Three variants of configuration of the heat exchanger on height for the case of the set height are considered. The variant at which capacity of the heat exchanger is minimum is defined. It is shown that the choice between other two variants is ambiguous and should be defined by means of calcula-tion. It is shown that in a case of air heater with coils of different length the heating medium tempera-ture on an exit from long coils should be calculated also. It is required for acceptance of measures from heating medium freezing.