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  1. #1
    Join Date
    Sep 2012
    Posts
    373

    Ductwork with R8 insulation better for attic?

    We still are not satisfied with all the issues related to HVAC that's going on in the house. The companies seem unwilling to help.

    We have noticed that when our upstairs A/C runs in the Summer, the air coming out of the registers is not very cold. whenever the temperature is below 80 outside, the airflow seems a bit colder. During our annual tune-up, the tech checked charges and everything was proper. The system is a Goodman SSX14 2-ton air conditioner with a Goodman CAPF3636A6 indoor coil that was installed a year ago. The furnace is a Lennox SL280v, and it was installed back in July. Airfow was lowered by the tech to 825 cfm (825 cfm for the first 7 minutes then speed increases) and that didn't help solve the issue. I'm now thinking it's the ductwork that's wrong since it has R6 insulation. None of the companies ever mentioned anything about the ductwork. Is this issue typical with attic systems?? Should the ductwork be replaced? Thanks.
    Last edited by 545GAlady; 04-15-2013 at 03:12 PM. Reason: additional info

  2. #2
    Join Date
    May 2008
    Location
    Central Fla.
    Posts
    309
    How hot is the attic getting, could be heat intrusion. May need an attic exhaust fan, how old is the home?

  3. #3
    Join Date
    Aug 2007
    Location
    Northern VA 38 degrees N by 76 degrees W
    Posts
    5,046
    Is either the unit or return in the attic?

  4. #4
    Join Date
    Jan 2008
    Posts
    1,859
    Check the temp coming out of the air handler, then check the temp coming out of the farthest vent.
    "Hey Lama, hey, how about a little something, you know, for the effort." And he says, "there won't be any money, but when you die, on your deathbed, you will receive total consciousness." So I got that goin' for me, which is nice. - Carl Spackler

  5. #5
    Join Date
    Sep 2012
    Posts
    373
    Quote Originally Posted by TwincamDave View Post
    How hot is the attic getting, could be heat intrusion. May need an attic exhaust fan, how old is the home?
    I will need to check temperature up there. We already have a solar-powered attic fan which has really brought down the attic temperature.

    The house was built in 2001-2002.

  6. #6
    Join Date
    Sep 2012
    Posts
    373
    Quote Originally Posted by second opinion View Post
    Is either the unit or return in the attic?
    The furnace is located in the attic. Thanks for asking.

  7. #7
    Join Date
    Sep 2012
    Posts
    373
    Quote Originally Posted by 2old2rock View Post
    Check the temp coming out of the air handler, then check the temp coming out of the farthest vent.
    Thanks for the reply. I checked supply temp last summer and it was reading 68*F and I forgot what the return temp was. Last weekend I checked it again and it read 58*F on the supply side and 72*F on the return side. Of course it was cooler outside when I checked temps last weekend. It was maybe in the 80's when I checked last summer.

  8. #8
    Join Date
    Jan 2009
    Location
    Keokuk, IA
    Posts
    5,520
    R8 may help, but I would suspect that air leaks are the biggest problem. Repalcing the ductwork (flex?) would kill 2 birds with one stone. You get better insulation, if installed properly and pulled tight your static pressure will drop and you'll get more airflow/capacity.

    You could also seal the attic and spray foam the roof deck, but that's a expensive alternative and has it's advantages and disadvantages.

  9. #9
    Join Date
    Aug 2007
    Location
    Northern VA 38 degrees N by 76 degrees W
    Posts
    5,046
    Do you have any other diagnostic information from the technician as far as temperatures and pressures? You should be closer to a 20 degree split if system was running correctly with 50% relative humidity.

  10. #10
    Join Date
    Oct 2010
    Location
    Anderson, South Carolina, United States
    Posts
    5,663
    You most likely have duct leakage causing the symptoms. A home energy audit would find the problem areas.

  11. #11
    Join Date
    Sep 2012
    Posts
    373
    The ducts were sealed back when the furnace was installed. I was hoping that will solve the issue, but it did not. Our first floor systems always blows out ice cubes, but not the upstairs system. We do plan to have an energy audit done.

  12. #12
    Join Date
    Sep 2012
    Posts
    373
    Quote Originally Posted by second opinion View Post
    Do you have any other diagnostic information from the technician as far as temperatures and pressures? You should be closer to a 20 degree split if system was running correctly with 50% relative humidity.
    As of now, I don't think I have any other diagnostic info from the technician. He never told me the actual pressures.

  13. #13
    Join Date
    Sep 2012
    Posts
    373
    Quote Originally Posted by motoguy128 View Post
    R8 may help, but I would suspect that air leaks are the biggest problem. Repalcing the ductwork (flex?) would kill 2 birds with one stone. You get better insulation, if installed properly and pulled tight your static pressure will drop and you'll get more airflow/capacity.

    You could also seal the attic and spray foam the roof deck, but that's a expensive alternative and has it's advantages and disadvantages.
    That will be nice, but we currently don't have the money for more insulation.

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