I'm currently shopping for a new furnace. I'm replacing an 80% (or
less) efficient standard furnace from 1991. I've had 3 quotes so far,
and the last one really threw me for a loop. The first two quotes were
from "national" companies, one affiliated with Trane, the other with
Lennox. The third was from a local HVAC shop.

The first two suggested that a 90% efficient 2-stage variable speed
furnace would solve some of my perceived problems with the
heating/cooling in my house (short cycling, difficult to cool converted
attic). After listening to their advice and the "facts" about how I can
save hundreds from my gas/electric bill, and that the system would pay
for itself in ~5 years, I started to feel comfortable with the idea of
plunking down $4500+ for a new furnace (with all the extras).

The third estimate was from the small local shop that exists on
word-of-mouth business. The sales/service tech laughed when I told him
he was the first guy to not try to sell me their top-of-the-line
furnace. He suggested a Carrier (actually Payne) standard 90% efficient
furnace. He was the only one to stick his hand in the blower and pull
out handfulls of dust, explaining that the previous owners didn't
service their furnace and that likely my evap coils were caked in gunk,
preventing air flow and reducing the effectiveness (and efficiency) of
my furnace. He thought that poor maintainance (and a furnace that was
too large) was likely the root of my problems. He also suggested that
it would be unlikely that I could get back as much of my intital cost
on a higher end furnace with just savings in gas and electricity. His
suggestion was to use the money I would save up front and put a
down-payment on some new windows if I wanted to really save
heating/cooling costs.

My home is from the 1950's with original windows and poor-fitting
hanging storm windows, approximately 2000 square feet. I live in the
suburbs of Chicago, so I probably run my furnace 4 months/year and run
the AC 2-3 months/year.

Does anyone have any thoughts on the real value of standard, 2-stage,
or 2-stage variable furnaces in older homes with less-than-perfect
insulation and windows? I was going to post this to alt.hvac but I
figured I would get redirected here anyways. I know some of those folks
read both groups.

pipco