The Thermosyphon Cooler Hybrid System (TCHS) integrates the control of a dry heat rejection device, the Thermosyphon Cooler (TSC), with an open cooling tower. This new heat rejection system embraces a “smart use of water,” using evaporative cooling when it is most advantageous and then saving water and modulating towards increased dry sensible cooling as system operations and ambient weather conditions permit. Johnson Controls partnered with the National Renewable Energy Laboratory (NREL) along with Sandia National Laboratories to deploy the TSC as a test bed at NREL’s high-performance computing (HPC) data center in the first half of 2016.