Economizer

from WordNet (r) 3.0 (2006)

economizer
    n 1: a frugal person who limits spending and avoids waste [syn:
         {economizer}, {economiser}]

from The Collaborative International Dictionary of English v.0.48

Economizer \E*con"o*mi`zer\, n.
   1. One who, or that which, economizes.
      [1913 Webster]

   2. Specifically: (Steam Boilers) An arrangement of pipes for
      heating feed water by waste heat in the gases passing to
      the chimney.
      [1913 Webster]