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  1. #1

    Is my AC charged properly?

    I just had a new 13 SEER 2 ton ac unit installed. New A coil and lines. The temperature drop is right around around 20 degrees, but the line temps make me wonder if it is fully charged. On my 30 year old 5 SEER unit when it worked properly, the large line was cold and the small line was hot to the touch. On the new unit the large line is cool, but not cold, and the small line is warm, but not hot. I guess I am trying to figure out if this is normal or if the installer might have shorted me on the refrigerant?

    The house is cooling normally as the temp is 55 degrees coming out of the register on a 83 degree day, but I am worried if it will be able to cool the house on a 100 degree day. Should I call the guy back out? Is there anything else I can check to determine if it was done properly?

  2. #2
    Join Date
    Dec 2005
    Location
    Cincinnati, Oh
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    5,094
    Quote Originally Posted by mpoore View Post
    I just had a new 13 SEER 2 ton ac unit installed. New A coil and lines. The temperature drop is right around around 20 degrees, but the line temps make me wonder if it is fully charged. On my 30 year old 5 SEER unit when it worked properly, the large line was cold and the small line was hot to the touch. On the new unit the large line is cool, but not cold, and the small line is warm, but not hot. I guess I am trying to figure out if this is normal or if the installer might have shorted me on the refrigerant?

    The house is cooling normally as the temp is 55 degrees coming out of the register on a 83 degree day, but I am worried if it will be able to cool the house on a 100 degree day. Should I call the guy back out? Is there anything else I can check to determine if it was done properly?
    Do a temperature in the return, and a temperature in the supply.
    Is the unit in the attic?
    "Better tell the sandman to stay away, because we're gonna be workin on this one all night."

    "Dude, you need more than 2 wires to a condenser to run a 2 stage heatpump."

    "Just get it done son."

    Dad adjusted

  3. #3
    Join Date
    Jul 2010
    Location
    nebraska
    Posts
    1,629
    That's the way they're supposed to run. Don't worry about it.

  4. #4
    Join Date
    Oct 2010
    Location
    Anderson, South Carolina, United States
    Posts
    7,477
    Sounds like its working good, let it be

  5. #5
    Join Date
    Oct 2010
    Location
    Anderson, South Carolina, United States
    Posts
    7,477
    Your old unit was probably overcharged causing it to have no superheat

  6. #6
    Join Date
    Mar 2009
    Location
    Mount Holly, NC
    Posts
    3,299
    the large line being cold indicates too low a superheat from being overcharged.
    the small line being warm, as in slightly above outdoor temp is perfect, and an indication of a clean condenser coil, and a good charge.
    if the small line is hot to the touch, unless it's 125F outside, indicates an inefficient condenser, that is likely quite dirty, and possibly overcharged.
    The TRUE highest cost system is the system not installed properly...
    The three big summer hearththrobs...
    Mel Gibson
    Dwane Johnson
    The A/C repairman

  7. #7
    Join Date
    Jul 2006
    Location
    Virginia
    Posts
    4,731
    Thats where the beer can cold charging method came from ,now days we use subcool and superheat the small liquid line should be about 5 to 10 degees above outdoor temp
    We really need change now

  8. #8
    Thank you all for the quick replies.

    The unit is not in an attic. It is ground level on the north side of the house.

    The consenus seems to be that its fine. Sounds like I am not used to a well running system.

  9. #9
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,538
    If you are maintaining <50%RH in the living space after a couple hours high cooling loads, you probably have a adequate charge of refrigerant and also correct air flow rate through the cooling coil. <50%RH is important for comfort and to growing mold/ dust mites.
    Also critical for indoor air quality is purging indoor polutants and renewing oxygen. Mechanically adding an air change of filtered fresh air in 4-5 hours is ideal when the home is occupied.
    Regards TB
    Bear Rules: Keep our home <50% RH summer, controls mites/mold and very comfortable.
    Provide 60-100 cfm of fresh air when occupied to purge indoor pollutants and keep window dry during cold weather. T-stat setup/setback +8 hrs. saves energy
    Use +Merv 10 air filter. -Don't forget the "Golden Rule"

  10. #10
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    6,323
    Quote Originally Posted by mpoore View Post
    I just had a new 13 SEER 2 ton ac unit installed. New A coil and lines. The temperature drop is right around around 20 degrees,

    The house is cooling normally as the temp is 55 degrees coming out of the register on a 83 degree day,
    but I am worried if it will be able to cool the house on a 100 degree day.

    Should I call the guy back out?
    Is there anything else I can check to determine if it was done properly?
    The unit is operating properly.
    [ Only call the tech out, If you wish to add another unit. ]

    However, the unit operating properly is no not the most significant parameter in determining whether is can cool to your satisfaction on a 100 degree day.
    If your house is 2,600 square feet in Canada, it might be adequate 97% of the time.
    If your house is 1,800 square feet in IOWA, it might be adequate ( < 80'F room temp.) 87% of the time in mid-summer.
    If your house is 1,800 square feet in Houston it might be adequate 65% of the time in mid-summer.
    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

  11. #11
    Join Date
    Jun 2005
    Location
    SW Wisconsin
    Posts
    5,006
    I just had a new 13 SEER 2 ton ac unit installed. New A coil and lines. The temperature drop is right around 20 degrees, but the line temps make me wonder if it is fully charged.

    The house is cooling normally as the temp is 55 degrees coming out of the register on a 83 degree day, but I am worried if it will be able to cool the house on a 100 degree day. Should I call the guy back out? Is there anything else I can check to determine if it was done properly?
    Okay, get a humidity gauge; hardware stores usually have them at a very low cost.

    A 2-Ton; R-410A; 13-SEER; @75F indoor temp & wet bulb 63F or, 51% relative humidity; Goodman data; temp drop is 19F; 75-19 is 56F.

    The humidity may be a little less than 51% which would result in an additional 1 degree drop; 'IF' the humidity is 51% then, I'd say the airflow is ballpark close enough to 400-CFM per/ton, or 800-CFM.

    Humidity levels have the major effect on the temp-drop numbers; a higher humidity means less drop, low humidity yields increased drop numbers.

    Additionally, you're taking the temp at a register therefore, the duct run would have some heat-gain resulting in the reality that the temp-drop is lower than 55F directly after the coil.

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