The results of a study of the exergy efficiency of the method of flue gas bypassing, which ensures the prevention of condensate formation in the gas exhaust ducts of boiler plants, are presented. The block diagram of a heat recovery system with gas bypassing and the corresponding balance exergy equation are considered. The study was carried out using a complex methodology, including structural-variant and integral balance methods of exergy analysis. According to the results of the study, it was found that with an increase in the amount of bypassed flue gases, exergy losses decrease, and the values of the heat exergy criterion increase due to a decrease in the heat output of the heat recovery plant.