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  1. #1

    We're about ready to purchase a new Bryant or Carrier HVAC system to replace a 35 year old Carrier furnace and a 10 year old York a/c.

    We plan to replace the furnace with either the Bryant Evolution 2 stage variable speed, etc. or the Carrier Infinity -- we understand they're both really the same items since they're owned by one company.

    The question is about which a/c unit to get. Our house has three levels (typical colonial) on three levels including a finished basement. Location is mid-Atlantic region. Two dealers are recommending a two-stage a/c (which obviously will work better with the Evolution or Infinity control). HOWEVER, a third dealer said that since my house was ducted with a single trunk across the basement ceiling which feeds the basement, first and second floors (through the walls and individual intakes and outlets in each room in the house) that we would find that in order to cool the second (top floor), that we would freeze on the first floor because of the way the 2 stage system works. He explained that the first stage would come on first with 1/2 the blower power (because the blower is also coming on at it's lowest setting), and the second stage wouldn't kick in until it got really warm upstairs, at which point in order to cool the second floor, we'd freeze on the first floor. IS THIS GUY CORRECT?

    For the past 35 years, (yup, we've been in one house for 35 years!) we've closed off the louvers in the basement and on the first floor in order to "force" most of the cool air upstairs.

    Another problem seems to be that there are virtually no single stage 15 seer a/c unit to be had in this area or nearby at the moment. One dealer checked and said that there are two in Texas (a fur piece from here) but that those dealers wouldn't give them up.

    How do I decide who's right? Should I insist on a one stage a/c unit or get the two stage one?


  2. #2
    Join Date
    Apr 2006
    Since your already going with either the evolution or the infinity fix the problem of the two stage by zoning the two floors if you think that is an issue. I just Installed a 4 ton evolution on a tri-level in NC and it works great for both floor and yes it has a 2 speed unit. So i would definately go with the two speed but i dont know the exact layout of the house. So if you think it could be a problem you can zone the infinity and evolution very easily.

  3. #3
    with a system like this you will be running the fan continuously. THus crweating a mixing box in the house. You should not have major temp differences like you usedto have.Opt for the 2 stage unit. it will provide better dehumidification for you.

  4. #4
    Thanks to Ngore22 and Tbox8098. Some more questions to both of you.

    Ngore22, how do you zone the two floors with one trunk line and without a major reconstruction job (which we're not willing to do)? The house is 2400 on the first and second floors. The finished basement is another 1200 sq. ft.

    tbox8098, is it a problem that the fan will run continously? Do the Infinity/Evolution systems do that automatically? Are you saying that the fan (either at the first or second stage) keeps the air moving enough so that there won't be a significant temp differential between the first and second floors on hot summer days? And, with the new system, do we still need to close up the louvers in the basement and on the first floor in the summer to "force" the cold air upstairs?


  5. #5
    This is scary that the contractors did not talk about continuous airflow. YOu are buying a furnace with a DC variable speed motor. THese are designed for continuous operation. This will give you more even aitflow as well a s constant filtration. These systems will provide as much comfort as possible out of a forced air system.

  6. #6
    Join Date
    Nov 2000
    Eastern PA
    While I like the concept of staging heat, I am not yet sold on the benefits of staging cooling in a fesidence.

    Heating variables are usually more dramatic then cooling variables are in the fact that heating variables are averaging 70Ί differentials in outside temperatures while cooling variables are only averaging 20Ί in outside temperatures.

    To incrementalize a 70Ί span makes sense whereas a 20Ί span is just not justifiable.

    Another issue I have with staged cooling systems is that so many installers are increasing the size of cooling equipment on the basis that it will mostly run on the lower stage. This is just a waste of money to justify oversizing equipment capacity to cover the butt of a contractor that is not that certain of his load calculation abilities.

    These of course are just opinions.
    Government is a disease...
    ...masquerading as its own cure…
    Ecclesiastes 10:2 NIV

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