My 3 yr old Lennox furnace g32 q375 is rated 93% Afue, but at 75000 input 68850 out that is 91.8% efficient not 93% Afue advertised. An Armstrong Ultra enhanced 95v g2d95au060v14b is Afue 94.5% . But at
60000 in 57000 out that is 95% efficient.The Lennox is an AC blower motor, Armstrong a more efficient DC blower motor , if this was a part of the calculation of Afue the Lennox would be even lower and Armstrong even higher, what gives on Afue, yes 1 % or
2 is important in calculating future costs and what is best.