Despite the recent scrutiny and criticism of primary-secondary chilled water pumping systems, many owners still decide these systems are appropriate for their facility. Factors such as simplicity, familiarity, and experience are considered, in some cases, to have benefits to the owner that overshadow efficiency and first costs. Primary-Secondary pumping is not appropriate for all projects, but when the decision has been made to use it, properly addressing technical aspects of such designs and adequately addressing facility users’ needs significantly contributes to the project’s success. This article explores key issues to consider when designing a primary-secondary chilled water plant. more