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  1. #1
    Join Date
    Oct 2015
    Posts
    2
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    Red face Thinking about upgrading my AC... Please help!

    Hi, just had our yearly check up. We have a goodman. it's about 11 years old. not the best, not the worst. has a hard time keeping up in the heat of the summer. we live in southwest florida. when i say trouble, we keep ac about 76 most of the day, 75 at night. on the hottest of days, it will be 8 or 9 o'clock at night and it's 77 or 78 still trying to keep up from the day. 2 kids, 2 adults and 1 dog in house. 1141 sq ft. currently have 2 ton.

    Was told about the financing deals at this time of the year, so decided to due my due diligence on a new unit, to be able to get it on my terms instead of the middle of summer and no specials. Not sure we are going to do anything... but 1st company came out with an estimate and calculated i should get 1.5 ton, but because one of the recommendations only came in 2 ton, the best of good better best, they recommend a 2 ton, variable speed TRANE XV 18.

    Anyone have any reviews on TRANE - good or bad? We are having another company come out tomorrow. Any suggestions on what we should do? Any suggestions on questions that should be asked. The company that came out first has been servicing our ac for the past few years. they have been great. haven't had any issues. i have been told that when looking at ac, you are more so looking at company that does install instead of actual brand. have also seen people say that the more energy efficient ones have a lot of problems... the more bells and whistles the more problem.

    the reason we are considering this also is for energy efficiency. we currently have a 12 seer. the new trade is 18 seer, has anyone replaced their units and noticed a large decrease in the power bill? sorry for all the questions, any input would be GREATLY appreciated!! thanks in advance!!

  2. #2
    Join Date
    Jun 2005
    Location
    SW Wisconsin
    Posts
    6,627
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    It is more cost-effective to do everything possible to improve the delivered Btuh efficiency of your existing system.
    The duct system Return-Air filter areas sizing should be evaluated because there is a lot of lost efficiency in all those areas.
    Dust leaks &/or insufficient insulation, etc.

    Extensive testing has shown that the average existing A/C unit is only delivering around 60% of its Rated Btuh...!

    If everything is not Performed Just RIGHT; & it rarely is; the 18-SEER might not deliver anymore than your existing 12-SEER...
    Installs can be messed-up...& too often are...

    Then look at your home for ways to reduce the heat-gain in summer & heat-loss in winter.

    Do your work before making any high cost decisions...

    Get others to help you do a load-calc & Sizing with this free online software.
    Do the load-calc without; & then with all the energy efficiency changes you plan to do.

  3. #3
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    9,815
    Post Likes
    it all depends on the QUALITY OF THE INSTALLER
    + Whether Your house is 8 or 108 years old
    ________________________ ,
    You might have to staaway from 95% of these

    http://www.dexknows.com/local/constr...alphabeticList
    Designer Dan
    It's Not Rocket Science, But It is SCIENCE with "Some Art". ___ ___ K EEP I T S IMPLE & S INCERE

    Define the Building Envelope and Perform a Detailed Load Calc: It's ALL About Windows and Make-up Air Requirements. Know Your Equipment Capabilities

  4. #4
    Join Date
    Oct 2015
    Posts
    2
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    Thread Starter
    Thanks, So far, I think i have come to the same conclusion. I am not blown away (pardon the pun) with what is out there. And from what I have researched, i may not save that much. I am having another company come out this morning, and talking to the first company later this morning and going to inquire about just doing some duct work to help with the efficiency.

  5. #5
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    9,706
    Post Likes
    I would keep the system simple with a variable speed blower at the most. +14 SEER single speed compressor is most practical. The variable speed blower allows accurate air flow adjustment to max moisture removal while cooling. This will get the a/c to maintain low humidity during significant cooling loads. Also allows slow economical air circulation during non-heat/cooling times of the air to maintain uniform temperatures throughout the home. The total variable speed a/cs are expensive, complicated to setup and maintain as they get old.
    In green grass southern climates many days with rainy cool weather with high outdoor dew points and low/no sensible cooling loads. The latent cooling load from adequate fresh air infiltration/ventilation plus the moisture from the occupants is about 2-4,000 btus per hour but sensible cooling is near zero. Variable speed a/cs are unable to remove enough moisture removal to maintain <50%RH during this condition. As they over-cool the home at a low speed upto 3^F, the lower indoor temperature elevates the indoor %RH 2.5% per degree of cooling. Plus at the end of the dehumidification mode, all the moisture on the cooling coil evaporates back into the home over the next hour. This raises the indoor %RH to previous levels. Not a good solution.
    A small whole house dehumidifier is good solution to this common problem. You can set the simple a/c for the temperature you want. A properly set up a/c will maintain <50%RH during long runs. As the cooling run time decrease evenings and cool wet days, the dehumidifier will maintain the desired indoor %RH at a minimal energy cost and avoid over-cooling. Our post are full of comments on poor humidity control during weather conditions that I described.
    During times of non-occupancy, you could turn off the a/c and allow the dehumidifier maintain low %RH at a low energy cost. The extra run time of the a/c during a cool-down also removes a lot moisture. For this concept to work well, the a/c should be large enough to cool the home down in a couple hours or when you have visitors in your home.
    I hope this type of thinking in not too revolutionary for you. If it is, go with plan A. I will understand.
    I have a home in Cape Coral and can show you well it works. Many of the upgrade home builders are going with this concept to meet the new fresh air recommendation of the FL code.
    Hope this helps. Keep us posted.
    Regards Teddy Bear
    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"

  6. #6
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    9,815
    Post Likes

    Energy Savings Estimate ... small unit - SW FL

    Quote Originally Posted by kebrady View Post

    Hi, just had our yearly check up. We have a goodman. it's about 11 years old. not the best, not the worst.

    has a hard time keeping up in the heat of the summer. we live in southwest florida.

    when i say trouble, we keep ac about 76 most of the day, 75 at night. on the hottest of days,
    it will be 8 or 9 o'clock at night and it's 77 or 78 still trying to keep up from the day.
    2 kids, 2 adults and 1 dog in house. 1141 sq ft. currently have 2 ton.

    Was told about the financing deals at this time of the year, so decided to due my due diligence on a new unit,
    to be able to get it on my terms instead of the middle of summer and no specials.

    Not sure we are going to do anything...
    but 1st company came out with an estimate and calculated i should get 1.5 ton,
    but because one of the recommendations only came in 2 ton, the best of good better best,
    they recommend a 2 ton, variable speed TRANE XV 18.

    Anyone have any reviews on TRANE - good or bad?

    I have been told that when looking at ac, you are more so looking at company that does install instead of actual brand. have also seen people say that the more energy efficient ones have a lot of problems... the more bells and whistles the more problem.

    the reason we are considering this also is for energy efficiency.
    we currently have a 12 seer. the new trade is 18 seer,
    has anyone replaced their units and noticed a large decrease in the power bill?


    sorry for all the questions, any input would be GREATLY appreciated!! thanks in advance!!
    One might be able to increase the comfort level AND save upto 33%
    However, 33% of a cooling season bill of $390 would be a net savings of ~ $130 per year.

    OPERATING COST Comparison of REPLACEMENT units of 14 and 18 SEER
    $ 748 in 10 years

    12 ______ SEER
    12.7 ______ constant
    1.058 ______ kw/hr per ton
    2.0 ______ tons
    2.117 ______ kw/hr ________ ________ _____________ 31 May
    ________ ______ ________ 24 hours/day ____________ 30 June
    ________ ______ ________ 184 Days _______________ 31 July
    ________ ______ ________ 4416 hours / season ______ 31 August
    ________ ______ ________ 42% Run time % ________ 30 September
    ________ ______ ________ 9.66 Hours/day _________ 31 October
    3,926 ______ kw-hours 1855 hours / season ________ 184 Days
    ______ ______ 12 SEER
    2,617 ______ 18 SEER
    1,309 ______ kw-hr Savings
    $0.10 ______ $/kw-hr
    $130.88 _____ $ Savings
    ______ ______
    3365 ______ 14 SEER
    2617 ______ 18 SEER
    748 ______ kw-hr Savings
    $74.80 ____ $ Savings / cooling Season
    $748.00 _____ 10 Years Savings
    Designer Dan
    It's Not Rocket Science, But It is SCIENCE with "Some Art". ___ ___ K EEP I T S IMPLE & S INCERE

    Define the Building Envelope and Perform a Detailed Load Calc: It's ALL About Windows and Make-up Air Requirements. Know Your Equipment Capabilities

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