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  1. #1

    A/C or heat load problem? please help

    I live in North Alabama and have had several techs check my a/c over the years and all have said it is doing all it can but it did not use to act this way the first two years I lived here and nothing has changed. First off, I haven't had any trees cut down and yes, I check my filter and replace it regularly. The air flow is fine and and I have no duct leaks. I have a 3 ton rheem unit on a 1970 sq. ft. home that was put in a year before I moved in house and have been here 6 years which would make the unit 7 years old. It works great when the temp. outside gets up to 92 or 93 and will hold set point or one degree above. when it gets 94-97 it will get to 2 to 3 degrees above setpoint and 97 plus 5 to 6 degrees above setpoint especially when the heat indicies are in the 100's. My house runs east to west so the morning sun only has two windows to come in by which I close the blinds and I have shade for when the sun sets on the west. On a 97 plus day it holds setpoint up tp around lunch then rises a degree almost every hour on the hour until about 7 or 7:30 pm that night then levels off and holds that temp. until about 8:30 or 9 and then it starts playing catchup the rest of the night. why does it feel warmer in the home from 4 - 8 pm . I know that is when the hottest temps are but isn't it suppose to blow about the same degree air from the supply vents all day? I had extra insulation put in last summer and can't tell a difference. One last thing that may be it, for my almost 2,000 sq. ft. home which is a ranch style home, I have only one return and it is a 20 x 25, is that too little or do you guys think I need another one on the opposite end of the house?

    Thanks for any help!

  2. #2
    Join Date
    Dec 2006
    Location
    Dallas
    Posts
    189
    have had several techs check my a/c over the years and all have said it is doing all it can
    Did they use any instruments to draw this conclusion?

    Sounds like your AC is not operating at it's designed efficiency as it used to 5+ years ago. As long as you don't ask Al Gore, it's safe to say your heat load has remained constant.

    I would find another, possibly more expensive HVAC company to tell you what's wrong with the AC.

  3. #3
    Join Date
    Jun 2005
    Location
    SW Wisconsin
    Posts
    5,033
    So it did okay the first two years. Did anyone add refrigerant to the system?

    An overcharge can considerable lower the BTUH capacity of the system.

    Cut the power, & look at the indoor blower wheel blades to see if they are free of lint, if lint is on them, then the underside of the A-Coil is probably partially lint blocked! I'd call a good contractor!

    If you have a cottonwood tree near or the clothes dryer vent is near the condenser it may be partially clogged! Never have water near the condenser unless all power is shut off to it, including the low voltage from the furnace or air handler.

    Also, Foam insulation, radiant barriers, & various window treatments will help reduce that big heatload. - Darrell

  4. #4

    what about the return?

    does a 20x25 seem too small for an almost 2,000 sq. ft. ranch style home?

  5. #5
    Join Date
    Jan 2004
    Location
    PA
    Posts
    68,785
    A bit small for 3 tons.
    But if it cooled ok for the first 2 years, that isn't the problem.

    When is the last time, the coils were cleaned?

    What temp are you setting your stat to?

    Is it possible teh first 2 years you were there, you had milder summers.
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  6. #6
    Join Date
    Dec 2006
    Location
    Middle Tennessee
    Posts
    11,347

    *

    i dont know about you guys but every year here in Tennessee it gets a little hotter!



    .

  7. #7

    coils cleaned

    each spring, this past time was in May. It mat have been milder but we always have days in July or August that are mid to upper 90's with heat indicies in the 100's. Like I ssaid cools fine on days up to low 90's but it is when it hits that 95 to 100 mark that it just seems to give out when it that hot between the hours from about 3 or 4 until 9 then it starts to catch up and then will freeze you out about midnight until lunchtime the next day. Sois it normal for it to rise a few degrees in this type of weather? Also, someone mentioned it may be overcharged, if it was overcharged, wouldn't it act up all the time and not just when it reaches the upper 90's?

  8. #8
    Join Date
    Jan 2004
    Location
    PA
    Posts
    68,785
    Over charged would tend to cool better on hot days then cool days.

    What temp are you setting your stat to?
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  9. #9
    Join Date
    Mar 2008
    Location
    Central Maryland
    Posts
    246
    Quote Originally Posted by hotinthesouth View Post
    each spring, this past time was in May. It mat have been milder but we always have days in July or August that are mid to upper 90's with heat indicies in the 100's. Like I ssaid cools fine on days up to low 90's but it is when it hits that 95 to 100 mark that it just seems to give out when it that hot between the hours from about 3 or 4 until 9 then it starts to catch up and then will freeze you out about midnight until lunchtime the next day. Sois it normal for it to rise a few degrees in this type of weather? Also, someone mentioned it may be overcharged, if it was overcharged, wouldn't it act up all the time and not just when it reaches the upper 90's?
    I had a system overcharged for 4 years. It worked OK at cooling and poorly at heating. When switching modes or stressed it would throw the circuit breaker.

    After I paid for a furnace, I found out my Heat Pump inside coil was linted up, and that was the reason the service man put in more coolant, he saw in A/C mode the return line had low pressure. The low pressure was from failure of the refrigerant to absorb heat, due to the lint, not from a leak.

    Now the A/C works better than ever.

    -HF

  10. #10
    Join Date
    Apr 2002
    Location
    Omaha, NE
    Posts
    1,561
    Quote Originally Posted by beenthere View Post
    Over charged would tend to cool better on hot days then cool days.............................................. .
    Please explain - I've never heard this before.

  11. #11
    Join Date
    Jan 2004
    Location
    PA
    Posts
    68,785
    Thats not gross over charged.

    Seen more then one that has 1/2 a pound or so extra, that cooled just a little better at 98 then it did without that extra 1/2 pound.
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  12. #12

    thermostat set

    at eiter 72 or 73 to answer your question. It may cycle on about 9:30 or 10 in the morning and drop back to 72 then about lunch it will go to 73,then about 2:00 will go to 74 then by 3 or 4 75, then by 5 or 6 76 and finally by 7 or 7:30 it will hit 77 and hold until about 8:30 then drop back to 76 and then plays catch up the erst of the night. This scenario goes on everytime it hits about 97 plus outside, up to 90 degress it works like a champion. During the temps outside like this I can't set it higher, for instance before I go to work to save money set it on 75 or 76 because when I come home it would be up around 80 or 81 and would really have to work overtime the rest of the night to get it at a comfortable temp. If it is just in the 80's I can turn it off and come home 8 hours later and it takes no time at all to cool down.

  13. #13
    Join Date
    Jan 2004
    Location
    PA
    Posts
    68,785
    It may have been sized to only do 20° cooler then outdoor temp. If so, what you are experiencing is normal.

    You said the coils were cleaned in spring. Do you remember them carring cleaner in to clean the coils.

    Your return grille is small. Your return duct may be undersized also. So adding another return may help. But could also cause a noise problem if your supplies are undersized also.

    What type of air filter are you using, hopefully, not a 3M filtrete in that small filter grille.
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