In a heating system, a gas burner having two sections which can either burn together at full load or be used singly for reduced heating.
An atomizer type of burner that has a primary and a main fuel manifold and two independent orifices—one much smaller than the other. The smaller orifice handles the lower flows, and the larger one deals with higher flows as burner pressure increases. This type of burner is more efficient than the simplex type of burner. See simplex burner.