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  1. #14
    Thanks Dan. Just sent email to you.

  2. #15
    Join Date
    Jun 2005
    Location
    SW Wisconsin
    Posts
    5,033

    Loads Appear Way Too High...

    Toledo, Ohio may be closest to him in SE MI; it has a winter 99% of -3F; 97.5% is +1F; 88F & 75F cooling.

    In cooling mode, that is a fairly high outdoor humidity, if design is 75F & 40 to 50% RH indoors the grains of moisture difference per lb of air is a fair amount. Wouldn't ever want to oversize cooling system...
    Yes; either terrible poor home efficiency or load-calc is skewed.

    Try running your own FREE whole house load-calc, - just for practice, only.
    On E&W line, Put all the wall & window square footage in the 1____ slot.
    Print & read the simple directions, then follow them:
    http://www.loadcalc.net/
    Last edited by udarrell; 04-25-2013 at 11:59 AM.

  3. #16
    Join Date
    Jan 2009
    Location
    Keokuk, IA
    Posts
    5,520
    For Toledo I have 3F.

    In various SE MI cities I have between 4-7F for winter design. Summer design is between 87-88F. Pretty low. WB of 71-72F. Very, very easy to oversize AC.

    My parents live in SE Michigan. Their AC is oversized. It's always cool and clammy. They have a 2.5 Ton AC in a 1200sqft 2 story condo with 2 shared walls. They probably only need 1.5 tons considering it should be running continously on a humid 88-90F sunny afternoon.

  4. #17
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    6,429
    Quote Originally Posted by pds22 View Post
    Thanks Dan. Just sent email to you.
    VERY SIMPLIFIED APPROACH using XCEL developed from blank spreadsheet
    -----| Q = U * a * dT |-----
    to your detailed, Professional Architectural drawings

    After detailed review of 650 Square feet of windows U 0.29, SHGC 0.26
    Total Q = 14,300 BTU/HR for windows

    Basic dimensions ~ 59 x 39
    Ceiling R-38
    Walls 6", R-19
    Infiltration 0.4 ACH

    72' F inside 2'F outside dT = 70'F
    _ First Floor 33,400 BTU/HR
    _ Basement 22,000 used R-4 [?] to soil temperature 45'F

    Second Floor 37,700 BTU/HR

    Summer loads is so low it seems that use of two 2-tons is oversizing the First Floor.

    Also, I need to use LOADCALC as udarrell has suggested.
    ___ NOT FOR Practice Only. ___
    Thermastor product seems appropriate for mild summer climate and this house size.
    http://www.thermastor.com/Ultra-Aire-XT155H/

    I don't have access to my Wrightsoft program due to contract assignment at this time.

    YOU WILL NEED MANUAL D with a detailed Duct Design.
    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. #18
    Join Date
    Jun 2005
    Location
    SW Wisconsin
    Posts
    5,033
    Infiltration 0.4 ACH
    I was wondering why you always use 0.4 ACH; I usually use 0.7, or even 0.8 ACH Until air sealing has been performed.

    I believe 0.7 is considered average natural Air Change(s) per Hour (ACH) until sealing is done.

    I use that Whole House load-calc, but it is hard to accept the low calcs it delivers. I thought it was getting the winter & summer designs too low until I checked Manual J design temps; it was correct.

    On the E&W line I add them together & put the sum in the #1 slot, or it doesn't seem to add it the amount in #2 slot.(?) I need to check that out again...

    I kept track of the Btuh my 57,000 output furnace took to heat my 2 story home with a deep basemant; even in the coldest sub-zero weather it kept it near 68-F at around 30,000-Btuh here in SW WI. That is also hard to believe on a 1937 farm home with a lot of windows with storms.

    I have a programmable SWING-temp thermostat so it goes below & slightly above 68F; that results in 15 to occasionally 20 minutes or more of runtime cycles; helps on efficiency.

    I use minutes of BTU used; 57,000-Output / 60-mins is 950-Btu/per minute; makes it easy to figure Btu use per hour.

  6. #19
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    6,429

    EXCELLENT THERMAL BUILDING ENVELOP

    Quote Originally Posted by udarrell View Post
    I was wondering why you always use 0.4 ACH; I usually use 0.7, or even 0.8 ACH Until air sealing has been performed.

    I believe 0.7 is considered average natural Air Change(s) per Hour (ACH) until sealing is done.
    0.35 ACH was the border line set in early versions of ASHRAE 62.2.
    0.4 ACH is achievable and a very good objective.
    LOW ACH values (< 0.5) can be used on recently built homes and definitely justified with good/premier builders.

    Granted, this value remains a point of debate in performing load analysis.
    One could use ACH = 1 or more on some pre-1980 homes

    Abridged Manual J8 provided.

    2,000 ___ Sq feet
    .... 9 ___ height
    18,000 ___ cubic feet
    .... 0.4 ___ ACH
    7,200 ___ cubic feet per hour
    .. 120 ___ CFM
    Last edited by dan sw fl; 05-01-2013 at 03:50 AM.
    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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