An exhaust device (116A, 116B, 262, 264, 266, 610, 612, 614, 616, 372, 374, 376, 378, 600, 972, 974, 976, 978, 1116), comprising: a fan plenum (119, 159, 308, 1155, 1204) with a fan (118, 168, 304); a jet plenum (103, 104, 178, 302, 242, 782, 784, 786, 788, 802, 804, 806, 808, 810, 812, 814, 816, 1114, 1202) having one or more jet openings (139, 1118) on a distal end thereof configured to create a planar jet (141, 185, 323); the jet plenum (103, 104, 178, 302, 242, 782, 784, 786, 788, 802, 804, 806, 808, 810, 812, 814, 816, 1114, 1202) being movably attached at a proximal end thereof to the fan plenum (119, 159, 308, 1155, 1204) to permit sliding movement of the jet plenum (103, 104, 178, 302, 242, 782, 784, 786, 788, 802, 804, 806, 808, 810, 812, 814, 816, 1114, 1202) relative to the fan plenum (119, 159, 308, 1155, 1204); the fan plenum (119, 159, 308, 1155, 1204) and the jet plenum (103, 104, 178, 302, 242, 782, 784, 786, 788, 802, 804, 806, 808, 810, 812, 814, 816, 1114, 1202) each having a respective flow-transfer opening (201, 202, 1206, 1208) that overlaps the opening of the other, the respective openings (201, 202, 1206, 1208) being shaped and arranged to remain overlapped in all positions to which the jet plenum (103, 104, 178, 302, 242, 782, 784, 786, 788, 802, 804, 806, 808, 810, 812, 814, 816, 1114, 1202) is moved relative to the fan plenum (119, 159, 308, 1155, 1204) such that an interior of the fan plenum (119, 159, 308, 1155, 1204) and the jet plenum (103, 104, 178, 302, 242, 782, 784, 786, 788, 802, 804, 806, 808, 810, 812, 814, 816, 1114, 1202) remain in fluid communication to allow air to flow from the fan (118, 168, 304) to the jet plenum (103, 104, 178, 302, 242, 782, 784, 786, 788, 802, 804, 806, 808, 810, 812, 814, 816, 1114, 1202) to the one or more jet openings (139, 1118) and form the planar jet (141, 185, 323) through the one or more jet openings (139, 1118); and, characterized in that, the planar jet (141, 185, 323) is aimed diagonally downward toward an appliance (170, 172, 3302) positioned underneath the exhaust device (116A, 116B, 262, 264, 266, 610, 612, 614, 616, 372, 374, 376, 378, 600, 972, 974, 976, 978, 1116); an exhaust intake (315, 382, 384, 386, 388, 1140, 1280) below the jet plenum (103, 104, 178, 302, 242, 782, 784, 786, 788, 802, 804, 806, 808, 810, 812, 814, 816, 1114, 1202) exhausting fumes through the exhaust intake (315, 382, 384, 386, 388, 1140, 1280),and the fan (118, 168, 304) having an intake at a top of the fan plenum (119, 159, 308, 1155, 1204) which is covered by a louvered grill (306, 240) of the jet plenum (103, 104, 178, 302, 242, 782, 784, 786, 788, 802, 804, 806, 808, 810, 812, 814, 816, 1114, 1202) when the jet plenum (103, 104, 178, 302, 242, 782, 784, 786, 788, 802, 804, 806, 808, 810, 812, 814, 816, 1114, 1202) is in a fully retracted position, thereby permitting air to flow into the intake. a fan plenum (119, 159, 308, 1155, 1204) with a fan (118, 168, 304); a jet plenum (103, 104, 178, 302, 242, 782, 784, 786, 788, 802, 804, 806, 808, 810, 812, 814, 816, 1114, 1202) having one or more jet openings (139, 1118) on a distal end thereof configured to create a planar jet (141, 185, 323); the jet plenum (103, 104, 178, 302, 242, 782, 784, 786, 788, 802, 804, 806, 808, 810, 812, 814, 816, 1114, 1202) being movably attached at a proximal end thereof to the fan plenum (119, 159, 308, 1155, 1204) to permit sliding movement of the jet plenum (103, 104, 178, 302, 242, 782, 784, 786, 788, 802, 804, 806, 808, 810, 812, 814, 816, 1114, 1202) relative to the fan plenum (119, 159, 308, 1155, 1204); the fan plenum (119, 159, 308, 1155, 1204) and the jet plenum (103, 104, 178, 302, 242, 782, 784, 786, 788, 802, 804, 806, 808, 810, 812, 814, 816, 1114, 1202) each having a respective flow-transfer opening (201, 202, 1206, 1208) that overlaps the opening of the other, the respective openings (201, 202, 1206, 1208) being shaped and arranged to remain overlapped in all positions to which the jet plenum (103, 104, 178, 302, 242, 782, 784, 786, 788, 802, 804, 806, 808, 810, 812, 814, 816, 1114, 1202) is moved relative to the fan plenum (119, 159, 308, 1155, 1204) such that an interior of the fan plenum (119, 159, 308, 1155, 1204) and the jet plenum (103, 104, 178, 302, 242, 782, 784, 786, 788, 802, 804, 806, 808, 810, 812, 814, 816, 1114, 1202) remain in fluid communication to allow air to flow from the fan (118, 168, 304) to the jet plenum (103, 104, 178, 302, 242, 782, 784, 786, 788, 802, 804, 806, 808, 810, 812, 814, 816, 1114, 1202) to the one or more jet openings (139, 1118) and form the planar jet (141, 185, 323) through the one or more jet openings (139, 1118); and, characterized in that, the planar jet (141, 185, 323) is aimed diagonally downward toward an appliance (170, 172, 3302) positioned underneath the exhaust device (116A, 116B, 262, 264, 266, 610, 612, 614, 616, 372, 374, 376, 378, 600, 972, 974, 976, 978, 1116); an exhaust intake (315, 382, 384, 386, 388, 1140, 1280) below the jet plenum (103, 104, 178, 302, 242, 782, 784, 786, 788, 802, 804, 806, 808, 810, 812, 814, 816, 1114, 1202) exhausting fumes through the exhaust intake (315, 382, 384, 386, 388, 1140, 1280),and the fan (118, 168, 304) having an intake at a top of the fan plenum (119, 159, 308, 1155, 1204) which is covered by a louvered grill (306, 240) of the jet plenum (103, 104, 178, 302, 242, 782, 784, 786, 788, 802, 804, 806, 808, 810, 812, 814, 816, 1114, 1202) when the jet plenum (103, 104, 178, 302, 242, 782, 784, 786, 788, 802, 804, 806, 808, 810, 812, 814, 816, 1114, 1202) is in a fully retracted position, thereby permitting air to flow into the intake.