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  1. #14
    Join Date
    Apr 2005
    Location
    Richmond, Virginia
    Posts
    365

    Post

    Don't you also need to know where the OP lives, what design temperatures he desires, and the orientation of the various windows and doors? How about the number of fireplaces and the number of people living in the house?

    In central VA - richmond - tidewater area design is 95 F 76 wb.

    Fireplaces are negliable since they would not be used for heating purposes. They do contribute to infiltration due to stack effect if the damper is not closed.

    For a family of 4 thats 450x4=1800 mbh total or .15 tons.

    Hopefully the sketch would have a north arrow, but you're right need the orientation of walls too.
    Sean Cantrell

  2. #15
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    6,432

    Cooling Load

    Originally posted by lit'l cat
    Should the outside or inside of a house be used to figure load calc. 1 contractor measured inside (sd 2.5 ton a/c) the other measured outside & sd (3 ton a/c)
    1,800 Sq.Ft., 300 Sq.Ft total Window area with Low E,
    _____ Use 2.5 Ton ____

    Low E ( S.H.G.C. ~ 0.46) requires 0.5+ ton less than CLEAR Glass ( SHGC 0.75). Room Temperature desired 75'F

    S.H.G.C. Solar Heat Gain Coefficient
    S.H.G.C. = 7/8 * Shading Coefficient

    100 Sq.Ft. difference in floor + ceiling area may make Cooling load difference of << 0.2 ton
    I use close to the Inside Area.
    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. #16
    Join Date
    Nov 2002
    Posts
    94

    Re: Cooling Load

    Designer Dan,

    Your post sd 1800sq ft use 2.5 Ton. My house is ~ 1600sq ft. In theory, that would make the tonnage even less, then wouldnt I have an airflow problem?

    Before you answer, this is more a general question since I realize you have no detailed info abour my house

  4. #17
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    6,432

    Exclamation Cooling Load Variations

    Originally posted by lit'l cat
    Your post sd 1800sq ft use 2.5 Ton. My house is ~ 1600sq ft. In theory, that would make the tonnage even less, then wouldnt I have an airflow problem?
    It ALL Depends on ...

    Blower + Blower Settings + Condenser +
    + Duct + Duct Transitions + Outlets + dT + %RH
    + Time of Day + Day + Month + ... +

    + Sunny + Cloudy + use of Ceiling Fans +
    whether you have several visitors +

    + How it ALL Works together AS A SYSTEM! ? ______
    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
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836

    Re: Re: Cooling Load

    Originally posted by lit'l cat
    Designer Dan,

    Your post sd 1800sq ft use 2.5 Ton. My house is ~ 1600sq ft. In theory, that would make the tonnage even less, then wouldnt I have an airflow problem?

    Before you answer, this is more a general question since I realize you have no detailed info abour my house

    Less tonnage on existings ducts is seldome a problem.The throw from the supply grilles will be less ,with less total cfms,unlikely enough less to be a problem.Todays top of the line two speeds,run on low most of the time,and there's no problem.

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