In chemical plants shell-and-tube heat exchangers are among the most frequently used apparatuses and costs of heat transfer usually determine the cost of a whole process. The definition of the optimum series of heat exchangers (J. Buzek, M. Buzanowski and J. Podkanski, Chem. Eng. Proc., submitted), and the application of elements from the series lead to the decrease in costs of heat transfer. Optimum series of heat exchangers can be created only if there is market demand for apparatuses suitable for various process parameters and costs of heat exchanger production and operation are known. During calculations combinatorial explosion can be avoided owing to certain properties of the cost functions of apparatuses forming the series.