Benchmark Air Source Heat Pump is a water heater that sources the heat from the air to heat water: Working principle is based on the Reversed Carnot Cycle. Usually, a Heat Pump water heater has four main components: evaporator, compressor, condenser and expansion device. The refrigerant is the medium to connect the four parts. With our technology the liquid refrigerant in the compressor will be pumped into high temperature and high pressure gas by using very little amount of electricity.