Abstract: An apparatus of a reactor or processing chamber comprising a chamber having a resistive heater disposed within a volume of the chamber, including a stage having a surface area to support a substrate such as a wafer and a body including at least one heating element, a shaft coupled to the body, a plurality of temperature sensors coupled to the chamber, each configured to measure a temperature at separate points associated with the surface area of the stage, and a motor coupled to the shaft and configured to rotate the resistive heater about an axis through the shaft. In this manner, the temperature sensors may measure a temperature at separate points of the surface area of the stage. A method of rotating a shaft and measuring a plurality of temperatures over the surface area of the stage or over a wafer seated on the stage with the plurality of temperature sensors.