The EX Series boilers fromMiura Boiler West, Inc. (Wheeling, IL) have rows of vertical water tubes sandwiched between two ring-shaped headers. Because the headers are only attached to the tubes, they float up and down with the tubes' thermal expansion and contraction. This cuts down on thermal shock and the stresses that cause leaky tubes, according to the manufacturer. The boilers reach full steam in 5 min and maintain 85% fuel to steam efficiency.