On Thursday, June 19, 2014 3:46:31 PM UTC-4, philo* wrote:
I have a 21 year old 80,000 BTU 80% efficiency gas furnace than I'm

looking to replace this year or possibly next. House is 1900 sq ft.

The only repair it's needed was an igniter.



Present ductwork and insulation is fine. I am getting new electric

service in a few weeks.



I am looking for a ballpark figure on what I should expect a contractor

to charge to replace the unit with a high-efficiency type...plus add

central air.



The existing ducting was designed for heating only. If you're lucky,
it may be adequate for AC too, which it is in many cases. Could be a
problem though if for example it's 2 stories, with the furnace in
basement. Heat rises, so old system might not have enough air capacity
to get enough cold air upstairs to cool properly. Sometimes some simple
things, like adding another return or two upstairs can fix that.

The quotes that were reasonable here in NJ to do a replacement
of furnace and existing AC from a couple years ago were in the
6500 - 7500 range. That was before rebates, tax credits, etc. I got
some that were a lot higher too. System was 120K BTU 94%, 2 stage furnace,
5 ton 14 SEER AC.

If you have a gas WH on the existing chimney, then you should have
a liner installed. Make sure that's part of the quote.



I live in Milwaukee and it only occasionally gets up to 100 F...

but we can get up to a week of sold 90+ degree weather.





What is a good, reliable brand?

I went with Rheem. Rheem is the same company that makes Ruud.
The old system was Ruud, 25 years old, only thing I ever had
a problem with is I had to put a hard-start kit on the compressor
because it was blowing fuses. I think that cost me $100 or so
and it worked for another 15 years. Had the Rheem 3 years and
very happy with it. 94% furnace, variable speed blower, 14 SEER
AC. I was a little skeptical about the ECM blower, they are
electronic and more costly to replace. But I like it. When the
old system came on, you knew it. The new one, the blower ramps
slowly and it's much quieter, less noticeable.

Another thing to consider is where you want the AC compressor.
Just before install, it suddenly dawned on me that the old one
was in the wrong place. It was right between the living room
and den, in the backyard. I realized that with just a little more
lineset, it could go on the end of the house, where it's totally
out of the way and by a bathroom. It was an easy move because
it was also right near the electric panel.

I would definitely get a two stage furnace too. Little difference
in price. With two stage, it fires at about 65% of capacity most
of the time, ie when maintaining the temperature. If the temp
has been set back, you increase it, etc, then it fires at full output.
It's also good for days when only a little heat is needed as it
runs a bit longer, giving time for the temp to even out.

I didn't get a 2 stage AC, but that's worth considering too. It
uses the lower output on mild days, allowing it to run longer and
get more of the humidity out. When you have only one output, it can
cool the house off before getting as much of the humidity out as
you might want. I finally opted against it, because it was a big
jump in price and for me it hasn't been much of an issue.

Make sure with the 2 stage furnace that the contract calls for a
2 stage thermostat. With that, the thermostat that knows what the
target temp and the actual temp are makes the decision on which output
level to call for. These furnaces can also work with a dumb single
stage furnace. In that case, the furnace makes the decision. It
starts at low stage and if after like 8 mins, it's still running,
then it goes to high. So, if you have the house at 60 and want
to get it to 70, you're wasting 8 mins running on low, where with
a 2 stage thermostat it would be running at high from the first
minute.

Also, consider what type of filtering system you want. I think it
comes down to two choices, a high MERV filter that is like 5 inches
thick or an electronic. I chose the MERV. Without an external filter
in the contract, you'll wind up with just one of the 1" crap ones
and no easy way to upgrade it.

Keep in mind that I'd rather have a good installer with the least
expensive eqpt than a crappy installer with the best eqpt. Actually,
when I lookd few years ago at CR, there was very little difference
in the service rates among brands. Some have better warranties and
you should check out that too.