The Taco Boiler Reset Control is a microprocessor-based control designed to regulate the supply water temperature from a single boiler based on the outdoor temperature. To avoid boiler short cycling and large temperature swings, the PC700 is able to continuously adjust the boiler differential. Standard functions include warm weather shut down, minimum boiler supply temperature setting, and a starting water temperature setting. The updated Boiler Reset Control utilizes an easy-to-use automatic reset ratio calculation to set the relationship between outdoor temperature and supply water temperature (heating curve) to provide optimum control and comfort. The control has a liquid crystal display that clearly shows the boiler supply temperature as well as the other monitored temperatures and settings. The operation of a hot water heating system can be improved by modulating the supply water temperature as the outdoor temperature changes. Using this approach, the heat lost from the building is matched by the heat input to the building.