here is an alternative Piped link(s):

https://piped.video/7J52mDjZzto

Piped is a privacy-respecting open-source alternative frontend to YouTube.

I'm open-source; check me out at GitHub.

[–] [email protected] 11 points 7 months ago

KNEW it was gonna be the technology connections video.

was literally just talking about, and recommended this video, IRL like 10 minutes ago.

[–] [email protected] 8 points 7 months ago* (last edited 7 months ago) (1 children)

THIS IS THE COMMENT THREAD YOU WANT TO LOOK INTO.

[–] [email protected] 1 points 7 months ago

who, me ?

[–] [email protected] 3 points 7 months ago

Here is an alternative Piped link(s):

https://piped.video/7J52mDjZzto?si=i57lMtNvpoLUxKGK

Piped is a privacy-respecting open-source alternative frontend to YouTube.

I'm open-source; check me out at GitHub.

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