Abstract: A heating assembly for a heat treating furnace is disclosed which includes a heating tube from which heat is transferred to the furnace and a burner disposed in the heating tube. The burner is connected to a source of mixed fuel and air and is constructed to define a mixture inlet section, a throat section and a discharge section. A primary mixture flow passage is defined by the throat section and secondary mixture flow passages communicate with the discharge section to impinge secondary mixture flows into the primary flow and impart a vorticular motion to the mixture flowing from the burner.The burner is constructed from a first relatively easily machined member which defines the inlet and throat sections and in which the secondary passages are formed. A second tubular cylindrical heat resistive member defines the discharge section and the members are shrink fitted together to enable reconditioning of the burner by replacement of the second member.