Chiller plant control optimization has achieved heightened popularity over time as computerized controls enable increasingly sophisticated algorithms to maximize plant efficiency. In a predicted backlash to the “black box” nature of proprietary optimization packages, engineers have developed simplified controls strategies that approximate optimization without the cost and complexity of a package. These strategies grew out of a need to prevent plant operators from switching to operating their plants manually when the causes of inadequate plant performance, accidental chiller shutdown, excessive cycling, or any of a number of problems could not easily be diagnosed.
In parallel, the push for maximizing plant efficiency has led to the adoption of code requirements for air- and water-side economizers. Economizers, though beneficial, add complexity that may undermine the goal of simplifying plant controls. This article examines water-side economizer control as well as plant optimization controls strategies with respect to water-side economizers.