Disclosed is a system for dielectrically processing a product in a radio frequency (RF) cavity. The system may include a cavity; an RF feeding module that includes a plurality of radiating elements configured to feed RF radiation into the cavity, and a plurality of dummy loads for receiving RF energy coupled from the cavity into the radiating elements; and the system includes a processor configured to (a) estimate an effect operating the system at each of a plurality of sets of operating parameters will have on the temperature of each of the dummy loads; (b) choosing among the plurality of sets of operating parameters at least one set based on the estimation; and (c) controlling the system to operate at the chosen at least one set of operating parameters.