Afue ratings for real?

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.
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Try posting in alt.hvac
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Post in alt pjmhvcrac, yea right.
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This is Turtle.
What did you do to Oscar to send you off like that ?
TURTLE
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This is Turtle.
You should not send people off to slaughter like that !
TURTLE
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This is Turtle.
the furnaces are rated or run to be rated at a all the same conditions like temperature, humidity, home air flow, combustion air temp., and gas and air flow to the furnace.
If you change one thing like gas pressure, temp. of conbuston air, Ability of the natural gas your burning, altitude your in, or the change of the temperature of any of the above. Your AFUE rating will change a great amount in the better or worst rating or condition.
So the Rating is just a good guess as to it will be in use but does rate it in one condition only to try to conpair.
TURTLE
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So Turtle are you saying screw afue check btus
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