When would a system be designed with chilled water as the cooling medium rather than direct expansion equipment?
• If the air conditioning system, no matter how small, was to be designed as a conventional displacement system then chilled water, with its inherent infinitely variable off coil temperatures, would generally be required. • Direct expansion systems have considerably less capital costs on small to medium sized installations. However, the capital costs of both types of systems become comparitive after about a cooling load of about 1000kW. (This figure varies greatly depending on the site layout.) • Chilled water should be used for systems where flexibility is required i.e. where partitions and room layouts are to be altered regularly.
