What Is Facility Water Loop?_
The facility water loop (FWL) is the building-side cooling water circuit that receives heat from the coolant distribution unit (CDU) and carries it to heat-rejection equipment such as cooling towers, dry coolers, or chillers. It is separated from the clean, treated server-side coolant loop by the CDU's heat exchanger, so the two loops never mix. In liquid-cooled GPU facilities, the capacity and supply temperature of the facility water loop set the ceiling on how much GPU heat the site can reject.
Technical Details
Liquid-cooled GPU deployments use two coupled loops. The server-side technology cooling system (TCS) loop circulates treated propylene glycol and water through cold plates and manifolds at tightly controlled chemistry and temperature. The facility water loop is the building infrastructure side — larger pipework, facility-grade water treatment, and connections to cooling towers, dry coolers, or chillers. The CDU's heat exchanger transfers heat between the two while keeping the server loop isolated. Key facility-loop parameters are supply water temperature, flow rate, and total heat-rejection capacity; warmer supply water (enabled by direct-to-chip cooling) allows more economizer hours and lower PUE. Sizing the facility loop for megawatt-scale rows of NVL72 racks is a primary constraint in liquid-cooled site design.
How Leviathan Systems Works with Facility Water Loop
Leviathan Systems connects CDUs to the facility water loop and verifies flow, temperature, and leak-tightness on the server side during commissioning, coordinating the interface with the facility's mechanical contractors.
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