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Thread: VisionPro

  1. #14
    Join Date
    Jun 2005
    Location
    Near Chicago, IL
    Posts
    3,316
    That government literature didn't give any hard numbers, just percentages.

    Obviously, it costs money to operate the HVAC system.

    Forced air heat seems to be able to recover an ambient temperature relatively quickly. My home is 72 degrees for about 8 hours a day in the heating season.

    Cooling doesn't seem to work that way, and I have found about a 3 degree swing to be about it, otherwise, the equipment is on for a much longer time to recover the temp.

    My home is shaded and on a slab, so if it is cooled to 77 at night, it takes a while for the AC to kick on at 80 during the day.

    I bet that if everyone raised their t-stat by 1 degree in summer and lowered it the same in winter, the energy savings would be much more than a setback stat.
    Proper Prior Planning Prevents Piss Poor Performance

    "There is hardly anything in the world that some man cannot make a little worse and sell a little cheaper, and the people who consider price only are this man's lawful prey. It's unwise to pay too little.
    When you pay too much, you lose a little money -- that is all. When you pay too little, you may lose everything, because the thing you bought was incapable of doing the thing it was bought to do.

    The common law of business balance prohibits paying a little and getting a lot -- it can't be done. If you deal with the lowest bidder, it is well to add something for the risk you run. And if you do that, you will have enough to pay for something better."

    John Ruskin


  2. #15
    Join Date
    Apr 2005
    Location
    Tampa, Florida
    Posts
    1,634
    I'm surprised no one's posted this yet, but...

    Do you have the dehumidify control (overcool) enabled? (If you hit the More button, do you get an option to change humidity levels?) If so, the adaptive recovery features gets disabled. Why, I'm not sure, but Honeywell confirms this is what it does. If you disable the humidity control, it will still show humidity % on the screen, but won't respond to it, and you'll have adaptive recovery working. Also, the stat can be configured for conventional recovery (just does exactly what the program says) or adaptive recovery (reaches the set points by the programmed times).

    The recovery algorithm in the Honeywell stats is pretty good about "learning" how well the system functions and usually won't let the temperatures get so far out of range that it wouldn't be able to recover on time. On my place, I have the set-back set to 85F, but never have seen it rise that high b/c the stat calls for recovery well before then.

    Also, when you first start running the adaptive recovery, it may take it a couple of days before it learns about how the system performs and how it needs to control it. It seems to take about a week before it gets into its usual pattern.

    [Edited by tpa-fl on 08-02-2005 at 08:08 AM]

  3. #16
    Join Date
    Sep 2004
    Posts
    51
    tpa-fl,

    Thank you! That is EXACTLY what I was looking for! I may give Honeywell a call myself to confirm, but that could explain what is going on.

    SirWired

  4. #17
    Join Date
    Apr 2005
    Location
    Tampa, Florida
    Posts
    1,634
    I'm still not sure why Honeywell chose to let the thermostat function like this. I called them when I first put the TH8321 in my place. They insist this is "normal" for it... but to me, adaptive recovery should work regardless of the overcool setting.

  5. #18
    Join Date
    Dec 2001
    Location
    Ocean Pines, MD
    Posts
    6,935

    Ask em'

    Why the switching is so damn noisey. Can't hear my system kick off and on but can damn sure hear the switches make. "Click-click on, click-click off".

  6. #19
    Join Date
    Apr 2005
    Posts
    13
    The noise is from the relays, there are triax.

  7. #20
    Join Date
    Jun 2001
    Location
    Louisville, KY
    Posts
    12,011

    Re: Ask em'

    Originally posted by Stamas
    Why the switching is so damn noisey. Can't hear my system kick off and on but can damn sure hear the switches make. "Click-click on, click-click off".
    cuz they've always been that way. my xt500c is made by hwell. i can hear it click long before the blower ramps to high.

  8. #21
    Join Date
    Jul 2003
    Location
    Philadelphia Pa.
    Posts
    461
    I don't know anything about relays but this is supposed to be a digital stat that doesn't have that inacurate metal bi metal switch. Why aren't the relays digital or electronic so that there is no sound? Is this not possible?

  9. #22
    Join Date
    Apr 2005
    Location
    Tampa, Florida
    Posts
    1,634
    That loud clicking is the sign of quality relays. There is an electronic equivalent to the relay, the triac, but they tend to be failure-prone, which is why your better thermostats use large relays which can handle the load and then some. My air handler's fan relay makes far more noise than the stat does. For recording studios, I usually put the stats in a closet or hallway and use remote sensors in the studios & control rooms to eliminate all extraneous noises.

  10. #23
    Join Date
    Jul 2005
    Posts
    171
    tpa-fi, I was liking your posts until that last one. You need to brush up on triacs. What do you think is inside of every dimmer in your house? That's 110v, not 24. And they switch on and off 120 times a second. Try to have a relay do that for 10 years. Ask Honeywell why they use relays. I'll bet you a beer they won't tell you triacs are unreliable.

  11. #24
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    5,994

    Exceeding Expectations

    When the temperatures well exceed Design Conditions,
    it is rather pointless to look for ANY type of Normalcy.
    ___ With BOTH People & Equipment! !! !!!

    L.O.L.

    A/C types KNOW THAT Much Better
    than psychologist and weathermen.

    NOT so COMMON Sen$e:
    Limit your setback to 4'F MAX.
    as a compromise between Comfort and Energy $avings.

    (Daytime 81'F, Evening 78'F for me).
    I guess one may expect
    about 1'F decrease in 40 to 60 minutes
    during late afternoon conditions.

    To Man & Machine,
    __ Simply perform the Best you can in Difficult Times!
    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. #25
    Join Date
    Jan 2004
    Location
    Midlothian, Virginia
    Posts
    195

    hot mass


    When you set the stat back think about this. Not only does your air temp rise. Everything in your home gets warmer. The furniture, the walls, the carpet, the dog, all get hotter. And you are asking an A.C. system to remove a pile of heat from this mass of materials, not just the air. well if your system is say a 24000 btu (2 ton)system it only removes 24000 btu per hour. A large set back allows a pile of btus to build up in all this mass. Lets make up a number 96000, well it will take 4 hours to remove this much heat plus all the heat entering the house while its removing this heat.

    I vote for not setting it back too much unless its a 2 stage system able to pull the heat down rapidly with extra capacity.

    Dont you just love this sight!
    Goodbyee stranger it's been nice. Hope you find your paradise! Hey it aint rocket science, "It's a Trade !"

  13. #26
    Join Date
    Sep 2004
    Posts
    51
    For tpa-fl's advice, I thank him very much.

    For everyone else... this has been a facinating discussion on the merits of setting back at all, recovery time, etc., but it had nothing to do with my question.

    My original question was why the "adaptive recovery" was not turning on the stat prior to the schedule time, as the brochure for the stat says it is supposed to.

    For those unfamiliar with the stat, the thermostat is SUPPOSED to measure the amount of time recovery took on previous days, and use that time to turn on the system at an appropriate time so the dwelling is AT the setpoint at the schedule time. This means the recovery time is calculated for you, and adjusts depending the weather.

    Most setback thermostats just turn the system on at the schedule time, which means you must figure out what the recovery time is on your own.

    This feature was not working at all, which was my problem. My VisionPro was not turning the system on prior to the schedule time. (It did during the winter.)

    Does anybody know if it would also take the Outdoor Temp Sensor into account? I think it would for a heat pump during heating season, but I don't know about cooling.

    --------------------------

    Now, as to why setbacks save money:

    Newton's law of cooling tells us that the rate of heat transfer is directly proportional to the difference of temperature between the two objects. That means that when your house is 75 degrees, and the outdoors is 95 degrees, you absorb twice as many BTU's / hr as when the house is 85 degrees. It's that simple. More BTU's / hr over X hours means more total work for the AC.

    NOTE: Some adjustment must be made for sunlight, as that is going to cause the house to heat up independent of the indoor or outdoor temperature.

    The exact amount of savings would involve some rather nasty calculus, and is dependent on too many factors to determine accurately. (Rate of cooling of the system, insulation, color of the house, outdoor temperature at different times of the day, humidity, amount of light hitting the house at different times of the day (which in turn depends on shade, latitude, cloudiness), etc. You get the idea.)

    SirWired

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