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.......

If it 80% or less efficent and you have a long heating season, run the
numbers. to see what you will save with a 94%. Otherwise no I wouldnt

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
something.
You might want to post your message in alt.hvac

Good luck!

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,
without dispute.

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.


--
My opinion and experience. FWIW

Steve

Hi,
My 9 year old(installed in '94) Carier furnace is still working like
new. HSI was replaced 2 years ago which was only trouble I had.
Tony


Steve wrote:
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,
without dispute.

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.

A properly installed, well-maintained modern furnace should last more than
20 years. Poorly installed, neglected equipment can fail in less than 5.
With that said, your 9 +/- year-old Lennox is probably nearing it's halfway
point. How long do you plan to stay in the house? If more than ten years,
you might want to replace the furnace at the same time as your evaporator
coil to take advantage of the labor savings. In my experience (20+ years,
HVAC), Lennox equipment generally holds up well over time. But, ignition
modules and blower motor replacements are not uncommon for any piece of
equipment over ten years old, and can run several hundred bucks. Forget
about efficiency payoffs and all that nonsense. Saving $50-$75/year on
utilities will eventually offset the initial expense, but it's not a good
enough reason to rip out a working appliance. A straight furnace
replacement in 5-10 years will absolutely cost much more than the additional
cost now.

Haggle with the contractor and do some research into who is best to use in
your area. You have heat, so there's no rush. Winter months are
historically much slower than summer for most gas guys, so you have a
decided advantage timing-wise. Whatever you do, make sure you get the right
job. It makes all the difference. Good Luck.
--
C.J.

Pull my pud to reply


"Bill" wrote in message
.com...
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.......

our furnace is probably 50 years old. it's a big cast iron thing.

everyone we asked told us not to change it because new furnaces have
crappier construction.

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).


--
My opinion and experience. FWIW

Steve

"Steve" wrote in message
...
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..

I assume you're talking to me.

it's oil-burning.
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
light anything.

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.

jj Your unit is probably 50 % efficent . You could put in a 90+ . And
your blower is taking alot more KWH than the new ones.. You should
replace it.

My home is 10 yrs old the a/c started to leak this spring, I opted for a new
furnace variable speed motor, and a 16 seer heat pump/ac 2 stage combo.

The furnace should last 20 yrs, I wanted the most efficiently I could get. I
installed a Maytag 10 yrs parts and labor, on both units, best in the
industry,

Tom


"Bill" wrote in message
.com...
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.......

"Bill" wrote in message
.com...
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.......

Not exactly in your same situation, but my oil furnace is 29 years old
(Weil-McLain) and still working OK. A bit noisy, a bit smelly at times, and
the efficiency's pretty low, though. I'd wait on a 9 year old unit. We're
selling our house in about a year, and we will replace the furnace before we
go. A new Buderus or Weil-McLain Gold will set me back about $4000.

Jon E

"Bill" wrote in message
.com...
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.......



Ok..forget I am in the trade...

First thing to keep in mind...the furnace, will break. Not IF, but WHEN.
Second thing..Lennox is complete utter no longer Amercian owned garbage.
Hard to get parts, expensive parts, and in general, you can get better for
the money.

Furnaces last more than 12 years....as long as it wasnt a Lennox Pulse...
(really)

If your unit is that old, and I assume its gas, it will be more than likely,
an 80% AFUE, meaning that for every dollar in fuel you burn, 20 cents at the
least goes up the flue.
Since you are getting a new condensor(outdoor unit for the AC) and a new
evaporator (part above the furnace) does it not make sense to replace the
furnace at the same time, since the labor will be much less now, you will
get a new parts warranty, and have the benefit of knowing the systems
completely matched, and designed to work together? Look into a 94% or higher
unit. A little extra work will need to be done, like honest to God PVC
intake and exhaust flues going outside, but its well worth it long term.

"j j" wrote in message
...
our furnace is probably 50 years old. it's a big cast iron thing.

everyone we asked told us not to change it because new furnaces have
crappier construction.

Then you are asking the wrong people.
Granted, they dont make tanks anymore.

For the last time...Maytags NOT got the best warranty...
And for sure does not have the best unit.....not by a long shot.
Hyundai went to a longer warranty too...but I damn sure wasnt gonna run out
and buy one.

"tflfb" wrote in message
...
My home is 10 yrs old the a/c started to leak this spring, I opted for a
new
furnace variable speed motor, and a 16 seer heat pump/ac 2 stage combo.

The furnace should last 20 yrs, I wanted the most efficiently I could get.
I
installed a Maytag 10 yrs parts and labor, on both units, best in the
industry,

Tom


"Bill" wrote in message
.com...
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.......

CBHvac wrote:

"j j" wrote in message
...

our furnace is probably 50 years old. it's a big cast iron thing.

everyone we asked told us not to change it because new furnaces have
crappier construction.


Then you are asking the wrong people.
Granted, they dont make tanks anymore.

Hi,
Big cast iron thingy alright but at what efficiency? Maybe your dollar
is going up the chimney more than heating your house.
How about doing some cost anaysis?
Tony

"Tony Hwang" wrote in message
news:XSVub.437257$pl3.49018@pd7tw3no...


CBHvac wrote:

"j j" wrote in message
...

our furnace is probably 50 years old. it's a big cast iron thing.

everyone we asked told us not to change it because new furnaces have
crappier construction.


Then you are asking the wrong people.
Granted, they dont make tanks anymore.

Hi,
Big cast iron thingy alright but at what efficiency?

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%....

Maybe your dollar
is going up the chimney more than heating your house.

Bingo...

How about doing some cost anaysis?

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.

Tony

http://www.hvacware.com/user-cgi/hvaconfig.pl

"Bill" wrote in message
.com...
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.......

"CBHvac" wrote in message
...

Hi,
Big cast iron thingy alright but at what efficiency?

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%....

so, let's say current furnace is 50% efficient.
let's say we get a 90% efficient one. how much less fuel is that per year?

"CBHvac" wrote in message
...

"j j" wrote in message
...
our furnace is probably 50 years old. it's a big cast iron thing.

everyone we asked told us not to change it because new furnaces have
crappier construction.

Then you are asking the wrong people.
Granted, they dont make tanks anymore.

what determines the efficiency of a furnace?

is it the fact that it's a tank (are modern furnaces different?) or the
burner itself?

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.

j j wrote:

so, let's say current furnace is 50% efficient.
let's say we get a 90% efficient one. how much less fuel is that per year?

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
furnace
y = the amount of fuel it takes to produce H by a 90% efficient
furnace

Therefo

..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
suppose YMMV.

Ermalina wrote:

j j wrote:

so, let's say current furnace is 50% efficient.
let's say we get a 90% efficient one. how much less fuel is that per year?

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
furnace
y = the amount of fuel it takes to produce H by a 90% efficient
furnace

Therefo

.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
suppose YMMV.

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.

About 40%.

--

Christopher A. Young
Learn More about Jesus
www.lds.org
www.mormons.com


"j j" wrote in message
...

so, let's say current furnace is 50% efficient.
let's say we get a 90% efficient one. how much less fuel is that per year?

"j j" wrote in message
...

"CBHvac" wrote in message
...

Hi,
Big cast iron thingy alright but at what efficiency?

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%....

so, let's say current furnace is 50% efficient.
let's say we get a 90% efficient one. how much less fuel is that per year?


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
tremendous payback.
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.

"j j" wrote in message
...

"CBHvac" wrote in message
...

"j j" wrote in message
...
our furnace is probably 50 years old. it's a big cast iron thing.

everyone we asked told us not to change it because new furnaces have
crappier construction.

Then you are asking the wrong people.
Granted, they dont make tanks anymore.

what determines the efficiency of a furnace?

The design, and the final AFUE rating.


is it the fact that it's a tank (are modern furnaces different?) or the
burner itself?

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.

"Stormin Mormonn" wrote in message
...
About 40%.

--

\

What formula you use to get that wrong number?


"j j" wrote in message
...

so, let's say current furnace is 50% efficient.
let's say we get a 90% efficient one. how much less fuel is that per year?