I am getting a new central A/C unit that has seen better days. It's 15+
years old, and it finally died. I was told they have to replace something
above the furnace (the condesor?). While they are here working on my
furnace, should I just get a new furnace too??
I have a Lennox furnace that is still working, but it's 9+ years old.
Manufactured in early1993.
Of course, they are offering me a package deal to also replace the furnace
if I want. Initially I said no, but I have no idea the average life
expectancy of an average furnace. If they only last 12 years (on average),
I hate to have them back out in a year or so.
Looking for advice for anyone that was in my situation.......
I am no expert but in my experience, a furnace will last much more than 10
or 12 years, and that is in a cold climate where it gets lots of use.
At the very least, I would get another heating contractor to come by and see
what he recommends, why and at what price. Even if he charges you a service
call for doing so. A second opinion is worth it for the peace of mind that
you are not being cheated by the first contractor. If the first contractor
objects strenuously to you getting a second opinion, I think that tells you
You might want to post your message in alt.hvac
You don't say if your furnance is liquid or gas fueled.
If the former, a furance of this vintage would be classified as a
'Pot-burner' and is considered to be very low efficiency.
In '69 I purchased a old house with a cast iron oil furnace. Used it for one
winter and found it to complicated to light for my wife, when I was away
from home for the beginning of the heating season.. She has to have the
serviceman come and that cost about $20..
The second season I installed a modern fuel oil furnace with all automatic
controls. Not only was it easier to operate (never had to light it), but it
was WAY MORE cost efficient. Since I did the installation myself, I only had
the cost of the furnace. I think I had the new furnace paid for in fuel
savings with in 3 years (when I sold the house).
I assume you're talking to me.
we've had this house for 2 winters already, this is the third. it burns a
lot of fuel, but the house has poor insulation (50 years ago they had no
insulation in the walls) and our consumption is similar to other people's.
I don't understand what you mean by "hard to light"
it lights itself. we have a thermostat that controls the burner. we don't
what do you consider as part of the furnace? the tank is cast iron and 50
years old, but the burner is not that old.
50% or 60% maybe? Seen a few old oil units that MIGHT make it to the 50%
range...and have seen more than one Chrysler Airtemp gas unit that was
feeling frisky if it saw 65%....
With AFUE ratings, its simple..
Figure, just on fuel, that if you have a 60% unit, 60 cents of the heat
generated, goes into the home, with 40 cents going off to heat the world...
now, with a 95% unit, only 5 cents goes away...not including the savings on
more energy friendly motors and controls.
If H is the amount of heat needed in a given situation, for example, to
heat your house this Winter:
Let x = the amount of fuel it takes to produce H by a 50% efficient
y = the amount of fuel it takes to produce H by a 90% efficient
.50x = .90y
So, y = (5/9)x = .56x
In other words, a 90% efficient furnace uses only 56% of the fuel used
by a 50% efficient furnace to produce the same amount of heat. So, a 90%
efficient furnace (THEORETICALLY) should save 44% in fuel. However, I
BTW, we live in the Midwest (COLD winters) and have a 25 year-old Amana
Air Command that is going strong and will not be replaced until it dies
or develops serious probs. The folks (a family business which has been
around for 3 generations) who maintain it, and who will be doing the
installation of the new one which replaces it, agree.
Give or take your situation, and usage, between 55%% to 62% less..Installed
correctly, depending on your fuel costs not, it could, theoretically, have a
Altho, I dont sell on the payback theory, since you have to pay to get it
installed, and it does cost every time you turn it on.
90% vs 50 = 40% savings, . One gas one is 96.6% , many are 94 and 95%.
And a variable speed blower may save 75% on your old units blower KWH
cost. Not knowing how much it runs It cant be figured , but it could
easily save 15$ a month in electric costs and boost SEER for central
air by 1 seer. Plus not pullng inside air for combustion helps. Your
unit wasnt designed for efficency. Nothing was then.
Both. Todays furnace isnt the one that you had when you grew up...(well..for
some it might still be..LOL) but seriously, huge design changes, computer
controls, secondary heat exchangers, better blowers...it all adds up.
In my opinion the only thing your going to gain from a new furnace it a bit
more sophisticated combustion controls and a new warrantee.. You may also
benefit from the fact that if something doesn't work properly on the totally
new installation, your installer and the OEM are totally responsible,
Selling you a new furnace just increases the AC installers profit margin and
simplifies his installation a bit..
But to answer your question, I would say 20 years is the outside limit on a
furnace.. There are a few elements in the combustion chamber that can burn
out but these can be replaced. Combustion controls have go to electronic,
but the old electrical stuff has worked fine for a long period and could be
depended on into the future or that could be up dated in an older unit.
The only time I would recommend upgrading is when someone has a furnace that
dates back to the 50s where fuel was very cheap and efficiency was not a
factor in the design. Anything from the late '70s on will be built with a
much higher efficiency and reliability.
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