m Ransley wrote:
Trader, I just posted the question of % difference at "The Wall" a
place of heating pros, I respect your point but believe in what I said
for the present. Stop by there it should be interesting.


Here's another way of looking at it. You put $100 of gas in, with 80%
efficiency, you get $80 worth of useful heat out. According to
Lennox, by going from 80 to 94.5, you save (94.5-80)/80, or 18.1% in
fuel cost. If that's true, then we can buy 18.1% less fuel, which is
$81.90. Take $81.90 and put it into the 94.5 furnace and we get
81.9x.945, or $77.40 worth of heat out, which is less than the original
80.

However, if you take 15.4% off the $100, you get $84.6 and put that
through 94.5, you get 94.5*84.6, which is $80

What Lennox is doing is just taking the differences in percent
efficiencies, which is mathematically incorrect. But it does give a
higher figure, which I'm sure they like