Abstract: A hand-operated lettuce-cutting appliance with a chassis has a cutter grid and positioning device for positioning the chassis on at least one support. The appliance further includes a guide well having a bottom end extending adjacent to and facing said cutter grid and a vegetable-pusher device mounted to slide along at least one column fastened to the chassis so as to extend parallel to the well. The vegetable-pusher device has a body shaped so as to engage in the well in order to push the vegetable through the cutter grid.

Abstract: The invention concerns a heat exchanger comprising at least one helically bound bundle of tubes, whereof the thermally conductive wall has a flattened and oval cross-section, whereof the main axis is perpendicular to that (X-X?) of the helix, while the width of the interstice separating two adjacent turns is small and constant, said bundle being fixedly mounted inside a casing (1) fitted with a pipe for evacuating gases generated by a burner (6), means being provided for circulating cold water inside said bundle, said exchanger being further designed so that the hot gases pass radially through the bundle via the interstices of the turns. Said exchanger is characterized in that the casing is made of heat-resistant plastic material and means are provided for ensuring mechanical containment of the beam in the axial direction, and for damping the thrust loads resulting from the fluid internal pressure, preventing their being transmitted to the casing.