Abstract: A gas supply manifold has upper and lower sheet metal walls defining a gas supply passage extending to an annular chamber defined between concentric openings within the walls. A gas burner unit mounts on the manifold and has concentric inner and outer walls defining an annular chamber which connects with the annular chamber in the manifold. A drawn sheet metal fitting engages a shoulder within the burner unit and includes a downwardly projecting tubular portion having a corrugated cross-sectional wall configuration defining helical candelabra threads. A drawn sheet metal nut has an upper flange portion projecting outwardly from a tubular portion having a corrugated cross-sectional wall configuration defining candelabra threads mating with and engaging the threads on the fitting to secure the burner unit to the manifold.