Air heater with a plurality of tubes positioned coaxially within one another

Claim 1

IN AN AIR HEATER HAVING AN OUTER CASING AND A GENERALLY CYLINDRICAL COMBUSTION CHAMBER FOR BURNING FUEL THEREIN, THE IMPROVEMENT COMPRISING AN AIR INLET AND AN AIR OUTLET OF SAID CASING, A PLURALITY OF SPACED APART SHELLS DISPOSED SUBSTANTIALLY COAXIALLY OF SAID COMBUSTION CHAMBER AND OF EACH OTHER, THE INNERMOST OF SAID SHELLS BEING CLOSED AT ITS UPPER END BY AN END WALL AND FORMING SAID COMBUSTION CHAMBER, THE OUTERMOST OF SAID SHELLS DEFINING ON ONE SIDE THEREOF WITH THE INTERIOR WALL OF SAID CASING A FIRST PORTION OF AN AIR PASSAGEWAY FOR FLOW THERETHROUGH OF AIR TO BE WARMED AND DEFINING ON THE OTHER SIDE THEREOF WITH THE NEXT MOST OUTER SHELL A PORTION OF A GAS PASSAGEWAY FOR FLOW OF PRODUCTS OF COMBUSTION THERETHROUGH, END MEANS CLOSING THE SPACE BETWEEN BOTH ENDS OF SAID OUTERMOST SHELL AND SAID CASING, SAID AIR INLET HAVING AN OPENING INTO SAID FIRST PORTION OF SAID AIR PASSAGEWAY, SAID NEXT MOST OUTER SHELL AND SAID INNERMOST SHELL TERMINATING SHORT OF THE BOTTOM OF SAID HEATER AND HAVING AN END WALL MEMBER JOINED TO THE LOWER ENDS THEREOF AND CLOSING THE SPACE THEREBETWEEN TO FORM A SECOND PORTION OF SAID AIR PASSAGEWAY, DUCT MEANS CONNECTING SAID FIRST AND SECOND PORTIONS OF SAID AIR PASSAGEWAY FOR FLOW OF AIR THERETHROUGH, SAID GAS PASSAGEWAY HAVING A CONNECTION WITH SAID COMBUSTION CHAMBER AND EXHAUST, SAID CASING HAVING AN UPPER PORTION AND A LOWER PORTION, MEANS FOR REMOVABLY SUPPORTING SAID UPPER PORTION OF SAID CASING UPON AID LOWER PORTION WHEREBY SAID UPPER PORTION IS LIFTABLE SUBSTANTIALLY VERTICALLY FROM SAID LOWER PORTION, A FIRST PART OF SAID SHELLS BEING MOUNTED IN SUSPENSION BY AND DEPENDING FROM SAID UPPER PORTION OF SAID CASING AND A SECOND PART OF SAID SHELLS BEING MOUNTED BY SAID LOWER PORTION OF SAID CASING, SAID LOWER PORTION OF SAID CASING INCLUDING A FLAME ENTRY PORT EXTENDING THERETHROUGH INTO SAID COMBUSTION CHAMBER.