Is my heat exchanger cracked?


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Old 12-27-09, 09:15 PM
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Is my heat exchanger cracked?

My Carrier 58dxc (60k btu) was placed in service 07/1992 and in November 92, I bumped the IDM heating speed from med-lo to med-hi to try to "push" some heat to a cold room in my brand new house. Since then, I've replaced the HSI ignitor, r&r'd the draft inducer motor, and drained an awful lot of condensate that got trapped behind the funk that keeps building up in the drain line between the draft inducer and the little collector tank every year. But its been a great furnace.
In Oct 09, I noticed a horrible stench coming from the combustion air outlet, getting worse every week, and the furnace seemed to be getting weaker every day. I opened up the combustion air path and found a bumblebees nest in the screen directly on top of the firebox at the end of the combustion air inlet line causing the smell, cleaned it out, checked for any other obstructions, and put it back together.
Now, the furnace is weaker then its ever been! Delta-T is only 18 degrees across the heat exchanger...84 degrees output with IDM set at either lo-mid or hi-mid! Worse, all 3 in-shot burners put out a perfect, stable blue flame straight into the heat exchanger until the IDM turns on, then the left and middle burner flames are immediately blown backward away from the heat exchanger!! Is my heat exchanger cracked?
 
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Old 12-27-09, 09:27 PM
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It sounds like the heat exchanger is near the end of its life after 17 years, but there may still be a warrantee on it if it is a good brand/model.

The symptoms do not sound good and your real efficiency could be down.

Do you have a couple of good CO alarms to warn you when the real crack really opens up, which does not take more then a hour or two (usually at night/very early morning) usually occurs.

Dick
 
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Old 12-28-09, 07:13 AM
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The flame blow back is a dead giveaway. That heat exchanger is junk. Is time to seek professional help. As suggested, the heat exchanger may be under warranty. I recommend shutting the furnace down. Not worth risking your health by running a defective furnace.
 
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Old 12-28-09, 05:10 PM
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Thanks Gents-
I do have CO detectors. Since I am the original owner, the H/E has a lifetime warranty! But I DONT know if that warranty includes labor to R&R the H/E, or even the cost of a service tech to come out to verify that its cracked!
 
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Old 12-28-09, 05:21 PM
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TURN IT OFF OR DIE!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Blow back when the fan turns on means that the indoor fan is blowing the flame out!

This is a death trap!

TURN IT OFF!

Warranty will cover the part not the labor. Unless parts and labor warranty was purchased.

Provide serial number and I'll look it up at Carrier.

TURN OFF THE FURNACE!!!!!!!!!!!!!!!!!!!!!!!!!!!!
 
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Old 12-28-09, 05:24 PM
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Originally Posted by starlifter-fe View Post
Worse, all 3 in-shot burners put out a perfect, stable blue flame straight into the heat exchanger until the IDM turns on, then the left and middle burner flames are immediately blown backward away from the heat exchanger!! Is my heat exchanger cracked?

I presume you mean that you get a good flame pattern until the fan that circulates the air around the house turns on?


The main burner should not turn on unless the inducer motor has turned on, come up to speed and caused the pressure switch to close.

Please clarify that.



Typically, heat exchanger warrenties get you a new heat exchanger only, and sometimes you may have to pay for the cost to ship the heat exchanger from the factory.

It's very unlikely any labor to inspect or replace the heat exchanger would be included in the warrentee, but now would be a good time to dig it out and see what it says.
 
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Old 12-28-09, 05:44 PM
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Originally Posted by Jarredsdad View Post
TURN IT OFF OR DIE!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Blow back when the fan turns on means that the indoor fan is blowing the flame out!

This is a death trap!

TURN IT OFF!

Warranty will cover the part not the labor. Unless parts and labor warranty was purchased.

Provide serial number and I'll look it up at Carrier.

TURN OFF THE FURNACE!!!!!!!!!!!!!!!!!!!!!!!!!!!!
I will turn it off. Thank you for your concern.
 
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Old 12-28-09, 06:19 PM
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By IDM, I mean Indoor motor; the 1/3 hp PSC motor that drives the squirrel cage blower that moves air through the house. The draft inducer is working fine, but the MGV would not open til the draft inducer creates enough differential pressure to close the pressure switch and energize the HSI ignitor. I can certainly see why one might think IDM stood for "induced draft motor" or In-ducer motor" though. I wish I could post a video of what I saw through the little viewing window. The fact that only 2 of the 3 burners does it causes me to believe it is a crack.
 
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Old 12-28-09, 06:25 PM
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Jarredsdad-
S/N is 0792A09275 Thank you.
 

Last edited by starlifter-fe; 12-28-09 at 06:28 PM. Reason: accidentally quoted myself
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Old 12-29-09, 03:19 PM
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Sorry, need full model number also.

Serial means it was made in the 7th week of 1992. 17 years, mabe 15 , 20 or 30 year warranty. Cross your fingers!
 
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Old 12-29-09, 03:23 PM
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58dxc doesn't work. Look again at the tag. Carrier is unfortunately not like Trane. With Trane all I need is the serial number.
 
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Old 12-29-09, 04:25 PM
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I was mistaken.............................
 
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Old 12-29-09, 05:02 PM
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Originally Posted by Jarredsdad View Post
58dxc doesn't work. Look again at the tag. Carrier is unfortunately not like Trane. With Trane all I need is the serial number.
Model is 58dxc060-GG
The manual says the H/E is warranteed "for the lifetime of the original owner" which I am.
Thank you again, Sir.
 
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Old 12-30-09, 02:29 PM
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Cool!

There are actually 3 seperate exchangers in there instead of one. I still can't get any history on your unit, must not have been registered for warranty at install.

Also have to contact Carrier myself as I don't have the ability to see prices for parts and my online ordering section is gone.

Good news is, I didn't see anything indicating parts are not available.

EC, mistaken about what?
 
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Old 12-30-09, 03:19 PM
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Originally Posted by Jarredsdad View Post
EC, mistaken about what?
I glanced all too quickly at your back to back 2-line posts and had a good laugh thinking and posting the fact (I thought) you made a reduntant post, while your sig quote talks about redundancy. Then I re-read and saw they were different, and erased my post.
 
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Old 12-30-09, 03:25 PM
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Being redundant yourself then?
 
 

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