Cost optimization of heat exchanger inventory in power cycles with one open feedwater heater is undertaken. In this regard, thermoeconomic analysis for an endoreversible power cycle with an open feedwater heater is shown. The scenarios of constant heat rejection and addition rates, power as well as rate of heat transfer in the open feedwater heater are studied. All cost functions displayed minima with respect to the high-side absolute temperature ratio (theta(1)). In this case, the effect of the Carnot temperature ratio (Phi(1)), absolute temperature ratio (xi) and the phase-change absolute temperature ratio for the feedwater heater (Phi(2)) are qualitatively the same. Furthermore, the constant heat addition scenario resulted in the lowest value of the cost function. For variation of all cost functions, the smaller the value of the phase-change absolute temperature ratio for the feedwater heater (Phi(2)), lower the cost at the minima. As feedwater heater to hot end unit cost ratio decreases, the minimum total conductance required increases. (C) 2014 Elsevier Ltd. All rights reserved.