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A colleague is trying to tell me that I should pay more and get a ceramic heater rather than a cheap convection room heater because I'll save money on electricity.

I have one like this:

Convection room heater

Sure it's 2kW but with the thermostat it's only on 1/5 of the time. It heats the room in about 15 minutes!

He has one like this:

Ceramic Heater

It's only 400W but with no thermostat, it's on all the time.

A watt only has so much energy...

I think my convection heater is just as efficient and a quarter of price.

Edit: This website claims they are 50% more efficient but this is the manufacturer's website...

Is it true that ceramic room heaters are more efficient?

Related Question: Are ion heaters significantly more efficient then normal electric heaters?

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We want to focus our attention on doubtful claims that are widely held or are made by notable people. So far, we only have your colleague, and for all we know he was drunk when he said it. Please provide some references to places where this claim is being made. –  Oddthinking May 2 '12 at 3:26
    
@Oddthinking Added reference in the question. –  Coomie May 2 '12 at 3:58
    
Please cite the actual claim, the site you linked does not claim 50% efficiency at all. –  Sklivvz May 2 '12 at 6:59
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Just a general note: Even when not more efficient, a different type of electric heater can be saving your money by reducing the energy used for heating while keeping the same subjective comfort level. This can be achieved e.g. by creating a different temperature distribution in the room. Convection heaters are sometimes said to heat esp. the upper part of the room. This depends on wall materials, furniture in the room, windows / door position, insulation used .... –  Suma May 3 '12 at 8:06
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All heaters are 100% efficient, by definition. Anything not immediately converted into heat (sound, light), will be absorbed by your walls and become heat anyway. And a watt does not "have energy". Watts are the rate at which energy is used. –  endolith May 3 '12 at 20:20
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1 Answer 1

up vote 11 down vote accepted

Short answer: No.

Long answer: A heater is about as efficient as you can possibly get for an electrical device. Almost 100% of the input energy that goes in is converted to heat[1]. For a newer heater to be 50% more efficient, it would have to use about 67% of the energy to give the same heat - which is difficult, because the original heater is already 100% efficient, so this new one would have to be 150% efficient.

Ceramic materials are very good electrical insulators and have excellent thermal conductivity. The only difference between his ceramic heater and your normal electric heater is the element is probably wrapped around a ceramic core and this then heats up the outer plate, whereas yours just has elements and relies on natural convection to circulate and spread the heat.

Both will be equally efficient at providing heat energy, but they provide it in different ways. Maybe the heat plate is better for heating up one part of a room, but the convection heater is good for the whole room, for example. If you were only using one part of the room, then it would be less efficient to heat up all of it.

There are heating systems that are more than 100% efficient - they are known as heat pumps. They are typically in excess of 300% efficient. However, a heat pump would require an external connection to outside the building to work, as it works by using the thermal energy from outside (and electricity is only drawn to move the heat one way.) And, they are very expensive.

  1. http://www.conservingelectricity.com/ElectricSpaceHeaters.asp
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Misses the point: Subjective heat matters and it isn't what you get if you assume perfect mixing within the room and thermodynamic isolation. –  matt_black Jul 12 '12 at 0:01
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Please provide some references to support your claims - e.g. ceramics are good insulators/conductors, heat pumps are more than 100% efficient, heat pumps are expensive, etc. –  Oddthinking Feb 10 '13 at 13:31
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Heaters that draw more power are slightly less efficient as they increase resistive losses in your house wiring which generates heat where you don't want it. This shouldn't be more than a few percent though; house wiring is generously sized to prevent just such heating. –  Nick T Nov 12 '13 at 20:21
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