Abstract: A gas powered pressureless steam cooker comprises at least one cooking compartment having a steam inlet, at least one steam generator located in close proximity to the cooking compartment, and a connector device means connecting a steam outlet of the steam generator to the steam inlet of the cooking compartment. The steam generator comprises at least one inshot gas burner, and an integrated heat exchanger unit/firebox within a water reservoir, the integrated heat exchanger unit/firebox being in heat exchange relationship with water within the water reservoir to create steam from water. The heat exchanger unit comprises a substantially S-shaped tube having a lower horizontal leg, a middle horizontal leg, an upper horizontal leg, a lower vertical web spacing the lower horizontal leg below the middle horizontal leg, and an upper vertical web spacing the middle horizontal leg below the upper horizontal leg.

Abstract: A gas powered, pressureless steam cooker has a connector tube for ingress of steam into the cooking compartment so that entry of a low temperature, wet steam can be minimized. The connector tube has a small diameter to constrain the entry of steam into the cooker compartment until it has reached a minimum velocity. A water reservoir is located alongside the oven compartment to the rear of the cooker and an integrated heat exchange tube and firebox are located in the tank. This tube is generally U-shaped, a lower horizontal leg opening at a mouth outside the water reservoir. An inshot burner fires into the lower horizontal leg and combustion gas flow through the U tube giving up heat to water in the reservoir. Additional heat exchange surface may be provided by channels through an upper leg of the U-tube from side to side. Flow of combustion gases may be optimized by the shape of the U-tube and at least a deflecting surface between a vertical web of the U and the upper leg of the U.