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  1. #1
    Join Date
    Jul 2008
    Location
    Houston, TX
    Posts
    4

    Home A/C Contractor

    I have been lurking around these pages for a couple of weeks trying to learn as much as possible. Currently, I have a 3 ton and 3.5 ton Heat Pump system that are 18 years old. My house is in very hot Houston. It is 3500sq ft total, with 450sq ft of that area upstairs surrounded by attic space on 4 sides. (Estimates show the load rating on the room alone to be 2 tons.) Humidity in the house is always a problem. It will never drop below 55%, and at times goes above 60%.

    After doing my research, I have decided to go with two Bryant Evolution systems, each zoned for 2 zones. (Main living area/Spare room upstairs. Kids bedrooms/Master bedroom suite.)

    The site has already helped me weed out several contractors. I have had estimates from 5 different companies and am trying to decide between the final 2. I was leaning toward one in particular until they answered a couple of questions today.

    1. On the Sales Agreement, I am assuming the “Zone Systems” are the Bryant Evolution Zoning Control. Is that correct?

    Answer - All Zoning systems work the same, I was going to use Duro-Zone.

    2. Will you be performing a Manual J and Manual D once we agree to move forward?

    Answer - Manual J and manual D are normally used in new construction or when adding living space to an existing building, to determine load and airflow requirements when installing a new system. They are not normally used in retro-fit situations. Since you will have a two stage compressor and variable speed furnace, you will have capacity load and airflow from two tons to four tons, or 800 cfm to 1600 cfm and 24000 btu to 48000 btu. We know we are not under sized, so a load calc is not really needed.

    So know I’m not sure how to take this.

    (1) Should I expect the Evolution System to have the Evolution Zoning Control? Is what he says accurate, “All Zoning systems work the same…”? Does the Evolution Zoning Control integrate more effectively?

    (2) I have read repeatedly here that a Manual J is necessary. What he says seems plausible. But should the Manual J be done without question?

    Any and all advice is appreciated. Thanks.
    Last edited by AndrewR69; 07-29-2008 at 03:21 PM.

  2. #2
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,119
    No other zoning system but the Bryant/Evolution, and Carrier/Infinity, zoning system can get the performace out of the Evolution 2 stage system that you want.

    High humidity is caused by excess air infiltration. Weather through leaky duct systems or teh nomes structure.
    And from over sized equipment.

    So if your current systems are over sized, then over sized 2 stage systems won't control the humidity any better, then what you currently have.

    So load calcs are needed for existing systems/structures also.
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  3. #3
    Join Date
    Jul 2008
    Location
    Houston, TX
    Posts
    4
    I certainly do understand the importance of performing the Manual J; how do you know the existing system was sized correctly. And I was very leary of this installer when he started to simply equate A/C size to square footage. But while discussing options, I really thought he was going to do the Manual J. But just to be sure, that is why I asked directly. I'm glad I did.

    Do you have any specifics as to why the Bryant/Evolution Zone Control is better than a different manufacturer, besided the obvious "they were made for each other." What sort of questions should I ask when it comes to setting up a zoned system?

  4. #4
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,119
    The Evolution and Infinity zoning systems are modulating.
    They open the dampers of other zones that are not calling to help keep them conditioned so as not to have to come back on 5 minutes after the calling zone is done.
    It might open 1 damper 20%, the next one 65%. It does this based on sensors input for load in that zone.
    It also controls the VS blower speed for better humidity control. And not just a slow down to 80% like others zone systems.
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