Combined intake and exhaust mechanism for heating unit

Claim 1

IN A HEATING UNIT COMPRISING A HOUSING HAVING A GENERALLY VERTICAL EXTERIOR WALL, A COMBUSTION CHAMBER IN SAID HOUSING, A COMBUSTION AIR INLET IN SAID WALL COMMUNICATING WITH SAID CHAMBER, MEANS FOR EXHAUSTING THE GAS OF COMBUSTION FROM SAID CHAMBER, THE LAST MENTIONED MEANS COMPRISING A COMBUSTION GAS PASSAGEWAY FROM SAID CHAMBER TOWARD SAID WALL TO SUBSTANTIALLY THE SAME LOCATION ON SAID WALL AS SAID AIR INLET, BLOWER MEANS FOR CAUSING CIRCULATION OF COMBUSTION AIR THROUGH SAID AIR INLET TO THE COMBUSTION CHAMBER AND CIRCULATION OF THE GAS OF COMBUSTION OUT SAID COMBUSTION GAS PASSAGEWAY TO THE EXTERIOR OF SAID HOUSING, SAID PASSAGEWAY INCLUDING A DUCT TERMINATING ADJACENT THE EXTERIOR OF SAID WALL AT SAID AIR INLET, AND MEANS AT SAID LOCATION FOR MAINTAINING SEPARATE THE INLET AIR FROM THE EXHAUST COMBUSTION GAS DURING INGRESS AND EGRESS OF RESPECTIVELY SAID AIR AND COMBUSTION GAS, THE LAST MENTIONED MEANS COMPRISING A SHIELD-LIKE MEMBER SECURED TO THE EXTERIOR OF SAID HOUSING AT SAID LOCATION AND ENCOMPASSING SAID AIR INLET AND THE EXIT END OF SAID DUCT, SAID MEMBER BEING ADAPTED FOR EXPOSURE TO THE ATMOSPHERE, SAID MEMBER COMPRISING, AN ARCUATESHAPED APERTURED FRONT WALL AND GENERALLY VERTICALLY ORIENTED LATERALLY SPACED SIDE WALLS CONNECTED TO SAID FRONT WALL, IMPERFORATE MEANS EXTENDING BETWEEN SAID FRONT AND SIDE WALLS AND DIVIDING THE INTERIOR OF SAID MEMBER INTO AN UPPER EXHAUST SECTION AND A LOWER AIR INTAKE SEC-