Who makes crah / crac / fan walls / in-row units for AI data centers

CRAH units draw chilled water from the facility loop (6.05) and blow conditioned air across server intake; CRAC units carry their own compressor instead of relying on facility chilled water. Fan walls and in-row units are denser evolutions of the same function, pushing more air per rack as air-cooled density rose before designs crossed over to liquid cooling. As AI racks move chip heat into liquid loops (Layer 5), CRAH capacity does not disappear — it typically shrinks to cover the residual air-cooled heat load per rack (networking, storage, lower-density equipment) plus emergency and backup air cooling, even in halls that are mostly liquid-cooled. Where a facility stays fully air-cooled, CRAH and fan-wall counts still scale directly with heat load. Investors should watch the shift in mix between CRAH-served air cooling and liquid-side CDUs as the main determinant of demand here, and how much redundant CRAH capacity operators retain per rack even in liquid-first designs.