Domestic use of heat pumps, how they work, and possible difficulties

Definition: Heat pump.

This is a machine based on thermodynamic principles (Physics) that can move energy in the form of heat from place to place. The ratio of the input heat to the output heat is called the coefficient of performance (COP) and is directly related to the temperature difference between input and output. Energy is required to operate the machine, which is often electricity but may be any source of mechanical power, this energy is NOT included in the COP, and varies directly with the temperature difference, and for large temperature differences can exceed the recovered energy from the output. In the case of refrigeration, this is normal as the output heat is effectively thrown away although in large systems it may be recovered for other low-grade heating purposes, typically supermarket space heating (M&S).

Definition: Heat pump.

This is a machine based on thermodynamic principles (Physics) that can move energy in the form of heat from place to place. The ratio of the input heat to the output heat is called the coefficient of performance (COP) and is directly related to the temperature difference between input and output. Energy is required to operate the machine, which is often electricity but may be any source of mechanical power, this energy is NOT included in the COP, and varies directly with the temperature difference, and for large temperature differences can exceed the recovered energy from the output. In the case of refrigeration, this is normal as the output heat is effectively thrown away although in large systems it may be recovered for other low-grade heating purposes, typically supermarket space heating (M&S).