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  1. #1

    Hmm

    We are trying to find the correct size unit for new construction of our guest house. The house is approximately 1600 sq feet under air. Two stories with only two windows on each floor. The first floor has ten foot ceilings. The second floor has 8 ft ceilings in the center for a span of about 12 feet going down to 4ft at the side walls. We would prefer to use one unit. We have been told 3.5 ton to 5 tons. Please help.
    thanks.

  2. #2
    Ask your contractor to show you the Load Calculation they did to determine the size unit the house needed. They should have a load calculation based on manual J

  3. #3
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    You can do your own Manual J load calculation on this site for a fee,click here; http://hvaccomputer.com/talkref.asp


    Your HVAC contractor should do it,but many can't or won't.

    Equally important are Manuals S ,to select equipment size,and Manual D to size the ducts.

    All the Manuals are from http://www.acca.org



  4. #4
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    6,274
    Originally posted by nick varie

    The house is approximately 1600 sq feet under air.

    Two stories with only two windows on each floor.

    The first floor has ten foot ceilings.
    The second floor has 8 ft ceilings in the center for a span of about 12 feet going down to 4ft at the side walls. We would prefer to use one unit.

    We have been told 3.5 ton to 5 tons. Please help.
    < ~ 3 Tons & ~ 1,200 CFM might be appropriate if you do not live in AZ or TX ,,,
    and more likely 2.5 ton and 1,000 CFM for northern U.S.
    or if ducts & house are well sealed

    Location ?
    Ceiling Insulation R-30 ?

    Outside Design Temp 94' F ?
    Inside Temp desired 76'F with < 50% R.H.

    4 windows = < 70 Sq. Ft total
    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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