Abstract: An integral water heating assembly is mounted to the tank wall or bottom of a water heater. The integral water heating assembly in accordance with the invention is able to detect conditions such as overheating of the heating element or boil dry conditions and accordingly switch off power to the heating element. This sensing and switching of the electrical power to the water heating element is accomplished without any sensing element external to the water heating assembly housing. The water heating assembly includes a sheathed heating element having ends which pass through apertures in the housing. The heating element preferably has a number of U-shaped bends and an intermediate section which contacts the housing at a point. The electrodes of the heating element are connected to a source of electrical energy through a control unit. The control unit includes a switching element for turning the power on and off, the switching element being controlled by a silicon chip.

Abstract: The temperature of a heating element (3), which heating element has a temperature dependent resistance, is measured by comparing the current through it with a user adjustable reference value. The AC voltage across a current sensing resistor (7) in series with the heating element (3) is compared in a comparator (9) with a reference AC voltage generated at a tap (6) of a voltage divider (8). The phase of the logic output signal of the comparator (9) indicates a first state in which the heating element (3) is too hot or is not conducting, or a second state in which the heating element (3) is too cold and conducting. A second comparator (16) detects whether or not the heating element (3) is conducting. A logic gate (18) and a latch (17) switch on the current through the heating element (3) in response to timed pulses from a timing circuit (15) and switch off the current through the heating element (3) when the heating element (3) is conducting and too hot.