A heater for heating air passing through a conduit to an aircraft cabin includes a first support ring in the conduit, defining an air passage there through. A plurality of serpentine heating elements is provided, with each heating element extending across the air passage and being supported at both sides of the air passage by the support ring. The serpentine heating elements are generally parallel to each other and evenly spaced in the air passage. A power supply supplies electrical current to the heating elements such that air passing through the air passage is heated by the heating elements. The heating elements may are non-planar, wavy, corrugated in shape, permitting them to be supported only at their side edges.