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Funny thing about heat pumps is, that they often operate with over 100% efficiency. Took some time for me to wrap my head around it.

by frxx 5y ago

akvadrako 5y ago
Nothing operates over 100% efficiency, it's just a trick. It would be like saying your gas boiler is 10000% efficient because of how little electricity it uses. What you are using as fuel is the heat in the outside air.
SigmundA 5y ago
Sorta like saying house with solar panels is over 100% efficient, technically true when measured against grid input. A air source heat pump is a solar assisted heating device pulling thermal energy from outside air (which is heated by the sun) into your home using electricity to gather it and move it inside. Heats pumps combined with solar panels is a a great combo BTW. Efficiency is always measured relative to something and cannot be over 100% in a closed system, heat pumps are not a closed system so no laws of physics are broken.
- hedora 5y ago
  Yeah, but heat out / electricity in is 5, but for an ideal (perfectly efficient) electric heater, is is only one. It's one of those sufficiently advanced technologies that seems like magic. Like, what if we powered a sufficiently efficient sterling engine with it, and used that to spin the compressor and fans? It's not obvious that it isn't a perpetual motion machine or some commercially available version of Maxwell's demon or something.
kumarvvr 5y ago
Depends on your calculation. If you are calculating the energy input to the system vs. heating output of the system, then yes, it will be more than 100% efficient. However, if you are calculating total energy input to the system vs. heating output of the system, then you are at less than 100% efficiency. The heat in the atmosphere, is also due to some energy consumed somewhere, whether man made or not.
- jwatt 5y ago
  Indeed. Applying it to the former case seems like an abuse of the word "efficiency" to me.

Funny thing about heat pumps is, that they often operate with over 100% efficiency. Took some time for me to wrap my head around it.

by frxx 5y ago

Funny thing about heat pumps is, that they often operate with over 100% efficiency. Took some time for me to wrap my head around it.

akvadrako 5y ago

Nothing operates over 100% efficiency, it's just a trick. It would be like saying your gas boiler is 10000% efficient because of how little electricity it uses. What you are using as fuel is the heat in the outside air.

SigmundA 5y ago

Sorta like saying house with solar panels is over 100% efficient, technically true when measured against grid input. A air source heat pump is a solar assisted heating device pulling thermal energy from outside air (which is heated by the sun) into your home using electricity to gather it and move it inside. Heats pumps combined with solar panels is a a great combo BTW. Efficiency is always measured relative to something and cannot be over 100% in a closed system, heat pumps are not a closed system so no laws of physics are broken.

hedora 5y ago
Yeah, but heat out / electricity in is 5, but for an ideal (perfectly efficient) electric heater, is is only one. It's one of those sufficiently advanced technologies that seems like magic. Like, what if we powered a sufficiently efficient sterling engine with it, and used that to spin the compressor and fans? It's not obvious that it isn't a perpetual motion machine or some commercially available version of Maxwell's demon or something.

kumarvvr 5y ago

Depends on your calculation. If you are calculating the energy input to the system vs. heating output of the system, then yes, it will be more than 100% efficient. However, if you are calculating total energy input to the system vs. heating output of the system, then you are at less than 100% efficiency. The heat in the atmosphere, is also due to some energy consumed somewhere, whether man made or not.

jwatt 5y ago
Indeed. Applying it to the former case seems like an abuse of the word "efficiency" to me.