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Natural Gas Fuel (37.3 MJ/cubic meter) (1000 Btu/cubic foot): 78 percent at 15 percent excess air or 80 percent at 5 percent excess air. Fuel Oil (ASTM D396 Grade 2, 4, 5, or 6): 83 percent at 15 percent excess air or 81.5 percent at 5 percent excess air. ................
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