Ultra-Low NOx Direct Fired Furnace Burners Eclipse Furnnox burners set new standards for emissions and flexibility. Tests show that the burners deliver lower emissions than any of its competitor’s burners. The Furnnox is capable of producing NOx emissions less than 30 ppm at 3% O2 in most high temperature applications. To achieve high efficiency, the burner is controlled on-ratio throughout the operating range and can be operated with combustion air temperatures as high as 1,100°F (600°C). The Furnnox Low NOx burner is made to last, with rugged dependability and reliability built in.