In a letter received by AERCO from Underwriter’s Laboratories on Oct. 3, 2006, the organization has confirmed the 99.2 percent operating efficiency of the Benchmark 2.0 Low NOx boiler (BMK2.0LN) when operated at 5 percent input with 60 degree F return water in a system designed with a 20-degree temperature rise.

AERCO invited UL to witness and review the efficiency testing of the AERCO Benchmark BMK2.0LN condensing boiler. Both full- and part-load thermal efficiency were tested in the presence of UL representatives between December 2005 and May 2006. Performance was measured at a variety of firing rates over the unit’s 100,000 to 2 million Btu/hr. operating range using return water temperatures between 60 degrees F and 180 degrees F, according to test protocols outlined in standard BTS-2000.

The resulting efficiency curves, published on the company’s Web site at, confirm AERCO claims of up to 99.2 percent efficiency.