For U.S. Customers only:

Preliminary AFUE Rerate of Modulating Condensing Gas Boilers

Viessmann Manufacturing Company (U.S.) Inc. is a member of the Air-Conditioning, Heating and Refrigeration Institute ("AHRI"), a trade organization that administers the Department of Energy’s ("DOE") efficiency test for residential furnaces and boilers.

AHRI recently notified the DOE that it discovered an error in the DOE test procedures that may result in inaccurate annual fuel utilization efficiency ("AFUE") test results. This is an industry wide issue affecting all models of residential condensing boilers that have two-stage or modulating input rates. 

As of March 11, 2013 and in accordance with AHRI directives, the AHRI certified Viessmann Vitodens boiler model nos. WB1B-26, WB1B-35, WB2B-19, WB2B- 26, WB2B-35, WB2B-45, WB2B-60, and WB2B-80 have been retested using the corrected DOE test procedures. These models are now relisted with corrected AFUE ratings in the AHRI Directory of Certified Product Performance. Viessmann boilers are highly efficient and continue to meet federal minimum AFUE for these products.

For further information, please click on the links below. 

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