Abstract: An electric heater (1) for a machine for preparing hot beverages, comprising —a metal body (2); —at least one electric heating element (3, 4), in particular adapted to generate heat when it is crossed by an electric current, arranged in the metal body (2); —a tube (5) for the passage of a liquid to be heated, arranged in the metal body (2); wherein an inner surface (6) of said tube (5) has a surface roughness (Ra) which is greater than 0.8 ?m, preferably greater than, or equal to 1 ?m.

Abstract: An electric heater including a metal body, in which a first pipe and a second pipe are provided in the metal body. The first pipe and second pipe are mutually distinct so as to be crossed by two distinct flows of fluid to be heated. A first heating stretch, a second heating stretch and a third heating stretch are arranged in the metal body. The first pipe and the second pipe are arranged between the first heating stretch and the second heating stretch. The third heating stretch is proximal to the second pipe and distal from the first pipe. The second pipe is arranged between the first pipe and the third heating stretch.

Abstract: A method and device for detecting the amount of limescale that accumulates in liquid heating devices, in particular for heating water. The method is capable of establishing, through simple temperature measurements, if the amount of limescale deposited on the heater element of a device for heating liquids is such as to jeopardize the correct operation thereof and provides the user with information on the need to clean the aforesaid heater.

Abstract: An electric heater (1) comprising:—a metal body (2);—a first pipe (11) and a second pipe (12) provided in the metal body (2), which are mutually distinct so as to be crossed by two distinct flows of fluid to be heated;—a first heating stretch (21), a second heating stretch (22) and a third heating stretch (23) are arranged in the metal body (2); wherein the first pipe (11) and the second pipe (12) are arranged between the first heating stretch (21) and the second heating stretch (22); wherein the third heating stretch (23) is proximal to the second pipe (12) and distal from the first pipe (11); and wherein second pipe (12) is arranged between the first pipe (11) and the third heating stretch (23).