An automated conveyorized oven includes a radiant heater assembly including a plurality of gas-fired radiant heaters positioned beneath the oven conveyor. Each heater assembly includes radiant heating elements in the form of perforate metallic plates, at the outer surface of which combustion takes place for elevating the temperature of the plates for generating radiant heat. Consistent and reliable operation is promoted by the provision of a control arrangement which acts to preclude flashback combustion upstream of the surface of the metallic heating elements, with the controls being operable to permit sufficient time for the heating elements to cool, after interruption of the gas supply thereto, before gas is resupplied to the heater units.