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  1. #1
    Join Date
    Aug 2012
    Posts
    7

    Confused POLAR FOAM and rusty leaking EVAPORATOR COILS

    We built our home in 2005 and had Polar Foam insulation put on all exterior walls, attics and between 1st and 2nd floor.

    Is anyone aware of the effects of polar foam on air handlers in attics? Two of three Trane units have had thus far in 7 years, each 2 new evaporator coils. Coils completely rusted out and leaking all refrigerant within 24 hrs. The 2.5 ton has required 2 new fan motors as well. The latest replacement on the 2.5 ton is an aluminum evaporator coil, but very pricey! The other unit, 2 ton for upstairs, had a burned up fan motor and completely rusted evaporator coil. Fan also completely covered in mold. It was recommended to replace the air handler and condenser. Thought it would be more cost effective. We did, but with a Broan. Now we can't get the air cool and humidity down unless we drop the thermostat to 72 degrees. Can't wait for my next electric bill.
    The upstairs is 1108 sq ft with a 2 ton 14 seer rating (cooling), and cooling capacity (Btuh) 24000. No clue if this means anything.
    Our third unit is in a closet on the main floor with no coil or fan issues whatsoever.
    All three Trane units have always been set at 77 degrees for cooling in the past, with cooling and humidity control excellent. Pretty good for Florida during the hottest time of year.

    It was also recommended to have two attic vents placed in the roof where the new Broan is located. Other than cutting into the foam and creating a hotter attic, this has not improved our situation. So far they have no other recommendations for us, other than slowing down the fan speed for better humidity control? I don't even feel the blower as it is, at the speed it is set at.

    Today we told the rep and installer that this unit is unacceptable as it is and to come up with a solution or removal and refund.
    Any ideas what the problem could be with the Broan?
    Any thoughts on foam insulation and air handlers in attics?

    Thanks,
    Delnan

  2. #2
    Join Date
    Dec 2001
    Location
    Ocean Pines, MD
    Posts
    6,935
    Some more info on the equipment, new and old, model #'s would help.
    Any other equipment installed when house was built to ventilate?

  3. #3
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    66,824
    You had a hole put in a foamed roof? Defeats the purpose of having it foamed.
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    How many times must one fix something before it is fixed?

  4. #4
    Join Date
    Aug 2004
    Location
    North Richland Hills, Texas
    Posts
    14,914
    The foam isn't "the" problem, but it is common for builders and HVAC contractors to completely fail at designing and installing appropriate HVAC systems for homes that are insulated with foam.
    Distressingly common...

    More than likely, you have a combination of issues, including over sized equipment, restrictive duct systems, off gassing of VOC's from all of the materials used to build, finish, and furnish the home, and not enough fresh air changes to purge it all.

    Also, whoever recommended ventilating the attic is clueless. You need to have the holes repaired, and seal the attic back up.
    If more government is the answer, then it's a really stupid question.

  5. #5
    Join Date
    Aug 2012
    Posts
    7
    Old unit Trane 2 ton model #4TEE3F31A1000AB serial # 4455MOCIV

    New unit Broan 2 ton model #B6UMAX24K-B serial #B6D120203989

    Unfortunately no other equipment installed to ventilate.

  6. #6
    Join Date
    Jan 2009
    Location
    Keokuk, IA
    Posts
    5,520
    An 1100 sqft all foam insualted upstairs likely doesn't even need 1.5 tons. Believe it or not, Florida is very humid, but not nearly as hito as people think it is in terms of designing equipment. It just stays hot year round and has no winter. But the design temperatures are no different than many parts of the midwest. Very common to have oversized equipment in the south.

    The old equipment probably had a smaller coil surface. THh newer higher effciency equipment has larger coils that don't dehumidify as well, but in lab testing (where they are only trying to move totla heat energy (latent & sensible), not control humidity).

    What can you do now? Have the airflow evaluated. You may be able to reduce the airflwo for better dehumidification. Make sure ductwork is sealed well. Foamed attics, especially if open cell foam was used and depending on how well sealed it is, can still allow a lot of humidity in there even if it doesn't get that hot. The indoor space being cooler, and hte wood roof deck being hot, will cause moisture ot migrate indoor in the afternoon. The process can reverse itself at night. It's still normal for a foamed attic to get to 90F in the later afternoon. But an unfoamed attic would be an unbearable 130F. Also, did they remove the insulation form the attic floor when they foamed the roof deck? You need ot have that insulaiton removed so the space can communicate with the conditioned space. Also, if it's cellulose, that material holds a lot of moisture.

  7. #7
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    66,824
    Quote Originally Posted by Delnan View Post
    Old unit Trane 2 ton model #4TEE3F31A1000AB serial # 4455MOCIV

    New unit Broan 2 ton model #B6UMAX24K-B serial #B6D120203989

    Unfortunately no other equipment installed to ventilate.
    I believe those are the air handler model numbers, post the outdoor units model number also.
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    How many times must one fix something before it is fixed?

  8. #8
    Join Date
    Aug 2012
    Posts
    7
    model # 4TWR2018A1000AB serial # 5161KT02F Trane

    model #NT4BD-024K Broan

  9. #9
    Join Date
    Oct 2010
    Location
    Anderson, South Carolina, United States
    Posts
    5,674
    My guess is the Unit is oversized thus creating high humidity in your house and air handler, due to short cycling

  10. #10
    Join Date
    Oct 2010
    Location
    Anderson, South Carolina, United States
    Posts
    5,674
    Also need to ventilate the house because it's choking!

  11. #11
    Join Date
    Jul 2006
    Location
    Virginia
    Posts
    4,515
    What was the reason for the larger unit other then more profit for the installer .

  12. #12
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    66,824
    Quote Originally Posted by catmanacman View Post
    What was the reason for the larger unit other then more profit for the installer .
    Cause the house is the same size as the last house they put that size A/C in.
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    How many times must one fix something before it is fixed?

  13. #13
    Join Date
    Aug 2012
    Posts
    7
    Both units are 2 ton. The previous Trane unit was 2 ton as is this one so he says. The unit says 2 ton.

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