Section 431.77 - Energy conservation standards and their effective dates(a)Gas-fired commercial warm air furnaces. Each gas-fired commercial warm air furnace must meet the following energy efficiency standard levels: (1) For gas-fired commercial warm air furnaces manufactured starting on January 1, 1994, until January 1, 2023, the TE at the maximum rated capacity (rated maximum input) must be not less than 80 percent; and(2) For gas-fired commercial warm air furnaces manufactured starting on January 1, 2023, the TE at the maximum rated capacity (rated maximum input) must be not less than 81 percent.(b)Oil-fired commercial warm air furnaces. Each oil-fired commercial warm air furnace must meet the following energy efficiency standard levels:(1) For oil-fired commercial warm air furnaces manufactured starting on January 1, 1994, until January 1, 2023, the TE at the maximum rated capacity (rated maximum input) must be not less than 81 percent; and(2) For oil-fired commercial warm air furnaces manufactured starting on January 1, 2023, the TE at the maximum rated capacity (rated maximum input) must be not less than 82 percent. 81 FR 2528 , Jan. 15, 2016