The Collaborative International Dictionary of English v.0.48:

Keelfat \Keel"fat`\, n. [Keel to cool + fat a large tub, a vat.]
   (Brewing)
   A cooler; a vat for cooling wort, etc. [Written also
   keelvat.] --Johnson.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Keelvat \Keel"vat`\ (k[=e]l"v[a^]t`), n.
   See Keelfat.
   [1913 Webster]