Viessmann Vitodens 100-W, B1HA – High Efficiency Wall Mount Condensing Boiler Overview Rated input 21 to 125 MBH – 6.2 to 36.6 kW Efficiency (AFUE) 95% Fuel Natural gas, propane gas Application range For residential homes and apartment units, new buildings and retrofits DHW heating On-demand DHW available with B1KA Combi boiler (up to 3.6 GPM). Ideal for apartment units and houses with one DHW draw point. Warranty Limited lifetime warranty in residential applications Additional features Compact, lightweight wall-mount design and zero clearance to combustibles make it a great choice for limited-space installations. Read more