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  1. #27
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    Quote Originally Posted by jeff520 View Post
    I have a TC803, and have found that it does not tell the truth in an apparent (programmed) attempt to make me happy with its accuracy and performance.
    Most of them. Just raise the temp 2 degrees, and it will report a different temp then it was reading before you changed it.

    A couple minutes later, they will revert back.
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  2. #28
    Quote Originally Posted by jeff520 View Post
    I have a TC803, and have found that it does not tell the truth in an apparent (programmed) attempt to make me happy with its accuracy and performance.

    The behavior I have observed is that whenever the ambient temperature is within about two degrees of the setpoint then the stat will tell me that the ambient temperature is at the setpoint.

    I can catch it at this "little white lie" by making a large ( five degrees or so) change to the setpoint, and the stat will then display the correct ambient temperature. To see this, you need to catch the stat when the ambient temperature has either overshot the setpoint by a degree or two, or when the ambient is approaching the setpoint with only a degree or two left to go. In both situations the stat will display the setpoint as being the ambient temperature until you make the big change to the setpoint and then the stat will display the true ambient.

    Had me fooled (dumb and happy) for a while just after the new system was installed. Then I checked the accuracy of the stat with a digital thermometer that displayed tenths of a degree and learned that the stat seems to have been programmed to report sucess with reaching the setpoint a little optimistically.
    Jeff.

    I'm glad to have validation that I'm not the only one to have noticed
    this.

    Now the question for the pros here is there a brand/ type of digital
    programmable stat that doesn't lie?

    I'm stopping myself from building my own.

    I have seen claims of how a great new "Energy Star" stat can save money,
    and wonder why. The only way I could see before that it could was if it
    had a greater hysteris / allowed more variation. But now I see by directly
    lying it can gain even greater efficiency!

    I guess it should not be a surprise to me that again the fundamental
    dishonesty of our current society rears its ugly head.

    A couple of months ago I went bezerk when a facilities guy told us that
    we would be happier with small. lower, noisier cubicles in our new building
    than we have now. Somehow there is this idea that if you sugar coat
    something enough it will sound good, even if it is bad for you.

  3. #29
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    A digital stat, will always have interference from its own heat generating circuits.

    A remote sensor won't.
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  4. #30
    Quote Originally Posted by a0128958 View Post
    If you want to continue doing what you've been doing, but in a more elegant and high-tech manner, you could replace your tstat with an AprilAir 8870 Communicating tstat, hook up an RS485 network cable from the tstat to a computer, and then be able to infinitely control and monitor the tstat in many ways, including those you may have not yet considered.

    For much less effort, I believe you can replace your tstat with many of the existing digital models on the market today, 'tune' the tstat for agressive settings (via tstat configuration settings), and be quite happy.

    Even my WR tstat that I illustrated earlier is 'tuneable' to be much more aggressive than what I illustrated. Mine is set for a Setpoint range of 1.2F for Heat and 1.7 for Cool, but it can be set more aggressively to 0.6 / 1.2 if I wanted it that way. And it's further tuneable for how aggressive the 2nd stage kicks in.

    And my guess is, the well regarded Honewell tstats on this forum have a lot more 'bells and whistles' to adjust aggressiveness, such that I'd be surprised if your needs couldn't be met.

    Best regards,

    Bill
    My older (6 years) Chronotherm IV does not have an installer adjustment
    for aggressiveness. You're saying any new Honeywell would? I don't
    know if its against forum rules, but could you recommend a specific
    stat that is adjustable for "agressiveness". Actually ideally want to
    be agressive in recovery, and even have some overshoot, but after
    that I'd like to try and force the cycles to be longer.

  5. #31
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    Honeywell TH5000, 6000, 8000 series, and IAQ stat all have it.
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  6. #32

    Let me make sure I understand

    Aggressiveness is a separate adjustment that will
    allow me to speed up the recovery even if it overshoots
    a bit? Increasing aggressiveness will not cause short
    cycling when "at crusing altitude"?

  7. #33
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    Aggressive won't make it recover quicker.
    It will just over heat, or cool depending which one you set to more aggressive.
    It gives it a slightly wider spread between on and off temp.
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  8. #34
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    Quote Originally Posted by bobRitchie View Post
    Jeff.
    Now the question for the pros here is there a brand/ type of digital
    programmable stat that doesn't lie?
    Hey Bob,

    Your gas gauge and speedometer are lying to you, too.

    I have three home digital thermometers, two with outside remotes. I can put them all together, including remotes, and guess what? No two of the five readouts have the same temperature.

    A man with one clock knows what time it is. A man with two is unsure.

    -HF

  9. #35

    aggressive mode

    So it basically adds some hysterisis.
    Which is a good thing to try and get longer
    cycles.

    But what's got me mad with my current thermostat
    is that its trying to sneak up on the final temperature
    in recovery, so much that it takes hours to really
    get there. And its saying its there when its still
    a couple degrees away.

    I do think a multiple sensor in different room approach
    might help. But I'd have to cut a bunch of holes in
    walls.

  10. #36
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    Why, are both your basement, and attic finnished.

    Disable Adaptive recovery, if its enabled.
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  11. #37
    No neither are.

    But I assume the sensors should be 4-5 feet from the floor. I
    don't think the ceiling would be a good place for the sensors?
    Or would it? If the ceilings a good place for sensors it would
    be very easy.

    So I need to cut holes to get the wires up from the crawlspace
    into the wall cavity. Or down from the attic.

  12. #38
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    The ceiling is a terrible place for a sensor for temp control.

    Any good contractor can get wires to the bedrooms.
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  13. #39

    Lying instruments

    What bothers me is not that instruments give different
    readings, and need calculation, but the modern stats
    have been programmed to lie. They "know" what the
    temperature, but report something different.

    That's what caused HAL to go crazy and murder the
    astronauts in 2001. ( Being programmed to lie. )

    I made a lot of trouble at IBM years ago trying to correlate
    3 different groups measurements of transistor parameters.
    The three different methods gave significantly different
    results on the same transistor. All three were happy until
    I suggested we compare ... But that wasn't a case of
    delibrately lies, just a difficult to do high frequency measurements.

    Actually my gas gauge lies like mad. I cruise for 100 miles on full,
    but when it hits 1/4 you'd better find a gas station fast.

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