This paper deals with the analysis of the steady flow of a semi-infinite expanse of rarefied gas bounded by its plane condensed phase by the methods of the discrete kinetic theory. The existence of the solutions of the corresponding boundary value problem is discussed. The relations among the parameters of the flow near the condensed phase and at infinity required for the existence of solutions are established. The problem of condensation of a vapor gas on its own condensed phase is then solved analytically for a particular discrete model and remarkable features of the flow are analyzed.