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  1. #1
    Join Date
    Jul 2006
    Posts
    2

    Confused

    We have a new townhome which is 3 stories and roughly 1900sqft. There are 2 units - one for the upstairs (bedrooms) and one for the bottom two floors. We're in Georgia so its been hot and humid lately.

    We keep the AC set to 72. The downstairs is fine, no problems at all. The upstairs is a problem. The unit is constantly running, and not only can it not maintain the temperature (it was 74 at midnight last night, with outside air temps in the mid to high 70's), but it is VERY humid. You can feel a noticable difference when walking up the stairs from the middle floor.

    Any ideas? Was this just a poorly designed system? Thanks.

    Dan

  2. #2
    Join Date
    Jul 2006
    Posts
    2
    Well, we had the HVAC contractor come out (again). This time, they sent a competent tech. He basically discovered that the evaporator was installed backwards. Nice one!

  3. #3
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    Could be too small,poorly designed ducts,dirty filter/blower/coil,etc..

    If it's too small look at adding attic insulation and a radiant barrier in the attic,before looking for a larger system,which will require larger ducts and cost more to run.

    1.Did it ever work properly?

    2.New or old?

    3.Been there long?

    4.What's the sq. ft. of the top floor and the model numbers of the equipment?

    5.Any idea of the R Value of the attic insulation?

    Best bet will be to have a Pro check it out.

  4. #4
    Join Date
    Jan 2006
    Posts
    79
    When you say humid and runs constantly I think you either have a window open, holes in the house or leaky duct work.

    Something somewhere to bring in the humidity as a unit that runs continuously should dehumidify good.

    Need to find someone who is willing to go into your hot attic to look everything over good.

  5. #5
    Join Date
    Apr 2002
    Posts
    11,808
    Its sometimes amazing.

    Air conditioning equipment is typically designed to maintain a space at 75 to say 78F and people want it 72 and colder inside.

    Loose weight, wear short sleeve shirts, hell run around naked at home. Turn on the ceiling fans

  6. #6
    Join Date
    Jul 2005
    Posts
    717
    Originally posted by Carnak
    Its sometimes amazing.

    Air conditioning equipment is typically designed to maintain a space at 75 to say 78F and people want it 72 and colder inside.

    Loose weight, wear short sleeve shirts, hell run around naked at home. Turn on the ceiling fans
    ************************************************** **
    There is nothing amazing about it, it's simple logic;
    some humans like it HOT, some like it COLD.

  7. #7
    Join Date
    Nov 2005
    Location
    Northern VA
    Posts
    512
    (This is written in the context of areas where there is significant humidity and it is not practical to have indoor RH below 50% or so - I can see how higher temperatures could be quite reasonable if your summer RH is, say, 20% indoors with almost no latent load.)

    The people who want mid temp refrigeration in their homes - I agree, that's very unusual and way beyond what normal residential equipment or construction techniques are intended for.

    But 72 degrees? That's on the cool end of normal. It used to BE normal. Now we've been steadily moving the setpoint up for what are basically political reasons, and a lot of people are balking. 78 degrees is the required indoor design temp for new construction in many areas, and that's just nuts. Few people are comfortable at 78, but they don't complain loudly enough to offset the national policy reasons - reducing the peak load on the electric grid, for example - that resulted in those regulations. 75 is a much more reasonable design temperature, and 72 upon request isn't out of line.

    IMO, more and more of ACCA's sizing guidance is based on optimizing energy conservation rather than comfort. Sure, not oversizing helps comfort by reducing humidity.. but making it so the system can only reliably maintain 78 is going too far.

  8. #8
    Join Date
    Apr 2002
    Posts
    11,808
    Originally posted by deejoe
    Originally posted by Carnak
    Its sometimes amazing.

    Air conditioning equipment is typically designed to maintain a space at 75 to say 78F and people want it 72 and colder inside.

    Loose weight, wear short sleeve shirts, hell run around naked at home. Turn on the ceiling fans
    ************************************************** **
    There is nothing amazing about it, it's simple logic;
    some humans like it HOT, some like it COLD.
    Should just give them slides that say warmer/cooler. Find some other way to cool the jets of the ovulating women

  9. #9
    Join Date
    Nov 2005
    Location
    Northern VA
    Posts
    512
    I think you were at least semi-joking, but I've seen what happens when you give consumers a warmer/cooler slide. It gets set all the way to warmer in the winter or cooler in the summer, then they regulate temperature with the on/off switch.

    I do this myself with most of those systems (individual fan coils, PTACs, etc) because the internal thermostats tend to be really bad.

    Oh, and for the hot flashes etc.. I don't think there's any way around the "overcondition the space, then open and close a window" solution. Maybe we should just call the outdoors an "economizer hot deck" and leave it at that.

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