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  1. #1
    Join Date
    Aug 2011
    Location
    south sout florida
    Posts
    32
    Post Likes

    New A/C to be installed on Florida Keys Concrete home What to go for

    Hello All

    I have concrete Well insulated 3200 sq Home in construction in the Florida Keys. It has Concrete roof with Closed cell Foam R40 on the Underside along with Reflective Roof top paint. I have Low E Glass inpact windows, Along with R 12 walls with an exterior Light Colored Paint (not a Heat Sink )

    This house is on stilts and Two Story 1600 SQ foot each Level. The Blue print shows 4 tons each level
    I think that is a bit much, The House has KOOL DUCK FOAM DUCTS in installed.
    I called the Guy whom did the Plans and hes said he Just Used 450 sq foot equal a Ton !!!! NO MANUAL J. I am concerned this is TOO much Air, A few A/c Contractors have Looked at it and they use the SAME 400-450 Formula......Even some have said after looking at the House maybe 650 sq foot per ton !!! So this aint getting it for Me. I Would like a Good Answer and Calculation Done.
    is there any way I could do the Calculation my self ? as it seems No ONE does these here in the Keys.

    The Second question is:
    The units I Have looked at TRANE, CARRIER, (Bryant) and the Goodman units all have Basic and then Upper Line.....Infinity, Evolution, Confort Net,
    I know thats a wide Spectrum however people tell me Corrosion is a Big factor here and maybe I should stick with a good Basic 16 SEER Model without all the bells & Whistles Since Service on these Souped up models could be an Issue in the future. I do however like the Humidity control ability on the Infinity and the Goodman confort net models. The A/c contractors tell me 7-10 year Life on these units if Maint Cleaning Condensing unit Monthly with Fresh water.

    Any input would be greatly Appreciated
    Coconut Sunrise in the Florida Keys

  2. #2
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    8,362
    Post Likes
    Last time I checked, the _FLORIDA Keys_ are actually a part of Florida.
    Have the FL Keys contractors become renegade firms and opted out of latest FL building code requirements?

    https://fl-monroecounty.civicplus.com/

    https://fl-monroecounty.civicplus.co...id=165?NID=167

    x

    https://www.acca.org/standards/codes/

    The builder and mechanical contract firm are operating outside the FLorida state law IMO.
    Calculation per ACCA Manual J is required at the time of permit and has been for more than a decade.

    ACCA Manual D is required for duct design.

    ____
    The local building department seems to be unaware of or perhaps rejected the latest state building code IMO.
    http://www.floridabuilding.org/fbc/t...ODE-Energy.htm

    https://fl-monroecounty.civicplus.co...x.aspx?NID=243
    __________________________
    I doubt that equipment sizing and any responses regarding HVAC installation are
    going to be truly worthy of consideration when provided by those not abiding by the _latest_ building codes.

    TRANE equipment life is best in this type of very corrosive environment.

    Two tons for each floor will BE adequate if BUILT AND TESTED TO FLORIDA CODE
    with a Foamed roof. Equipment and duct work SHALL BE in the conditioned space.

    Total Glass area should generally be < ~180 square feet per 1,600 square foot floor.
    WINDOW AND SLIDING GLASS _ _ S.H.G.C. MAXIMUM 0.30 _ _
    http://www.ecodes.biz/ecodes_support...Efficiency.pdf

    You can perform an analysis using the ACCA Manual J abridged edition.
    https://www.acca.org/standards/

    If you have any issues that show you need > 2 tons per 1,600 sq feet,
    you may contact me via e-mail ( address is in my profile).
    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

  3. #3
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    8,362
    Post Likes
    Last time I checked, the _FLORIDA Keys_ are actually a part of Florida.
    Have the FL Keys contractors become renegade firms and opted out of latest FL building code requirements?

    https://fl-monroecounty.civicplus.com/

    https://fl-monroecounty.civicplus.co...id=165?NID=167

    x

    https://www.acca.org/standards/codes/

    The builder and mechanical contract firm are operating outside the FLorida state law IMO.
    Calculation per ACCA Manual J is required at the time of permit and has been for more than a decade.

    ACCA Manual D is required for duct design.

    ____
    The local building department seems to be unaware of or perhaps rejected the latest state building code IMO.
    http://www.floridabuilding.org/fbc/t...ODE-Energy.htm

    https://fl-monroecounty.civicplus.co...x.aspx?NID=243
    __________________________
    I doubt that equipment sizing and any responses regarding HVAC installation are
    going to be truly worthy of consideration when provided by those not abiding by the _latest_ building codes.

    TRANE equipment life is best in this type of very corrosive environment.

    Two tons for each floor will BE adequate if BUILT AND TESTED TO FLORIDA CODE
    with a Foamed roof. Equipment and duct work SHALL BE in the conditioned space.

    Total Glass area should generally be < ~180 square feet per 1,600 square foot floor.
    WINDOW AND SLIDING GLASS _ _ S.H.G.C. MAXIMUM 0.30 _ _
    http://www.ecodes.biz/ecodes_support...Efficiency.pdf

    You can perform an analysis using the ACCA Manual J abridged edition.
    https://www.acca.org/standards/

    If you have any issues that indicate > 2 tons per 1,600 sq feet is required,
    you may contact me via e-mail ( address is in my profile).
    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
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    8,522
    Post Likes
    Quote Originally Posted by coconut sunrise View Post
    Hello All


    Any input would be greatly Appreciated
    Coconut Sunrise in the Florida Keys
    Just went to a day long seminar on moisture control in homes in Naples, FL. put on by a building expert.


    The main points are to keep the water out of the walls and roof.
    Bring in fresh air when the house is closed up at a moderate like an air change in 4-5 hours when occupied. FL has a code that will be enforced.
    Medium eff. simple a/c.
    Supplemental dehumidification enough to maintain <50%RH inside when closed up. This allows a/c off when unoccupied. The dehumidifier will maintain <50%RH without any a/c.

    Units like the Ultra-Aire are being used to provide fresh air ventilation and supplemental dehumidification. many of the attendees at this conference use this brand of dehumidifier. It installs next to the a/c with a control on the wall that controls the fresh air and %RH. It uses the a/c ducts to circulate the fresh air and dehumidify the home when desired.
    Regards TB

    http://ultra-aire.com/products/dehum...ra-aire-xt105h

    AIA_FLaSW_Save_the_Date._Building_Seminar_.pdf
    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"

  5. #5
    Join Date
    Jun 2005
    Location
    SW Wisconsin
    Posts
    6,606
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    Is there any way I could do the Calculation my self ? as it seems No ONE does these here in the Keys.
    http://www.loadcalc.net/ Free online calc.; print results U can't save results; could give a few dollars for using the software your choice. NO room by room calculations.

    Do the floors separately.
    After you think U have load-calc right for that floor print it; click on the sizing link; it will size both heating & cooling modes for that floor; print results for reference.

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