An electrical heater has first and second heater elements, each having a hairpin-shaped metal tube with an upstream and a downstream leg and tube ends adjacent each other. An electrical resistance wire surrounded by insulation powder extends through the tube. Electrical terminals join to the wire and protrude from each of the tube ends. Conduits enclose the upstream and the downstream legs of the heater elements, providing a continuous annular flow path. A manifold has heater element passages for end portion of the legs. An inlet passage in the manifold leads from an exterior portion of the manifold to the annular flow path surrounding the upstream leg of the first heater element. A transfer passage within the manifold leads from the annular flow path surrounding the downstream leg of the first heater element to the annular flow path surrounding the upstream leg of the second heater element.