Page 1 of 3 123 LastLast
Results 1 to 13 of 31

Thread: VisionPro

  1. #1
    Join Date
    Sep 2004
    Posts
    51

    VisionPro 'adaptive recovery'... isn't

    After reading this board I had my installer put in a 8321 VisionPro last fall. Well, the setback bit doesn't seem to be working just right. One thing I thought this T-stat was supposed to do is to look at how long setback recovery took on previous days, and use that to make sure that the temp is at the setpoint AT the schedule time. (The cheapo setback I used before STARTED the unit at the schedule time.)

    Well, with the recent heat here, I find that the durned thing can't recover until hours after the schedule time.

    Evening setpoint is 78 @ 6:30, daytime is 85. By the time I get home, it is reading 83. It doesn't seem to get it down to 78 until 10PM or so.

    I know that 85 is a high daytime setback, but I thought the thermostat was supposed to be smart enough to figure this out and start recovery at the correct time.

    On a not-scorching-day, I looked at the stat @ 6PM, the inside was 81, and it STILL hadn't turned the unit on. No way is a properly sized-unit going to cool by three degrees on a hot day in half an hour. Right?

    I went ahead and put the thing on perm. hold for the past few 100+ days because of this.

    Is there some setting my installer forgot to turn on, or is the "Adaptive-ness" limited to .5 hr or so?

    It seemed to work okay in the winter...

    SirWired

  2. #2
    Join Date
    Sep 2004
    Posts
    51
    Argghhh! The posting system needs to warn you if you put double-quotes in the subject line! The subject line was SUPPOSED to read VisionPro "Adaptive Recovery"... isn't.

    SirWired

  3. #3
    Join Date
    Dec 2001
    Location
    Ocean Pines, MD
    Posts
    6,984

    WARNING!

    On properly sized HVAC systems you probably won't have the capacity to recover in that kind of heat, especially that much of a setback. The thermostat doesn't know the size vs load of your system. It's an air conditioner, not a refrigerator. We warn customers to be careful the amount of the setback and when to use it, especially with heat pumps in the heat mode. Maybe a 2-stage system would be the ticket for you.

  4. #4
    Join Date
    Jun 2003
    Location
    Jacksonville, FL.
    Posts
    4,313
    Sirwired, your tstat is doing what it's programmed to do. Nothing's wrong - operator error. It's a tstat not an A.I.

  5. #5
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    34,084
    I put mine on hold on the last heat wave. Stat was trying to cool the house down but with high heat & humidity, the cooling unit just couldn't. Also, intelligent recovery looks at past days too. If you suddenly turn hot, it may not turn on soon enough even if the unit is oversized enough to recover.

  6. #6
    Join Date
    Jun 2005
    Location
    Near Chicago, IL
    Posts
    3,317
    Your temperature swing in cooling mode is too much.

    It is much more cost effective to choose a milder temperature and setback. I choose 80 during the day and 77 at night. It is much easier for the system to cool an additional degree or two if needed.
    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


  7. #7
    Join Date
    Aug 2003
    Location
    Fort Worth, TX
    Posts
    11,324
    Any energy savings you are hoping to achieve with this wide of a range of setback setpoints is self defeating. Narrow the range and you'll actually be spinning the meter a lot less than now. I would go no higher than 80 as your unoccupied temperature setpoint and then stay with the 78 as the occupied temp if that is your comfort level (too warm for me, but YMMV).
    • Electricity makes refrigeration happen.
    • Refrigeration makes the HVAC psychrometric process happen.
    • HVAC pyschrometrics is what makes indoor human comfort happen...IF the ducts AND the building envelope cooperate.


    A building is NOT beautiful unless it is also comfortable.

  8. #8
    Join Date
    Jan 2005
    Posts
    340
    Originally posted by neophytes serendipity
    It is much more cost effective to choose a milder temperature and setback.
    Not true....the greater and longer the setback, the larger the savings.

    http://www.energy.ca.gov/efficiency/...HERMOSTATS.PDF

  9. #9
    Join Date
    Sep 2001
    Location
    Vancouver Canada
    Posts
    996
    travisfl


    I don't care what the government says about setback tstats. If you set it back more than the system can recover you will be running your unit constantly and be at an uncomfortable temperature level as well. There is a point beyond which you can setback your temps and save money as well as acheive the desired comfort level. I would say in A/C mode you should not look for swings of greater than 2 degrees. Usually you are bringing the air back on upon arival home after work, this is also in the hottest part of the day and most systems begin to lose ground at this time. So now you are asking the system to recover a large temp difference as well as overcome the heat of the afternoon. This is not a realistic situation for a properly sized system. Your system is designed to maintain a set temp level not recover vast temp differences. So even if you do save a couple of bucks by large setbacks it will be at the cost of comfort.
    "Go big or Go Home"

  10. #10
    Join Date
    Jul 2002
    Location
    Zelienople, Pa
    Posts
    2,965
    Originally posted by travisfl
    Originally posted by neophytes serendipity
    It is much more cost effective to choose a milder temperature and setback.
    Not true....the greater and longer the setback, the larger the savings.

    http://www.energy.ca.gov/efficiency/...HERMOSTATS.PDF
    I wouldn't believe this to be true in this circumstance.

    I personally designed sir's system.
    The design temps in Raleigh, NC are 75 inside @ 92 outside.

    It was reaching 105 during the peak of the days when he was having most problems recovering.

    This was the hottest July Raleigh has had in 50 years!
    My systems never shut off except maybe 4-5 hours at night.
    I made the same mistake of setting my tstat back to 77 while I'm at work and 74 when I get home.
    The temps in my house even climbed to 78 until after midnight!
    How tall are you Private???!!!!

  11. #11
    Join Date
    Jan 2005
    Posts
    340
    [QUOTE]Originally posted by Yellow Dot
    I wouldn't believe this to be true in this circumstance.
    Note that I'm not referring to comfort or the amount of time required to return the conditioned space to the design temperature. Having said that, the statement relative to setback energy savings is true, it is a matter of physics.

  12. #12
    Join Date
    Sep 2001
    Location
    Vancouver Canada
    Posts
    996
    It's like argueing evolution against creasion theory, until you can give some definitive data on energy saving by setting back as opposed to maintaining temps on A/C I will not be convinced. As far as I am concerned customer comfort is the reason that we install systems, not energy efficiency. If I can save $50 per month and sweat my bag off it is pointless to have an a/c system. I can also save $.05 by pissing in the dark and not turning on the light. But any savings are returned by cleaning materials needed. There is cost involved in comfort, I leave it to you to decide which is more important to you. I say if you can afford to run the a/c and maintain comfort levels go for it. If cost saving is more important you are welcome to sit in the heat.
    "Go big or Go Home"

  13. #13
    Join Date
    Jan 2005
    Posts
    340
    Originally posted by Black Adder
    It's like argueing evolution against creasion [sic] theory
    Yes, that would be the case exactly. Science vs non-science.

Page 1 of 3 123 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Comfortech Show Promo Image

Related Forums

Plumbing Talks | Contractor Magazine
Forums | Electrical Construction & Maintenance (EC&M) Magazine
Comfortech365 Virtual Event