# Carrier 48SS Heat Exchanger Rupture



## bengineer (Mar 3, 2005)

We have a Carrier 48SS package unit installed in Oct. 1994. Last November, the circuit board failed and had to be replaced. We were still having intermittent problems, so I called a different service contractor. He looked a little further, and found a huge hole in the heat exchanger. It's like it just blew-out right at a bend. The service tech said the board failure was definitely due to the heat exchanger rupture. Talked to Carrier, and they said if we can show we've maintained the unit for the last 5 years, they'll cover it under the warranty, which is 10 years. I do the cleaning myself, so it looks like we're on the hook for the repair. Are heat exchanger problems common with Carrier units? Any ideas on how to deal with Carrier?

On top of everything, Carrier is completely out of stock on the replacement. We've been without heat in that part of the house for a week, and it will be another 4 or 5 days before the new heat exchanger gets here.


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## NickTech (Feb 13, 2005)

well, a welding contractor can be hired to fix the hole. have it tested by and hvac guy with a "smokey" test. but since you are 4 -5 days from getting a new one, i'm sure a supplimental heater would due till then. since you were responsible for the professional maintainance of it, send carrier a spread sheet with a time line of dates, maintainance scheduling and repairs done by you in the past. if you are not a licensed contractor, they will pick it up in a heart beat thru conversation. if you can prove you are a technician, then you shouldn't have a problem......double check your warranty if it states that annual maintainance was required for them to honor the warranty in the first place. by the way, if carrier is out of stock of replacement heatexchangers, that a good indication that there are alot of them out there failing.... if all fails this a perfect lesson that proves annual maintainance by a trained professional is well worth the cost. thank goodness that second guy you called found the leak in the heat exchanger. that leak is a perfect way to kill your family as they slept. !!! ANNUAL MAINTAINANCE !!! :cheesygri


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## tinner73 (Nov 23, 2004)

what caused the HX to crack? has the furnace been over-fired? airflow issue? at 11 years old.........i'd personally would be looking for a new furnace.


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## dmnoland (Jun 10, 2006)

I'm so sorry to dig up such an old thread but i also have a eleven year old Carrier 48ss with a hole (from rust) in the he. I had my hvac tech look at it today and he will check on parts Monday. 

Can a hole in a he really just be welded or patched? After all, it's just metal, right? If the answer is yes, how long (best guess) will that repair last? 
I know the risks of co2 and want to fix this thing as cheap and safe as possible. I'm just a carpenter and in this economy I have not been working normal hours so $ is a serious factor.

Thank You!

David.


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## beenthere (Mar 5, 2009)

Those heat exchangers are so thin. Welding isn't a real option.


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## flashheatingand (May 3, 2008)

theoretically... why not use a high temp mastic?


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## hvaclover (Oct 5, 2008)

Not there's a real professional fix.


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## beenthere (Mar 5, 2009)

flashheatingand said:


> theoretically... why not use a high temp mastic?


Its a duct sealer. NOT a heat exchanger sealer.


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## flashheatingand (May 3, 2008)

I just googled high temperature mastic, and there was something that could withstand about 1250 degrees c. I am not saying this is a good solution. But, lets just say a customer doesn't have the money for a new furnace. Someone mentioned welding over the crack. I just thought this might be a feasible alternative. Is it the best route to go... of course not. But, would it work? 

Honestly, I don't know. I imagine, the crack would just grow, but if it's safe, and would work, why not?


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## flashheatingand (May 3, 2008)

Have a good week-end guys.


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## LJSMITH1 (May 27, 2009)

You might want to try taking it to a old school radiator repair specialist. If the tubing is Cu, then it can be silver soldered or brazed. If its aluminum, then it may be possible to TIG weld it. Be sure to fully evacuate the coil before applying heat and cap it soon after the repair is finished. You have little to lose to try. If it doesn't hold, then you must replace it.


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## hvaclover (Oct 5, 2008)

Straight concrete was used around here to seal Ht EX holes and cracks

That's old school before my time, but after tearing out whole bunch of old units and seeing the repaired ht ex, I gotta say it works fine.


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## beenthere (Mar 5, 2009)

High temp mastic, still won't have the same expansion rate as teh heat exchanger metal. So it would crack open. And you'd still have a cracked heat exchanger.

Fossil fuel fired hot air heat exchangers are not made of copper.

TIG welding would not work very well either. The expansion rates are too different between the filler and the HE.
Most good welders. Won't so it anyway.


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## LJSMITH1 (May 27, 2009)

beenthere said:


> High temp mastic, still won't have the same expansion rate as teh heat exchanger metal. So it would crack open. And you'd still have a cracked heat exchanger.
> 
> Fossil fuel fired hot air heat exchangers are not made of copper.
> 
> ...


 
OP didn't say what material, but it is probably Aluminum. A good TIG welder can absolutely fill this in and have a gas-tight repair. I have had a few radiators and oil coolers repaired this way and they handle decent internal pressures (30-90psi).

However, if this was my equipment, a replacement would be the only option I would consider...:thumbsup:


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## beenthere (Mar 5, 2009)

Automotive Radiators and oil coolers don't have the surface area that his furnaces heat exchanger does.
That is what makes them hard to repair.

I've seen cast iron welded(as in a boiler, and it lasted for several years). Has no bearing on the OP's furnace though.


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## MechAcc (Feb 27, 2005)

The heat exchanger is not repairable. The AGA, American Gas Association, which is one of the testing agencies for furnaces recommends that repairs to residential gas furnace heat exchangers be limited to tightening fasteners and replacing gaskets. Welding is not an option. In most cases many of the Carrier heat exchangers not only crack but also rust through. Many of these problems can be reduced by having the unit properly sized for the heat and cooling load and the duct work properly sized for the equipment. If this is a package unit the drain on the cooling system must have a drain trap. Lack of a drain trap will allow water to be sprayed onto the heat exchanger by the blower causing it to rust out.

Have the system tested and checked by a professional yearly.

Replace the filter monthly.


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