The present disclosure relate to a controller system and method for use in storage-style water heating systems that offers significant opportunities for energy saving. The controller system can adjust the water heating system in response to energy demand patterns of user fixtures. The controller system can detect quantity of heated water usage and produce a heated water usage profile. The controller system can determine the quantity or volume of the used heated water without a mechanical flow meter. The controller system can include a cost-effective, accurate, and easy-to-install water temperature sensors that provide measurements of the differentials between water temperatures without direct contact with the water. The water temperature sensors can be cost-effective and easy-to-install sensors that are attached to the water pipes through a strap or other attachment methods.