Chilled water systems work similarly to direct expansion (DX) systems with the exception that instead of refrigerant, water flows through the system. The chiller uses an internal refrigeration cycle to chill water in a chiller barrel. Once inside the chiller barrel, the chiller removes heat from the water through heat transfer to a colder internal refrigerant loop. Water is then pumped through the chilled water system where it eventually passes through air handling unit coils and the water removes heat from the air stream, cooling the building.
Chilled water systems are typically used in medium and large sized commercial buildings, where it is more cost-effective to use a centralized system and the required maintenance can be performed by building personnel. Smaller facilities can also benefit from the operating efficiency of chillers, but the first cost of a chilled water system for smaller projects is often enough to dismiss it in favor of less costly alternatives.
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