Advanced condensing technology
CU3A Series gas-fired condensing boiler with stainless steel Inox-Crossal heat exchanger and MatriX dome gas burner. Rated input: 19 to 199 MBH (single) / 1592 MBH (cascade).
The benefits at a glance
- Compact, floor-standing gas condensing boiler from 19-199 MBH.
- High efficiency of 95% AFUE on all models.
- High-temperature operation of up to 90°C (194°F).
- Vitocrossal Pocket Design with wide water passageways allows for system/full flow applications. No dedicated boiler pump required and eliminates primary/secondary piping.
- MatriX dome gas burner with 5:1 turndown ratio to ensure high efficiency and extremely clean combustion.
- High water volume extends the burner run time and reduces cycling.
- A self-calibrating Lambda Pro combustion management system ensures optimal combustion efficiency at all times regardless of gas/air quality. Simple commissioning with no field adjustments and adjusts to all fuel types (NG and LPG).
- Durable, reliable, and long service life with Inox-Crossal stainless steel heat exchanger and high mass design.
- Multiple venting options and configurations with vent lengths up to 198 ft.
- Multi-boiler installation with 8 boilers up to 1592 MBH.
The right choice for new construction or retrofits
With its combination of high-temperature capability, high mass (water volume), floor-standing design, condensing stainless steel construction and modulating gas burner, the Vitocrossal 300, CU3A is the ideal choice for boiler retrofits or new construction. From homes equipped with high mass cast iron radiators, to homes with multi-zone high-temperature fin tube radiators, and new installations with high DHW requirements – the Vitocrossal 300, CU3A is the best choice on the market today.
With a limited lifetime warranty in residential applications, you can be sure your investment will deliver long-lasting value year after year. For detailed terms and conditions, see the warranty sheet.
Exceptional performance and reliability
The vertical stainless steel Inox-Crossal heat exchanger offers ideal conditions for intensive utilization of hot gases, resulting in efficiencies of up to 98%. The smooth stainless steel surfaces allow the condensate created by the condensing process to simply run off downwards. This creates a permanent self-cleaning effect, ensuring high efficiency, long service life and reduced maintenance.
Highly efficient and environmentally responsible products
ENERGY STAR qualified products meet strict energy efficiency guidelines set by the U.S. Environmental Protection Agency and the Department of Energy. The ENERGY STAR Most Efficient designation recognizes boilers with an efficiency rating of 95% AFUE or higher. Viessmann Vitodens boilers and Vitocrossal 300 CU3A boilers meet these criteria.
Sustainability is a top priority for us, particularly during product development. As early as the design stage, we ensure that raw materials are used in the production process in a way that protects natural resources. Our products are built for high thermal efficiency and long service life. At the end of their service life, Viessmann products are professionally recycled and valuable raw materials are returned to the manufacturing and material cycle.