Abstract: An overheating and scaling control device for a fluid heating apparatus, such as a domestic water heater, removes the hot fluid in the heater when demand ceases. A piston (46) mobile within a case (28) separates the latter into two compartments (32, 36) respectively connected to the cold water supply pipe (16) and to the hot water discharge pipe (22). In operation, the pressure in pipe (16) is higher than the pressure in pipe (22) and piston (46) is moved to the left. On stopping, the pressures are equal in both pipes and spring (40) moves piston (46) to the right. Cold water is fed into the exchanger tube (20), so that the hot water contained in the latter is discharged into pipe (38) and compartment (36).

Abstract: A heating body is provided for a gas water heater in the form of a vertical tubular chamber (1) obstructed at its upper end by a heat exchanger (2) itself having a pipe section (4) through which the water to be heated flows, the rear (6) and side (7,8) portions of the wall of said chamber being formed by a protective metal sheet (11) lined on the inside with a refractory material body (10). The front portion (9) of said wall is a heat conducting metal panel adapted so as to form a capacity or chamber (16) through which the water to be heated flows just upstream of the exchanger.