Low NOx (Nitrogen Oxide) burners are designed to control fuel and air mixing at each burner in order to create larger and more branched flames. Peak flame temperature is thereby reduced, and results in less NOx formation. In the initial stage, combustion occurs in a fuel rich, oxygen deficient zone where the NOx are formed.
Due to state EPA regulations, an increasing number of U.S. residents are in need of heating HVAC equipment designated as: "Low NOx". Even if you do not live in a state that requires it, a low NOx appliance is still a great choice for those concerned about the environment.