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  1. #1
    Join Date
    Mar 2001
    Posts
    288

    Hello everybody I am building a new house again. This house will be 2421 square feet, R-19 in the walls and R-38 in the attic, built on a slab. I will run a heat load calc to be sure, but it appears a three ton unit will be used.

    This new house will have two-stage cooling and I prefer two zones...(to be able to zone off the bedrooms during the day.) Does the superdehumidify function work well with the infinity control and zoning controls? Will there be a master thermostat that determines "heat" or "cool"? Can one zone be superdehumidifying?

  2. #2
    Join Date
    Jul 2002
    Location
    37760
    Posts
    420
    yes, yes, good question, but guessing no from sensor input criteria and mixed air.

  3. #3
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    Cool to dehum works very well ,but currently it only senses the RH at the "Master" control.

    It comes with a panel to control 4 zones ,so I'd consdier using all 4.

    "Master" control in the main living area,master bedroom,other bedrooms,then your choice,maybe the home office,or kitchen and nook,both rooms that can changing loads.

  4. #4
    Join Date
    Mar 2004
    Posts
    1,042
    Infinity/Evolution zoning is the cat's meow. Nobody can quite match it as yet.

    Humidity control isn't zoned, though. Except for bathrooms and kitchens while they are in use, humidity varies very little from room to room in a house, so there's no need to zone it. Zoning focuses on getting the temperatures to do what you want, and as long as the humidity is fine at the master thermostat, it should generally be fine throughout the house.

    The Infinity system, incidentally, doesn't just dehumidify or superdehumidify; it's not that granular. The system continuously adjusts blower speed to get the appropriate balance of cooling and dehumidification for current conditions. I believe it chooses from the following CFM per ton levels as it does so: 275, 300, 325, 350, 375, 400. There may be more than that, but I've seen it do all of those.

    Basic zoning systems may not be able to decide on heating versus cooling on their own. Nicer ones typically use a "voting" system to decide whether to heat or cool (if 2 zones want heat and 1 wants cooling, it will focus on heating the two, and if it has time later, it will cool the other). In general it's very rare in residential that you'd have zones calling for heating and cooling at the same time. All traditional zoning systems use a regular thermostat in each zone, and a zone control board that controls what the airflow dampers are doing and negotiates what the furnace/AC/etc should be doing. That means that to adjust any zone, you have to physically go to that zone to poke at the thermostat.

    The Infinity system control setup is as follows:

    You have one Infinity control that is the "master". That is the one that measures the humidity. From it can control any aspect of any zone in the house individually- current temp, heating setpoint, cooling setpoint, program schedule; you can also control all the zones at once if you want them to do the same thing.

    Other zones don't have to have an Infinity control in them; it's your choice. They can use a "Smart Sensor", which is a temperature sensor in a small beige box on the wall, with no buttons or displays at all. They just transmit the current temperature back to the master control. The interesting point with that setup is that you can control the entire house from one point, but ONLY that one point. If you want to spend the extra money, you can use another Infinity control in place of a Smart Sensor in any or all of the non-master zones. All of the Infinity control boxes are the same, and they communicate with one another digitally, so you can do anything on one that you could do on another.

    If you do have a second (third, etc.) Infinity control, you can also see/adjust/program any zone in the house from that point, just like you could at the master control. The only difference in master/non-master is the location of the humidity measurement (any of them can see and adjust the current humidity and the current humidity setpoint, though). So it's not necessary to have more than one Infinity control, but can be nice to avoid having to run around the house, up/down stairs, etc., to adjust a setting.

    You can set up the system so that each zone has an upper and lower temperature limit, though, and the system will choose between heating and cooling as needed to satisfy all of the zones. I believe it uses the voting system when zones want heating and cooling at the same time. If you don't use the Auto mode, then you select Heat or Cool, and of course the system will only do one or the other. Auto versus Heat versus Cool is system-wide. It doesn't matter which Infinity control you make that selection on, though. Whatever you do on one will show up on all the others.


  5. #5
    Join Date
    Mar 2001
    Posts
    288

    Thank you for the detailed information. So it appears the Infinity thermostat and zoning logic works in near perfect harmony with the rest of the HVAC to optimize staging of heating and cooling equipment and fan speed to maintain desired temperature and humidity setpoint.

    Now if say one small zone is calling for cooling--I would assume the unit would kick on 1st (low) stage....would that one zone get a strong blast of air, or could some of the conditioned air be dumped off in another zone? With four zones, one zone could be coming on while another is being satisfied so is there any chance of short cycling the equipment? I would hate to see the unit shut down only to come right back on for a different zone...I'd assume maybe a minimum run time or something could be established?

    Thanks everybody. The builder prefers I use and work directly with HIS HVAC sub, but he is willing to let me hire my own if I don't like his HVAC man. (His HVAC sub does do good work from what I have seen) Anyone here in the Huntsville, Alabama area?



  6. #6
    Join Date
    Mar 2004
    Posts
    1,042
    Infinity's claim to fame is making everything work together to avoid all of that inelegance. It's different. Everything communicates digitially. It doesn't depend on a yes/no thermostat at each zone to tell it if it needs conditioning now or not. The Control always knows the current temperatures and setpoints for every zone. It knows the relative duct capacity of each zone (it measures it). The zone dampers aren't on/off, either; each one adjusts through a range of 16 positions.

    First operating strategy: When it is running the heating/cooling equipment, it sends air out to the zones proportionally. The purpose of this is to divide up the conditioned air is such that all of the zones will satisfy their demand for heating or cooling at the same time. It adjusts that air proportioning continuously as the equipment runs. For example, you can see a screen on the control where it shows that, for example, it's sending 700 cfm of cooling upstairs, 300 downstairs, and 50 to the basement. The effect is that since all of the zones got all of the conditioning they needed on a single equipment cycle and satisfied at the same time, they will take a similar amount of time before they need conditioning again. So there's generally no need to try to force all of your airflow into a single zone. This same strategy also keeps you from switching to a higher equipment stage until it's absolutely necessary; older zoning systems would delay second stage operation by timing or the number of zones calling. This system won't switch to second stage until it actually can't meet demand with the first stage, regardless of cycle length or the number of zones calling.

    Second operating strategy: If you really really have to condition a single zone and the others aren't in synch with its needs, send as much air as you can to that first zone and find somewhere reasonable to put the rest. If the kitchen gets hot from cooking and its ductwork can only handle 300 CFM, but your first cooling stage is 600 CFM, send 300 to the kitchen. Then send the excess to one or more other zones that are flagged vacant or are fairly close to their cooling setpoints. It would have decided that the kitchen can only handle 300 CFM through a procedure it goes through every day at 1pm; it opens the dampers one at a time and uses the brains of the variable speed motor to measure the static pressure of that zone at different airflow rates.

    So having four zones versus two isn't going to make it clunky. If anything, having more zones gives the system more options when it needs to make a decision. It also gives it more information and control so that it can do things like handling the kitchen and the rest of that floor separately, instead of assuming that the whole floor behaves the same way. Or a sunny room, great room, etc.

  7. #7
    Join Date
    Mar 2001
    Posts
    288
    Wyounger:

    Wow. You really understand how this works inside and out. Sounds like the ultimate in HVAC. This is something I definitely want. Sounds expensive, fortunately for this house HVAC and insulation get the upgrade $$$.

    (I upgraded the insulation and HVAC in my current house and my power bills are half of the neighbors' bills...and I keep my place 68-72* in summer....neighbors cool to 76-78 to SAVE on utilities....go figure)

    I guess I will now ask you about DUCT WORK. Duct work will be in the attic. I don't want to handicap this system with inferior ducting, however looking at the current man's work it is nice and neat.... but let me just go ahead and ask if I should do anything special with the ducts other than making sure they are sized properly and don't leak. Any R-value you would recommend for an attic install?


  8. #8
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    6,428
    Originally posted by jared
    Sounds expensive, fortunately for this house HVAC and insulation get the upgrade $$$.

    ,,, and my power bills are half of the neighbors' bills...and I keep my place 68-72* in summer....neighbors cool to 76-78 to SAVE on utilities....go figure)

    Any R-value you would recommend for an attic install?
    8.
    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

  9. #9
    Join Date
    Mar 2004
    Posts
    1,042
    Basically you just want to size the ductwork generously. In a traditional system, you tried to constrain the ductwork strategically, in such a way that you got the right amount of airflow to each part of the house. The Infinity is going to do that balancing for you, and it would rather have the option of sending lots of airflow to a zone that particularly needs it at the moment.

    So if you give the ductwork for each zone more airflow capacity than it would normally need, the system will handle balancing out how much airflow goes where, and when one zone needs extra airflow, it will have the ductwork capacity to actually send it there. If the ductwork were sized traditionally, it would respond to the extent it could, but might be a little constrained by the ductwork to a given zone. If you give yourself a little headroom, it has the flexibility to send lots of air to that zone should the need present itself. No need to go crazy overbuilding the ducts either, though; it's not like you're going to expect the system to air condition the master bedroom even if you build a bonfire in it

  10. #10
    Join Date
    Mar 2001
    Posts
    288
    Thank you!! I have learned a lot! I take it the Infinity zoning and Evolution zoning products are the same....does the infinity control keep track of statistics like % of run time in high speed/low speed?

    I figure on returns in every room except kitchens and bathrooms....

  11. #11
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    6,428
    Originally posted by jared
    I figure on returns in every room except kitchens and bathrooms....
    Returns (or jumpers) for each room with a door (not bathrooms) is mandated in FL Buidling Code.

    It is highly likely that 70'F can not consistently achieved with a 3-ton unit in a 2,420 S.F. residence.

    Unless, of course, if there are < 10 windows and No sliding glass doors with a the use of a zoned system,
    I guess you may come close.

    I am always open to learning a Better Way.
    If you can consistently cool a 2,420 S.F. AL residence with a more normal area of ~ 350 S.F. glass area, let me know and I and the rest of the world can become copy-cats.

    ... sounds like a "right-size" A/C might be 4 ton, 2-stage, INFINITY 3+zones system.

    Do you wish to have a great insulation upgrade that may help in getting to a 3-ton system?
    http://www.airtightinsulation.com
    Then the R-6 duct work would be more than adequate.

    One clieint is having
    all walls and attic ceiling
    spray foamed with this R-7/per inch product.
    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

  12. #12
    Join Date
    Mar 2001
    Posts
    288

    Thanks Dan! I have seen the spray on foam before, but I am still learning more about it. I am interested...I do think three tons is too small, but I haven't run a load calc yet. I sure do wish Infinity/Evolution had availability in 1/2 ton sizes...


  13. #13
    Join Date
    Feb 2006
    Posts
    468
    Since you are building a new house either sprayfoam the attic or design the house so that ductwork is in conditioned space.

    An astonishing amount of heat gain / loss can be avoided if the ducts are all in the conditioned space.

    You can do this via soffits and other architectural techniques that both provide spacial separation between rooms as well as keep ducts out of hot attics.

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