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  1. #1
    Join Date
    Sep 2019
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    Checking heat exchangers

    Hello. I'm a homeowner with a question about heat exchanger crack detection methods.
    My wife was told by a technician that we had a crack in our heat exchanger, and that it needed to be replaced. Made sense, until my wife told me that the inspection method used.

    His method was to squeeze the heat exchanger pipes, and look for flex.
    The flex evidently indicated that a crack existed, otherwise they wouldn't flex.
    They red tagged it and shut it down, with dire warnings about certain, immediate, horrible death if we ever tried to restart it, if we ever thought about restarting it ourselves, or even looked directly at the furnace while some else suggested restarting it without proper repairs.
    I might be misremembering some of that, but that was the gist.��

    So... first of all, with an older heat exchanger, squeezimg the pipes seems like a great way to crack it, if it's not already cracked.
    Second, is it true that the pipes should have zero flex?

    I decided to read up and after carefully doing visual inspection, I turned it back on to do my own tests.
    1. Flames are even and steady, no rollback detected.
    2. After 4 hours, CO2 meter at nearest vent indicated ppm dropped from 580 to 422. I don't know if there's a correlation between CO2 and CO levels, though.

    I've left it on for now, so basically I'm wondering:
    1. Is that a valid method of looking for cracks in the heat exchanger?
    2. Am I going to die a horrible screaming death if I don't go turn it back off immediately?

    PS I am planning to have it inspected by a different company in the next week, just in case. I want to live.

  2. #2
    Join Date
    Jun 2014
    Location
    Dover, DE
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    CO2 is carbon dioxide.
    CO is carbon monoxide. This is the silent killer. Over the counter CO meters that are UL listed are purposely set to trip at levels exceeding 70 PPM CO. You could already be suffering from the early effects of CO poisoning by this point.
    No, squeezing the heat exchanger is not acceptable. How did he even get to the heat exchanger to squeeze it?
    Ask for the combustion test results to prove his claim.
    I havent failed. Ive just found 10,000 ways that wont work. - Thomas Edison

    Its not whether you get knocked down, its whether you get up. - Vince Lombardi

    "In this house we obey the laws of thermodynamics" - Homer Simpson

    Local 486 Instructor & Service Technician

  3. #3
    Join Date
    Aug 2002
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    Never heard of a squeeze test. Heat exchanger metal is rigid and I got some strong hands but dont think I could see anything from a squeeze.

    Also how did he get enough access to squeeze the heat exchanger?

    Only way I could see someone squeezing the heat exchanger is to remove it from the unit or have a large panel off which would be better to do a visual test.

    If it has a visible crack or immediate safety issue, a combustion test will show with unstable reading or a rise of O2 when the fan starts.

    I would lean on the side of caution and not use the unit as your wife may have been misunderstanding the techs explanation. And get the tech to show you the issue, or have a another quality hvac contractor verify if there is or not an issue.

  4. #4
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    Sep 2019
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    Thread Starter
    Combustion test "looked okay", but I don't have a copy of actual results.
    Understood about the CO vs CO2, just didn't know if there was any correlation between levels of each. I have multiple CO detectors (4), including one next to furnace at 5 ', but no chirps so far.

  5. #5
    Join Date
    Jun 2014
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    Dover, DE
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    Are they UL listed CO detectors?
    I havent failed. Ive just found 10,000 ways that wont work. - Thomas Edison

    Its not whether you get knocked down, its whether you get up. - Vince Lombardi

    "In this house we obey the laws of thermodynamics" - Homer Simpson

    Local 486 Instructor & Service Technician

  6. #6
    Join Date
    Sep 2019
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    Thread Starter
    I talked to him too. He told me that CO could seep in, he told my wife that a crack could cause the gas to build up and explode. I asked multiple times for confirmation of that one, because wow. He also went to his truck to get "fresh batteries" to put in my fireplace remote receiver, to show me that it was broke and I needed to spend $340 to replace it. As soon as he left I put a different set of fresh batteries and it fired right up. This is one of several things that led me to become a bit suspicious.

    I'll play it safe, though, and get a different inspector out here this week, use it minimally until then. Thank very much for the replies, I really appreciate it.

  7. #7
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    Sep 2019
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    Thread Starter
    And yes, all UL listed detectors.

  8. #8
    Join Date
    Jun 2014
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    Dover, DE
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    Quote Originally Posted by CSK View Post
    And yes, all UL listed detectors.
    They shouldn’t be trusted then.
    Non-UL listed low level detectors are superior, and much more trustworthy.
    I havent failed. Ive just found 10,000 ways that wont work. - Thomas Edison

    Its not whether you get knocked down, its whether you get up. - Vince Lombardi

    "In this house we obey the laws of thermodynamics" - Homer Simpson

    Local 486 Instructor & Service Technician

  9. #9
    Join Date
    Sep 2019
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    Thread Starter
    Yuenlieu Detection Systems(tm) Our de-listing is a sign of Quality!"

  10. #10
    Join Date
    Sep 2015
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    Ontari-ari-ari-o
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    Quote Originally Posted by CSK View Post
    I talked to him too. He told me that CO could seep in, he told my wife that a crack could cause the gas to build up and explode. I asked multiple times for confirmation of that one, because wow. He also went to his truck to get "fresh batteries" to put in my fireplace remote receiver, to show me that it was broke and I needed to spend $340 to replace it. As soon as he left I put a different set of fresh batteries and it fired right up. This is one of several things that led me to become a bit suspicious.

    I'll play it safe, though, and get a different inspector out here this week, use it minimally until then. Thank very much for the replies, I really appreciate it.
    He's full of crap. There are numerous proper ways to test for an actual crack like for example... actually seeing one. A combustion analyzer is a great tool the last crack I found I was clearly able to show the homeowner as the CO readings went from 0 to well over 1000. Anyway the only red flag I need to see is the scare tactics from the tech. I don't do that stuff if the unit is unsafe I tag it, cap the gas line so the homeowner can't easily turn it back on (it is DANGEROUSLY unsafe to use right?) and I will find them a cost to replace the heat exchanger ASAP as well as the cost of a new unit so they can weight their options and decide on their own.

  11. #11
    Join Date
    Jan 2013
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    I carry a Milwaukee inspection camera good size to look thru the burners going into heat exchanger and I also remove the high limit and check them thru there

  12. #12
    Join Date
    Mar 2018
    Location
    Chico, Ca #StateofJefferson
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    Lol, I like your sense of humor! Never heard of this test but it makes a little sense, if you can squeeze or crush a heat exchanger by hand then its definitely bad, although I found two cracked heat exchangers today that would have passed his test, 2 tubes rusted out at the welds, but the rest of the metal looked new

  13. #13
    Join Date
    Jul 2007
    Location
    Virginia
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    Quote Originally Posted by CSK View Post
    PS I am planning to have it inspected by a different company in the next week, just in case. I want to live.
    Here is a good place to search for a qualified contractor who is trained in Combustion Performance and CO safety - https://www.myhomecomfort.org/why-yo...monoxide-test/
    Instead of learning the tricks of the trade, learn the trade.

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