The Boiler Control 261 is designed to stage two on/off boilers using Outdoor Temperature Reset. It can be used in applications ranging from a single zone of baseboard, multiple baseboard and fan coil zones, to dedicated set point heating in commercial buildings. This control regulates a single heating water temperature through Outdoor Temperature Reset and/or set point target control. It is capable of controlling (stage and rotate) up to 2 on/off boilers, or a single 2 stage boiler, as well as the system pump.