Vapor generator

A bottom supported vapor generating unit comprising walls forming a setting containing pressure parts including horizontally extending upper and lower drums, at least one bank of upwardly oriented tubes connected at their opposite ends to said drums, some of the walls including upright tubes forming sides of a furnace chamber, said upright tubes being connected at their opposite ends to horizontally extending upper and lower headers, the lower headers being disposed substantially below said lower drum, and means for bottom supporting the lower drum including rigid upright columns at spaced positions along the length thereof, said bottom support means constituting the normal support means for substantially all of the weight of said drums and tube banks, and means for bottom supporting at least some of the lower headers including resilient means at spaced positions along the length thereof, said last named bottom support means constituting the normal support means for substantially all of the weight of said upper and lower headers and upright tubes.