Explains briefly the fundamental concept of open chilled water systems. Goes on to explore design considerations necessary for the successful application of employing cooling water directly in the chilled water system with or without the use of a heat exchanger. Deals with thermal, chemical and hydraulic phenomena. Concludes that the use of open cooling tower water directly in chilled water systems for winter cooling requires considerably more design attention than simply changing the source by a series of valving. Presents the issues involved in a constructive manner to that the designer can avoid possible problems.

KEYWORDS: Free cooling, chilled water supply, designing, cooling towers, hydraulic installations.