Heatpumps have been in use for many years now and the basic principle is displayed in virtually everyone’s home, the fridge in your home basically extracts the heat from the inside the fridge and discharges it into the air on the back of the fridge.
A heatpump is designed to extract heat from the earth or water, it then passes through a plate heat exchanger where the low grade heat is transferred to the refrigerant. It then passes through a compressor and from there to condesor/heatexchanger for your heating system, the gases then pass to an expansion valve and back to the evaporator.
During this process the low grade heat extract (3 to 5°C) is increased to give a flow temperature of 35°c. the amount of heat generated can be between 4 and 5 times the amount of electricity used to power the unit. This means a CoP of between 4 and 5 ( 400 to 500% efficient).