Hi. Getting bids for a new gas furnace in the house (don't need AC).
We got a couple bids, and they all gave them for the 80% efficient
furnaces, not the 90%+ efficient ones. They said that we wouldn't
recoup the cost of the more efficient one through utility savings <over
the lifetime of the unit>, and that the 80% efficient one has very few
moving parts, and thus has less need for repair and maintenance, whereas
the high efficiency ones (some claim >97%) are far more complicated, and
thus more susceptible to breakages/misalignments/etc. Furnace brands
were Bryant and Trane.
Can anybody speak to any of these issues, or share about their decision
in a similar situation? Also, the local gas company offers a $200
rebate and a $350 tax credit to get a >90% efficient unit.
Willamette Valley, Oregon. AC is not an issue, *very* rare around here.
Our days peak at about 90 degrees F, with an occasional day (1 or 2
per summer) of ~100 degrees F. Low humidity. It cools down to about
55deg at night, and the house stays cool during the day. So, no, AC not
Joseph Meehan wrote:
What you're talking about is a "condensing furnace". It has an extra
stage in the heating process. I read somewhere that even if the unit is
well made, it can still be a problem, because a lot of HVAC techs don't
know how to work on these units and they might screw it up.
The cold air from intake goes through a first heat exchanger that
exchanges heat with furnace vent which condenses the water out of
combustion waste. The pre-warmed air enters a second heat exchanger
which exchanges heat with the combustion.
The first stage heat exchanger takes an advantage of latent heat of
water. Not surprisingly, this process makes liquid water which needs to
be drained out just like air conditioning drain.
Condensing furnaces cool the exhaust gas to the point where the steam
condenses to liquid water.
Requires a drain -- to drain off the water. Which is often corrosive by this
Needs also venting and air intake through PVC tubes, instead of through the
steel flue pipe you presently have. It's doable, I know... I've helped
install a bunch of them.
The rebate sounds like a good clincher to encourage to go with the 90 plus
This is Turtle.
If you live in Oregon the 90%+ AFUE will pay for it'self if the installer don't
kill you on the installation cost.
If you live in the Southern states where you don't use much heat. The 90%+ AFUE
will usely not pay for it'self.
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com ).
90+ will pay back how quickly depends on what you pay, what are your
costs to heat.
The 96.7 % Carrier -Bryant is limited to one 38000 btu model of their
line up the smallest one of course, kind of a bait BS deal . The
higher btu models are apx 94.5% There is a formula I forgot it , but
the savings of a 82 vs 94.5 are greater than 12.5% , more like 14% . If
you have a significant heating season go for the highest % efficiency
and get the 10yr warranty, as gas goes up your payback time will go
down. The trend is up. The VS DC motors will give additional
electric savings you should consider, yes when they break they cost more
to fix, so get the 10 yr warranty . Also VS DC can give better comfort
by running on a lower speed continuosly and with AC can run a
dehumidistat with aproximatly double the moisture removal. Get a load
calc done first , you may be oversized.
The 90+% efficient furnaces are condensing units as noted in another post.
Which means a pump and a way to get rid of the resulting water. However,
another big difference is that the 90+% combustion air comes from the
outside and then is subsequently discharged to the outside, both through 4
in. PVC piping. Built into the cost savings is the cost of using air
that you have already paid to heat (from within the house) for combustion
purposes (80% unit)? More uneven heat, more drafts as the air being sent up
the chimney has to be replaced by outside air. You could do the arithmetic
relative to the cost and considering the escalating cost of gas your payback
time frame may be shorter than you think. Check into your Utility company,
they often offer significant rebates for the more efficient furnaces with
the variable speed motors. I got a $450 rebate which was almost half the
cost difference between the two furnaces--and then I would estimate that I
saved approx $150 this winter in gas costs.
Installers prefer to install what they know, and most installers don't know
very much. Thy make mony by installing the same thing over and over, even
if it is outdated---the customer usually doesn't know any better and they
can do it with their eyes closed.
If they tell you not to get a condensing furnace, don't get a condensing
furnace from them. Find someone who knows condensing furnaces. They are
prefectly reliable now---they used to have problems when they first came
out 15+ years ago.
I no longer even install 80% units. The 90%+ are much more reliable than the
units of only 4 years ago, and installed correctly, they will last as long
If the installing company isnt wanting to sell you one, that means they are
not familiar with them, and dont realize that they are doing you no favors
with the 80%.
If you dont need AC, you must be in a more northern clime, where you WILL be
using your furnace more. The 90% unit can indeed pay for itself...
I have been installing Carrier High Efficiency furnaces for about 6
years now, and i keep going back to previouse clients, not to repair
or replace, but to ask about the savings, and keeping a mental note
for myself for future customers. And the response is overwhelming,
THEY SAVE MONEY, BIG TIME. As for the company that won't get into
90%+, he's right, they probly don't like the extra work involved in
running new vent, fixing HWT Venting, Running drain lines and setting
up the control board to work properly with existing equipment, or even
running new stat wire and T-stat to properly control the new
equipment, so they stick to what is EASY. Sad , these new furnaces
are awsome. But do get the 10 year warrenty as there are some small
and expensive parts that like anything else out there, can go bad. I
just bought a house, and one of the selling features was that it had
new furnace, A/C , and HWT.
The first thing i did when i moved in, was throw out the 2 year old
lenox 80%, and drop in a Carrier MVP High efficiency Furnace, It is
1/2 as loud, 14%+- more efficient, and as a bonus Carrier/Bryant carry
a nice warranty as well as parts being easy and cheap to find, unlike
Lenox who have a tendency to make their own parts, and are very
difficult to work on.
Hope this helps....
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