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  1. #27
    Join Date
    Aug 2009
    Location
    Beatrice, NE
    Posts
    8,760
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    Quote Originally Posted by Artietech View Post
    This is why I do not work with builders or new construction. Too much time up front to do it right that they do not want to compensate for.
    This is why my new construction is limited to custom work, I don't do it for nothin'.

  2. #28
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    9,087
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    Quote Originally Posted by BNME8EZ View Post
    Warm air is buoyant, cold air is heavy.
    __________ _ _ _ /\ _ _ /\ _ _ ___ B.S.

    not THE VALID reason that MORE AIR IS REQUIRED FOR COOLING.

    Q = cfm* dT * 1.08 <- Valid Reason
    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. #29
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    9,087
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    Quote Originally Posted by mnoone View Post
    I am getting ready to have a new HVAC system installed in my house. I've had 4 different companies come out to quote the work. Normally I'd have two come out - but I just didn't get a good vibe from the first three. The 4th I actually liked though.

    My house is 1600 square feet and I currently have
    a 30 year old central furnace that works fine
    that is using 60 year old rigid ducting throughout the house.

    First and second vendors want to add a couple new vents (go from 9 to 11), and expand my two 2x14 boots to 4x14 (the rest are 4x14). They also both wanted to increase my return duct from 14" to 16" diameter

    Third vendor wants to tear out all my old rigid ducting and replace it all with flex. Not sure about sizing. Also mentioned adding at least one vent.

    Fourth vendor wants to tear out all ductwork, replace it all (with new rigid), and add 7 vents (go from 9 to 16).

    All of them are quoting ~3-4 ton ACs, and 60-80KBTU furnaces. This is in Northern California.

    The fourth vendor is the only one who took floor plan and ran calculations with some sort of software (didn't catch the name - but some sort of specialized HVAC software). The others seemed to just use some rule of thumb to size furnace and AC.

    So - my questions:

    • Does 16 registers seem like a lot for a 3.5 ton AC?
    • My current furnace works fine (with 14" return and 9 registers). Does it make sense that I would need to enlarge return and add more registers to add cooling?
    • If it does make sense - why couldn't I just enlarge the ductwork going to the vents but not add so many vents? Would it get noisy?
    • What can I do as a homeowner to make sure these guys are sane?
    START OVER:
    _______ So you are trying to add A/C in a 1,600 sq ft N Calif ranch built in 1956.

    1ST: Blower Door Tet required to determine Infiltration.
    _____ AND SEAL THE HOSUE AS REQUIRED.


    2ND: Original Windows ?
    ___ No Wall insulation.


    ZIP _ _ _ _ _

    N Calif might in the millions (or billions) of acres.
    We are only concerned with ONE HERE.
    Attached Images Attached Images
    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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