Originally Posted By: rrushing This post was automatically imported from our archived forum.
Trying to repair a cracked heat exchanger would be, how the old saying goes… Throwing good money after bad.
Repairing a cracked heat exchanger is the equivalent of trying to repair a chared conductor in an FPE panel. DON'T REPAIR THE SYMPTOM, REPAIR THE CAUSE OF THOSE SYMPTOMS!!
The unit is at the end of it's life expectancy, it doesen't deserve to try and be put on life support (that it would never get off). Replacing the heat exchanger is 3/4 the cost of replacement, after it's all said and done. That remaining 25% get's you a new unit good for another 20 +years, if serviced regularly. That's if you can find anyone willing to take on the responsibility of doing the repairs. Trying to go the cheap way will only give you (maybe) a couple of years til this old unit (the remaining components) hits you up for more costs. Without replacement you still have an OLD UNIT.
My recommendation is replacement of the entire unit, if in fact you have a cracked heat exchanger.
If it were a horse, it would have a couple of broken legs... What would you do?
Originally Posted By: rrushing This post was automatically imported from our archived forum.
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If the furnace is not under warranty, replace it.
The warranty doesen't matter. If it's cracked, it needs replacement regardless of the warranty. Obviously, it would not be under warranty or the homeowner would not be concerned with the replacement cost.
"The long drawn out way" was my conveyance to assist the homeowner in making an educated decision and to expound upon Jerry's post.
Originally Posted By: dbowers This post was automatically imported from our archived forum.
Scott -
As a past factory service rep for a HVAC manufacturer, I hope to GOD that you're a homeowner or realtor asking this question - AND - not a home inspector. If I ever discovered another HI in my trade area telling this type of info to buyers or realtors most of us would bend over backwards looking for ways to try and help put you out of business.
A crack or hole in a heat exchanger will not AUTOMATICALLY let carbon monoxide leak out BUT it can AND you never know when or if it will do so.
Originally Posted By: wwarner This post was automatically imported from our archived forum.
time which may result in a significant increase of these pollutants.
If this has not already been proven a chemical and physical fact of combustion, then why the need for a heat exchanger at all? Why not run a furnace as say a campfire without the smoke? With a campfire, we can see the pollutants resulting from combustion (complete and incomplete), but with natural gas, we cannot always see this even though the pollutants are still there.
As a father and husband, would I rely on some web site to to tell me that my fuel burning appliances are consistently in prime condition and there is no fluctuation in the quality of fuel I use, therefor I need not concern myself about the effects of incomplete combustion; or do I rely on scientific facts concerning the properties of combustion (complete and incomplete) and the mathematical probability that all is well with these fuel burning systems 100% of the time? 
I prefer the latter.
Originally Posted By: wwarner This post was automatically imported from our archived forum.
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It's not unwillingness to spend money for my family, it was to do so when there seemed doubt as to whether a cracked HE would /actually/ cause a health threat. Many internet sites suggested that it would not, and therefore why would one spend money on something that is not a threat?
Scott,
I believe you're not reading these sites correctly.
They are simply stating that cracked heat exchangers do not MAKE CO. This statement is true.
But...
A cracked heat exchanger most certainly will allow combustion gases and pollutants (like CO) to enter eventually.
MYTH #1 - Cracked Heat Exchangers Make CO. I would like to know who started this myth. CO is produced as a result of incomplete combustion. A cracked heat exchanger might allow products of combustion to enter the air stream. In some rare cases, it can cause flame impingement when air from the blower enters the heat exchanger.
Please view these sites carefully. I had to read twice before I understood what he was trying say. I found it hard to believe someone was saying CO is not a health threat. This is NOT what they are saying. They are simply trying to state that people are misinformed as to what causes or makes Carbon Monoxide.
Originally Posted By: Scott Logan This post was automatically imported from our archived forum.
I am, in fact, a homeowner asking these questions, and I’m not telling any sort of information. On the contrary, I’m asking for information.
I thank all of you who responded for your advice and will be repalcing the furnace once I get a few bids.
Scott
dbowers wrote:
Scott -
As a past factory service rep for a HVAC manufacturer, I hope to GOD that you're a homeowner or realtor asking this question - AND - not a home inspector. If I ever discovered another HI in my trade area telling this type of info to buyers or realtors most of us would bend over backwards looking for ways to try and help put you out of business.
A crack or hole in a heat exchanger will not AUTOMATICALLY let carbon monoxide leak out BUT it can AND you never know when or if it will do so.
Originally Posted By: Gary Reecher This post was automatically imported from our archived forum.
Scott I am a HVAC Service Tech. A crack in a heat exchanger is a defect in the metal. Cracks occur when the metal is stressed many times from heating and cooling. The Gas Research Institute that performs testing of furnaces states in their inspection guidelines that if a crack is seen in a heat exchanger that the heat exchanger or the furnace is to be replaced. A heat exchanger is a curved surface with air blowing over it. NO ONE and I mean NO ONE can state with absolute certainty what is going to happen. Yes most times air will blow into a crack back into the burner chamber stopping the flow of gases into the house. But there are always exceptions to this. The day I found this exception I wished I had carried a video camera . I do now. Was doing an inspection on a furnace and watched in awe as the flame from the pilot light over bar lifted off and was pulled into a crack.
Even if fumes are not pulled into the crack eventually enough air is going to be pushed into the burner chamber to force the flame to roll out. When this condition happens high CO is being produced due to flame disruption and impingement. If you are lucky enough to have a furnace with a flame roll out switch, a safety to shut off the gas valve, that's all that will happen. If you are not then the flames will continue and burn wiring and maybe you'll be lucky enough that the wires will short out the transformer to close the gas valve.
A furnace with a cracked heat exchanger is like a car with a tire that has the side wall balooning. Sure you can operate both but for how long before a disaster happens. Get the heat exchanger or the furnace replaced.
