The AUX heat pump is a versatile unit designed to work with a wide range of heat consumers such as underfloor heating, radiators and fan coil units. AUX heat pumps are available in capacities from 4.3kW to 16.1 kW. The heat pump uses as much as 75% free energy from the air, while electricity is used only 25%. In practice, this means that the unit extracts heat from the outside air and releases it into the building with little electricity. Energy efficiency in heat pumps is determined by the COP, which determines the amount of heat delivered to the amount of electricity consumed. The higher the coefficient of performance, the greater the energy efficiency. The higher the COP, the higher the efficiency, and thus the savings. A heat pump is one of the most cost-effective and environmentally friendly heating systems.