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  1. #1
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    Corrosion on Cooling Coil



    I have a house that is about 5 years old I am getting Corrosion on in my cooling coils right at the place that the copper coil is held straigt by what appears to be a piece of galvanized metal. Does anyone have experience with this? Doesn't seem like coils should fail after 5 years. Attached is a picture. any help woudl be appricaited.
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  2. #2
    Brian_UK's Avatar
    Brian_UK is offline Moderator I am starting to push the Mods: of RE Site Moderator : and general nice guy
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    Re: Corrosion on Cooling Coil

    I agree, that metal should not be corroding,

    What is the greenish foam on the pipework from and what is it ?
    Brian - Newton Abbot, Devon, UK
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    Re: Corrosion on Cooling Coil

    It looks like time for a new coil. Make shure the pan drain is open to prevent standing water. How old is it, that looks about right for a 12+ yr coil

  4. #4
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    Re: Corrosion on Cooling Coil

    Quote Originally Posted by THE DUDE View Post
    It looks like time for a new coil. Make shure the pan drain is open to prevent standing water. How old is it, that looks about right for a 12+ yr coil
    The coil is 5 years old!

  5. #5
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    Re: Corrosion on Cooling Coil

    2012-06-129513-42-1895431.pdf

    That is soapy water to help us locate leaks - was sprayed on just before the pic was taken.

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    Re: Corrosion on Cooling Coil

    I think your coil might be suffering from a phenomina called 'formicary corrosion' This isn't down to one manufacturer supplying duff coils - more environmental conditions.

    Do a search and a whole new world will open up!

    Basically certain chemicals in the building attack the copper and cause a minute pit to form - sometimes too small to see. This corrosion tunnels through the copper, not directly but like it's other name 'Ants Nest Corrosion'

    How to actually prove this is the problem is a bit beyond me. You would need to get the coil tested by a specialist.

    How to remedy if this is the case? Well sorry, again this is a bit beyond me, and I feel the AC and refrigeration industy at this moment. There are spray on coil treatments which may help, different coil materials maybe?
    It is only in recent times that AC has become more common in the home and it would seem a combination of chemicals given off by paint, carpet, perfumes... add to that the fact that air change rates could be lower than before means these concentration may have risen.

    Like I say this seems to be a fairly new phenomina maybe not applicable to your situation and you may well hit a brick wall seeking a solution but good luck anyway.
    Last edited by Tayters; 03-10-2012 at 10:45 PM. Reason: Dropped an H.
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    Re: Corrosion on Cooling Coil

    Customers not been bleaching the drainpan and drain have they?
    Mostly found in Oxfordshire, UK :)

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    Re: Corrosion on Cooling Coil

    I've seen a few painted aluminum coil failures over the years, but those were on older equipment and resulted in replacements. This is an '06 unit that deserves many more years of operation - and the leak is actually more of a weakening, not completely worn through to open a gaping hole, but more or less has worn through enough to weaken the integrity of the tubing resulting in some small, fine cracks.

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    Re: Corrosion on Cooling Coil


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    Re: Corrosion on Cooling Coil

    I've got the same situation in a dx unit which has been serving in a photolab. Air is pregnant of ammonia, which is known to be aggressive to copper. Coil was leaking in multiple places and it's only 1.5 years old.

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    Re: Corrosion on Cooling Coil

    was the coil treated when it was installed?? you need an dx unit running on full fresh air and a remote return air sensor, also an exhaust fan to remove hazardous fumes

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    Re: Corrosion on Cooling Coil

    Regarding the issue I mentioned here is some info from Carrier on it. There a good article that's more from a chemists stance which explains the nuts and bolts if you search for it as well.

    http://www.hydro-temp.com/help/drawi..._Corrosion.pdf

    Cheers, Andy.
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    Re: Corrosion on Cooling Coil

    Quote Originally Posted by install monkey View Post
    was the coil treated when it was installed?? you need an dx unit running on full fresh air and a remote return air sensor, also an exhaust fan to remove hazardous fumes
    No, it's a close control unit. All recirculated air.

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    Re: Corrosion on Cooling Coil

    Possibly cathodic corrossion due to poor grounding/earthing of all components. Starts with galv/ zinc and steel surfaces and moves to copper.

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