Abstract: The present invention generally relates to an insulating heater jacket, and more particularly, to a silicone rubber and a heater controller for an insulating heater jacket. According to the present invention, the use of the silicone rubber molded out of a mixture of polymethyl vinyl silica oxide solutions improves durability. Furthermore, a duplex heating pad is provided using first and second heaters, and a microprocessor and a temperature sensor monitor malfunction of the dual heating wires and perform control in such a manner that upon malfunction of one of the heating wires, the other heating wire can be operated. Therefore, there are advantages in that temperature can be accurately controlled and reliable performance can be always ensured without any malfunction.