One of the energy-efficient technologies is the use of injectors in heat supply systems. Steam-water injectors are very sensitive to changes in the thermodynamic parameters of water and steam. The operating range of such devices is limited to boiling liquids. The search for ranges of thermodynamic parameters that ensure the operation of the injector in real conditions of functioning of heating networks is an urgent task. The maximum energy-saving effect can be achieved by replacing devices that reduce steam pressure by injectors in which there will be a simultaneous decrease in steam pressure, heat transfer between steam and return network water to achieve the necessary thermodynamic parameters of the mixed flow. The article presents the results of modeling the operation of a steam-water injector with a cylindrical mixing chamber, taking into account the actual values of temperatures and pressures in the heating network. With constant parameters of hot steam, the possible ranges of the injector for the temperatures and pressures necessary for the implementation of temperature schedules for regulating heating networks are determined. The procedure for identifying input parameters that ensure the implementation of temperature schedules of heating networks has been carried out. Equations are obtained that allow one to determine the temperature of the water leaving the injector from the injection coefficient for the found working pressure ranges of the injected water.