DURATECH® heat pumps utilize the sun’s free heat by collecting and absorbing energy from the outside air. This energy is then transferred to the pool water. Your existing pool pump circulates the water through the heater and warms the pool. The unit contains a fan that draws in outside air and directs it over the surface of the EVAPORATOR (energy collector). The liquid refrigerant within the EVAPORATOR coil absorbs the heat from the outside air and the refrigerant becomes a gas. The warm gas passes through the compressor where it is compressed to form a very hot gas, which then passes through the CONDENSER (water heat exchanger). It is here that the heat exchange occurs as the hot gas gives up the heat to the cooler swimming pool water circulating through the coil. The pool water becomes warmer and the hot gas is cooling down as it flows through the CONDENSER coil, returns to its liquid form and, after passing through the expansion valve, the whole process begins again. The use of a highly efficient, low sound rotary or scroll compressor, a low noise fan and an oversized heat exchanger, makes the unit to be extremely quiet in operation. Example: the DURA 8 at 10m distance gives only 32 db(A).