Simply efficient

The new Vitocrossal 300 CU3A

In a recent interview with Steve David, director of Sales-East at Viessmann Manufacturing U.S., talked about the new compact, gas-condensing, floor standing Vitocrossal 300 CU3A boiler.

For the past 20 years, Steve’s career has focused on promoting, designing and integrating high efficiency hot water heating systems. These systems commonly include high efficiency condensing and traditional boiler technology along with renewable technologies, such as biomass and thermal solar systems 

Steve’s experience of 15 years in mechanical contracting and two years with energy auditing enable him to bring a practical outlook to the installation of high efficiency renewable heating technologies.  

PHC: What is the Vitocrossal 300 CU3A?

SD: It’s a highly efficient stainless steel gas-fired condensing boiler available in four sizes ranging from 94MBH to 199MBH, with a 5:1 turndown ratio. Since its release 15 years ago in Europe, we’ve sold over 100,000 units in Europe, 34,000 of them in the last four years alone. June marks the introduction of the Vitocrossal 300 to the U.S. market, where we expect it be very popular.

PHC: What makes the Vitocrossal 300 CU3A distinctive?

SD: First of all, it’s a high-mass design that means large water volume for the BTU/H input, therefore it isn’t flow sensitive.  Contractors will love that it’s simple; because of the high-mass design, there is no primary/secondary piping to deal with, no low-loss headers to build into the system. And it’s a floor-standing unit — it’ll fit in the same footprint as your old cast-iron sectional. Installation really is as simple as connecting the existing supply and return piping. Slide out, slide in — boom. That’s it. I like to call it, “simply efficient.” This is not to say that you should keep the old pumps after many years of service. There is great opportunity for utility savings with the new VFD pumps.     

PHC: Is simplicity built into the design?

SD: Absolutely! All the pipe connections are in the back, and the vent connection is low to the ground for convenient connection to existing chimney openings. You can also sidewall vent this unit up to 190 feet. The combustion management system is self-commissioning; when the burner starts it automatically self-calibrates. Natural gas to liquid propane is also simple with no orifice to change. You don’t need a combustion analyzer — the burner does all the work. The heat exchanger design actually washes itself when operating in the condensing mode, ensuring good heat transfer. The menu driven control and quick start-up guide simplify system commissioning

PHC: What about the efficiency side of the equation?

SD: Think of it this way: on average, we in the U.S. pay about $0.90/therm for natural gas. In Germany, they pay about $3.00/therm, more than three times as much. In order to succeed in Europe, a boiler has to be efficient — and the CU3A delivers. The combination of our LambdaPro combustion technology, which continually adjusts the burner for optimum combustion efficiency, and our proprietary heat exchanger, delivers up to 95 percent AFUE. You just can’t reach that kind of efficiency with a conventional sectional boiler or many of the other condensing boilers on the market. 

PHC: What about build quality?

SD: Look inside. It’s all Viessmann manufactured parts, and they’re all proven with a track record of durability. The heat exchanger is made from the best titanium alloy available for industrial applications, SA240-316Ti. We’re talking a minimum lifespan of 20 to 25 years and in the real world, it’s usually much longer. For the burner, the Vitocrossal 300 CU3A uses our MatriX radiant dome—it’s whisper-quiet and brings NOx emissions down to just 20ppm. The controller is our Vitotronic 200 KW6B, which allows you to control the boiler and the system, including DHW. The boiler has 0-10 volt output to control a system variable speed pump. You can control up three temperatures: high temperature direct from the boiler and two low temperatures via mixing valves, besides DHW production.

PHC: What are the target applications for the CU3A?

SD: For retrofits, there’s obviously a huge opportunity anywhere you have high water temperatures and a high mass design: old homes with cast iron radiators, homes with multi-zone fin tube baseboard radiators, and homes with high DHW demands. Because of the easy swap-out with old sectionals, it’ll be great in many small commercial applications too.

It’s also perfect for new construction. With the Vitocrossal 300 CU3A, you get a packaged boiler that doesn’t need primary/secondary piping — you save big on installation costs. There’s less piping, fewer pumps, fewer valves — and best of all, less installation time.

PHC: What is the cost for the CU3A?

SD: We’re pricing the Vitocrossal 300 CU3A very competitively. With incentives from natural gas providers, it’ll cost little more than most floor standing boilers in the marketplace. However, when you add in the savings you get in the simple installation—and the lifetime value of durable parts and low maintenance demands—you’re getting an incredible value.

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