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  1. #14
    Join Date
    Sep 2008
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    10
    Zip is 70592.
    Aircooled53, you're right, the freon change is a big factor in this decision to upgrade now.
    The downstairs seems to be fine regardless of outside temps, I think
    this has alot to do with how much cool air falls down the open stairway from upstairs, and that also contributes to why the upstairs is not as cool as I'd like. The top floor is generally always too warm, enough to draw complaints from visitors. The second floor is ok on the days with moderate temps you described.
    I'm gonna visit Carrier's site to check out the model you recommended.
    And yes, that was also the type of advice I eventually wanted to get into. I wanted to see what efficiency range was appropriate, then get recommendations for good candidates within that range.
    Still have alot to learn, I'm very glad I found this site this early in the process. Thanks.

  2. #15
    Join Date
    Jan 2004
    Location
    Lancaster PA
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    68,097
    This is the history I got for your zip code for last year. I don't know if it was an average year or not.

    But, the average temps they show, would put you into the mid cycle rate that SEER is based on.
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  3. #16
    Join Date
    Jun 2004
    Location
    4H: Hot, Humid Houston H.O.
    Posts
    3,304
    I am a homeowner west of Houston TX, about 80 miles from the coast. I have seen big reductions in energy use from installing high SEER equipment. In my case 25-30 kwh/day seem to be unrelated to cooling or heating, and in the long hot humid summer 35-45 kwh/day now goes to AC usage. My equipment is the American Standard "Allegiance 18" 2-stage AC, 17.25 rated SEER with my coil. This is the same product (practically) as Trane XL-19i which claims "up to" 19.5 SEER but that is only with one particular tonnage and coil. Before going with the new AC, did everything I could to improve duct sealing and other HVAC malfunctions.

    If you want to optimize cost, the better single stage systems might come out ahead. The XL15i series can attain 15+ SEER, the 2-stage XL16i can rarely do a full SEER number better, and there is an initial cost savings. Often 2-stage systems are described as "comfort systems" in an effort to explain why they are a good choice despite the higher cost. Because the payback could be quite long in terms of years. Still I like them.

    The Trane/A-S controls are a good step behind the Carrier Infinity in terms of sophistication. If you look into the Infinity, you might find features you really like. As always, the most important factor is finding a good HVAC pro to do a proper installation.

    Personally I find that a dehumidifier helps comfort with a higher temperature on the wall thermometer. With inside temperature and outdoor not being so very different, this can make for a significant reduction in heat gain from outdoors. Remember that your maximum temperature exists for only a few hours each day, you have many more hours well off the day's max. Your summer is much like ours and I believe we have the same problems of living in a hot-humid climate.

    Hope this helps -- Pstu

    P.S. My Manual J book says design conditions for Lafayette LA are 94F dry bulb, 78F wet bulb. For Houston TX it is 94 db, 77 wb. That one degree wet bulb, represents a measurable difference in humidity loading. IMO you will not resolve your room/floor temperature issues unless you get a room-by-room Manual J and address airflow to the problem areas, a whole-house Manual J will not suffice.

  4. #17
    Join Date
    Jun 2007
    Location
    The Twilight Zone
    Posts
    2,964
    Quote Originally Posted by limagicman View Post
    The SEER, which is the Seasonal Energy Efficiency Ratio, measures cooling from 82 degrees outside to 80 degrees inside. EER, Energy Efficiency Ratio, measure cooling from 95 degrees outside to 80 degrees inside. The EER is more meaningful in predicting your actual energy usage. Many system that are 19 SEER (Trane for example) have EER's that are in the 10's or 11's. A 13 SEER system, when measured by EER would be more efficient.
    The SEER measurement of EER at 82F ambient is for a fixed speed fan in the air handler.

    For a variable speed fan in the air handler, SEER is calculated from EER across a range of temperatures. The range is from 67F to 102F, in increments of 5 degrees. However, the weight percent of each "bin" temperature is not the same.

    Here is the weight%:
    67F----21.4%
    72F----23.1%
    77F----21.6%
    82F----16.1%
    87F----10.4%
    92F----5.2%
    97F----1.8%
    102F---.4%
    -------------
    Total = 100%

    The lowest 3 temps account for 66% of the value of the SEER calculation (thus the "seasonal" representation). This is why I hate SEER. Who runs their a/c at 67F and 72F ambient? I don't.

    The reason why 2-stage condensers have such a high SEER# is their ability to run on first stage at reduced capacity. First stage has a much higher EER than second stage, thus the high SEER#. The more a 2-stage condenser runs on first stage, the more the operating cost savings for the homeowner compared to a single-stage unit (because of the high EER# on 1st stage and lack of cycling on/off).

    I agree that EER is more meaningful in determining true operating costs. EER is also calculated across a range of ambient temps, but it is published by the ARI at 95F ambient.

    To the OP:
    Regardless of your SEER choice, you should look for a 12 minimum EER. You also want as close to the rated btu's as possible: a 3.5 ton system should be 42,000 btu's, not less.

    You can use the American Refrigeration Institute (ARI) website to check EER and system btu's if you know the model numbers:

    www.ARIDirectory.org.

    Take care.

  5. #18
    Join Date
    Jan 2004
    Location
    Lancaster PA
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    68,097
    Quote Originally Posted by gary_g View Post



    You can use the American Refrigeration Institute (ARI) website to check EER and system btu's if you know the model numbers:

    www.ARIDirectory.org.

    Take care.
    Its now the ARHI.

    By the way, did you ever check to see at what OD temp your system has a total on time that exceeds 45 minutes in an hour.(or switches from 3 to 2 CPH).
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  6. #19
    Join Date
    Jun 2007
    Location
    The Twilight Zone
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    Quote Originally Posted by beenthere View Post
    Its now the ARHI.

    By the way, did you ever check to see at what OD temp your system has a total on time that exceeds 45 minutes in an hour.(or switches from 3 to 2 CPH).
    My Honeywell stat from HD doesn't track compressor run time (neither does the VisionPro). I don't think that I can change or check the cycles per hour with my current thermostat.

    I know what you're thinking: I can benefit from a 2-stage condenser because average summer temps in Baltimore are in the 80's, and I'll run on first stage a lot. I would also be able to raise the setpoint a few degrees because of lower humidity in the home from running on first stage. Considering what I paid for my 14 SEER Goodman last year, I would never recover the additional cost of X thousand dollars for a 2-stage condenser over the life of the equipment.

    Take care.

  7. #20
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,444
    Quote Originally Posted by *SSS* View Post
    I'mSome background:
    Lafayette, La, about 40 miles from the coast, hot and humid for about 8 months out of the year.
    IThanks, Shell
    Any interest in real humidity control during wet cool weather? Regards TB
    Bear Rules: Keep our home <50% RH summer, controls mites/mold and very comfortable.
    Provide 60-100 cfm of fresh air when occupied to purge indoor pollutants and keep window dry during cold weather. T-stat setup/setback +8 hrs. saves energy
    Use +Merv 10 air filter. -Don't forget the "Golden Rule"

  8. #21
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,097
    [QUOTE=gary_g;1985803

    I know what you're thinking: I can benefit from a 2-stage condenser because average summer temps in Baltimore are in the 80's, and I'll run on first stage a lot. I would also be able to raise the setpoint a few degrees because of lower humidity in the home from running on first stage.

    Take care.[/QUOTE]

    Actually, thats not what I was thinking.

    I can't track my run times with the stat either.
    But, did check it several times during various ambients. Both during the day, and some evenings. Just to double check its cycling. And capacity at the different ambients.

    Along with using several different stats on it, to see what effect they had on it, and comfort.
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  9. #22
    Join Date
    Sep 2008
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    10
    Quote Originally Posted by teddy bear View Post
    Any interest in real humidity control during wet cool weather? Regards TB
    Yes, as lower humidity makes higher temps "feel" cooler, correct? Whatcha got in mind?

  10. #23
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,444
    Quote Originally Posted by *SSS* View Post
    Yes, as lower humidity makes higher temps "feel" cooler, correct? Whatcha got in mind?
    I promte the ability of maintaining <50%RH without operating the a/c during wet cool weather or when the home unoccupied. By using a whole house dehumidifier with enough capacity to ro remove 4 lbs per hour of moisture regardless what the cooling load is, comfort and IAQ is assured.
    During high cooling loads, your properly set-up a/c will keep your home dry. During wet, cool weather with low/no cooling loads, the dehumidifier removes the moisture for a fraction of the cost of cooling. The results of all this ideal temperature with ideal %RH eventhough you have extra capacity for hot weather and extra company. thermastor.com Ultra-Aire. There are others. Regards TB
    Bear Rules: Keep our home <50% RH summer, controls mites/mold and very comfortable.
    Provide 60-100 cfm of fresh air when occupied to purge indoor pollutants and keep window dry during cold weather. T-stat setup/setback +8 hrs. saves energy
    Use +Merv 10 air filter. -Don't forget the "Golden Rule"

  11. #24
    Join Date
    Sep 2008
    Posts
    10
    Been away a while.

    Gary G., thanks for the insight on how SEER is calculated, and the EER suggestion. I'll check out my current ratings on the AHRI site.

    pstu, you bring up a good point regarding top tier single stage vs entry level two stage systems, I'll have to look at that more closely as purchase time comes closer, and I start requesting local quotes.

    The Infinity stuff is nice though, and looks like it is along the lines of what I'm interested in. I havent found a dehumidifier in that line-up though?
    Which dehumidifier are you using? How much higher do you set your thermostat when you are running the dehumidifier?

    Not quite up to speed yet on the Manual J, I'll get there.
    I'm sure all of this will make sense soon.
    Thanks guys.

  12. #25
    Join Date
    Sep 2008
    Posts
    10
    tbear, thanks for bringing that product line to my attention, I'll certainly keep it in mind. Definitely another area I need to study.

    Simple question- does variable speed imply two stage? Variable speed relates to fans, right? And two stage to compressors I think, but do single stage systems benefit from variable speed fans?

    Is there an FAQ somewhere that explains the basic theory behind HVAC? I've got a ton of stupid questions. Thank you.
    Last edited by *SSS*; 09-14-2008 at 05:55 PM. Reason: Repeatedly repetitive

  13. #26
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,097
    VS blowers enhance the performance of single stage A/Cs also.
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