Abstract: This invention relates to a method for exchanging heat between one fluid and another fluid by using a heat exchanger, and circulating at least the one fluid through a fluid flow channel within a body made of a material which is a good heat conductor as well as a good conductor of electric current, so that the fluids become in heat exchange relationship through the walls of the body. The improvement includes insulating the body from electric current flow therethrough, so that, in use, the tendency for progressive precipitation of solid particles from the fluids onto the wetted surfaces of the body is substantially reduced.