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Brownfield liquid cooling upgrades

Brownfield upgrades add liquid cooling to existing air cooled halls. Options run from rear-door heat exchangers and liquid-to-air CDUs that need no new facility water, to tapping chilled water with liquid-to-liquid CDUs, to full new warm water loops. Structural, power and water constraints decide what is feasible.

Also called: retrofit, rear door heat exchanger, RDHx, liquid-to-air CDU, hybrid cooling retrofit

Options

Rear-door heat exchangers (for example Legrand ColdLogik) cool rack exhaust air with water. Liquid-to-air CDUs (Vertiv CoolChip CDU 70, Eaton RAA22 and RAA32, CoolIT AHx range) run direct-to-chip loops and reject heat to room air without facility water. Liquid-to-liquid CDUs can connect to existing chilled water but may be limited by its temperature and capacity.

Constraints

Floor loading, ceiling height for pipework, existing chilled water temperature and spare capacity, electrical capacity per rack, and leak risk over live equipment. Air handling still has to remove residual heat.

Sourcing considerations

Ask for a site survey, phasing plan with live operations, flushing and commissioning method, and how capacity is rated at your existing water temperatures. Munters and others market air-to-liquid upgrade paths.

Questions to ask suppliers

  • Existing chilled water temperature and spare capacity
  • Whether a liquid-to-air CDU or RDHx avoids new pipework
  • Floor loading and pipe routing
  • Live-site installation method and risk controls
  • Residual air cooling load after retrofit

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Suppliers with public evidence

Listed alphabetically. Inclusion means a public source shows the company offers products or services for this technology. It is not a ranking or endorsement. Compare these suppliers.

Sources (5), last checked 18 Oct 2026
  1. CL20 ProActiveRDC (opens in a new tab), Legrand, accessed 18 Oct 2026
  2. Vertiv CoolChip CDU (opens in a new tab), Vertiv, accessed 18 Oct 2026
  3. Eaton CDU (liquid-to-air section) (opens in a new tab), Eaton, accessed 18 Oct 2026
  4. CoolIT CHx2000 FAQ (AHx liquid-to-air) (opens in a new tab), CoolIT Systems, accessed 18 Oct 2026
  5. Munters CDU (upgrade path) (opens in a new tab), Munters, accessed 18 Oct 2026

Last checked 18 Oct 2026 by CoolPower Index research (automated, sourced). Report a correction.