"Jim Redelfs" wrote in message
...
Imagine all the added elbow room if the adjoining water heater was GONE
during
a furnace retrofit. Well, that's what I'm going to be doing (See Downsize
Water Heater ) in
a
little less than two weeks.

I didn't comment on the WH thread, but again, look at resale. If you go
back with a tank type unit and you'll be selling soon, will the smaller one
fill the whirlpool tub for the new owner? For the 20-25 dollars difference
between the 40 and the 50, I'd go with the fifty. I have seen home
inspection reports that comment on the size of the WH not being enough to
fill the tub.

My contractor wants to DOWNSIZE to 75k from the 100k size of my
14-year-old,
conventional (spec) gas furnace. Of course, this will be done with a "90"
(or
better) model. He claims that the improved efficiency of the new furnace
will
compensate for the difference. Do you agree?

Yes and no.

He also mentioned, after taking measurements TWICE, that I need an
18-inch-frame unit and that a bigger unit would require a reducing "boot",
which he represents as a compromise. What's with that?

Simply called a transition. Furnaces come in 3 basic widths, 21", 17" and
14".

Then there's the PVC vent(s) outside. He claims that it is legit to use
only
ONE - an exhaust line - that the furnace uses INTERIOR air for combustion.
He
represents this as a DESIRABLE way to EXCHANGE interior air with fresh.

That depends. I use OA for any 90% furnace that is in living space
(basement or closet installation). Some attics get it, but very few
crawlspaces.

I am old enough that this furnace may well be part a big part of the
resale
value of our home. He wants to install a "Weathermaker" furnace and a
Rheem
ac condensing unit outside. He says that the Weathermaker FURNACE is
virtually the same unit as a Rheem so this would be an up-front
cost-saving
issue ONLY, assuming he's right. What about resale then?

Most people out there look at the age of the furnace, not the brand. The
one concern would be a matched system to get the proper efficiency for the
AC.

He further says that the condensing units are different and therefore,
recommends a Rheem unit outside.

As long as it's a ARI match, that's fine. Rheem has scroll compressors and
WK still uses recips. Scrolls will last longer.