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
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.
I think your local guy gave you honest and correct advice. As much as
I'm in favor of high efficiency appliences etc, if your windows are
that old and leaky, that would be the place to start. In fact, I would
put that ahead of replacing your current furnace- it may just need
good maintenance and could last a few more years, but suit yourself as
far as that goes and listen to the advice of this guy who looked at it.
If it is too large, it will tend to short cycle, more so as you plug
leaks/ improve insulation.
I'm replacing it because it has 2 cracked heat exchangers. This was
discovered when a repairman was out to replace the igniter that had
gone out. He ordered us not to run the furnace, but it's cold! I'm
aware of the risks and have a working CO monitor in the house. Even if
I could replace the heat exchangers under warranty (which I can't) I
feel that this is a sign of things to come, so the furnace must be
Are you crazy? CO monitors have been known to fail. If you don't wake up one
morning, will you have enough life insurance to take care of your family? If
one of your family members doesn't wake up, will you be able to live with
the guilt? Turn the damn thing off and get some supplemental heat. That
local contractor can probably have a new heater and (unconnected)
refrigerant coil installed within days of you signing the contract.
No, I don't think I'm crazy. Just realistic. I've done some research
and I don't believe that there are any notable cases of a CO death
based on a cracked heat exchanger. Usually it's something else that has
gone wrong with the furnace. I will be replacing it within a few days.
Like I said, I'm aware of the risks... Okay, maybe I am crazy.
I guess you must be extremely lucky, and nothing bad has ever happened to
you. It's not realistic to think that because the odds are low, it won't
Each year, according to CPSC, there are more than 200 carbon monoxide deaths
related to the use of all types of combustion appliances in the home.
Exposure to carbon monoxide reduces the blood's ability to carry oxygen.
Often a person or an entire family may not recognize that carbon monoxide is
poisoning them. The chemical is odorless and some of the symptoms are
similar to common illnesses. This is particularly dangerous because carbon
monoxide's deadly effects will not be recognized until it is too late to
take action against them.
Carbon monoxide exposures especially affect unborn babies, infants, and
people with anemia or a history of heart disease. Breathing low levels of
the chemical can cause fatigue and increase chest pain in people with
chronic heart disease. Breathing higher levels of carbon monoxide causes
symptoms such as headaches, dizziness, and weakness in healthy people.
Carbon monoxide also causes sleepiness, nausea, vomiting, confusion, and
disorientation. At very high levels it causes loss of consciousness and
About Combustion Gases/Carbon Monoxide
Every year about 500 people die in their homes from carbon monoxide
poisoning. In some cases an entire family dies from this completely
preventable death. What is carbon monoxide? It is a poisonous gas that
interferes with blood's ability to carry oxygen. Carbon monoxide is produced
when a fuel is burned, such as natural gas, propane, fuel oil, wood,
charcoal, and gasoline. In furnaces, boilers, water heaters, wood stoves,
and fireplaces, carbon monoxide and other products of combustion are vented
to the outside through the chimney.
The "national" companies hire contractors to do the installs. You're paying
the overhead and profit for two companies, plus a salesman's commission.
Every appliance is required to have a sticker saying how much it will cost
on average to run. Compare a two stage vs. a standard 90+ furnace, and you
may find that the added cost is not worth the payback. Also remember that
two stage furnaces have a higher frequency of repair rate.
The tech from the small shop was telling you straight. They want your
business, but are not willing to lie to get it. Payne is a good brand. Go
with the highest efficiency air conditioner you can get, as long as it isn't
Puron (R-410A). Right now, my Payne wholesaler only has 12seer units. In the
spring, they'll get 13seer units. Go with the local guy and put the savings
into windows and doors.
I thought all AC units now used R-410A (Carrier calls it Puron). A Trane
dealer told me that Trane was also using R-410A. He also said that both
Trane and Carrier were experiencing leakage problems because of higher
I know for a fact that Rheem/Ruud and Payne still make R-22 units. If they
think R-410A leaks are a problem, wait until untrained techs start trying to
add refrigerant the same way they've been adding R-22.
There is a U. S. Federal tax credit in force for 2006 for buying at a
certain level of efficiency. It is a little quirky with the standards
so I could not get it because I needed a packaged unit and none met
the standards. However you should check into it, it may sway you
toward the higher efficiency unit.
Interesting. According to http://www.house.gov/jct/x-60-05.pdf (page 82
of the pdf) a qualifying furnace (for the $150 tax break) has to be 95%
"A qualified natural gas, propane, or oil furnace or hot water boiler
is a natural gas,
propane, or oil furnace or hot water boiler with an annual fuel
utilization efficiency rate of at
Now, Trane's top of the line Varaible 2-Stage furnace is 93% AFUE...
so, I'm not really sure if that is a realistic tax break right now for
current furnace technology. I don't know about water heaters. Who
knows, maybe there is someone out there that can benefit from this tax
Thanks for the idea though!
I think the answer to the question of 80% vs 90% is based on info you
should have. Take your last gas bills from a full winter and see how
much you spent on gas. Or better, see how much more you are spending
this year with rates higher and factor that in. Come up with an
estimate of how much you will use per year going forward. Then take
11% of that number. That is about how much you will save with 90% vs
80%. You current furnace may be even less efficient, so you may save
more, but it's a starting point. Now you can figure how many years
it will take to recover the higher cost. In Chicago I think the
coclusion you will come to is that 90% does make sense, provided you
intend to live in that house for a reasonable period.
I also doubt that the cooling problem in an upstairs location is going
to be solved by a new furnace. This is typically a problem with poor
air flow to that area, either supply ducts, returns or both. Did any
of the contractors bother to carefully examine that? That problem can
be very difficult to solve if there is no easy way to add bigger/more
ducts. Did they do a load calc to figure out the correct furnace size?
Thanks. I'm planning on getting a 90% efficient furnace. My real
question was about 2-stage and variable speed furnaces. Although the
more I read about it, I don't think the varaible speed furnace is the
silver bullet to my problems, especially with the age of my house and
less-than-perfect insulation/windows. I'll probably just go with a
No one has done a load calc yet. They all say that before installing
they will do a load-calc to ensure the correct size, although everyone
has suggested 80,000 btu.
Load calculations sound real nice, and make a good impression. In reality,
the new equipment (and it's air flow) must match your existing duct work.
BTW, In my state there's a 3 day "cooling off period" in which consumers can
change their mind. This can be waived by the consumer in an emergency.
I agree that insulation is important, but do a heat loss on an average older
home. Then change the R-value of the attic. Then go back and change the
infiltration value. I think you'll see why windows can be a better
I don't think so. And sixteen might not have done it. In my case I
was willing to pay the extra for a sixteen (which would have made it
for an air conditioner) but a packaged heat pump had to have a HSPH if
It does not exist.
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