Replace Heat Exchanger or Furnace
 

I originally posted this on alt.hvac, but received a courteous
suggestion to post on this group.

I can either replace a heat exchanger for about $400 (part under
warranty, labor based upon actual time), or buy a new furnace installed
for a net price of $2,600.

Old furnace: 90% Carrier with a clogged secondary heat exchanger (still
works for about 15 minutes at a time until the limit switch trips, so
can maintain temp in current 30 degree weather). 88,000 BTU.
Manufacturing date of 1989, but some evidence suggests it was installed
in 1992. I replaced the motherboard a few years ago (did it myself for
about $125). The igniter was replaced a few weeks ago (free because the
service guy broke it during the tune & clean). Other than that, I think
all the parts are original. I think it has a lifetime heat exchanger
warranty (part only). Clogged secondary was diagnosed by: 1) Tripping
of Limit cutoff switch; and 2) Soot in exhaust pipe.

New furnace: 94-96% Carrier Infinity 96. 80,000 BTU. Net cost of
$2,600, which is $3,550 less: $150 Carrier rebate, $170 for paying cash
(rather than credit), $150 utility company rebate, $400 for replacing
a Carrier (bad heat exchanger program?), and $80 for tune and clean
performed 10 days ago. 10-year parts and labor warranty. Lifetime heat
exchanger warranty (part only). Because it is replacing a 90% Carrier,
it is a pretty direct swap-out. The new unit is a little shorter, so a
short collar to bridge the gap. PVC air supply and exhaust pipes are
fine.

Situation: South East Wisconsin. I'm guessing the new furance will save
$200/yr, but also make the house more comfortable because of the
multi-stage, and hopefully a little more quiet.

Because of rebates, a single stage 90% Carrier is only $300 cheaper,
and the other 2 stage Carrier is about $150 cheaper. The comparable
Lennox is about $500 more expensive (primarily due to the $400 Carrier
rebate). I have not priced a Trane or Rheem.

I currently have 2 furnaces, and the other Carrier is identical, except
for being a smaller BTU. If I replace the furnace, I would keep the old
one for spare parts.

Questions:
1) Any thoughts on replacing the heat exchanger, or the whole furnace
(seems like the age of the furnace is on the edge of being "old")?
2) Does the price seem reasonable?
3) How can I determine if they will install it right?
4) Did they cause the problem when they tuned the furnace (dislodged
rust that clogged the secondary)? Service man did say the heat
exchanger was rusting, but should last a few more years.
5) If they didn't cause the problem, should they have been able to see
the problem during the tune and clean (the problem arose when I set
back the thermostat 5 degrees when we were away for the weekend, and
the furnace needed extended run time to warm up the house)?

Thanks in advance for your help.

Replace Heat Exchanger or Furnace
 

Cant it be blown clean, what did Carrier say, its not leaking Co right,
so it is still good, not cracked. Why is it sooted up , burning
improperly. Im no pro, but those are a few things to think about. A new
unit is only 94.5 max efficiency in Carriers larger than 38000, btu
input models.

Replace Heat Exchanger or Furnace
 

"Tokai" wrote in message

I can either replace a heat exchanger for about $400 (part under
warranty, labor based upon actual time), or buy a new furnace installed
for a net price of $2,600.

Using just logic alone, I'd replace the heat exchanger, since it appears
you're getting it under warranty. It will take a long time to recover the
cost of a new furnace, even if you DO realize the savings you calculated.
The last few % of effeciency is questionable in my mind - you already have
an efficient furnace. Heat exchangers should last a lot longer than that -
have someone you trust (if you can find such a furnace guy) evaluate this
situation. Why did the first one get plugged up.

Other reason I would not send more moeny to the same furnace company, or use
the same contralctor that cleaned your present furnace, is: many furnace
heat exchangers last a lot longer than 10 years. You got some junk there
and are thinking of buying more of the same.

It's a trap to build a crappy furnace, than offer you discounts and rebates
to sell you more crap. I dispise that.

Rich

Replace Heat Exchanger or Furnace
 

Tokai wrote:
I originally posted this on alt.hvac, but received a courteous
suggestion to post on this group.

I can either replace a heat exchanger for about $400 (part under
warranty, labor based upon actual time), or buy a new furnace installed
for a net price of $2,600.

Old furnace: 90% Carrier with a clogged secondary heat exchanger (still
works for about 15 minutes at a time until the limit switch trips, so
can maintain temp in current 30 degree weather). 88,000 BTU.
Manufacturing date of 1989, but some evidence suggests it was installed
in 1992. I replaced the motherboard a few years ago (did it myself for
about $125). The igniter was replaced a few weeks ago (free because the
service guy broke it during the tune & clean). Other than that, I think
all the parts are original. I think it has a lifetime heat exchanger
warranty (part only). Clogged secondary was diagnosed by: 1) Tripping
of Limit cutoff switch; and 2) Soot in exhaust pipe.

New furnace: 94-96% Carrier Infinity 96. 80,000 BTU. Net cost of
$2,600, which is $3,550 less: $150 Carrier rebate, $170 for paying cash
(rather than credit), $150 utility company rebate, $400 for replacing
a Carrier (bad heat exchanger program?), and $80 for tune and clean
performed 10 days ago. 10-year parts and labor warranty. Lifetime heat
exchanger warranty (part only). Because it is replacing a 90% Carrier,
it is a pretty direct swap-out. The new unit is a little shorter, so a
short collar to bridge the gap. PVC air supply and exhaust pipes are
fine.

Situation: South East Wisconsin. I'm guessing the new furance will save
$200/yr, but also make the house more comfortable because of the
multi-stage, and hopefully a little more quiet.

Because of rebates, a single stage 90% Carrier is only $300 cheaper,
and the other 2 stage Carrier is about $150 cheaper. The comparable
Lennox is about $500 more expensive (primarily due to the $400 Carrier
rebate). I have not priced a Trane or Rheem.

I currently have 2 furnaces, and the other Carrier is identical, except
for being a smaller BTU. If I replace the furnace, I would keep the old
one for spare parts.

Questions:
1) Any thoughts on replacing the heat exchanger, or the whole furnace
(seems like the age of the furnace is on the edge of being "old")?
2) Does the price seem reasonable?
3) How can I determine if they will install it right?
4) Did they cause the problem when they tuned the furnace (dislodged
rust that clogged the secondary)? Service man did say the heat
exchanger was rusting, but should last a few more years.
5) If they didn't cause the problem, should they have been able to see
the problem during the tune and clean (the problem arose when I set
back the thermostat 5 degrees when we were away for the weekend, and
the furnace needed extended run time to warm up the house)?

Thanks in advance for your help.

Hi,
Soot? Rust? How come?
Tony

Replace Heat Exchanger or Furnace
 

I recently bought the house, and this is the first time I have had the
unit tuned and cleaned. So, the problems are not due to the company I
called (unless he did something to clog up the secondary).

What I understand is: The primary heat exchanger has rust on it. He
said the AC coils and the Humidifier could contribute to the problem.
The smaller second furnace (same age and type) does not have a
humidifier, and he said the heat exchanger looked good on that one.
Other than that, I have no idea what is causing the rust. The furnaces
are in a nice dry basement. Humidity use to be 50+% in the summer, but
we installed a whole house dehumidifier that keeps it in the 40% range.
If it was a prior humidity problem, I would have expected both furnaces
to be affected equally.

He said soot in the exhaust pipe is a sign of a clogged secondary. My
guess is that exhaust gas from the primary has to bypass the clogged
secondary, and somehow creates a soot problem in the exhaust pipe.
Maybe the soot is suppose to deposit in the secondary and be cleaned
out by the condensate?

Replace Heat Exchanger or Furnace
 

Tokai wrote:
I originally posted this on alt.hvac, but received a courteous
suggestion to post on this group.

I can either replace a heat exchanger for about $400 (part under
warranty, labor based upon actual time), or buy a new furnace installed
for a net price of $2,600.

Old furnace: 90% Carrier with a clogged secondary heat exchanger (still
works for about 15 minutes at a time until the limit switch trips, so
can maintain temp in current 30 degree weather). 88,000 BTU.
Manufacturing date of 1989, but some evidence suggests it was installed
in 1992. I replaced the motherboard a few years ago (did it myself for
about $125). The igniter was replaced a few weeks ago (free because the
service guy broke it during the tune & clean). Other than that, I think
all the parts are original. I think it has a lifetime heat exchanger
warranty (part only). Clogged secondary was diagnosed by: 1) Tripping
of Limit cutoff switch; and 2) Soot in exhaust pipe.

New furnace: 94-96% Carrier Infinity 96. 80,000 BTU. Net cost of
$2,600, which is $3,550 less: $150 Carrier rebate, $170 for paying cash
(rather than credit), $150 utility company rebate, $400 for replacing
a Carrier (bad heat exchanger program?), and $80 for tune and clean
performed 10 days ago. 10-year parts and labor warranty. Lifetime heat
exchanger warranty (part only). Because it is replacing a 90% Carrier,
it is a pretty direct swap-out. The new unit is a little shorter, so a
short collar to bridge the gap. PVC air supply and exhaust pipes are
fine.

Situation: South East Wisconsin. I'm guessing the new furance will save
$200/yr, but also make the house more comfortable because of the
multi-stage, and hopefully a little more quiet.

Because of rebates, a single stage 90% Carrier is only $300 cheaper,
and the other 2 stage Carrier is about $150 cheaper. The comparable
Lennox is about $500 more expensive (primarily due to the $400 Carrier
rebate). I have not priced a Trane or Rheem.

I currently have 2 furnaces, and the other Carrier is identical, except
for being a smaller BTU. If I replace the furnace, I would keep the old
one for spare parts.

Questions:
1) Any thoughts on replacing the heat exchanger, or the whole furnace
(seems like the age of the furnace is on the edge of being "old")?
2) Does the price seem reasonable?
3) How can I determine if they will install it right?
4) Did they cause the problem when they tuned the furnace (dislodged
rust that clogged the secondary)? Service man did say the heat
exchanger was rusting, but should last a few more years.
5) If they didn't cause the problem, should they have been able to see
the problem during the tune and clean (the problem arose when I set
back the thermostat 5 degrees when we were away for the weekend, and
the furnace needed extended run time to warm up the house)?

Thanks in advance for your help.

this is Turtle.

you want use to tell you about a problem here of furnases.

You have a 90% afue furnace that can be fixed for $400.00 + free parts.


You can get a new 94%-96% afue furnace for $2,600.00 which will save
you $200.00 a year.

The saving between the old one and buying a new one is $2,600.00 -
$400.00 = $2,200.00 to try to make up for with the savings of the new
furnace with $200.00 a year savings. At this rate , it will be 11 years
before you get your money back by way of savings of $200.00 a year.
then if you figure in if you took this money and put it CD's it will
double every 10 years. then this 11 years turns into 21 years.

how long are you going to be in this house ?

How Old are you ?

You will be looking for a new one about the time you get your money
back.

You tell me what you want to do after reading this.

TURTLE

Replace Heat Exchanger or Furnace
 

After double-checking, it seems to be the Flame Rollout Switch.

The circuit board was giving the 33-error code, which is Limit Switch
or Flame Rollout Switch. According to the wiring diagram, there are 3
sensors on the same circuit:

LS - Limit Switch, overtemp - auto reset
ALS - Auxillary Limit Switch, overtemp - manual reset
FRS - Flame Rollout Switch

According to Note #6, ALS is only on downflow models. On mine, the
returns enter the bottom side of the cabinet, and the hot air goes out
the top. I assume that it is an upflow model, and thus does not have an
ALS switch.

The sensor that is tripping is level with the burners (primary heat
exchanger), and on the left. It is a manual reset switch. The other
sensor that is wired in parallel is about level where I would guess the
secondary heat exchanger is. Since the sensor that is tripping is a
manual reset, it does not appear to be LS. By process of elimination, I
assume the switch that is tripping is FRS - Flame Rollout Switch.

The manual does say to check for adequate combustion air and exhaust as
possible problems, as well as the blower.

I compared the intake and exhaust of both furnaces. The furnace having
problems is the larger of the two. The good (smaller) furnace has a
strong flow in the draw and exhaust, and the exhaust is humid and
odorless. The problem furnace has larger pipes, but the flow is
noticeably weaker (covered up the intake with my hand). The exhaust
also has a slight odor, and gives me a headache pretty quickly. That
same odor is slightly noticeable around the problem furnace (there is a
CO detector in the room that has not gone off). I rodded about 5 feet
into each pipe from the outside (about one half of the length), and I
did not hit anything, and it did not make any difference.

Finally, a new problem is the furnace is starting to drip. It is new
because it is just started dripping down the air filter.

Thanks for your help.

Replace Heat Exchanger or Furnace
 

I would probably repair the existing furnace, but then again, I have no
idea how much damage a humidifier does to a furnace. Here in Maryland
you would have to be on crack to want a humidifier, sicne it is already
humid here year round. My furnce was built in 1982 and is working fine.

Replace Heat Exchanger or Furnace
 

After further analysis, I have finally accepted that once you are past
the break-even point, it doesn't matter what happens. I use to think
that having alternatives in different phases of their life would affect
the analysis.

I talked a little more with the service department, and it is $350 to
replace the secondary heat exchanger, or $800 for primary and
secondary. I did not think there was that much more labor to replace
both. In any case, for my breakeven analysis I will assume $800 since
the primary is likely to fail before the break-even date. So given the
options of $800, $2,600, 5% interest rate, and $200/yr savings, the
break-even is 11 years. Less if the old furnace needs more parts
replaced.

If the old furnace has to be replaced after 1 year, then it is
self-evident that I should not have replaced the heat exchanger. If the
old furnace lasts to 1 year before break-even, then I would have to
spend $2,600 in year 10 to get a new furnace vs. $0 for a 10 year old
furnace. Seems like I am still better off with the new furnace today.
What about year 5? $800 today and $2,600 in year 5, or $2,600 today.
I'm still better off with a new furnace because I have saved $200 per
year in fuel costs.

The only time reparing the old furnace seems to make sense is if the
new furnace has to be replaced before the break-even date. With a 10
year parts and labor warranty, that scenario would have a $0 cost.

I plan on living in the house for at least 8 years. Then the youngest
will be in college, and we will think about downsizing. I'm guessing at
least 10 years before we move, if ever.

The only remaining variable that could work against replacing the
furnace is whether the fuel cost savings are realized. Assuming a
marginal 2% increase in efficiency (vs. a possible 4%) and the DC
blower, the $200/yr should be achievable.

Thanks for helping me to clarify my thinking.

Replace Heat Exchanger or Furnace
 

"Tokai" wrote in message
ups.com...
After further analysis, I have finally accepted that once you are past
the break-even point, it doesn't matter what happens. I use to think
that having alternatives in different phases of their life would affect
the analysis.

I talked a little more with the service department, and it is $350 to
replace the secondary heat exchanger, or $800 for primary and
secondary. I did not think there was that much more labor to replace
both. In any case, for my breakeven analysis I will assume $800 since
the primary is likely to fail before the break-even date. So given the
options of $800, $2,600, 5% interest rate, and $200/yr savings, the
break-even is 11 years. Less if the old furnace needs more parts
replaced.

If the old furnace has to be replaced after 1 year, then it is
self-evident that I should not have replaced the heat exchanger. If the
old furnace lasts to 1 year before break-even, then I would have to
spend $2,600 in year 10 to get a new furnace vs. $0 for a 10 year old
furnace. Seems like I am still better off with the new furnace today.
What about year 5? $800 today and $2,600 in year 5, or $2,600 today.
I'm still better off with a new furnace because I have saved $200 per
year in fuel costs.

The only time reparing the old furnace seems to make sense is if the
new furnace has to be replaced before the break-even date. With a 10
year parts and labor warranty, that scenario would have a $0 cost.

I plan on living in the house for at least 8 years. Then the youngest
will be in college, and we will think about downsizing. I'm guessing at
least 10 years before we move, if ever.

The only remaining variable that could work against replacing the
furnace is whether the fuel cost savings are realized. Assuming a
marginal 2% increase in efficiency (vs. a possible 4%) and the DC
blower, the $200/yr should be achievable.

Thanks for helping me to clarify my thinking.

Round and round you go--with all the variables/scenerios you have there is
no simple answer. If it requires so much thinking than it's probably best
to replace the furnace. Your analysis makes reminds me of the following
saying " Figures don't lie, but liars can figure". In the end, after all
the figuring, the answer will come out the way you want it to.
MLD

Replace Heat Exchanger or Furnace
 

responding to
http://www.homeownershub.com/mainten...ace-74114-.htm
billyEM wrote:
What you really want to remember about investing in your home:

Don't do it just because its right and you can afford it. Be a skinflint.
Lowering pollution and fuel consumption is not your role here on earth.

A home is made to be flipped and maximally return money. Money!!! Money!!!

Replace Heat Exchanger or Furnace
 

I would get a estimate on a GOODMAN furnace with air.

Replace Heat Exchanger or Furnace
 

Honey! Why are the dot foo people here, again? And for a five year old
thread?

--

Christopher A. Young
Learn more about Jesus
www.lds.org
..

"billyEM" wrote in message
roups.com...
responding to
http://www.homeownershub.com/mainten...ace-74114-.htm
billyEM wrote:
What you really want to remember about investing in your home:

Don't do it just because its right and you can afford it. Be a skinflint.
Lowering pollution and fuel consumption is not your role here on earth.

A home is made to be flipped and maximally return money. Money!!! Money!!!

Replace Heat Exchanger or Furnace
 

On Dec 28, 9:27*pm, "Stormin Mormon"
wrote:
Honey! Why are the dot foo people here, again? And for a five year old
thread?

--

Christopher A. Young
Learn more about Jesus
*www.lds.org
.

"billyEM" wrote in message

roups.com...
responding tohttp://www.homeownershub.com/maintenance/replace-heat-exchanger-or-fu...billyEM wrote:

What you really want to remember about investing in your home:

Don't do it just because its right and you can afford it. Be a skinflint.
Lowering pollution and fuel consumption is not your role here on earth.

A home is made to be flipped and maximally return money. Money!!! Money!!!

It is interesting that this thread started back up exactly 5 years to
the day after it originally began: December 28.

Could it be that someone's/some server's system date is screwed up?

Replace Heat Exchanger or Furnace
 

What's worse, is that I just guessed five years. I was going to say three.

Christopher A. Young
Learn more about Jesus
www.lds.org
..

"DerbyDad03" wrote in message
...
Honey! Why are the dot foo people here, again? And for a five year old
thread?


It is interesting that this thread started back up exactly 5 years to
the day after it originally began: December 28.

Could it be that someone's/some server's system date is screwed up?

Replace Heat Exchanger or Furnace
 

On Dec 29, 9:19*am, "Stormin Mormon"
wrote:
What's worse, is that I just guessed five years. I was going to say three..

Christopher A. Young
Learn more about Jesus
*www.lds.org
.

"DerbyDad03" wrote in message

...

Honey! Why are the dot foo people here, again? And for a five year old
thread?

It is interesting that this thread started back up exactly 5 years to
the day after it originally began: December 28.

Could it be that someone's/some server's system date is screwed up?

Whoops...and I just simply trusted your math. Silly me.

It's actually 6 years later.

Man, does time fly!

Replace Heat Exchanger or Furnace
 

replying to RichK, ExpressMechTech1 wrote:
Soot issues in these furnaces are caused by rusted or otherwise clogged burner
venturis. This chokes off most of the primary combustion air and you get
bright yellow flames and loads of soot. It is an order of magnitude worse on
propane models. Carrier is very good about warranty support on these but it is
important to choose a competent tech. The burners must be replaced also, and
again replaced if they ever go bad in future to prevent a repeat.

--
for full context, visit https://www.homeownershub.com/mainte...ace-74114-.htm

Replace Heat Exchanger or Furnace
 

replying to m Ransley, ExpressMechTech1 wrote:
The primaries would probably be easy enough to clean. The secondaries clogg
prettty good and they are a separate module that can be replaced. I dont see
how they could practicaly be cleaned, especially with propane soot
https://www.homeownershub.com/img/bz