The present invention provides a control system for a bathing unit that comprises a heating module, a thermal element and a heating module controller. The heating module includes a body that defines a passage through which water can flow, that has an inner surface and an outer surface. The heating module further includes a heating device that is operative for heating the water that flows through the body. The thermal element is mounted to the outer surface of the body such that the thermal element is in thermally conductive communication with water flowing through the body. The heating module controller is operative for obtaining temperature information associated with the thermal element for detecting at least in part on the basis of the temperature information the sufficiency of water flow through the body.