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  1. #1
    Join Date
    May 2018
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    Central Florida
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    Walk in sweating insulation on suction line

    At my site, we have 72 walk in freezers and coolers. Most of them are in un-conditioned spaces.

    We have an ongoing issue with many of them with the suction side sweating.... the outside of the INSULATION sweating. It sweats so badly that it drips off of the insulation onto the top of the boxes, collects in pools of water and then runs down the wall at the lowest point. The walk in freezers seem to be the worst.

    Our largest freezer collected so much water on top recently that the whole top of the box got heavy with water and completely fell in costing thousands of dollars for an outside contractor to come in and fix.

    Any ideas on why the insulation would sweat excessively?

  2. #2
    Join Date
    Sep 2007
    Location
    edmonds wa
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    Is the insulation old and brittle, may need to replace with a higher R rating and then a vapor shield over that.
    UA Local 32 retired as of Jan 2020

  3. Likes R600a, BALloyd liked this post.
  4. #3
    Join Date
    Jul 2019
    Location
    Oklahoma home its in the name
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    1,260
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    I would think it was poor quality or too thin. How thick is it?
    Quote Originally Posted by 3.14 View Post
    At my site, we have 72 walk in freezers and coolers. Most of them are in un-conditioned spaces.

    We have an ongoing issue with many of them with the suction side sweating.... the outside of the INSULATION sweating. It sweats so badly that it drips off of the insulation onto the top of the boxes, collects in pools of water and then runs down the wall at the lowest point. The walk in freezers seem to be the worst.

    Our largest freezer collected so much water on top recently that the whole top of the box got heavy with water and completely fell in costing thousands of dollars for an outside contractor to come in and fix.

    Any ideas on why the insulation would sweat excessively?
    Sent from mars using Tapatalk

  5. #4
    Join Date
    May 2018
    Location
    Central Florida
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    204
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    Thread Starter
    I’m not there now but I would say 3/4 inch walls and about 5 years old.

    To me it does not look very deteriorated.

    The large WIF that had the roof fall in made us suspicious of high humidity in the ceiling area above the box, so we put in two LARGE exhaust fans to try and move some air... to no avail. The sweating off the suction line insulation is just as bad.

    We also have fire sprinklers penetrating through the roof of all walk-ins at regular intervals. Above the boxes the fire sprinkler lines are insulated.... same thing.... the INSULATION on the fire sprinkler lines are forming condensate and adding to the problem.

  6. #5
    Join Date
    Jan 2010
    Posts
    19,279
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    Quote Originally Posted by 3.14 View Post
    I’m not there now but I would say 3/4 inch walls and about 5 years old.

    To me it does not look very deteriorated.
    I've got insulation older then that out there and they don't sweat.
    Might be a geographical thing.

  7. #6
    Join Date
    May 2018
    Location
    Central Florida
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    Thread Starter
    East central Florida here.

  8. #7
    Join Date
    Jan 2010
    Posts
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    Yeah I'm up north in Ohio so humidity isn't typically a issue this time of year.

  9. #8
    Join Date
    Aug 2002
    Location
    Southold, NY
    Posts
    27,164
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    1/2 -3/4” wall minimum
    Seal the ends

    Replace all of it!

  10. #9
    Join Date
    May 2014
    Location
    Bay Area California
    Posts
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    It's probably all about the temp of the suction line, and the dew point of the air where the piping is. Remember, the insulation does not stop heat transfer, all it does is slow that heat transfer down.

    There have been a couple of sites where we had to put insulation over the insulation. Take one box, maybe the worst one, take it off line. Then strip the existing insulation, and put new on it, the thickest available. Then put another layer on top of that. Following good practices.

    How old is the install? And what type of insulation?
    I do a triple evac with nitro to remove non condensables.

  11. #10
    Join Date
    Nov 2009
    Location
    Richmond, working under tarps
    Posts
    971
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    if the sweating is really an issue

    bring in a dedicated insulating company and have it done

    we would bring in a local contractor that did our NHH3 systems

    done right and forever, just make there are NO leaks

  12. #11
    Join Date
    Apr 2003
    Location
    Maple Grove, MN
    Posts
    3,351
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    This issue usually starts with the hangers. The insulation either gets cut to go around the hangers, or the hangers compress the insulation and create a weak spot. Zip ties create the same problem. The insulation gets compressed or cut and then doesn't work good in those spots, and then the Armaflex turns into a big sponge. Elbows have the same issue. The insulation gets compressed and thinner as it goes around the elbow.

    Indy's post above probably has the best advice. Getting a professional insulating company out to redo stuff would probably be money well spent.
    If at First You Don't Succeed, Skydiving Is Not for You.

  13. #12
    Join Date
    Oct 2009
    Location
    Raleigh, NC
    Posts
    953
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    It's very simple stuff. You need to know the line temperature and the normal dewpoint of the air around the insulation. The surface of the insulation must stay below dewpoint. Consult the insulation manufacturers installation charts using this information to determine wall thickness required. I would guess you would need at least one inch thick closed cell (Armaflex) insulation, WELL SEALED to stop your problem. The old insulation is likely waterlogged now and there is no saving it.

    Sent from my Pixel 2 using Tapatalk

  14. #13
    Join Date
    Jan 2010
    Location
    Sea to Sky
    Posts
    3,650
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    I have seen it in grocery store runs when the insulation was never sealed properly to begin with, combined with age and being compressed.

    Those lineset saddles they sell now really help prevent insulation damage that can cause this problem.

    You will never stop it unless all the insulation is replaced properly.

    As mention....maybe get some pro insulators to do it.

    Sent from my SM-G965W using Tapatalk

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