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  1. #1
    Join Date
    Jun 2008
    Posts
    4

    new HVAC not cooling

    We recently had a contractor install a new unit (a Bryant Puron 2.5
    ton in a 1500sq/ft 3br/2ba home) a couple of months ago. This week
    we've had some really warm weather with temperatures in the 90s
    nearing 100 degrees. The problem is the unit is not cooling the house.
    The unit runs all day and doesn't drop the temperature below 78
    degrees. Our older unit never had this problem.

    We called the contractor that installed the unit out and he said that
    was normal. He told us that these units won't cool more than 20
    degrees below the ambient air temperature. He also said that the fact
    that our ducts are in the celing makes this problem worse. Something
    doesn't sound right here. I mean, our old unit cooled the house fine
    and that unit was smaller (2 ton).

    What's going on here? Is he correct or lying? Can you guys educate me on this? Should this unit be capable of cooling the house better than it's doing now?

  2. #2
    Join Date
    Aug 2005
    Location
    San Diego,CA
    Posts
    285
    Quote Originally Posted by wifeunit View Post
    We recently had a contractor install a new unit (a Bryant Puron 2.5
    ton in a 1500sq/ft 3br/2ba home) a couple of months ago. This week
    we've had some really warm weather with temperatures in the 90s
    nearing 100 degrees. The problem is the unit is not cooling the house.
    The unit runs all day and doesn't drop the temperature below 78
    degrees. Our older unit never had this problem.

    We called the contractor that installed the unit out and he said that
    was normal. He told us that these units won't cool more than 20
    degrees below the ambient air temperature. He also said that the fact
    that our ducts are in the celing makes this problem worse. Something
    doesn't sound right here. I mean, our old unit cooled the house fine
    and that unit was smaller (2 ton).

    What's going on here? Is he correct or lying? Can you guys educate me on this? Should this unit be capable of cooling the house better than it's doing now?
    2.5 tons still sounds a little undersized. Whats the humidity like? Eventually you should be able to get your room temp down to 72-74f. Did he run a heat load calc. on your home? or did he go by rule of thumb???
    Sink or Swim!
    A Man has to know his limitations..
    To be old and wise, one must be young and dumb..

  3. #3
    Join Date
    Mar 2007
    Location
    Myrtle Beach, SC
    Posts
    2,919
    If he put in a bigger system and it cools less, something is wrong.

    Where are you located?

    Here in Myrtle Beach, SC we design for 20 degree temperature difference between outside and inside. If this was Tuscon AZ, the design difference would be much higher. If you are in Upper NY, likely you would have a smaller design difference.

    You have not provided enough information for a good answer.

    He should have done a manual j load calculation. Did he? Did he test for proper air flow? Did he seal the ducts? Did he check sub-cooling superheat on the new system? Did he match the indoor coil & outdoor unit?
    Remember, Air Conditioning begins with AIR.

  4. #4
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    "He told us that these units won't cool more than 20
    degrees below the ambient air temperature."

    Only true if that is what it was designed/sized to do,at a certain outdoor temperature,which could be the case.

  5. #5
    Join Date
    Aug 2005
    Location
    San Diego,CA
    Posts
    285
    Well yeah, a/c is designed to give you a 20 degree split...if its 80f inside your home then should have a 60f supply air. But eventually your ambient air should come down. Whats the model # on the condenser? model # on the evap coil?
    Sink or Swim!
    A Man has to know his limitations..
    To be old and wise, one must be young and dumb..

  6. #6
    Join Date
    Mar 2004
    Location
    Illinois
    Posts
    6,959
    Quote Originally Posted by yorkdude View Post
    Well yeah, a/c is designed to give you a 20 degree split...if its 80f inside your home then should have a 60f supply air. But eventually your ambient air should come down. Whats the model # on the condenser? model # on the evap coil?

    Has nothing to do with split.

    We size our systems with the guarantee that we can make it 20 degrees cooler inside than outside.

    100 degrees outside
    80 degrees inside

    You might think that's not good enough, however walk outside and then back in and you'll see it's working.

    Why design that way you ask? It hit's 100 degrees here once maybe twice a year during the extremely hot weather.

  7. #7
    Join Date
    Jun 2008
    Posts
    4
    Quote Originally Posted by Kevin O'Neill View Post
    If he put in a bigger system and it cools less, something is wrong.

    Where are you located?

    Here in Myrtle Beach, SC we design for 20 degree temperature difference between outside and inside. If this was Tuscon AZ, the design difference would be much higher. If you are in Upper NY, likely you would have a smaller design difference.

    You have not provided enough information for a good answer.

    He should have done a manual j load calculation. Did he? Did he test for proper air flow? Did he seal the ducts? Did he check sub-cooling superheat on the new system? Did he match the indoor coil & outdoor unit?
    I'm located in the South - near north Alabama specifically. As to what tests were performed - I have no idea. He did replace both the indoor and outdoor unit not sure if they're matched though.

  8. #8
    Join Date
    Aug 2005
    Location
    San Diego,CA
    Posts
    285
    Dang....If its 100f outside, i would defenitely be upset with only 80f inside...
    Sink or Swim!
    A Man has to know his limitations..
    To be old and wise, one must be young and dumb..

  9. #9
    Join Date
    Jun 2008
    Posts
    4
    Quote Originally Posted by yorkdude View Post
    2.5 tons still sounds a little undersized. Whats the humidity like? Eventually you should be able to get your room temp down to 72-74f. Did he run a heat load calc. on your home? or did he go by rule of thumb???
    Humidity can get high at times. I'm in Alabama - northern part of the state not near the gulf coast. Today the temp got around 93 with a dewpoint of about 66 - so today wasn't too bad in terms of humidity.

    As to the heat load calc. - not sure.

  10. #10
    Join Date
    Jun 2008
    Posts
    4
    Quote Originally Posted by yorkdude View Post
    Well yeah, a/c is designed to give you a 20 degree split...if its 80f inside your home then should have a 60f supply air. But eventually your ambient air should come down. Whats the model # on the condenser? model # on the evap coil?
    This is a Bryant Puron system. Suppose to be a 2.5 ton.

    condenser model #: 213ANA036-C
    evap coil model #: FY4ANF030

  11. #11
    Join Date
    Mar 2007
    Location
    Myrtle Beach, SC
    Posts
    2,919
    3 ton outdoor, 2.5 ton indoor. Maybe a Bryant dealer will know if it is a good match.
    Remember, Air Conditioning begins with AIR.

  12. #12
    Join Date
    Aug 2005
    Location
    San Diego,CA
    Posts
    285
    Quote Originally Posted by wifeunit View Post
    This is a Bryant Puron system. Suppose to be a 2.5 ton.

    condenser model #: 213ANA036-C
    evap coil model #: FY4ANF030
    Hah! I agree with kevin, call the maunufacturer find out how they feel about a 2.5 ton coil with a 3 ton cond. I have heard of people doing similar mismatch things but always run into problems per hvac-talk. i think it should be all 3 ton if thats even the size you need.
    Sink or Swim!
    A Man has to know his limitations..
    To be old and wise, one must be young and dumb..

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