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  1. #1
    Join Date
    Mar 2004
    Location
    Grottoes VA
    Posts
    5,856
    I installed this unit 2 years ago. RPMC-030/RBHK21J

    Customer complains of high humidity and the wood floors are buckeling so bad the front door won't open.

    RA 42.8%RH and 71.9 DB
    SA 58.8%RH and 53.8 DB (sorry no WB, mine broke)
    OA 68 DB (a cool day and not a good time to check a/c

    HO's hygrometer reads 68%

    Dehumidifier (in living room) reads between 50-55%

    House is shaded most days and temps have been in the 90's with high humidity (60%).

    Vapor barrier in crawl is present but not a solid sheet, no standing water in crawl.

    House is 1800sq feet with many large windows and 12 foot ceilings.

    The a/h is set for 15% less cooling airflow and -10% airflow as well as 2.5 ton.

    Customer does not complain of lack of cooling.

    I am trying to locate blueprints for load calc.

    Any help or ideas are welcome.
    Karst means cave. So, I search for caves.

  2. #2
    Join Date
    Feb 2004
    Posts
    2,597
    clogged dryer vent.

  3. #3
    Join Date
    Mar 2004
    Location
    Grottoes VA
    Posts
    5,856
    I never thought of that, but dryer is on oposite side of house from buckeling floor. I will check though.
    Karst means cave. So, I search for caves.

  4. #4
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    33,914
    You said RA has 42% RH? That's extremely low to me! We are pretty dry right now. Let me mosey out and see what mine reads... 48% in here, usually reads 52-56% in steamy weather. ComfortR is turned on, TXV coil, 425 CFM/ton airflow.

  5. #5
    Join Date
    Aug 2003
    Location
    Fort Worth, TX
    Posts
    11,292
    How's the ductwork, especially the supply runs? Are they in the attic or crawler? A supply leak could create a negative pressure in the house, causing humid outdoor air to infiltrate through cracks and gaps in the home's construction. If the subfloor below the hardwood floors is a little leaky, humid air drawn in from the crawler could easily warp the floor.

    As for getting wet bulb temps without a sling psychrometer, one of these can be handy:



    Your indoor return wet bulb is about 58F and the supply is around 48F WB.
    • Electricity makes refrigeration happen.
    • Refrigeration makes the HVAC psychrometric process happen.
    • HVAC pyschrometrics is what makes indoor human comfort happen...IF the ducts AND the building envelope cooperate.


    A building is NOT beautiful unless it is also comfortable.

  6. #6
    Join Date
    Mar 2004
    Location
    Grottoes VA
    Posts
    5,856
    The supplys and return's are in the crawl. The duct work is intact just not super tight.

    Any idea how to fix the moisture infiltration.

    Thanks for the chart, I will set it as wallpaper.
    Karst means cave. So, I search for caves.

  7. #7
    Join Date
    Dec 2003
    Posts
    2,366
    In my oppinion releative humidity can only be measured consistently accurate by obtaining the wet-bulb temperature with a sling psychrometer. The unit does not sound oversized. The floor may be buckling because of something unrelated to the ac unit. I would return on a hot day with a sling-psych and get an accurate reading before worrying to much about it.

  8. #8
    Join Date
    Apr 2004
    Posts
    7,680
    I'm with Bald, why would the return air have a RH of 42.8 and the house have a RH of 50-55% or 68%. If the unit is not getting humidity back to it, it cant remove it.

    Get ya a good sling and recheck this place. Somthing aint right.

    Also, consider adding a two stage stat, connect Y2 to the ODD terminals and configure it for ODD. This will give you a quazi two stage system. When you use the BHK, it should be done on every job since it has the ability and the only cost add is a two stage stat which you probably use any way. When the unit calls for Y1, you will get about 850 CFM and a great latent capacity. as the load increases you would kick it up to 1000 CFM and increase the sensible capacity to overcome the sensible load.


  9. #9
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    6,243

    Question Floor Condition

    Originally posted by shophound
    If the subfloor below the hardwood floors is a little leaky, humid air drawn in from the crawler could easily warp the floor.
    Possible Causes in general:
    1. A/C System
    2. Building Envelope
    3. Internal Source

    1. It appears that A/C system is operating rather well.

    2. I'd have to re-emphasize Shophound's idea of "leaky floor" due to humidity infiltrating from crawl space as a plausible source. Perhaps, even a continuous minor leak can create buckling problem over an extended time period.

    Age of house is __ ?

    3. __
    Designer Dan
    It's Not Rocket Science, But It is SCIENCE with "Some Art". ___ ___ K EEP I T S IMPLE & S INCERE

    Define the Building Envelope and Perform a Detailed Load Calc: It's ALL About Windows and Make-up Air Requirements. Know Your Equipment Capabilities

  10. #10
    Join Date
    Mar 2004
    Location
    Grottoes VA
    Posts
    5,856

    Re: Floor Condition

    [QUOTE]Originally posted by dan sw fl
    Originally posted by shophound

    Age of house is __ ?

    3. __
    11 years old.

    Doc, I think her hygrometer is inaccurate, I measured the RA at the return grille, about 10 feet from her Hygrometer.
    I should have put the 2 stage stat in but she didn't want any other t-stat but the one she has. She is a little eccectric (sp?).
    Karst means cave. So, I search for caves.

  11. #11
    Join Date
    Jul 2005
    Posts
    171
    I suspect buckling not related to hvac. I don't know what your "buckling" looks like, but if you leave liquid water on hardwod you wil get "cupping", meaning the edges of each strip will curve up so each strip becomes concave and a gap will be evident between adjacent strips.
    Have a flooring contractor check the moisture content of the wood. They have a moisture meter with two sharp prongs that they stick into the wood and get an instant reading. They will also tell you what caused the buckling.


  12. #12
    Join Date
    Jul 2005
    Posts
    171
    Is there maybe a humidifier on the air handler that somebody forgot to turn off for the summer?

  13. #13
    Join Date
    Apr 2004
    Posts
    7,680
    I dont know, I still think something else is wrong I cant imagine her complaining of high humidity at 42%. At 72 degrees with 42% rh, she ought to be complaining shes freezing. Thats like a 56 WB return and a 48 degree WB supply.


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