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  1. #1
    Join Date
    May 2006
    Posts
    19

    Question Zone Controller - TZ4 vs Harmony III

    Background: I'm building a new, one story house in Central Florida. Furnace is Lennox G60V with two stage heat and variable speed blower. A/C compressor is Lennox XC21 with two stage compressor. Home has four HVAC zones.

    Dealer proposes to control the Lennox equipment with Honeywell TZ4 zone controller and Honeywell TH8320U1008 main T'stat with 3 TH5110D1006DAG T'stats for other zones. There will be Honeywell dampers, including bypass.

    My question: Will the Honeywell TZ4 properly control the system, including making full use of the variable speed motor? I had been expecting a full Lennox system including Harmony III zone controller and SignatureStat T'stat to control the system and lower humidity.

    Are there advantages to the Honeywell controls over Lennox that I am missing?

    Cap

  2. #2
    Join Date
    Sep 2006
    Location
    Houston, TX
    Posts
    33
    Go with the Harmony III. Besides the obvious reason that it is designed specifically for the Lennox heating and cooling products. The Harmony III adjusts the airflow to match the requirements of each zone as long as the zone airflow falls between the minimum and maximum airflow of the air handler. If the zone or zones airflow requirement is below the minimum airflow of the air handler a bypass or dump will be required. I don’t have all the particulars on the Honeywell TZ4 but it appears to need a bypass duct with a barometric damper (not recommended for VS motors) or a modulating damper to regulate airflow (static pressure) similar to other 3rd party zoning systems that use only two airflow rates 1st stage and 2nd stage. The Harmony III adjusts cooling and heating capacity (1st stage or 2nd stage) through the discharge air sensor and adjusts airflow by the PIAB (Percentage Into Adjustment Band) settings on the Zone Control Panel that are determined by the load calc.
    In my experience keep your zones above the minimum airflow of the air handler even if you have to reduce the total number of zones. Also take into consideration the minimum capacity of your condensing unit. The XC21-060 is approximately 3.5-tons in 1st stage. If your smallest zone is barely above the air handler minimum, say 500cfm or 1 to 1.5-tons, then you will need to address the lack of airflow to the coil to avoid coil freezing in cooling mode and overheating the heat exchanger in heating mode.

  3. #3
    Join Date
    Sep 2006
    Location
    Houston, TX
    Posts
    33
    Forgot this earlier, the Harmony III has a high and low temp setting that cycles the system between off, 1st stage and 2nd stage heating and cooling that is set up on the zone control panel. This should prevent coil freeze up and over heating the heat exchanger. However, with excessively small zones the equipment can cycle between the three stages quite a bit. More wear and tear on the equipment. That's why I prefer to keep the zones close to 50/50 or near the low capacity size.

  4. #4
    Join Date
    Mar 2005
    Location
    burlington county n.j.
    Posts
    9,748
    have not seen that honeywell system but i have put in the harmony systems.

    for the reasons stated in racjm's post i would stick with the harmony.

  5. #5
    Join Date
    Feb 2006
    Location
    Taylors, SC
    Posts
    403
    Quote Originally Posted by capthomas View Post
    I had been expecting a full Lennox system including Harmony III zone controller and SignatureStat T'stat to control the system and lower humidity.



    Cap
    I agree with the above recommendations of sticking with the harmony III zone board. Also, with the harmony III, regardless of what type of equipment with however many stages you have, all you need is a 1 heat/1 cool conventional stat. You do not have to have the sig. stat. The reason I say this is I have found that most customers that have one hate the thing although there are some people out there that love them. I would, if you havent used one, ask to atleast play with one before deciding to buy four and have them mounted.
    Poor planning on your part doesn’t necessarily constitute an emergency on my part.

  6. #6
    Join Date
    May 2006
    Posts
    19
    Thanks for the feedback.

    Cap

  7. #7
    Join Date
    Sep 2006
    Location
    Houston, TX
    Posts
    33
    I would also recommend installing a multi-stage thermostat for zone 1. This way if the Zone Panel fails a service tech can bypass the zone panel (if needed) and your equipment will still function as a multi-stage system until any replacement parts can arrive.

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