There are three types of cooking oil heating systems:
Internal direct electric heating
Electric heating elements are fitted into the base of the frying kettle allowing minimal oil content.
The benefits of this process are low capital cost, minimal maintenance and consistent heating conditions; however this method has the highest direct operation costs.
Internal Direct Gas Heating A continuous stainless steel tube is fitted into the base of the kettle. An external gas burner fires heat into and along the tube, heat is transferred into the surrounding cooking oil.
This highly efficient system achieves very low operating costs.
External Direct Heating by Electricity or Gas An external heat exchanger provides a greater degree of heat input where
internal heating is insufficient.