Article is devoted to a question of maintenance of effective protection of the cooling tower shell, using the screen with ventilated air gap. The purpose of the work is to determine the optimal parameters of the air gap by the calculation of heat and humidity and aerodynamic mode. In this article, there are calculations showing influence of temperature conditions and thickness of a ventilated air gap on warm, humidity and aerodynamic modes of its work.The thickness of the 140-160 mm of an air gap, provided on the heating air inlet gap, provides the ability to assimilate air moisture throughout the layer and to remove it in an atmosphere which prevents moisture condensation on cold surfaces of the concrete shell.