The Benefits at a Glance - Available in two sizes with input range from 12 to 125 MBH. - Efficiency up to 98% at full modulation and 95% AFUE. - Lasting performance with Viessmann-made SA240 316Ti stainless steel Inox-Radial heat exchanger constructed to CSA B51 and ASME Section IV. - Low emission combustion and continuous efficiency from Viessmann stainless steel MatriX cylinder burner with Lambda Pro combustion management system. - Wide modulation range up to 6.5:1 to precisely match load conditions. - Fast heat-up with innovative DHW Storage Tank Loading System comprised of plate heat exchanger, DHW loading pump and storage tank. - Compact and hygienic DHW storage with Viessmann-made SA240 316Ti stainless steel tank (26 USG). - Ten-minute peak flow of 60 gallons (model B2TB-35 only)* and continuous DHW draw of 3.3 GPM.* - Space-saving design with small footprint and zero side clearance to combustibles. - On-board Vitotronic control features large display with text and graphics for straightforward, menu-driven programming and operation. - Simplified installation with pre-installed pressure / temperature relief valves, fully enclosed heating expansion tank and circulation pump, and built-in 3-speed DHW / space heating pump with diverter valve. - Multiple venting options with vent length up to 180 ft. - Exceeds Energy Star Efficiency Requirements. - High-altitude operation capability up to 10,000 ft. / 3,000 m.