Abstract The district heating systems supply heat to a wide range of consumers. In the heat source of such systems, highly efficient technologies are used for the combined production of electrical and thermal energy mainly based on steam turbine installations with backpressure turbines or turbines with adjustable steam extractions. Combined production leads to a reduction in fuel consumption (fuel saving) compared to the separate production of the two energy products. The fuel saving resulting from cogeneration reduces carbon dioxide emissions. Combined production affects the amount of fuel saved, leading to a reduction in emitted emissions, both the size of the heat load realize to consumers and the temperature of the water that enters from the return pipeline of the district heating systems into the heat source. In backpressure steam turbine installations, the district water is heated by the steam that enters the boiler-condenser, and in steam turbine installations with adjustable steam extraction, it is heated in a district heater by steam extracted from the turbine. The purpose of this paper is to study the influence of the temperature of return district heating water on the performance of a backpressure steam turbine installation for cogeneration.