The refrigerant vapour passing through the tubes is condensed by giving up its heat to the air stream. The remaining water drains down into a water tank at the bottom of the condenser casing. The water is drawn out of the tank, and pumped back to the water distribution system. The coils in an evaporative condenser are generally the bare pipe because the high rates of heat transfer from the wetted external coil surface to the air eliminates the need for fins. The evaporation rate of the circulated water is about 5%, and an equal amount of makeup water is provided to the system by means of a float valve located in the water tank.