Carrier 58STA vs. 58CVA, is extra $ for variable speed blower, 2 stage worth it?
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  1. #1
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    Nov 2012
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    Carrier 58STA vs. 58CVA, is extra $ for variable speed blower, 2 stage worth it?

    I'm getting a new AC and Heating system installed. I'm told there is a $ increase in price, for the whole system, if I choose the Carrier 58CVA110-20 vs. the 58STA110-16. For the AC, I'm going with the 24ABB348 which is a 13 SEER.

    The 58CVA is a 2-stage furnace w/ a variable speed blower motor. Is this really worth the extra $? Is it going to help at all in the summer with the AC, in terms of improving some of the rooms that don't get enough cooling, or just help in the winter with rooms that don't get enough heat? What are my savings really going to be in both the winter and summer with the 58CVA versus the 58STA?

    Another thing, is the contractor doesn't really plan on installing an extra wire for the, so, would I still get benefit of the variable speed blower without the extra wire?

    Important: I need to be assured that a variable speed blower won't make my AC work worse in terms of problematic rooms versus the rooms that get the most cooling. Will the AC work at least as well as it currently does for the problematic rooms with a variable-speed blower? Does variable-speed ever make AC work worse for problematic rooms?

    ADD: I also have the option of a Carrier 2-stage furnace without variable speed blower which I assume is going to be midway between cost of 58CVA and 58STA....would 2-stage without variable speed be worth considering?


    Thanks,

    J.
    Last edited by beenthere; 11-28-2012 at 05:16 AM. Reason: price

  2. #2
    Join Date
    Jan 2008
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    1,948
    Uneven room temps are usually cause by poor duct work and design. No furnace will solve the problem.
    "Hey Lama, hey, how about a little something, you know, for the effort." And he says, "there won't be any money, but when you die, on your deathbed, you will receive total consciousness." So I got that goin' for me, which is nice. - Carl Spackler

  3. #3
    Join Date
    Oct 2010
    Location
    Anderson, South Carolina, United States
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    Pricing is not allowed it will be edited out. If you have undersized/leaky duct then the variable speed could make problems worse and use more power than a standard motor. With 2 speed heat if not way oversized it will produce longer run times which will more evenly heat the house.

  4. #4
    Join Date
    Nov 2012
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    39

    Single speed models # ending in 16 (1600 CFM) vs. dual speed model # ending in #20

    I ntoiced that the two choices of furnaces with single-speed blowers that they are pricing for me have a number that ends in -16, which I understand means 1600 CFM. The dual-speed ends in -20 which means 2000 CFM. Any idea why they would choose 16 instead of 20 for the single speed model? (all of which are 110K BTU)

    Thanks,

    J.

  5. #5
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    Jun 2003
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    Madison, WI/Cape Coral, FL
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    6,231
    Quote Originally Posted by Jreality View Post
    Another thing, is the contractor doesn't really plan on installing an extra wire for the, so, would I still get benefit of the variable speed blower without the extra wire?

    Important: I need to be assured that a variable speed blower won't make my AC work worse in terms of problematic rooms versus the rooms that get the most cooling. Will the AC work at least as well as it currently does for the problematic rooms with a variable-speed blower? Does variable-speed ever make AC work worse for problematic rooms?

    ADD: I also have the option of a Carrier 2-stage furnace without variable speed blower which I assume is going to be midway between cost of 58CVA and 58STA....would 2-stage without variable speed be worth considering?


    Thanks,

    J.
    Low speed air circulation does a poorer job of getting heating cooling to hard to get to areas of the home. As the air flow shows, the distribution of the conditioned air goes the path of least resistance. Extended duct systems need engineered air flow. The idea of reducing air flow 40% and expecting good distribution is over looked.
    VS blowers are easir to fine tune the air flow to get the ideal air flow for correct coil temperature. Correct coil temperature is necessary for ideal moisture removal. A good tech can change air flow without a VS blower.
    Buying a mediun system without the ideal control wiring is a waste.
    If humidity control is an issue, consider a whole house dehumidifier as an important part for times of the year when there low/no cooling loads and outdoor dew points are +60^F.

    Regards TB
    Bear Rules: Keep our home <50% RH summer, controls mites/mold and very comfortable.
    Provide 60-100 cfm of fresh air when occupied to purge indoor pollutants and keep window dry during cold weather. T-stat setup/setback +8 hrs. saves energy
    Use +Merv 10 air filter. -Don't forget the "Golden Rule"

  6. #6
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    Nov 2012
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    Is the furnace with the VS motor a waste of money as well, without it wired to a 2 stage thermostat? I don't even have humidifier and don't plan on getting one.

  7. #7
    Join Date
    Jan 2009
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    Keokuk, IA
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    The VS motor will make that 13 SEER Perform equal to a 14 SEER unit and will save energy when heating whem the blower is running.
    Althogh it can consume more energy if you have undersized ductrokr.


    You must have a big house in a cold climate to need 110k BTU's. 110k could heat many 3500+ sqft homes in northern climates. Many temperature imbalances can be greatly improved with proper equipment sizing. Smaller is better. 2 stage will also help increase run times. 2 stage is for comfort.

  8. #8
    Join Date
    Jun 2001
    Location
    Moore, Oklahoma, United States
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    Quote Originally Posted by motoguy128 View Post
    The VS motor will make that 13 SEER Perform equal to a 14 SEER unit and will save energy when heating whem the blower is running.
    Althogh it can consume more energy if you have undersized ductrokr.


    You must have a big house in a cold climate to need 110k BTU's. 110k could heat many 3500+ sqft homes in northern climates. Many temperature imbalances can be greatly improved with proper equipment sizing. Smaller is better. 2 stage will also help increase run times. 2 stage is for comfort.
    +1. That huge furnace will cause uneven temperatures, not solve them. From a comfort prospective you are better off spending the money fixing the house leaks than buying fancier HVAC equipment. A 70k single stage may be plenty once the leaks are all fixed.

  9. #9
    Join Date
    Nov 2012
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    39
    Everyone I talk to wants to put in a 110K BTU 80% furnace in my house. My existing one is 125,000 BTU input but I'm told it's only 65% or 70% efficient, and not 80% My existing furnace model# is Carrier 58GP125-3

  10. #10
    Join Date
    Jun 2001
    Location
    Moore, Oklahoma, United States
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    Contractors are scared to undersize, so most end up putting in a furnace twice the size needed.

  11. #11
    Join Date
    Nov 2012
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    39
    I doubt 110K is twice the size needed, given that my townhouse is over 3K square feet, if you include the finished basement.

  12. #12
    Join Date
    Nov 2004
    Location
    SW FL
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    6,225
    Quote Originally Posted by Jreality View Post
    Everyone I talk to wants to put in a 110K BTU 80% furnace in my house. My existing one is 125,000 BTU input but I'm told it's only 65% or 70% efficient, and not 80% My existing furnace model# is Carrier 58GP125-3
    Eliminate the guess work with a blower door test, Then Manual J calc.

    What are your gas bills over the last 24 months?
    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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    Nov 2012
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    My highest gas bill over the past 12 months was $169.76 for the billing month ending on Jan 20th 2012, and during the prior year, the highest was $220.50 for that same billing month (ending in Jan 20th, 2011). During the year before that, my highest bill was $285.92 for that same billing month (ending in Jan 20th, 2010). I'm in Northern NJ.

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