Terraced heaters

Claim 1

A HEATER COMPRISING A HOUSING WHICH INCLUDES A FLOOR AND A PAIR OF LONGITUDINALLY EXTENDING SIDE WALLS OPPOSITELY DISPOSED RELATIVE EACH OTHER AND SPACE APART TO EMBRACE A CHAMBER IN THE HOUSING; EACH SIDE WALL COMPRISING A PLURALITY OF ADJAENT PLANAR SURFACES ONE ABOVE THE OTHER, EACH PLANAR SURFACE HAVING A BOTTOM AND TOP EXTREMITY AND BEING UNINTERRUPTED BY ANY PROJECTIONS INTERMEDIATE THE ENDS; REFRACTORY FACING ON THE PLANAR SURFACES ON THE CHAMBER SIDE THEREOF; STEP MEANS ALONG THE BOTTOM EXTREMITY OF EAC PLANAR SURFACE PROTRUDING INWARDLY FROM THE PLANAR SURFACE, THE STEP MEANS DEFINING A PLURALITY OF ELONGATED ADJACENT TROUGHS PARALLEL WITH THE PLANAR SURFACE, THE TROUGHS OCCUPYINGT A MAJOR PORTION OF THE LENGTH OF THE STEP AND BEING ALIGNED AND APPROXIMATELY COEXTENSIVE WITH THE SURFACE; BURNER MEANS DISPOSED TO INJECT FLAME INTO EACH TROUGH TO SUBSTANTIALLY FILL THE TROUGH, COMBUSTION BEING SUBSTANTIALLY COMPLETED IN THE TROUGH, SO THAT HOT COMBUSTION GASES PASS IN SWEEPING RELATIONSHIP OVER SUBSTANTIALLY THE ENTIRE AREA OF EACH OF THE PLANAR SURFACES FOR UNIFORMLY HEATING THE REFRACTORY THEREOF TO INCANDESCENCE; A PLURALITY OF VERTRICALLY EXTENDING TUBES MOUNTED APPROXIMATELY MIDWAY BETWEEN THE SIDE WALLS AND POSITIONED TO RECEIVE RADIATION FROM THE PLANAR SURFACES; EACH OF THE TROUGHS HAVING A STEEP RIM ON THE SIDE ADJACENT THE TUBES TO DIVERT THE HOT COMBUSTION GASES FROM THE TUBES; FLOW MEANS FOR COURSING A PROCESS FLUID THROUGH THE TUBES; FLUE MEANS FOR EXHAUSTING COMUBSTION PRODUCTS FORM THE CHAMBER.