Chillers make cold water or water/glycol fluid mixture in order to cool buildings or processes. Often used in conjunction with coils in air handlers, chillers receive warm fluid from the air handler coil or process load, lower the temperature of the fluid, then a pump returns the fluid to the air handler coil or process. Chillers come in 2 main varieties: air-cooled and water-cooled. An air cooled chiller rejects the heat absorbed from the building or process directly to the outdoor air using refrigerant to air coils and fans that blow outdoor air directly over those coils. A water cooled chiller rejects the absorbed heat to an additional fluid loop that can then reject the heat through a secondary device such as a cooling tower (more common) or dry cooler (less common).