The planned work includes the replacement of the existing Viessmann heating boiler, including all ancillary systems, with a modern Vaillant heating system. The positions include all services necessary... The planned work includes the replacement of the existing Viessmann heating boiler, including all ancillary systems, with a modern Vaillant heating system. The positions include all services necessary for the proper and technically sound operation of the system. We require a site visit before submitting a bid to confirm appropriate equipment. For further information contact BerlinEinkauf@state.gov