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  1. #14
    Join Date
    Jun 2001
    Location
    Moore, Oklahoma, United States
    Posts
    4,296
    Think about what happens if the 2 ton can't do the job. It will be 75 or 77 that unusually hot afternoon. Not a big deal. The smaller unit will give lower bills from less cycling losses.

  2. #15
    Join Date
    Jun 2006
    Location
    Richmond, VA
    Posts
    2,916
    Quote Originally Posted by 54regcab View Post
    Think about what happens if the 2 ton can't do the job. It will be 75 or 77 that unusually hot afternoon. Not a big deal. The smaller unit will give lower bills from less cycling losses.
    If you look at the product ratings for whatever equipment sized based upon the manual j, there is no "2 ton" out there that will cover the load. Like dan said...look at the ratings....no way a "024" will cover that load even on the sensible side....

  3. #16
    Join Date
    Jun 2001
    Location
    Moore, Oklahoma, United States
    Posts
    4,296
    Internal shading on the windows will cover the difference when near design conditions. Expecting to leave the west windows exposed on a day that hotter than design will lead to oversizing. As I've said, my 2 ton in the same size house is good for a 25 degree difference from indoor to outdoor temps. I know the houses are different, but I have a hard time believing that a 2 ton can't pull a 15 degree difference in a 1600sqft house if the west windows are shaded. Yes the data will show lower than 24K output, but charts are based on 95 outdoor temps, not 88. Not sure how much difference that makes.

    Of course the extra 1/2 ton probably won't cause humidity issues, and it would be the "safe choice".

  4. #17
    Join Date
    Jun 2001
    Location
    Moore, Oklahoma, United States
    Posts
    4,296
    I'm surprised nobody else has mentioned doing something with zoning/fixing ductwork on a 3 story structure. How would it even be possible to heat/cool evenly without at least some manual dampers?

  5. #18
    Join Date
    Jun 2006
    Location
    Richmond, VA
    Posts
    2,916
    At 85degrees outdoor and 75/63 indoor a 2ton bryant Heatpump only puts out 22460Btu total and 17360 sensible........Just about the same as all the rest of them.

  6. #19
    Join Date
    Jun 2001
    Location
    Moore, Oklahoma, United States
    Posts
    4,296
    I've wondered about real world capacity vs. rated capacity. In the Rheem/Ruud value series the 13SEER and 14SEER both are rated for the same capacities and even have the same compressor. However the 14SEER unit has about twice the coil surface area. I would think with a larger coil the 14SEER would perform at 95 like the 13SEER does at 85 or so...

  7. #20
    Join Date
    Jun 2006
    Location
    Richmond, VA
    Posts
    2,916
    pull up the actual product ratings at your OD temp, ID temp and cfm....

    or specifically the expanded product ratings..

  8. #21
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    6,295
    Quote Originally Posted by 54regcab View Post
    Why the 1/2 ton oversize by everybody?
    NOT..

    Use ACCA Manual S
    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

  9. #22
    Join Date
    Dec 2012
    Location
    Sagamore Hills, OH 44067
    Posts
    8
    Thank you everyone for your help! It's very much apprecieated.

    Happy Holidays,
    Steve

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