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  1. #53
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    Mar 2013
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    Quote Originally Posted by dan sw fl View Post
    2.83 Tons for 1,500 Sq Foot First floor + 270 Sq Ft Clear, Single Pane Windows
    0.79 S.H.R. - Sensible Heat Ratio
    91'F - 75'F

    0.46 Air Change per Hour Natural Winter
    0.28 A.C.H. Natural Summer

    4.28 Tons total
    2,662 Sq Feet Floor / 396 SF Glass / 1999 Built

    Glass Load = 55.9% of total U-Factor 0.93 S.H.G.C. 0.63

    Option:
    https://www.suntekfilms.com/Default....DealerZip.aspx
    Surprising!

    Does that account for the partial coverage of the sliding glass doors and I think she said one other window? That load still just sounds awfully high to me.





    Sent from my Moto Z (2) using Tapatalk

  2. #54
    Join Date
    Nov 2004
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    SW FL
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    Quote Originally Posted by football45 View Post
    Dan,

    Thank you it is much appreciated. I have a 1.5 ton handler and condenser upstairs.

    I was about to sign a proposal for a 3 ton VS handler and 2.5 ton condenser.

    Given the required 4.28 total based on your calculations, I'd be undersized for the home with a total of 4 tons.

    If I go with a 3 ton handler and condenser, then I'd be at 4.50 and a little bit oversized.

    So the question is in a very hot and humid climate which is the better option?
    It depends on actual MEASURED ACH Natural and S.H.G.C. after applying SunTek film.

    Without additional information or enhancements, 3-Ton 2-Stage.!

    T-stat set to < 76'F CREATES Relative Humidity issues (R.H. > 54%).

    Replacements will ALWAYS be Difficult to address accurately given
    ' loose definition ' of any/all BUILDING THERMAL ENVELOPE parameters.
    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. #55
    Join Date
    May 2018
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    Thread Starter
    Quote Originally Posted by dan sw fl View Post
    It depends on actual MEASURED ACH Natural and S.H.G.C. after applying SunTek film.

    Without additional information or enhancements, 3-Ton 2-Stage.!

    T-stat set to < 76'F CREATES Relative Humidity issues (R.H. > 54%).

    Replacements will ALWAYS be Difficult to address accurately given
    ' loose definition ' of any/all BUILDING THERMAL ENVELOPE parameters.
    Thanks it's a tough choice, dont have the budget for a 2 stage. So it's either a 3 ton VS with 3 ton condenser or a 3 ton VS with 2.5 ton condenser. AHRI certified systems.

  4. #56
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    Nov 2004
    Location
    SW FL
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    It's All About Windows and Infiltration

    Quote Originally Posted by shellkamp View Post
    Surprising!

    Does that account for the partial coverage of the sliding glass doors and I think she said one other window? That load still just sounds awfully high to me.

    Sent from my Moto Z (2) using Tapatalk
    Area =~ 400 Sq Feet
    ______ SINGLE, PANE NON-TINTED Windows / Sliding Glass Doors (SGD)

    SGD = 128 Sq Feet with ~ 10 foot ' overhang '
    Windows = 270 Sq Feet

    My INITIAL calculation is Not likely to be on the low side.

    - - - SIMPLIFIED - - -
    Your SOLAR IRRADIANCE Load : _ _ ,_ _ _ BTU/HR
    remember SHGC = ~ 0.8 for Clear
    __ Q = Area * SHGC * Solar Radiation
    ____ = 320 * Solar Radiation

    whereas todays windows would be
    ____ = 0.2 * 400 = 80 * Solar Radiation

    __ Window CONDUCTANCE Load: _ , _ _ _ BTU/ HR
    ___ U- Factor =~ 0.9
    ___ Q = dT * U * Area
    _____ = dT * 360

    http://www.solarelectricityhandbook....rradiance.html
    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

  5. #57
    Join Date
    May 2018
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    Thread Starter
    Quote Originally Posted by dan sw fl View Post
    Area =~ 400 Sq Feet
    ______ SINGLE, PANE NON-TINTED Windows / Sliding Glass Doors (SGD)

    SGD = 128 Sq Feet with ~ 10 foot ' overhang '
    Windows = 270 Sq Feet

    My INITIAL calculation is Not likely to be on the low side.

    - - - SIMPLIFIED - - -
    Your SOLAR IRRADIANCE Load : _ _ ,_ _ _ BTU/HR
    remember SHGC = ~ 0.8 for Clear
    __ Q = Area * SHGC * Solar Radiation
    ____ = 320 * Solar Radiation

    whereas todays windows would be
    ____ = 0.2 * 400 = 80 * Solar Radiation

    __ Window CONDUCTANCE Load: _ , _ _ _ BTU/ HR
    ___ U- Factor =~ 0.9
    ___ Q = dT * U * Area
    _____ = dT * 360

    http://www.solarelectricityhandbook....rradiance.html
    Dan, sorry but you're getting a bit technical for me to understand. Based on your calculations and experience, if my budget only allows for a 1 stage, would you recommend a 3 ton handler and 3 ton condenser or should I be okay at 3 ton handler and 2.5 condenser?

  6. #58
    Join Date
    May 2018
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    Thread Starter
    Quote Originally Posted by dan sw fl View Post
    It depends on actual MEASURED ACH Natural and S.H.G.C. after applying SunTek film.

    Without additional information or enhancements, 3-Ton 2-Stage.!

    T-stat set to < 76'F CREATES Relative Humidity issues (R.H. > 54%).

    Replacements will ALWAYS be Difficult to address accurately given
    ' loose definition ' of any/all BUILDING THERMAL ENVELOPE parameters.
    I found a dealer with the right price for a 3 ton 2 stage. If stage 1 runs at 70% then itll run at 2.1 tons, but wont there be a significant decrease in air flow and air distribution potentially not enough cooling capacity, meaning the bedroom that's always warmer on the longer run may not get enough air flow?

    There seems to be mixed opinions on this forum regarding 2 stage systems and whether they actually are better for dehumidification.

  7. #59
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    Mar 2013
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    Treasure coast, FL
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    Quote Originally Posted by football45 View Post
    I found a dealer with the right price for a 3 ton 2 stage. If stage 1 runs at 70% then itll run at 2.1 tons, but wont there be a significant decrease in air flow and air distribution potentially not enough cooling capacity, meaning the bedroom that's always warmer on the longer run may not get enough air flow?

    There seems to be mixed opinions on this forum regarding 2 stage systems and whether they actually are better for dehumidification.
    There's going to be a 30 percent reduction in airflow in first stage.

    I've never had a complaint about two stage equipment concerning dehumidification that wasn't an equipment malfunction or duct/building envelope related.

    Again; run time is what's facilitating better or worse dehumidification, and not so much the amount of equipment stages or the listed capacity of the unit.

    Your warm room will continue to be warmer than the rest of the house unless you get the ductwork corrected.


    Sent from my Moto Z (2) using Tapatalk

  8. #60
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    May 2018
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    Thread Starter
    Quote Originally Posted by shellkamp View Post
    There's going to be a 30 percent reduction in airflow in first stage.

    I've never had a complaint about two stage equipment concerning dehumidification that wasn't an equipment malfunction or duct/building envelope related.

    Again; run time is what's facilitating better or worse dehumidification, and not so much the amount of equipment stages or the listed capacity of the unit.

    Your warm room will continue to be warmer than the rest of the house unless you get the ductwork corrected.


    Sent from my Moto Z (2) using Tapatalk
    In a 2 stage how does the system know whether theres enough air flow in 1st stage to adequately cool the home and when to switch to second stage full capacity instead?

    With a VS air handler and 2 stage condenser I would still be able to lower the blower speed on the dip switch if I needed to try to obtain additional humidification correct?

    I just dont want a situation where it's running in 1st stage at around 2.1 tons and there's not enough overall airflow to adequately cool the spaces.

    Regarding that warmer room, it's the only part of the 1st floor that has unconditioned ducts in an attic. The ductwork runs from the conditioned areas through a cut out of cinderblock foundation into an attic. That ductwork has been checked and there is not an issue with leakage. The air flow coming out of the supply duct is less than the other supply ducts on the floor. The attic has batt insulation, but I'm thinking of adding more blow in insulation, and slightly restricting the flow of air at other supply ducts to push more air back there.

  9. #61
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    Jan 2019
    Location
    Vero Beach, Florida
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    Quote Originally Posted by football45 View Post
    I found a dealer with the right price for a 3 ton 2 stage. If stage 1 runs at 70% then itll run at 2.1 tons, but wont there be a significant decrease in air flow and air distribution potentially not enough cooling capacity, meaning the bedroom that's always warmer on the longer run may not get enough air flow?

    There seems to be mixed opinions on this forum regarding 2 stage systems and whether they actually are better for dehumidification.


    If a company is offer the same 2 stage system for way less than everyone else. You got to ask yourself how bad are they hurting for work or is there a reason why they’re going so cheap

  10. #62
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    May 2018
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    Thread Starter
    Quote Originally Posted by Deathpunch0311 View Post
    If a company is offer the same 2 stage system for way less than everyone else. You got to ask yourself how bad are they hurting for work or is there a reason why they’re going so cheap
    I know I cant talk about pricing on here but let's just say my other quotes were variable speed condensers not 2 stage. The 2 stage is not significantly more than the 1 stage.

    It's just a matter of whether the 2 stage with VS handler will work better for me.

  11. #63
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    May 2018
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    Thread Starter
    Quote Originally Posted by football45 View Post
    I know I cant talk about pricing on here but let's just say my other quotes were variable speed condensers not 2 stage. The 2 stage is not significantly more than the 1 stage.

    It's just a matter of whether the 2 stage with VS handler will work better for me.
    Any last thoughts about the 2 stage 3 ton vs single stage 3 VS ton handler with a 2.5 ton condenser?

    My main concern would be that the 1st stage may not move enough air to my longer runs if its operating at 70% (~2.1 tons) to adequately cool. Is that a valid concern? I'm making the decision no later than Tuesday and plan on living in the home at least 10 yrs so I dont want to screw this up.

  12. #64
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    Jan 2019
    Location
    Vero Beach, Florida
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    Me personally I don’t like mismatched units. (3ton ahu on a 2.5 CDU).

    I’ve seen a lot of places cool just fine with a 2 stage unit running in 1st stage.

    Variable speed blowers move as much air as the board and program inside of the blower tells it too. Example 2-5 minutes run at a certain percent 5-7 another percent. It will only go to 100% if it’s running for a long period of time.

    It doesn’t matter what’s installed. As long as it’s installed right and charged right it will cool no matter what

  13. #65
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    May 2000
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    Indianapolis, IN, USA
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    As long as a match is AHRI rated, it isn't a mismatch. Take Rheem, for example, in CT and VS air handlers, they don't make an 030 so a 2.5 ton has to be on a "3 ton" air handler. Key is having an installer smart enough to set the blower speed down. 10% change of that happening

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