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  1. #1
    Join Date
    May 2008
    Location
    Bergen County, NJ
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    36

    AC Usage & Humidity

    I recently posted an issue I was having with my AC in this forum and received A LOT of great help/advice so I have another question. During the warmer months when people use their A/C's, isn't the indoor humidity suppose to go down?

    I'm noticed that my indoor humidity is about 45 - 60% when the temp is at about 73 - 75 degrees. The A/C servicing my second floor (where I'm noticing the issue) is a 2 ton Weather King. My second floor is about 700 - 800 square feet. Something worth mentioning is that I'm also having an issue with my system not being balanced so one of my bedrooms gets a lot cooler (in the summer) / warmer (in the winter) than my other bedrooms and I found out that the HVAC installer didn't install dampers.

    So my question is would it be normal for an area that's being air conditioned by a central AC have such a high humidity level? If not, what should I be checking for?

    Thanks!

  2. #2
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,704
    It depends on teh humidity of your area, and how often your A/C runs also.
    2 tons sounds a little big for 800 sq ft.
    your blower may need slowed a little.
    Have your install install dampers and slow the blower.
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  3. #3
    Join Date
    Dec 2006
    Location
    Middle Tennessee
    Posts
    11,347

    *

    50% is a good humidity level

    even i think your system is oversized, and i dont say that too often!

    as stated slow the blower down for lower humidity percentages!



    .

  4. #4
    Join Date
    Apr 2002
    Posts
    11,808
    a ton for 400 square feet sounds like a home in the tropics with no insulation

    you must be upstate NY, not all that humid up there, otherwise I think you would end up with higher RH

  5. #5
    Join Date
    Jan 2004
    Location
    Lancaster PA
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    67,704
    Quote Originally Posted by Airmechanical View Post

    even i think your system is oversized,

    .
    You sir. Are an imposter, posting under airmechanicals name. He would never say that.
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  6. #6
    Join Date
    Dec 2006
    Location
    Middle Tennessee
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    Quote Originally Posted by beenthere View Post
    You sir. Are an imposter, posting under airmechanicals name. He would never say that.

    your correct, i would never say that, someone must have hacked into my computer yesterday



    .

  7. #7
    Join Date
    Jan 2004
    Location
    Lancaster PA
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    67,704
    Quote Originally Posted by Airmechanical View Post
    your correct, i would never say that, someone must have hacked into my computer yesterday



    .
    LOL
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  8. #8
    Join Date
    Aug 2003
    Location
    Fort Worth, TX
    Posts
    11,283
    Quote Originally Posted by CoquiLostInNY View Post
    I recently posted an issue I was having with my AC in this forum and received A LOT of great help/advice so I have another question. During the warmer months when people use their A/C's, isn't the indoor humidity suppose to go down?

    I'm noticed that my indoor humidity is about 45 - 60% when the temp is at about 73 - 75 degrees. The A/C servicing my second floor (where I'm noticing the issue) is a 2 ton Weather King. My second floor is about 700 - 800 square feet. Something worth mentioning is that I'm also having an issue with my system not being balanced so one of my bedrooms gets a lot cooler (in the summer) / warmer (in the winter) than my other bedrooms and I found out that the HVAC installer didn't install dampers.

    So my question is would it be normal for an area that's being air conditioned by a central AC have such a high humidity level? If not, what should I be checking for?

    Thanks!
    Are you noticing these swings in humidity during the course of a day, or at random times you measure? Are the temperature swings concurrent with swings in humidity, or does the temperature hold fairly steady while humidity swings?

    If the latter, be sure you are not running your indoor blower continuously. Let it cycle with the outdoor unit.

    Oversizing is not the only contributer to inadequate dehumidification. If the house leaks in outdoor air like a sieve, the a/c can be overwhelmed and not be able to keep up with removing enough humidity to keep you comfortable. Being this is an upstairs area, you may have light fixtures and other ceiling penetrations that are leaking air into or out of the attic, which means you are not containing the air you are paying to cool as well as it should be.

  9. #9
    Join Date
    May 2008
    Location
    Bergen County, NJ
    Posts
    36
    Thanks for the info. I'll have my new HVAC guy take a look at my ducts to see if any air is leaking and if he could slow down the blower. He can probably do this when he installs the dampers the originally HVAC installer FAILED to install. One thing that the new HVAC guy said overall is that a 14" x 8" return duct was really small for an entire second floor so he's talking to me about making it larger.

    BTW - The house is located in Bergen Co, NJ. As for the humidity levels throughout the day, I would say that the level remains the same all day/night long. In terms of the A/C usage, the thermostat is set to run automatically so from one of the post I'm guessing I should try running the fan on constant.

  10. #10
    Join Date
    Jan 2004
    Location
    Lancaster PA
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    67,704
    24/7 fan operation can increase humidity.
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  11. #11
    Join Date
    May 2008
    Location
    Bergen County, NJ
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    Oh... okay! I must have misunderstood. I'll leave my thermostat to "auto".

    Thanks,

  12. #12
    Join Date
    May 2008
    Location
    Bergen County, NJ
    Posts
    36
    Some more questions regarding high humidity levels.

    I was recently told by my new HVAC guy that the original installer never installed filters in either of my units (he actually left the construction filter in) so I went out and purchased some disposable 3M three month filters which I installed. In addition I set the small fan in my attic to automatically turn on when the temp reaches 75 instead of 90 like previously set.

    After installing the filter and turning on the attic fan I noticed the humidity in my second level jumped to 62 percent during the night time hours but during the day the level dropped down to 49 - 52 percent. Could installing the filter or turning on the attic fan made my humidity problem worst?

    Also, while at Home Depot picking up the filters I started talking to the sales guy and explained my situation. He said if my return register was too small (its only 25" X 18") that my system could be straining to suck in the humid air. Is this true? If so, how large should I make my return if I have a total of 14 supply registers, 9 which I constantly leave open.

    Thanks.

  13. #13
    Join Date
    Apr 2007
    Posts
    6,285
    Did you get pleated filters?

    If your guy is already telling you your system is restrictive those things won't help just fyi.

    If your attic fan leaves your attic in a negative pressure and not sealed off completely from the house (most likely not unless you know it is) it can cause higher outside air infiltration rates. Then it would depend on outdoor conditions to know which direction the humidity will go.

    I like using dew points because % RH can be deceptive unless understood.

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