Abstract

A continuous flow or flash electric water heater, for example for use in a coffee making machine, includes a compound heating structure made up of at least two elongated generally parallelepyred shaped massive heating bodies of a material having a high thermal conductivity, such as brass. Each body has at least one heat input face and a longitudinal passage for flow of water to be continuously heated. The bodies are positioned side-by-side with the passages parallel to each other and with a heat input face of each body facing a heat input face of the next adjacent body. At least one flat PTC electric heating element is positioned between each four of facing heat input faces and a casing made up of two elongated channel-like casing halves, each U-shaped in cross section and having two side flanges, houses the heating structure and forces the bodies together with the heating elements therebetween. The side flanges of the casing halves are overlapped and fixedly secured together along their entire length by a permanent soldered, welded or crumped metal joint so that the bodies and PTC heating elements within the casing are acted upon by a controlled force, transmitted by the casing through the bodies, normal to the heat input faces, for the full life of the water heater. The flow passage can be formed by a hair-pin shaped continuous pipe nested in a groove in the bodies or by a hole running through each body and joined to form a continuous flow path by aligned openings in the facing heat input faces.