Cogeneration turbines vacuum system, besides the condenser, includes hot water network heaters. When the steam pressure in the lower heating extraction is below the barometric pressure, an additional amount of air enters the first hot water heater (HWH-1) that is then evacuated into the condenser. This can lead to vapor pressure increase in the condenser and to the main condensate oxygen contamination, especially with significant rate of air evacuated into the condenser. To increase the efficiency of the hot water plant, a special ejector was developed and installed at the combined heat and power plant to evacuate non-condensable gases from the horizontal type hot water heater. The ejector has two-stages with a pre-cooler and employs a number of technical solutions aimed at its efficiency and reliability improving. By cooling water the ejector is connected to the main condensate line behind the main ejectors. Heating steam drainage from the ejector is removed to the HWH-1 condensate pot. Estimated pressure at the ejector suction is Р н = 25 kPa. The ejector applying to air evacuation from the HWH led to a decrease in condenser vapor pressure by 0.12 kPa. An additional effect results in the turbine's own needs steam savings due to the fact that the HWH ejector steam consumption is 5 times lower than that of the turbine main ejector. It is shown that with small amounts of sucked air the HWH ejector can be used in a single-stage version, since the pressure ratio at the outlet of the ejector first stage to the pressure in the first stage receiving chamber is less than 1. To turn off the first stage of the ejector, it is necessary to install an individual valve on the first stage steam supply pipeline.