An exergetic method of really existing cogeneration heat and power plant operation analysis is elaborated and plant`s thermodynamic processes effectiveness evaluation is presented in the given report. Power plant`s technical and economical report for a long time of operation period was used for numerical efficiency indexes evaluation. Numerical calculations shows twice as high value of the total thermal efficiency index (related to the total combustion heat of consumed fuel) against the exergetic efficiency index (57% and 27% correspondingly). That lets to think regarding theoretical possibilities to find methods for more efficient application of combustion heat. The method of an exergetic analysis will give certain contribution for designing and efficiency optimization of complicated heat & power systems.