A method of heating molten glass in a forehearth with a burner that extends into the forehearth above the molten glass from a side wall of the forehearth is described, wherein the fuel and oxidant outlets (29,30) open in a direction which is upstream or downstream relative to the direction (D) in which said molten glass is flowing. Relative dimensions and orientations of the oxidant / fuel conduits and outlets, design of the refractory material encasing the conduits, oxidant and fuel velocities at their respective outlets and the ratio of oxidant to fuel velocity are controlled to reduce formation of soot, reduce damage to conduits and refractory material and reduce condensation of material from the molten glass.