The Vitotronic 200 and 300 controls are high-tech, digital outdoor reset controls for Viessmann boilers that manage the entire heating system--boiler, tank and multiple-temperature heating circuits, from standard to the most sophisticated. Features include multiple operating programs, programmable switching times, modulating or 2-stage burner control, mixing valve control, DHW supply management, remote control options, Quick-Connect plug-in system, integrated diagnostic system, and a building management interface option. Viessman Mfg. Circle 9.