All Ultra boilers feature AFUE efficiencies in the range of 92.0 - 93.0%. These are some of the highest efficiencies in the industry, however, Ultra boilers, when used in common low temperature applications have annual efficiencies of 98.0%. The Weil McLain Ultra Series 3 boiler exceeds all of the requirements of the Department of Energy’s ENERGY STAR program. Besides being Ultra High Efficient, the Ultra boiler is environmentally friendly. Through PhD Technology and the use of our high grade burner, the Ultra boiler produces less NOx while exceeding all current environmental codes and is certified by South Coast Air Quality Management District (Rule 1146.2) in California.