Abstract: A gas burner is provided with a shaped part at its upstream end for the admission of primary air and gas, the shaped part 24 being monolithic with the burner and having openings 34, 36 for the admission of primary air from above, and is downwardly open for admission of air from below, the part receiving a primary air shutter 52 which is generally cylindrical to fit in telescoping relation upon the burner end part 24, the shutter having a lower slot 56 to accommodate the seam 18 of the burner, and the shaped part having a downwardly open saddle 38 adapting the burner upstream end to be seated on a gas spud.

Abstract: The base construction comprises base rails along each side and each end, with each of the rails having the shape in transverse cross section of an upwardly open channel with the outer leg of the channel having a height greater than the inner leg, and the inner leg having a horizontal flange projecting inwardly from along the top of the inner leg, and separate pan means forming the bottom walls for both the outdoor air flow section and the separate indoor air flow section, each including a horizontal wall and an upturned flange along each edge, the pans nesting in the frame formed by the rails, the assembly thus formed being secured together by spot welding the upturned flanges to the outer legs, and the horizontal walls of the pans along their margins to the inwardly projecting horizontal flanges of the rails.