An algorithm for thermal analysis of condensing heat exchangers in steam-turbine units, which makes it possible to account for unusual structural design of equipment, both original, and also as a result of modernization, as well as the effect of the location of the equipment in the process-flow diagram of a turbine plant and a number of other factors reflecting all interrelations between the equipment and other components, is proposed. Results of optimization thermal analyses of a condenser in accordance with the proposed algorithm, on the basis of which parameters were selected for its optimization, and also a comparison of computed data with data derived from tests of the modernized equipment, are presented.