A method for controlling temperatures in an epitaxial reactor for use in a wafer-production process is provided. The method is implemented by a computing device coupled to a memory. The method includes transmitting, to a heating device in a first zone of the epitaxial reactor, an output power instruction representing a base output power. The method additionally includes determining an actual time period for a temperature in the first zone of the epitaxial reactor to reach a target temperature, determining a difference between the actual time period and a reference time period, determining an output power offset based on the difference, and storing the output power offset in the memory in association with the heating device.