The circulating electric heater series heats the heat transfer oil through forced convection. It is a heating method that uses a pump to pump heat transfer oil into the heating chamber at one end of the heater, and after heating, it flows out at the other end of the heater. It is a heating method that is forced to circulate by a pump. Compared with traditional heating methods, it is energy-saving, scientifically processed, easy to install and use, and has significant economic benefits.