How Can a Heat Pump Be More Efficient Than 100%?

I read somewhere that heat pumps are more efficient than resistance heaters. And this really got me confused. A resistance heater turns 100% of its input energy into heat. Where else would its energy go? So how on earth can anything be more efficient than 100%?

Well, after much research, it turns out that while a resistance heater turns 1 watt of electricity into 1 watt of heat energy, a heat pump can use 1 watt of electricity to move 3 or 4 watts of heat energy into a building.

I still can’t figure out why this doesn’t violate any laws of energy conservation or Thermodynamics? It seems like you could move 3 or 4 watts of heat energy into a heat engine and get back at least more than 1 watt. I’d still like to find out what prevents me from getting extra energy out of such a system.

Anyway, here were the best resources I found on that subject, but I’m afraid we’ll need an expert in Thermodynamics with a knack for putting complex concepts into laymen’s terms in order to answer this question fully.

  1. http://home.howstuffworks.com/question49.htm
  2. http://www.eco-hometec.co.uk/Heat%20Pump%20Efficiencies.htm
  3. http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/heatpump.html
  4. http://rabi.phys.virginia.edu/105/2005/ps8s.html

Here are all of the searches I did:

  1. Why is a heat pump for efficient than a space heater
  2. how does a heat pump work?
  3. “Heat pump” thermodynamics resistance heating
  4. “heat pump” + violates + “conservation of energy”

[tags]Thermodynamics, heat pump, conservation of energy, carnot cycle, heat engine, free energy[/tags]

Posted by Greg Pinero (Primary Searcher) on Mar 6th, 2006 and is filed under Idle Curiosities, Other, Uncategorized.

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2 Responses to “How Can a Heat Pump Be More Efficient Than 100%?”

  1. Hendrik42 says:
    August 9th, 2006 at 3:47 pm

    Hi Greg,

    have a look here: http://en.wikipedia.org/wiki/Heat_Pump
    and here:
    http://en.wikipedia.org/wiki/Carnot_heat_engine

    Heatpumps do not violate the laws of thermodynamics. They do not “create” energy, they “move” energy. They move it from one medium (heatpumps use air, brine, water) with “low” temperature to an other medium (or the same) with “higher” temperature.

    Remember school? Where they thought you that if you change the temperature, pressure or volume of something, at least one of the other parameters will also change? Thats the basis of heatpumps or the carnot process. It is totally cool physics.

    An expanding medium will take energy from its environment. Always. No matter what the temperature of the environment. Period. Now you move that expanded medium and compress it. It will then release the energy it took while expanding.

    You can take energy from the environment as long as there is some (so until it reaches minus 273 degrees Celsius, Zero Kelvin) or until the machine you use for that (heap pump) freezes.

    Hope that helps.

    Regards, Hendrik

  2. Greg Pinero (Primary Searcher) says:
    August 9th, 2006 at 4:12 pm

    Hendrik, thanks, it is starting to make more sense. I’ll take a look at your links and hopefully that will help too.