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I can understand there being a cost difference if you used gas vs electricity to heat your home.

But for heaters using the same energy source, how can they be more or less efficient than each other?

I always thought that heat is generally a product of inefficiency. A halogen lightbulb is wasteful because for it to be bright, it radiates a lot of heat.

But I often hear the claim that cheap heaters will consume more energy. For example, this website (http://www.build.com.au/electric-heating) claims "The cheaper the electric heater, the less efficient it's likely to be”.

This is not the only place I’ve heard this. People often recommend certain types of heaters or certain brands of heaters to save on heating costs.

So if this is true, how is this inefficency caused and where is the energy lost to?

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  • $\begingroup$ possible duplicate of How efficient is an electric heater? $\endgroup$
    – pentane
    Commented Mar 2, 2015 at 13:12
  • $\begingroup$ A reason why cheaper electric heaters are less efficient is that they are often smaller for the amount of heat (in Watts) they put out. So the air that comes off them is hotter, and more likely to go straight to the ceiling, where it is lost through convection. So while the efficiency of the heater itself is the same, the efficiency of the heater heating the air in the room is reduced. $\endgroup$
    – bjem
    Commented Nov 25, 2016 at 3:46

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For electric "resistive" heat, you have a point. Energy in equals energy out, so it shouldn't matter if you're heating your house with a 1000 Watt heater or ten 100Watt light bulbs: both should produce the same result. In practice, you have to worry about getting the heat where you want it. If the warm air all floats up into a layer on the ceiling, you'll likely have to turn up the thermostat compared to a system that keeps the heat near the ground (say with baseboard heating and some ceiling fans).

For non-electric heating, things aren't as simple. For gas and oil heat, a lot of the energy goes out the chimney. So efficiency has a lot to do with how to minimize that loss, for example with counter-current heat exchangers and such. Also, obtaining just the right fuel/air mix for full combustion, without adding too much air (which will be lost in the exhaust) is a factor.

Finally, it is possible to have an electrically powered heat exchanger (an air-conditioner running backwards). This can be more efficient than "resistive" heating because it pumps heat from one place to another, rather than creating it by brute force.

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