The Miura LX Series design consists of rows of vertical tubes sandwiched between two rectangular headers.  Both headers are encased in a castable refractory with only the tubes exposed to flame and/or combustion gases.  The upper header is attached to the lower header only by the tubes; as the tubes expand and contract, the headers float up and down accordingly.

This floating header concept greatly reduces stress and allows for the use of cold feedwater without the fear of significant thermal shock.  The "leaky tube" problems associated with firetube and bent watertube designs have been eliminated.