Chilled Water Thermal Storage Tank Manufacturer: Stratified Tank Engineering A chilled water thermal storage (TES) tank looks like a simple box of water, but the manufacturer's job is to make it behave like a precision hydraulic device. The performance lives in the thermocline, the diffuser, and the usable temperature difference, not in the steel. This article covers what a chilled water TES tank manufacturer must engineer to deliver real storage. A chilled water TES tank