The Vitogas 50, RS Series from Viessmann Manufacturing Company (US) Inc. (Warwick, RI) is available with single- or two-stage burners in three input size ranges: 500, 800, and 1,050 MBtuh. Control options include the Vitotronic 100 Series for basic applications or the digital Vitotronic 200 and 300 Series for multitemperature heating applications.