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  1. #1
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    Default Will a furnce heat exchanger crack with excessive heat?

    My little brother called me asking this question.
    From my understanding the fan on an oil furnace, on a 15 yr old unit on a Mfg.. Home did not turn on, and the furnace kept buring to the extent that everthing on the outside melted with the heat.
    The home owners insurance company agreed to pay to fix the smoke damage and damage to the exterior of the furnace.

    The heating contractor then found that the heat exchanger was cracked and would not repair it, and stated the home inspector should of found the cracked exchanger.

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    Phoenix AZ Resale Home, Mobile Home, New Home Warranty Inspections. ASHI Certified Inspector #206929 Arizona Certified Inspector # 38440
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  2. #2
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    Default Re: Will a furnce heat exchanger crack with excessive heat?

    Well the heating contractor did him a favor by not repairing it.
    It malfunctioned to the point of doing damage and the hi-limit safety did not shut it down. At this point the cracked heat exchanger is immaterial in my opinion since the unit should be replaced, not repaired.
    Of course home inspectors are supposed to find everything... even though we know the truth is different than the contractors opinion.

    Yes, in this instance over firing of the furnace to the degree that you describe could cause a crack but there is no way to prove or disprove it. I would think the insurance should pay to replace everything damaged by the fire including replacing the furnace, IMHO.

    Jim Luttrall
    www.MrInspector.net
    Plano, Texas

  3. #3
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    Spring City/Surrounding Philadelphia area
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    Default Re: Will a furnce heat exchanger crack with excessive heat?

    I'm pretty sure excessive heat can kill a heat exchanger Dan. That's why units are equipped with limit switches to keep the unit from overfiring and thermal stress.

    As for the comment from the HVAC contractor that the HI should have caught the cracked heat exchanger, that's debatable at best and an irresponsible statement at worst. How long ago was the home inspected?

    "It takes a big man to cry. It takes an even bigger man to laugh at that man". - Jack Handey

  4. #4
    Ted Williams's Avatar
    Ted Williams Guest

    Default Re: Will a furnce heat exchanger crack with excessive heat?

    It seems possible to me that an exchanger could be cracked by the fan's failure and ensuing build up of excess heat, but that's chicken and egg now. The unit is most likely shot and the insurance company should just replace it.


  5. #5
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    Default Re: Will a furnce heat exchanger crack with excessive heat?

    Quote Originally Posted by Nick Ostrowski View Post
    I'm pretty sure excessive heat can kill a heat exchanger Dan. That's why units are equipped with limit switches to keep the unit from overfiring and thermal stress.

    As for the comment from the HVAC contractor that the HI should have caught the cracked heat exchanger, that's debatable at best and an irresponsible statement at worst. How long ago was the home inspected?

    The home owner just bought it and was moving in. It's a couple hrs from your part of the country.

    From what I heard, [ it's 2nd hand]. The inspector just turned the unit on for a couple min at the furnace switch and said everthing was OK. I don't know if he said anything about the heat exchanger.
    It was a repo. I'm not sure if the home would of had any oil in the tank.
    My brother is working on cleaning up the smoke damage, and trying to help the owner get the furnace covered.
    Where it stands now they are not willing to replace the furnace.

    Last edited by Dan Harris; 11-23-2010 at 11:03 AM.
    Phoenix AZ Resale Home, Mobile Home, New Home Warranty Inspections. ASHI Certified Inspector #206929 Arizona Certified Inspector # 38440
    www.inspectaz.com

  6. #6
    David Bell's Avatar
    David Bell Guest

    Default Re: Will a furnce heat exchanger crack with excessive heat?

    A 15 year old oil furnace is reaching its life expectancy. Oil burners require yearly service and there may be some records available from the previous service Co. that could show previous problems. Safety controls ,like any other control, can fail. Newer units have redundant safeties for this reason. You may be able to check to see if the furnace manufacturer had any recalls for exchanger problems.


  7. #7
    Bruce Hutton's Avatar
    Bruce Hutton Guest

    Default Re: Will a furnce heat exchanger crack with excessive heat?

    I would think the excesive heat would seperate some molecules in the metal & be an asset to the crack.
    JMO


  8. #8
    Join Date
    Oct 2010
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    ventura, ca
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    Default Re: Will a furnce heat exchanger crack with excessive heat?

    Quote Originally Posted by Bruce Hutton View Post
    I would think the excesive heat would seperate some molecules in the metal & be an asset to the crack.
    JMO
    Home inspections have finally reached the molecular level!

    Here in CA we perform our inspections to a Standard of Practice.
    For example CREIA or ASHI (intNachi - Never heard of it!)

    Discover - Disclaim - Defer (Jerry McCarthy)

    Here's my Disclaimer - under HEAT EXCHANGER
    "The heat exchanger portion of a gas or oil fired heater is difficult to access without
    disassembly, and cannot be adequately checked during a, none invasive, limited visual inspection.
    We recommend a service contract be placed on the unit and a heating contractor
    called to verify the condition of the heat exchanger prior to close of escrow inspection
    period."

    Here's my routine disclaimer.
    Inspectors Comment:
    We see no evidence of an annual safety check for this unit.
    Disclaimer:
    "As a matter of routine, we recommend that all gas fired appliances have a
    comprehensive safety check up by a qualified, state licensed, contractor
    of the applicable type, as part of a real estate transaction. Home inspection
    evaluations of gas fired heaters are limited, and do not provide invasive, or
    scientific testing".

    Disclaimers are everything.
    I wonder what verbiage the inspector in question has in his report.
    Clear, accessible disclaimers together with Standards of Practice
    show the inspector's effort to educate the client as to the limitations of
    the inspection. All my clients are required to read and sign a copy of the CREIA
    Standards and an amendment which states that they agree that this inspection
    is designed around and limited to those Standards.

    Also - all disclaimers and all inspectors comments are highlighted in Blue
    in the report.

    Example - I recently performed and inspection where rodents were
    nesting inside the plenum. I entered my standard infestation
    comment - bingo - the heater was replaced. No body wanted to argue the
    health aspects of rodents in the plenum. Here's that disclaimer.

    Inspectors Comment:

    "Obvious past rodent activity - widespread rodent droppings in plenum.
    Disclaimer:
    Where obvious rodent activity is noted - The potential for unhealthful air being
    distributed via the heater or A/C system into the habitable space - is raised.
    Further comprehensive testing by an expert in an applicable field is recommended,
    prior to the close of escrow inspection period."

    I know - some will say - All these disclaimers will knock you out of the market place.
    However - one or two good law suits and your future as an HI is questionable.

    Discover - Disclaim - Defer!

    mf

    Last edited by matt faust; 11-25-2010 at 02:09 PM. Reason: I wanted to edit.
    Matt Faust
    Real Estate Inspector

  9. #9
    Bruce Hutton's Avatar
    Bruce Hutton Guest

    Default Re: Will a furnce heat exchanger crack with excessive heat?

    Quote Originally Posted by matt faust View Post
    Home inspections have finally reached the molecular level!

    Here in CA we perform our inspections to a Standard of Practice.
    For example CREIA or ASHI (intNachi - Never heard of it!)

    mf

    WOW! MAtt

    Dan had a Question:
    Will a furnce heat exchanger crack with excessive heat?

    I read the post - There was a problem with excessive heat inside the unit to the extent that it melted things on the outside of the cabinet.
    I would think throwing the ASHI / internahi book at the furnace technician will get them no where...But have the technician try to explain how the heat exchanger will not crack under excessive heat?
    That technician has no way of knowing if the crack was there before the excessive heat!

    He wasnt asking how do you write your report or what guidelines you operate under!!!

    Don't throw the standards book at me!!!!!!!!


  10. #10
    Join Date
    Feb 2009
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    Southern Vancouver Island
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    4,546

    Default Re: Will a furnce heat exchanger crack with excessive heat?

    Quote Originally Posted by Dan Harris View Post
    The home owner just bought it and was moving in. It's a couple hrs from your part of the country.

    From what I heard, [ it's 2nd hand]. The inspector just turned the unit on for a couple min at the furnace switch and said everything was OK. I don't know if he said anything about the heat exchanger.
    It was a repo. I'm not sure if the home would of had any oil in the tank.
    My brother is working on cleaning up the smoke damage, and trying to help the owner get the furnace covered.
    Where it stands now they are not willing to replace the furnace.
    What he said may not match what he wrote, or what the buyer thinks he said or thinks he wrote.

    If I had only checked the fan I might have said "Well that part's ok", but in my report, there would be comments such as "no oil, unable to run the furnace". Forget about a home inspector seeing a crack in a heat exchanger. We would only see the ocassional one that was easily visible. The heating contractor could help by explaining this to the insurance adjuster instead of pointing a finger at the home inspector. That serves no purpose, and is now hurting the home owner. Why can't we all just get along???

    John Kogel, RHI, BC HI Lic #47455
    www.allsafehome.ca

  11. #11
    Join Date
    Jun 2010
    Location
    Vancouver
    Posts
    202

    Default Re: Will a furnce heat exchanger crack with excessive heat?

    The furnace tech was flexing his muscles and trying to show his off techincal abilities as what he can see. A home inspector is not going to rip the furnace apart to make sure everything is working to the ninth degree. The furnace tech was pointing fingers cause he was just scared to foot the blame himself, when in reality it was just worn out and failed. It is like any system out there. it might work in the short term but a true test is full time running, but show me a home owner who wants a full time home inspector moving in. let me know as I wouldn't mind a nice warm place to go for winter... lol


  12. #12
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    Mar 2007
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    Near Philly, Pa.
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    Cool Re: Will a furnce heat exchanger crack with excessive heat?

    Inspecting for cracked heat exchangers (HX) is a specialty unto itself and beyond the scope of a Home Inspector. Most HVAC technicians are not trained or equipped to discover HX cracks. First of all, locating cracks in a HX should be done using several techniques, visual inspection, whether aided with a scope or naked eye being only one. Combustion analysis is another. There are also dyes or water injection, which are controversial but sometimes very effective. However, you need to be trained in the various types of HX construction & materials, where to predict cracks such as at crimp rings, how cracks manifest themselves, what kind of lighting and visual inspection angle/ perspective is best to pickup cracks, etc. Then you have the larger issue of access. Basically, to do a thorough job, you would need to pull the coil off the furnace. Also, what about your secondary HX?

    I would steer clear of commenting on HX cracks as a HI. Basic operation is one thing but this goes beyond. Also, a visual inspection is a snapshot in time. Can this HVAC tech prove the HX crack occurred before the HI and not after? What caused the crack? HXs crack from a variety of issues but the most common is uneven heating. You can have 'normal' operation of the blower with one burner not firing properly and crack a HX. You can also have a corrosive atmosphere contribute to it, including simple high Rh%.

    The unit should be replaced because it was operated for an extended period without the blower stripping heat off it. The next questions are, why did the limit switch not shut it down within a minute, was this limit bypassed and who was the last HVAC tech in there to service it? Why did the blower take a dump? Broken belt? Seized up? Not oiled? There should be a record of the seller's due diligence with service and a detailed record from the service provider showing comprehensive service that includes testing all safeties and servicing the blower, then measuring delta T and TESP along with combustion analysis. Usually, there will be a harbinger before a blower dies---noise, drop off in performance noted by homeowner, rising amp draw, change in delta T and duct pressures, etc. Did the homeowner install a 3M Filtrete pleated filter that clogged up and burned up the motor? A lot of other considerations in this case that go well beyond a HI. The insurance company should pay for the furnace then they can subrogate to whomever they suspect is responsible for the furnace.

    Keep the fire in the fireplace.

  13. #13
    Bruce Adams's Avatar
    Bruce Adams Guest

    Default Re: Will a furnce heat exchanger crack with excessive heat?

    Dan
    The question was can a furnace overheating cause a heat exchanger to crack. The answer is YES.
    What did the inspector say about the furnace?? Was the home buyer with the inspector at the time of the inspection? Was there indications that the furnace had been getting to hot? Did the inspector report that he ran the furnace at the time of the inspection? Did he report that there was no fuel for the furnace at the time of the inspection?
    Was the HVAC person there during the inspection? If not how can he say that the Inspector should have seen it? Can the HVAC person say when the Heat Exchanger cracked?
    Over the years I have heard from the repair person that the inspector should have seen it. Can remember one that when I inspected the furnace I reported that the furnace was very dirty. had an uneven flame, and Had a bad hi-limit switch. and recommended that the furnace be further service and evaluated by a qualified HVAC person. The repair person was called by the home owner at that time. Was cleaned and serviced. Nothing was said about anything wrong with the unit. I was called by the service Tech. and asked what I meant by the hi-limit switch was bad and how did I know it was bad. I explained to him how I checked the unit and how it was performing. He informed the buyer I didn't know what I was talking about. Less than six month later I was called by the buyer and was informed that there was a crack in the heat exchanger and the service tech had said that I should have seen it as it was there before the home was inspected by me. The buyer said that the service tech says that I should have to purchase them a new furnace. After talking with the buyer found out that the second service person was from the same company that looked at the furnace at the time of purchase. After talking with the HVAC company they fired the person that did the service at the time of the purchase. And paid for the new furnace to the buyer.
    Bruce


  14. #14
    David Bell's Avatar
    David Bell Guest

    Default Re: Will a furnce heat exchanger crack with excessive heat?

    Bruce, I find it amusing that the tech said you didn't know what you are talking about but in the same breath says you should have found a crack in the exchanger. I have seen more than a few cracked heat exchangers in my time, but have never diagnosed one during a routine maintenance. There was always a significant event that had prompted an in depth inspection. More often than not a customer would complain of an odor upon start up of the furnace. Most cracks will release flue gas when the heat exchanger is cold. The crack tends to seal up when the exchanger gets hot. Units that have "plugged" due to poor setup or a lack of maintenance should always be checked.


  15. #15
    Join Date
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    Santa Rosa, CA
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    2,479

    Default Re: Will a furnce heat exchanger crack with excessive heat?

    Quote Originally Posted by Bob Harper View Post
    Also, a visual inspection is a snapshot in time. Can this HVAC tech prove the HX crack occurred before the HI and not after?
    Bob,

    Thanks for that. Hopefully homeowners and heating contractors will peruse this post.

    This brings up a question that I have never been able to get answered, even though I ask it nearly every time I talk to a heating contractor.

    How quickly can a crack develop in a heat exchanger? Is this something that happens quickly, over a number of weeks, or is it the standard "depends"?

    Department of Redundancy Department
    http://www.FullCircleInspect.com/

  16. #16
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    Jun 2010
    Location
    Vancouver
    Posts
    202

    Default Re: Will a furnce heat exchanger crack with excessive heat?

    Hi Gunnar. in regards to your question the best answer I think is depends. there are a lot of variables with each install that will affect it. over time and experince will narrow it down with each model but like everything else out there generally there will be a general pattern over time that will develope but each case has to be inspected on it's own merits. Just like every house is different so will the heat exchangers with some generalizations happening.


  17. #17
    Bruce Adams's Avatar
    Bruce Adams Guest

    Default Re: Will a furnce heat exchanger crack with excessive heat?

    Quote Originally Posted by David Bell View Post
    Bruce, I find it amusing that the tech said you didn't know what you are talking about but in the same breath says you should have found a crack in the exchanger. I have seen more than a few cracked heat exchangers in my time, but have never diagnosed one during a routine maintenance. There was always a significant event that had prompted an in depth inspection. More often than not a customer would complain of an odor upon start up of the furnace. Most cracks will release flue gas when the heat exchanger is cold. The crack tends to seal up when the exchanger gets hot. Units that have "plugged" due to poor setup or a lack of maintenance should always be checked.
    I had reported at the time of inspection that the furnace was very dirty and there was an uneven flame on the flame spreaders. I also reported that the hi-limit switch was shutting the unit down every three minutes. With all the carbon build up on the visible parts of the heat exchanger. I did inform the buyer that I believed there to be a cracked heat exchanger and that the carbon can hide the crack. I also told the buyer that there was no reason for me to go further with the unit and they should get there own HVAC person to check the unit. They chose to go back to the seller to have the unit checked and evaluated. The unit was a five year old Rheam. I do not believe the filters had ever been changed in the five years. I removed the filters at the time of the inspection. I also ran the unit for about 30 minutes. The buyers chose to believe the Tech. I had a copy of the techs report in my file. I also had pictures of the heat exchanger at the time of the inspection. I have learned over the years to not trust the Techs. And it makes allot of difference on who they are working for. I have always recommended to the buyer they hire there own people to evaluate something.
    Bruce


  18. #18
    David Bell's Avatar
    David Bell Guest

    Default Re: Will a furnce heat exchanger crack with excessive heat?

    Quote Originally Posted by Gunnar Alquist View Post
    Bob,

    Thanks for that. Hopefully homeowners and heating contractors will peruse this post.

    This brings up a question that I have never been able to get answered, even though I ask it nearly every time I talk to a heating contractor.

    How quickly can a crack develop in a heat exchanger? Is this something that happens quickly, over a number of weeks, or is it the standard "depends"?
    Most of the cracks i have seen are due to hot spots. Places that have had poor airflow around them or more typically on welds near the top of barrel type heat exchangers. These are things that can take weeks to develop.


  19. #19
    Bruce Adams's Avatar
    Bruce Adams Guest

    Default Re: Will a furnce heat exchanger crack with excessive heat?

    Quote Originally Posted by Gunnar Alquist View Post
    Bob,

    Thanks for that. Hopefully homeowners and heating contractors will peruse this post.

    This brings up a question that I have never been able to get answered, even though I ask it nearly every time I talk to a heating contractor.

    How quickly can a crack develop in a heat exchanger? Is this something that happens quickly, over a number of weeks, or is it the standard "depends"?
    This question can not be answered even by the experts. If conditions are right the crack can happen overnight or over a long period of time. I have found a cracked heat exchanger in a three year old 80% furnace and have done 85 year old furnaces that were still doing what they were manufactured for. There is not a tech out there that can tell you when that crack happened. If a seller tells you that he just had the furnace checked and there is nothing wrong with it. Look closer at the furnace.
    Bruce


  20. #20
    Join Date
    May 2009
    Location
    Washington State
    Posts
    358

    Default Re: Will a furnce heat exchanger crack with excessive heat?

    Quote Originally Posted by matt faust View Post
    Home inspections have finally reached the molecular level!

    Here in CA we perform our inspections to a Standard of Practice.
    For example CREIA or ASHI (intNachi - Never heard of it!)

    Discover - Disclaim - Defer (Jerry McCarthy)

    Here's my Disclaimer - under HEAT EXCHANGER
    "The heat exchanger portion of a gas or oil fired heater is difficult to access without
    disassembly, and cannot be adequately checked during a, none invasive, limited visual inspection.
    We recommend a service contract be placed on the unit and a heating contractor
    called to verify the condition of the heat exchanger prior to close of escrow inspection
    period."

    Here's my routine disclaimer.
    Inspectors Comment:
    We see no evidence of an annual safety check for this unit.
    Disclaimer:
    "As a matter of routine, we recommend that all gas fired appliances have a
    comprehensive safety check up by a qualified, state licensed, contractor
    of the applicable type, as part of a real estate transaction. Home inspection
    evaluations of gas fired heaters are limited, and do not provide invasive, or
    scientific testing".

    Disclaimers are everything.
    I wonder what verbiage the inspector in question has in his report.
    Clear, accessible disclaimers together with Standards of Practice
    show the inspector's effort to educate the client as to the limitations of
    the inspection. All my clients are required to read and sign a copy of the CREIA
    Standards and an amendment which states that they agree that this inspection
    is designed around and limited to those Standards.

    Also - all disclaimers and all inspectors comments are highlighted in Blue
    in the report.

    Example - I recently performed and inspection where rodents were
    nesting inside the plenum. I entered my standard infestation
    comment - bingo - the heater was replaced. No body wanted to argue the
    health aspects of rodents in the plenum. Here's that disclaimer.

    Inspectors Comment:

    "Obvious past rodent activity - widespread rodent droppings in plenum.
    Disclaimer:
    Where obvious rodent activity is noted - The potential for unhealthful air being
    distributed via the heater or A/C system into the habitable space - is raised.
    Further comprehensive testing by an expert in an applicable field is recommended,
    prior to the close of escrow inspection period."

    I know - some will say - All these disclaimers will knock you out of the market place.
    However - one or two good law suits and your future as an HI is questionable.

    Discover - Disclaim - Defer!

    mf
    Great Disclaimer Matt -


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