This paper is a result of several years of work on the silicon floating zone (FZ) process. Starting with numerical calculations of RF current density distribution, heat transfer, and thermal stresses, theoretical results are compared with FZ experiments. The simplified numerical models show qualitatively and quantitatively useful results for designing RF inductors under the assumption of steady-state growth and for sufficiently low disturbances by the field of the inductor slot. Above all, the thermal influence of modifications of the inductor profile can be predicted more accurately.