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  1. #1
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    Infinity 24VNA9 AC 5 Ton vs Infinity 24VNA0 AC 5 Ton

    How much of a difference will the variable speed (that goes anywhere from 40% to 100%) make versus the 5 stage that can go as low as 25% (but only in larger increments)?

    I had one guy tell me that if staying in a home for the long term going from dual stage to variable was a no brainer but then a second contractor gave me quotes on a 5 stage.

    I'll be coming from a 19 year old single stage system, so I'm sure either will have a big effect on my summer AC bills but is the variable *that* much better? (I was already discounting the 2 stage because the price difference to the 5 stage wasn't that much so I couldn't see going that route.)

    Aside from efficiency, is there anything else I should be thinking about when deciding which to go with? Any concerns with reliability, future repairs, etc?

    Any input would be greatly appreciated. Thanks!

  2. #2
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    Do NOT base it on saving money when using it. Base it on comfort.

    Repair costs, while not usually factored in, should be considered. The more complex the system(no matter what it is) will make repairs more costly.

    Installation is the greatest factor!!!!
    The Food Stamp Program, administered by the U.S. Department of Agriculture, is proud to be distributing the greatest amount of free meals and stamps EVER.
    Meanwhile, the National Park Service, administered by the U.S. Department of the Interior, asks us to "Please Do Not Feed the Animals". Their stated reason for this policy "... the animals become dependent on handouts and will not learn to take care of themselves."
    from an excerpt by Paul Jacob in Sun City, AZ

  3. #3
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    Quote Originally Posted by orangecrushv View Post
    How much of a difference will the variable speed (that goes anywhere from 40% to 100%) make versus the 5 stage that can go as low as 25% (but only in larger increments)?

    I had one guy tell me that if staying in a home for the long term going from dual stage to variable was a no brainer but then a second contractor gave me quotes on a 5 stage.

    I'll be coming from a 19 year old single stage system, so I'm sure either will have a big effect on my summer AC bills but is the variable *that* much better? (I was already discounting the 2 stage because the price difference to the 5 stage wasn't that much so I couldn't see going that route.)

    Aside from efficiency, is there anything else I should be thinking about when deciding which to go with? Any concerns with reliability, future repairs, etc?

    Any input would be greatly appreciated. Thanks!
    Yes

    What size you actually need and what the ducts can handle!

  4. #4
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    Thread Starter
    Quote Originally Posted by pacnw View Post
    Do NOT base it on saving money when using it. Base it on comfort.
    I guess it’s the accountant in me that likes to quantify by $... but what if I reword my question as how much better of a job does one do over the other?

  5. #5
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    Thread Starter
    Quote Originally Posted by pecmsg View Post
    Yes

    What size you actually need and what the ducts can handle!
    Let’s assume 5 ton is correct (the old system was that size and three contractors recommended that size for the replacement) and also believe the ducts will cover 2000 CFM (even though the contractors really varied in their measurements... but that was another thread &#128512 How much of a difference is there going from one type to another?

  6. #6
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    Quote Originally Posted by orangecrushv View Post
    Let’s assume 5 ton is correct (the old system was that size and three contractors recommended that size for the replacement) and also believe the ducts will cover 2000 CFM (even though the contractors really varied in their measurements... but that was another thread ��) How much of a difference is there going from one type to another?
    Let's NOT assume 5 ton is correct.

    You need to find a contractor that will do a calculation for both load(need) and duct size(capability). Until you find that contractor, you have not found a competent contractor to install your equipment!!!

    5 tons is a large, large need/capacity. Be sure of this, FIRST.
    The Food Stamp Program, administered by the U.S. Department of Agriculture, is proud to be distributing the greatest amount of free meals and stamps EVER.
    Meanwhile, the National Park Service, administered by the U.S. Department of the Interior, asks us to "Please Do Not Feed the Animals". Their stated reason for this policy "... the animals become dependent on handouts and will not learn to take care of themselves."
    from an excerpt by Paul Jacob in Sun City, AZ

  7. #7
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    Quote Originally Posted by orangecrushv View Post
    Let’s assume 5 ton is correct (the old system was that size and three contractors recommended that size for the replacement) and also believe the ducts will cover 2000 CFM (even though the contractors really varied in their measurements... but that was another thread &#128512 How much of a difference is there going from one type to another?
    We all know what A S S U M E stands for.

  8. #8
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    Your first assumption just cost you thousands over the equipments life if your wrong, do a manual j and find out for sure. Your second assumption, about the ducting, is something I've never seen. I've never ran across a 5 ton that was able to deliver 5 tons of cooling into the structure, youd be much better served by 2 basic but properly sized (much smaller) systems than a "high efficiency" 5 ton anything. What did the contractors say would happen when either system ramps down and the airflow drops to a trickle because the ducting is oversized? Did they mention any need for zoning? As far as difference in comfort, I doubt you'll notice any but I've seen lots of people make the mistake of assumptions and your post sounds like your on that trail, your not buying the hvac system, your buying the best damn person you can find to size and install one correctly, very few systems get that kind of care because it takes time and time equals money. Find your contractor first and let them worry about the brand

  9. #9
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    Thread Starter
    Quote Originally Posted by pacnw View Post
    Let's NOT assume 5 ton is correct.

    You need to find a contractor that will do a calculation for both load(need) and duct size(capability). Until you find that contractor, you have not found a competent contractor to install your equipment!!!

    5 tons is a large, large need/capacity. Be sure of this, FIRST.
    So what's the key to finding that? I had two contractors do a lot of measuring and calculating but came up with very different answers.

  10. #10
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    Quote Originally Posted by orangecrushv View Post
    So what's the key to finding that? I had two contractors do a lot of measuring and calculating but came up with very different answers.
    Find a contractor that will do it right.
    Manual “J “ load loss calculation is the only way to know !

  11. #11
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    Mar 2018
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    Chico, Ca #StateofJefferson
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    You can go to Loadcalc.net and they have a free block load manual j you can use. This will tell you how many BTU's your home gains or loses at the design temp for your locale. A contractor worth your money will do a room by room version of this to determine how many cfm each room needs, but give it a try. Most homes in this country have oversized equipment on undersized ducting. This costs more money in faster equipment break downs, higher energy bills and reduced comfort. This site also has a contractor locator map

  12. #12
    Join Date
    Nov 2004
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    Quote Originally Posted by orangecrushv View Post
    So what's the key to finding that?

    I had two contractors do a lot of measuring
    and calculating but came up with very different answers.
    Factors

    Location: Dallas ___ Design Temperature: 99.5 'F / 74.5'F
    ___________________________________ DB/ WB
    ______________________________ Dry Bulb / Wet Bulb

    Age of Residence: Built 2001 ?

    Ceiling_ R-30
    Walls _ R-13
    Floor __ R- ___ ?

    Infiltration < 0.4 A.C.H. Natural
    _________ Air Change Per Hour

    # of Stories ___ ?

    Size: 2,500 Sq Feet or ______ ?
    IF < 2,500 SF + < 25 years old, 4-ton could well be adequate

    _ Note: _ 4 ton * 370 CFM /Ton = ~ 1,480 CFM Minimum

    Type of Windows: Double Pane,
    __________ ? __ S.H.G.C. < 0.35

    # of Windows & Orientation
    North
    South
    East
    West

    Total Glass area < ~ 330 Sq Feet ?

    My Gmail address: racingdan11
    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

  13. #13
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    Indianapolis, IN, USA
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    The 5 stage is a rotary compressor, the variable speed is a Copeland scroll on a Carrier. Personally I'd trust the scroll over the rotary for reliability. I'm old, I remember when Fedders tried a rotary in a big split.

    Zoning? Just remember if you are blowing 25% of your air into a 5 ton duct system, there could be velocity issues where distant vents don't get much air. To me, best use of a variable speed or 5 stage unit is if you have Infinity zoning. Otherwise, a 2 stage might be a better bet.

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