Economic applies to material wealth and to business or household enterprise. Economical means "prudent in management," "not wasteful," "thrifty." Thus one refers to "economic resources" and "economical management," to "economic problems" and "economical living." Examples: "The Brown family moved to a smaller house for economic reasons." "Mrs. Brown learned to be economical in budgeting household expenses."
Dictionary of problem words and expressions. Harry Shaw. 1975.