US Patent 7308193 Non-metallic heating element for use in a fluid heater

An electric fluid or water heater is shown in which the heat generation is accomplished by a non-metallic element. The heating element exploits properties of carbon black based polymers. These basic elements have both electrically conductive and electrically restive properties. Metal strips are injection molded into the carbon black body of the heating element with physical contact between the metal and the carbon black. When current is passed through the metal strips, the resistivity of the carbon black causes heat to be generated. Prior art metal heating elements are subject to corrosion and degradation of performance over time. In addition, the inflow and outflow pipes may be constructed in the same manner to heat fluid en route.