Temperature change is a chronic problem that affects many chilled-water systems. Return water from the system is coming back cooler than design, meaning that it cannot be used effectively. Temperature change is an energy waster, and it can be a big problem if it limits the capacity of the chiller plant.
There is some dispute in the engineering community about the causes and cures of temperature change. This article examines temperature change at four of the air-handling units (ahu's) serving the Indiana University Chemistry Building and how the problem was addressed.