A fluid heater of the continuous flow type, comprising a fluid channel having a first fluid channel section (35), at least one substantially cylindrical metal pipe (2), a heating device (6) preferably having two tubular heating elements (6a, 6b) spaced apart from each other over equidistant circumferential sections of the metal pipe, and heat conducting means for providing a heat-conducting connection to the metal pipe (2), wherein a fluid guiding core (30) made of plastic is disposed in the metal pipe (2) and forms the first fluid channel section (35) between the metal pipe and the fluid guiding core (30), wherein the first fluid channel section (35) runs substantially helically in the form of a groove in an outer surface of the fluid guiding core, and wherein the fluid channel has a first fluid connector for fluid supply means and a second fluid connector for fluid discharge means, wherein the fluid guiding core (30) further comprises a substantially coaxial second fluid channel section (34) disposed therein, which is connected in series to the first fluid channel section (35). In the region of a first end of the metal pipe (2), a fluid connector assembly may be provided which includes both the first fluid connector (24a) and the second fluid connector (24b), such that fluid is supplied and discharged in the region of the same end faces of the metal pipe (2). A sealing plug (50) is provided in the region of the second end of the metal pipe (2).