First floor system might be oversized - Page 2
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  1. #14
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,630
    Incorrect set up on the IAQ.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  2. #15
    Join Date
    Sep 2012
    Posts
    373
    Quote Originally Posted by udarrell View Post
    What is the design & layout of the main duct?

    On the main trunk, every couple of take-off runs or a number of feet, it should transition to a smaller trunk to keep static pressure up which helps the airflow to the distant rooms.

    Might be able to have dampers installed on the closer branch duct take-offs to force more airflow to the distant registers.

    If the Supply ducts & Return duct system, along with the RA filter areas are sized large enough, with a 4-Ton blower it should be able to deliver the right amount of air to those distant rooms...

    Should have had a load-calc performed, before sizing the A/C!
    There's more than one trunk coming out of the ductboard. One is large (main one), and there's three smaller ones. The main one has ducts coming off of it.

    Dampers are something I've been thinking about for a while.

    The company who installed the XR15 said they did load calculation, but I don't exactly if they actually did one or not. Contractor from company who installed furnace did do a load calculation, but he used a "wheel" to drive around the first floor to calculate size.

  3. #16
    Join Date
    Sep 2012
    Posts
    373
    Quote Originally Posted by beenthere View Post
    Incorrect set up on the IAQ.
    That's most likely what I'm thinking.

  4. #17
    Join Date
    May 2004
    Location
    south louisiana
    Posts
    3,125
    I use a rolling tape measure.
    what he was doing was measuring the house to
    determine how many sq ft.
    ideally he would have measured windows, distance
    to overhang of roof, size of overhang and orientation
    of each window. also amount of shade if applicable.

    I love my rolling tape measure, makes these
    measurements fast. still need tape measure..but
    not to measure perimeter.

    best of luck.
    The cure of the part should not be attempted without the cure of the whole. ~Plato

  5. #18
    Join Date
    Jan 2009
    Location
    Keokuk, IA
    Posts
    5,520
    It' too late now, but I question the quality of their load calculation. Its probably not too far off depending on you shading and window size, number and location. THe thing abotu GA is that it is fairly hot and humid, but not extremely hot and humid, but does have a very long cooling season and short winter.

    Being a little short on airlfow isn't a bad thing in your climate. 350 CFM per ton is a good nominal airflow target anyway, that what your getting at 1225. 1060 for 5 minutes too is also OK when it first starts, and should be OK for dehumidify on demand.


    I think overall you'd be better off with a 3 ton system sicne that's all you ductwork can manage. I wodner how accurate some of the number and "guesses" were that they used on that load calculation.

  6. #19
    Join Date
    Sep 2012
    Posts
    373
    Quote Originally Posted by motoguy128 View Post
    It' too late now, but I question the quality of their load calculation. Its probably not too far off depending on you shading and window size, number and location. THe thing abotu GA is that it is fairly hot and humid, but not extremely hot and humid, but does have a very long cooling season and short winter.

    Being a little short on airlfow isn't a bad thing in your climate. 350 CFM per ton is a good nominal airflow target anyway, that what your getting at 1225. 1060 for 5 minutes too is also OK when it first starts, and should be OK for dehumidify on demand.


    I think overall you'd be better off with a 3 ton system sicne that's all you ductwork can manage. I wodner how accurate some of the number and "guesses" were that they used on that load calculation.
    I can't recall exactly if they checked window size, numbers, etc. All I remember is them checking square footage. We are gonna call someone from a company we've never used before (they seem to have excellent reviews) and we shall see what he finds. I'll give an update once that happens. Thanks for your information.

  7. #20
    Join Date
    May 2004
    Location
    south louisiana
    Posts
    3,125
    sizing by sq ft isn't sizing it is an old rule of thumb sizing.
    paying for an accurate load calc is the first step to having
    a properly sized unit. sized for your specific house, not just
    xxx tons for xxx sq ft.

    best of luck.
    The cure of the part should not be attempted without the cure of the whole. ~Plato

  8. #21
    Join Date
    Sep 2012
    Posts
    373
    Quote Originally Posted by energy_rater_La View Post
    sizing by sq ft isn't sizing it is an old rule of thumb sizing.
    paying for an accurate load calc is the first step to having
    a properly sized unit. sized for your specific house, not just
    xxx tons for xxx sq ft.

    best of luck.
    That's true. We should have gotten more estimates before the units were replaced. All 8 returns are pretty noisy (All you can hear is air rushing through). Three of the returns branch off of the 12" duct. Two of them branch off of one of the 10" ducts, and two branch off from the other 10" as well. The 6" return duct has its own grille in the basement (10" x6"). The other returns are all 14" x6" grilles and they are located on the lower wall on the first level. I am thinking that maybe the 6" should be replaced with a larger duct (maybe a 10" or 12"). The contractor can determine what's needed to be done.

  9. #22
    Join Date
    Dec 2011
    Location
    Grass Lake, MI
    Posts
    251
    You do not have enough R/A!!! I'm sure you have other duct work issues and a need for balancing dampers, but you need more R/A. I will emphasize, more R/A!

  10. #23
    Join Date
    Sep 2012
    Posts
    373
    Quote Originally Posted by jpbhvac View Post
    You do not have enough R/A!!! I'm sure you have other duct work issues and a need for balancing dampers, but you need more R/A. I will emphasize, more R/A!
    I know, its something that really needs to be done. It's really a shame that both contractors we have had in here before said the return air is fine. Any more returns added will have to be installed in the basement since there's no room on the first level.

  11. #24
    Join Date
    Jun 2005
    Location
    SW Wisconsin
    Posts
    4,810
    Quote Originally Posted by 545GAlady View Post
    I know, its something that really needs to be done. It's really a shame that both contractors we have had in here before said the return air is fine. Any more returns added will have to be installed in the basement since there's no room on the first level.
    If there are any appliances in the basement that can be back-drafted, Returns in a basement can be very dangerous!

  12. #25
    Join Date
    Sep 2012
    Posts
    373
    Quote Originally Posted by udarrell View Post
    If there are any appliances in the basement that can be back-drafted, Returns in a basement can be very dangerous!
    The two returns for the basement system are located very FAR away from the appliances (basement is finished and utilities are in a room). The 6" return for first floor system is also far away.

  13. #26
    Join Date
    Jun 2005
    Location
    SW Wisconsin
    Posts
    4,810
    Quote Originally Posted by 545GAlady View Post
    The two returns for the basement system are located very FAR away from the appliances (basement is finished and utilities are in a room). The 6" return for first floor system is also far away.
    Okay, that is GOOD...

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