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Thread: A/C Unit size

  1. #1
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    Default A/C Unit size

    Had a 2000 sq ft ranch home with a 3 1/2 ton A/C unit. Too big? If so what kind of issues can this cause? Thanks

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    E.D.S
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  2. #2
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    Default Re: A/C Unit size

    As long as it is balanced with the proper evaporator and size furnace, it shouldn't be a problem, That is exactly the setup that I have.

    If you choose not to decide, you still have made a choice.

  3. #3
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    Default Re: A/C Unit size

    Home has a boiler for floor radiators. Air handler is in attic. Tonsof breaks in the ducts, not insulated properly, and the attic unit is very rusty and dirty. I called those things out of coarse. Just thought I remember hearing something about if a unit is too big it can be an issue.

    E.D.S
    Home Inspections
    Lic.#450.010534

  4. #4
    Bob Spermo's Avatar
    Bob Spermo Guest

    Default Re: A/C Unit size

    No real way to tell unless a load calculation using Manual J, D and S is completed. Without knowing the insulation, the windows, the direction the house faces, etc it is a guess as to the correct size for the A/C.


  5. #5
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    Serving SC & NC
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    Default Re: A/C Unit size

    Commenting on the adequacy of BTUs is beyond the scope of a home inspection unless you are a specialist in HVAC. Just tell the client the size and refer it to a licensed contractor. Done.

    Joe Funderburk, CBO, CMI
    Alpha & Omega Home Inspections, LLC
    Serving SC & NC

  6. #6
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    Illinois
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    Default Re: A/C Unit size

    Thanks a lot guys. I did exactly that mentioned the size and asked for further evaluation from HVAC.

    E.D.S
    Home Inspections
    Lic.#450.010534

  7. #7
    Join Date
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    Maryland
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    Default Re: A/C Unit size

    Eric,
    -Coil freezes stops cooling house.
    -System has a short cycle so humidity is not reduced and air feels cold and clammy.
    -Duct work super cooled and condensate forms.
    quick start of a list.


  8. #8
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    Chicago IL
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    Default Re: A/C Unit size

    3.5 ton in 2000 sqft. is fairly standard around here depending on conditions, etc. If it's oversized, then probably not by much. I wouldn't sweat this size on that one.

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  9. #9
    Join Date
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    Melbourne, FL
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    Default Re: A/C Unit size

    1.5 Ton central HVAC system in a 2000 sq. ft. home pretty standard; If moisture is a problem look for something else. Had one inspection where homeowner was really proud he had installed 5.0 ton unit in a 1500 sq. ft. home said it worked real well problem was interior wall were covered with moisture droplets. Asked him if the white pipe next to the condenser ever discharged any water? "No of course not" was his answer, nor would he give me the name of the installer.


  10. #10
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    Dec 2007
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    Holladay, UT
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    Default Re: A/C Unit size

    I've always used as a general rule and I mean general, 1 ton per every 550 square feet for this area (Utah). If I were to see say a 5 ton in a 1500 sq foot house as Thomas saw it would raise a red flag. A 3.5 ton in a 2000 square foot house seems just right. If a unit is too big it will not run long enough and won't properly dehumidify as Thomas also alluded to.

    Tom Rees / A Closer Look Home Inspection / Salt Lake City, Utah

  11. #11
    Join Date
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    Sparks,NV
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    Default Re: A/C Unit size

    Quote Originally Posted by Tom Rees View Post
    I've always used as a general rule and I mean general, 1 ton per every 550 square feet for this area (Utah). If I were to see say a 5 ton in a 1500 sq foot house as Thomas saw it would raise a red flag. A 3.5 ton in a 2000 square foot house seems just right. If a unit is too big it will not run long enough and won't properly dehumidify as Thomas also alluded to.
    There are guys in Vegas that say 1 ton per 400 sqft. I live in the north part of the state 1600 sqft gets 3 ton. This is exactly why I wouldn't use that type of calculation with out knowing the construction and system demands in your own area. As mentioned you have to at least run manual J or something similar to really know. Best to refer it out.

    Nevada IOS#1730
    Nevada Energy Auditor #30
    775-342-4767 www.homecsi.com

  12. #12
    Join Date
    Sep 2007
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    Fredericksburg, VA
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    Default Re: A/C Unit size

    I agree with Gary- A lot would depend on the seasonal temperatures in the area, humidity levels, home insulation, number of stories or living levels. In VA, 3.5 Tons for 2000 SF would be a bit overkill. I usually see 2.5 tons. But sometimes the homeowner demands a bigger unit and of course someone will sell it to him.

    The above statements are expressed solely as my opinion and in all probability will conflict with someone else's.
    Stu, Fredericksburg VA

  13. #13
    Join Date
    Apr 2009
    Location
    Melbourne, FL
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    180

    Default Re: A/C Unit size

    Very true Stuart, it is better to slightly under size the condenser; in my market we see many installations where if the condenser, properly sized, is a 3.5 ton unit the air handler is sized for a 4.0 ton system. This seems to give a better movement of air in our hot climate. Over sizing the system can lead to moisture problems.


  14. #14
    Join Date
    Aug 2011
    Location
    United States
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    Default Re: A/C Unit size

    Quote Originally Posted by Tom Rees View Post
    I've always used as a general rule and I mean general, 1 ton per every 550 square feet for this area (Utah). If I were to see say a 5 ton in a 1500 sq foot house as Thomas saw it would raise a red flag. A 3.5 ton in a 2000 square foot house seems just right. If a unit is too big it will not run long enough and won't properly dehumidify as Thomas also alluded to.
    Iím in Arizona and I totally agree with your logic. Square foot of home to BTUís would vary according to type of home, building materiel and technology used. Example Ė I would recommend using 280 square foot per ton for an older manufactured home (here in Phoenix), older Block home with single glaze windows - 325, 2x4 stick built in the early 80ís to late 80ís - 350 to 400 and newer homes with R30+ in the attic, dual glaze with low E Ė 500 to 525. I just inspected a Short sale, 2070 square foot, two story built in 2005 in San Tan Valley with a 2012 3 ton Day-Night condensing coil (ground mounted, split system) with living space over the Garage. Listing agent said that someone stole the old unit and she had a Contractor install the new one (Listing agent Translation of Contractor Ė a guy with a truck & Hammer). According to the HVAC contractor the buyer hired, the home should have had a 48,000 btu unit, the builder (pulte homes) said that they build high efficient homes and a 42,000 btu condensing coil was installed in that home and sized properly. Although I did not talk to the buyers HVAC contractor, he and I did agree on the sizing of the unit and we also agreed on installing two units a new 2.5 ton upstairs and re-ducting the 3 ton for just down stairs.
    Question Ė anyone know of a spread sheet or a online calculator for sizing a condensing coil?

    Thoughts are things too!!!

    Nick J Alati
    Alati's Inspection Service LLC
    hhtp:\\Phoenix Home Inspector, Arizona Commercial Inspections, AZ Property Inspectors, HUD, FHA, VA Alatiís Inspection Service LLC


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