The basic Principle of Air Source Heat Pumps
A heat pump basically works on the same principle as a refrigerator, which removes heat from the food that is being stored in it (i.e. cooling) while generating heat to be exhausted out the back of the fridge (i.e. heating). A heat pumps works in the same way but in a reverse fashion and with greater power. The pump is removing heat from the air and redistributes this heat into the desired location through the heating system. This uses only a small amount of energy as most of the heat energy is coming from the outside air.