Patent ID: 8744252

Claim:
A tankless water heater, comprising: at least one straight tube formed of quartz; at least one heating element mounted in contacting relation to said at least one straight tube so that heat is transferred from said at least one heating element to said at least one straight tube by conduction; a first end of said at least one straight tube in fluid communication with a source of liquid fluid under pressure; a second end of said at least one straight tube in fluid communication with a point-of-use outlet; an elongate insert disposed concentrically within a lumen of said at least one straight tube; said elongate insert having a diameter less than a diameter of said lumen; a helical ridge formed in said elongate insert along its extent and extending from said elongate insert by a nominal extent; said nominal extent being relative to a distance from said elongate insert to an interior wall of said at least one straight tube; said helical ridge constraining liquid fluid flowing through said at least one straight tube to flow radially outwardly as a turbulent flow into contacting relation to said interior wall of said at least one straight tube, said turbulent flow inhibiting build-up of mineral deposits on said interior wall and said elongate insert; said tankless water heater heating liquid fluid flowing through said at least one straight tube when said at least one heating element is in electrical communication with a source of electrical power; and said at least one straight tube having a dry external surface.