Source : Webster's Revised Unabridged Dictionary (1913)

Economizer \E*con"o*mi`zer\, n.
   1. One who, or that which, economizes.

   2. Specifically: (Steam Boilers) An arrangement of pipes for
      heating feed water by waste heat in the gases passing to
      the chimney.

Source : WordNet®

economizer
     n : a frugal person who limits spending and avoids waste [syn: {economiser}]