Definition
A Coolant Distribution Unit (CDU) is the central pump-and-heat-exchanger module at the heart of a liquid cooling system. It circulates coolant to the equipment, regulates that coolant's temperature and pressure, and exchanges the collected heat into the facility's chilled or warm-water loop. In short, the CDU is the bridge between the technology cooling loop touching the chips and the larger facility cooling infrastructure.
How a CDU works
Inside a CDU, a heat exchanger keeps two fluid loops separate: the clean, controlled secondary loop that runs to the equipment, and the facility's primary loop that carries heat away to a cooling tower, dry cooler, or chiller. Pumps drive the secondary coolant at a set flow rate, while sensors and valves hold the supply temperature and pressure within the band the hardware needs. CDUs come in rack-mounted (in-rack), end-of-row, and large standalone configurations sized to the heat load they serve.
CDUs in Bitcoin mining
Hydro and immersion ASIC miners reject heat far more densely than air-cooled units, and a CDU is what makes that practical at scale. It delivers contaminant-free coolant at a controlled temperature to direct-to-chip cold plates or immersion tanks, then hands the captured heat to the facility loop, where it can even be reused for space or process heating. Keeping the equipment loop isolated also protects expensive hardware from facility-water contaminants.
The fluid a CDU circulates for immersion or two-phase systems is typically a non-conductive dielectric fluid. For the air-cooled alternative, compare with free cooling.
In Simple Terms
A Coolant Distribution Unit (CDU) is the central pump-and-heat-exchanger module at the heart of a liquid cooling system. It circulates coolant to the equipment, regulates…