An immersion heater is an electric heating apparatus consists of a bundle of tubular heating elements which are submerged in a tank or container to heat a liquid, such as water, oils of various viscosity, viscous materials, solvents, process solutions, liquidous chemicals, and gases. It is designed and used for direct contact heating to increase or maintain the temperature of the fluid to attain required values for process indicators such as temperature, viscosity, pressure, solubility, or miscibility.