The Collaborative International Dictionary of English v.0.48:

Teache \Teache\ (t[=e]ch), n. [Cf. Amer. Sp. tacha, tacho.]
   (Sugar Manuf.)
   Any one of the series of boilers or evaporating pans in which
   the cane juice is concentrated in making sugar; especially,
   the last boiler of the series. --Ure.
   [1913 Webster]

   Note: The 1890 edition had the following etymology for
         teache: [Cf. Ir. teaghaim, Gael. teasaich, to heat.].
         Presumably a speculation which proved incorrect?