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  1. #14
    Join Date
    Jan 2007
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    Stongsville Oh
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    The issue in my mind is as a service person we are the ones that assess the equipment. We are to inform the customer of a problem with the equipment. If we find worn belt we tell them, worn pulleys, we tell them, cracked heat exchanger we tell them. It is up the the customer to give a PO to replace ht ex or replace equipment. Not unlike our cars when we take them in for service. If the idler arm is worn he tells us, our cars are not locked down because it could be dangerous and cause loss of control, it is up to us at that point to get it replaced. It shouldn't be in our scope to try to determine what type of crack is ok and what isn't. The fact is if there is a crack it will only get worse not better. We cannot answer how it happened or how long it will last. It is broken and should be repaired, that is our job.
    ckartson
    I didn't write the book I just read it!

  2. #15
    Join Date
    Aug 2002
    Location
    manitowoc wisconsin
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    4,947
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    I put paint in a paint sprayer & added 90 psi to it.Paint comes out just fine.
    Are you following this?
    A hairline crack is stressed metal.
    Try to think of it as bending a piece of metal back & fourth.
    I know this will make it weak/stressed but cannot tell you when it will split in two.
    Take your time & do it right!

  3. #16
    Join Date
    Feb 2014
    Location
    Phoenix Az.
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    11
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    If it was me wouldn't take any chances I would replace heat xchanger life is better than death anytime

  4. #17
    Join Date
    Jan 2010
    Location
    Toronto,Ontario Canada
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    395
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    well. i was taught a cracks a crack. doesnt matter how small it is. and my boss brang up a good point. we dont know when we are going to be back so before it gets worse shut it down when you have a chance.

    I had gone to many calls where i condemmed the rtu and other companies went there and turned it back on. and then the following winter go back and its tripping on rollout.

    Sometimes you just have to play it safe and take pics of the hex. and hope they do the right thing and replace the hex. its another thing to claim a crack when there isnt a crack.

    Customers believe our word and you just have to be honest. Do your job and do it right with a smile. (-:

    *sometimes if the crack is very easy to spot i would ask one of the managers to come up on the roof and see it his/her self. depending if they want to or not! haha most of them are afraid to go on a roof


    Sad thing is about all these cracks, they all can be avoided with doing a proper maintenance change belts filters at least twice a year. Sad fact but its true.......
    Get er Done!

    Do what has to be done
    when it has to be done
    as well as it has to be done
    And doing it all the time.

  5. #18
    Join Date
    Mar 2013
    Location
    Billington Heights, NY
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    21,628
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    Quote Originally Posted by akelesis View Post

    Sad thing is about all these cracks, they all can be avoided with doing a proper maintenance ... Sad fact but its true.......
    Not true, using your logic - all maintained furnaces never crack.

    At some point the metal will fail, whether due to age, manufacturing defect or poor install. Maintenance is needed to identify when and where the cracks occur, not to prevent them.

  6. #19
    Join Date
    Nov 2006
    Location
    Southeastern Pa
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    Sadly, all the maintenance in the world will not prevent a defective heat exchanger. Heat exchangers are made of various types and qualities of metal. Some will last for a very very long time. I have Lennox units that are 13 years old that have never had a heat exchanger problem, and never had a heat exchanger replaced. I have Carrier units that are half that old where there is a hole I can stick my pen into.

    It's the metal, and the associated costs in producing the part that are the controlling factors in hx life. Mfgs can make a heat exchanger that would last 30 years. They instead predict how long the unit will last overall, and use that as a benchmark for hx quality.

    Quote Originally Posted by akelesis View Post
    well. i was taught a cracks a crack. doesnt matter how small it is. and my boss brang up a good point. we dont know when we are going to be back so before it gets worse shut it down when you have a chance.

    I had gone to many calls where i condemmed the rtu and other companies went there and turned it back on. and then the following winter go back and its tripping on rollout.

    Sometimes you just have to play it safe and take pics of the hex. and hope they do the right thing and replace the hex. its another thing to claim a crack when there isnt a crack.

    Customers believe our word and you just have to be honest. Do your job and do it right with a smile. (-:

    *sometimes if the crack is very easy to spot i would ask one of the managers to come up on the roof and see it his/her self. depending if they want to or not! haha most of them are afraid to go on a roof


    Sad thing is about all these cracks, they all can be avoided with doing a proper maintenance change belts filters at least twice a year. Sad fact but its true.......
    [Avatar photo from a Florida training accident. Everyone walked away.]
    2 Tim 3:16-17

    RSES CMS, HVAC Electrical Specialist
    Member, IAEI

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  7. #20
    Join Date
    Jul 2008
    Posts
    1,023
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    Thread Starter
    My main point was regarding hairline cracks in commercial equipment absolutley an atmospheric vented fan temp or time on would expose a co risk- on say a a continuos fan Rtu with induced draft if the flame " ROLLS OUT" clearly the fan pressure overcomes the negative pressure INSIDE the ht exc- so how is co leakage possible u absolutly positively take pictures show customer lock out ect- I was more interested in discussing the physics not ethics and I agree even the most well maintained unit is subject to failure

  8. #21
    Join Date
    Nov 2006
    Location
    Southeastern Pa
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    Basically, I have bern told that the American Fuel Gas people say that no defects are acceptable for safe operation.

    As for the physics of how the CO can get out in the situation you described, it is simple. Gaseous vapors dont't always behave as expected. Due to turbulence, pressure can force air into the hx and at the same time, force flue gasses out into that airstream.

    It would be nice and comforting to think that blower pressure would ensure that all of the flue gasses are pulled along by the inducer, but that idea is not 100% reliable in practice.
    [Avatar photo from a Florida training accident. Everyone walked away.]
    2 Tim 3:16-17

    RSES CMS, HVAC Electrical Specialist
    Member, IAEI

    AOP Forum Rules:







  9. #22
    Join Date
    Feb 2011
    Location
    Peoria, IL
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    Quote Originally Posted by timebuilder View Post
    Sadly, all the maintenance in the world will not prevent a defective heat exchanger. Heat exchangers are made of various types and qualities of metal. Some will last for a very very long time. I have Lennox units that are 13 years old that have never had a heat exchanger problem, and never had a heat exchanger replaced. I have Carrier units that are half that old where there is a hole I can stick my pen into.

    It's the metal, and the associated costs in producing the part that are the controlling factors in hx life. Mfgs can make a heat exchanger that would last 30 years. They instead predict how long the unit will last overall, and use that as a benchmark for hx quality.

    This is the sad truth, it comes down to cost of material, how often they can sell you another one. its business, Things years ago lasted a long, long time. But if it does, you cant sell another one to the same person for a long long time. (stealing from the bionic man series) We have the technology to build it better.

  10. #23
    Join Date
    Jan 2006
    Location
    Powell River, BC, Canada
    Posts
    763
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    Realist: is that an oil frurnace HX? If so, what brand/model? Just curious, as I have many oil furnaces in my area and I don't recognize the HX from the pic. Thanks!
    Where are you? Are you done yet? I got ONE more call for you.....

  11. #24
    Join Date
    Mar 2011
    Location
    Portsmouth, VA
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    53
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    I always condemn the unit when I see this condition.

  12. #25
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    Mar 2013
    Location
    Billington Heights, NY
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    21,628
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    looks like it may be a horizontal drum?

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