Device for improving the production of heat by cogeneration comprising a hot source producing steam which is expanded in a turbine the exhaust of which is connected to an air condenser (4) which removes heat, and comprising at least one second auxiliary condenser (5) in the form of a water condenser, the cooling liquid of this water condenser (5) being directed to a plant or equipment (B) in which its heat is extracted and used, then the liquid is returned to the water condenser; the water condenser (5) is incorporated into the air condenser (4).