steam power plants utilize high pressure and low pressure feedwater heaters to increase overall system efficiency . both types of feedwater heaters generally include a subcooling zone that is separate from a condensing zone . the viability of the separation of the zones is critical to the efficiency of the overall system , specifically with regard to the inefficiencies inherent in the leakage of steam from the condensing zone into the subcooling zone . an improvement in the viability of that zone separation for such feedwater heaters is taught by the use of dual end plates for the subcooling zone to create a triple layer of separation between the condensing and subcooling zones to prevent unwanted and inefficient steam leakage .