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  1. #1
    daniel nantell's Avatar
    daniel nantell Guest

    Default re- How much a/c needed

    Building a 144 sq ft sunroom , will have glass on 3 sides, How much a/c do you think would be adequate, thanks for any help.

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  2. #2
    Join Date
    Oct 2003
    Rockwall Texas

    Default Re: re- How much a/c needed

    You don't need AC, you need a buzz fan.

    Typically, a 1/2 ton unit would cool 500-600 sq.ft. depending on the heat load.


  3. #3
    Join Date
    Feb 2008
    Chicago IL

    Default Re: re- How much a/c needed

    Rooms like that are why Manual J exists. Glass on three sides equals tons of heat gain. Is this a conventional build or an aluminum/glass enclosure butted up against the side of the house? There are a few points I would consider
    - what direction is the room facing
    - will you be installing retractable shade screening on the roof portion
    - regardless of construction type spend the extra money and put in an operable skylight or the narrow slit vent windows along the top (if an ALU box)
    - consider installing an AC unit for this space only, like one of the Sanyo or Samsung wall mount splits
    - make provisions for a ceiling fan
    "The Code is not a ceiling to reach but a floor to work up from"

  4. #4
    Join Date
    Dec 2008

    Default Re: re- How much a/c needed

    Are you doing the actual construction??

  5. #5
    Join Date
    Mar 2007
    Ormond Beach, Florida

    Default Re: re- How much a/c needed

    "How much a/c needed"

    Enough to do the job ... and no more.

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( )

  6. #6
    Bruce Adams's Avatar
    Bruce Adams Guest

    Default Re: re- How much a/c needed

    There are to many variables on this one. Type of construction. Type of windows being used. Is it open to the other parts of the home. Can it be connected to the HVAC to the home. How much sun will it get. Call a HVAC company to come check it for what is needed. Get two or three bids by honest companies for dependable units. Stay with dependable units.

  7. #7
    Bob Spermo's Avatar
    Bob Spermo Guest

    Default Re: re- How much a/c needed

    Markus is absolutely correct - have a Manual J and Manual S done. If you want the addition done IAW the 2009 IECC add a Manual D calculation.

  8. #8
    Join Date
    Jul 2008

    Default Re: re- How much a/c needed

    I just ran a quick load for you. Assuming very tight construction, that the roof is very well insulated, that the project is facing south and the walls are very well insulated as well, you are using a window with an insane U of less than .38 with low E coating and with a light interior shading device and about 180 SF of glazing equally facing the three exposures.

    Total heat gain is over one ton. 542 CFM with a 20 F temp rise after the coil.

    You could greatly reduce that by eliminating windows and turn the addition so that it faced north, but then it wouldn't be a sun room would it?


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