This new line of tank-less electric water heaters is ideal for point-of-use installations in individual rooms or the entire home. Each unit features a copper and brass heat exchanger, all-metal housing, and ranges in size from a cigar box to a large shoe box. It comes in six capacities from 3 kilowatt to 27 kilowatt. Cost: $228 (point-of-use) to $892 (whole-house). Rheem Manufacturing Co. 866-720-2076.