Efficiency in electric space heaters (?)

[peritonlogon]

I wasn't sure where to post this and this forum seems to fit it best.

The reason behind this question is, that in shopping for a space heater I've run across this stament "greater efficiency" or something like it, on a lot of boxes. This makes no sense to me....I thought heat more or less equaled inefficiency. I even saw this "greater efficiency" statement along side a "since it has no moving parts it has" which made me think "I wonder how long it would actually take for the couple of watts the fan on this one uses to turn into warmth?"

The question is, is there such a thing as a more efficient electric space heater? And if so, how is it more efficient? Now, I know that a radiant heater is, in a sense, more efficient because you need not heat the air, and 1 radiant heater can heat 4-5 people sitting outside, but that's not the type of efficiency I mean. Also, I had an old space heater that would heat itself up and then trip the circuit breaker without actually adding much heat before it tripped, but I think that is a function, not necessarily of it's heating efficiency, but rather, of its dissipation.

So, I guess the question is, can a space heater running at 120 volts and 1500 watts produce more or less heat than another one running on the same amount of power, assuming, say, they're both inside a 12 ft cube black plastic box?
And how much more efficient could it be?

[arahant]

I don't see how. I'll be interested if there is something I'm missing.
I'm assuming it's a marketing thing...if you call them on it, they can fall back on one of the definitions you supplied.
The most I could think of would be that heaters that emit light are probably 'less efficient' because, in practice, you aren't using them in a black box. I would say the effeciency of a heater should be measured only by the heat (not light). So moving parts don't matter, but EM radiation would....

Hmm...I guess a motor would emit some EM...maybe that's the explanation.

[BigBuffet]

The new ones have electo-mechanical hemis

[_brady_]

I think the efficiency of the heaters is how much of the used electricity is converted into heat.

A 1000 watt heater with 75% efficiency would only convert 750 watts into heat, but you'd be paying for all 1000 watts of electricity.

So you'd want the more efficient heater to minimize electricity "waste".

[vhawk01]

[ QUOTE ]
I think the efficiency of the heaters is how much of the used electricity is converted into heat.

A 1000 watt heater with 75% efficiency would only convert 750 watts into heat, but you'd be paying for all 1000 watts of electricity.

So you'd want the more efficient heater to minimize electricity "waste".

[/ QUOTE ]

Right, but if all you need is 750 watts you can use an 800 watt heater with 94% efficiency and now you gotta pay for only 800 watts. Energy waste and wasted cost are the same thing from your perspective.

[arahant]

[ QUOTE ]
I think the efficiency of the heaters is how much of the used electricity is converted into heat.

A 1000 watt heater with 75% efficiency would only convert 750 watts into heat, but you'd be paying for all 1000 watts of electricity.

So you'd want the more efficient heater to minimize electricity "waste".

[/ QUOTE ]

His point, though, was 'how can you have an ineffecient space heater'. Most devices are ineffecient because they emit heat...the energy has to go somewhere.

I assume all space heaters are hugely effecient.

[Metric]

You're absolutely right -- it's a ridiculous claim. Maybe one will be 99.9% efficient and another might be 99.99% efficient (using a "backwards" definition of "efficient"). As someone already mentioned, about the only way the energy isn't going to be turned into heat is if it's going into sound or radio waves -- some form of energy that can escape the house before going to heat. And I doubt your average toaster puts out much energy in those forms.