Abstract: A heater for heating flowing fluid. The heater comprises a cylindrical heating chamber comprising an inlet at one base and on outlet at a second base. The flowing fluid traverses parallel to the chamber. A resistive heating element is received in the chamber wherein the resistive heating element comprises a rectangular base. The rectangular base comprises a long axis and short axis and the long axis is parallel to the chamber. The base comprises a multiplicity of first slots on one side and a multiplicity of second slots on a second side. A double helix filament is received in the first slots and the second slots.