The Vitogas 50, RS Series atmospheric gas-fired boilers from Viessmann feature single- or two-stage burners for improved fuel economy. The boilers are available in three input size ranges: 500, 800 and 1,050 mbh (161, 234 and 308 kW). Control options include the electromechanical Vitotronic 100 series for basic applications or the digital Vitotronic 200 and 300 series for multi-temperature heating applications. The boilers also feature a sectional cast-iron heat exchanger design for easy transportation. www.viessmann.comViessmann.