Possible Thermostat problem

Discussion in 'HVAC Heating & Cooling' started by jeff_bathroom, Jul 11, 2013.

  1. jeff_bathroom

    jeff_bathroom Member

    Messages:
    202
    Location:
    Florida
    Odd that I'm having to post this so soon after my last incident.
    My wife and I noticed that despite the temperature displayed on the thermostat,
    the house did not feel as cold as usual. The return is located near the floor, so I also
    noticed that when I walk by, the carpet next to the return felt very cold. Neither of us
    remember ever noticing a cold carpet there.
    So, I got a couple of cooking thermostats and placed them next to the wall thermostat.
    The a/c temp was set for 73 and the house thermostat was showing that temperature. But,
    the cooking thermometers and our bodies told us that the temperature was really between
    75 to 77. I checked the little manual that came with the thermostat and noticed that it had
    batteries in it. I never knew that til now. It's supposed to be for when the power goes out.
    But of course if the power goes out, you have no a/c anyway. But, I replaced the batteries
    and reinstalled the unit onto the wall. Then the temperature registered 77, matching the
    cooking thermometers more or less.
    So, I thought that was neat and went on to set the temp to 73 and I let it run awhile.
    Then I noticed the coldness on the carpet again. It seems what is happening is that the fan
    that is set to auto is shutting off sooner than it normally should. Then the cool air being produced
    up in the attic is just naturally falling downward and leaking out of the inflow vent. I had noticed
    that before when the carpet was cold. I could hear the air handler in the attic and put a piece of
    paper onto the vent and it fell to the floor. So, I then set the fan to continuous ON to see how it behaves.
    The house actually feels cool like it should. My bare feet are cold right now which is how it should
    be if I have the a/c set to 73. However, now the thermostat shows a temperature of 70 and my
    food thermometer shows 72 to 73. So, now the thermostat seems off by three degrees downward
    instead of off by three or four degrees upward as it was before replacing the batteries.
    Think I just have a bad thermostat? Would a bad thermostat also account for the "auto fan" maybe
    not working properly?
  2. DonL

    DonL Jack of all trades Master of one

    Messages:
    4,517
    Location:
    Houston, TX
    The thermometer being off a degree or two is no big surprise.

    If the battery that you changed was a Coin type battery, then it is used to hold programming when the power is Off.

    You may want to check and make sure that the thermostat is programmed for the type of system that you have.

    If the battery went dead then most likely the Type went back to 0, the default.

    0 is fine, if that is your System Type, If not then you need to reset it.


    Good Luck.
  3. jeff_bathroom

    jeff_bathroom Member

    Messages:
    202
    Location:
    Florida
    The unit is actually connected to house power and I think the battery is only to display the temp when the power is out.
    The batteries are two AA. So, I don't think the system type got reset. Thanks for the thought though.
    btw; I tried auto fan again and sort of forgot about it because I work from home and got tied up with some actual work.
    I heard the outside unit making more noise than usual....an audible groaning noise. When I turned the fan on continuous,
    the excessive noise went away. It's as though the cold air not being moved was causing the unit a problem.
    Last edited: Jul 11, 2013
  4. DonL

    DonL Jack of all trades Master of one

    Messages:
    4,517
    Location:
    Houston, TX
    You tried Autofan ?

    That is where it needs to be normally, or the indoor fan will run continuous.

    It sounds like your Thermostat may be miss-wired, or the system type is not set properly.

    If the outdoor unit is making noise, then the Freon/Coolant Levels may be off, or the fan can not dissipate the heat properly.

    What problem was you having ?. Maybe I missed something. ("Odd that I'm having to post this so soon after my last incident.")


    Good Luck.
  5. jeff_bathroom

    jeff_bathroom Member

    Messages:
    202
    Location:
    Florida
    I had an unrelated issue last week.
    The thermostat has been working fine since we bought the house. So, the wiring has not changed
    and it has not been reprogrammed unless it deprogrammed itself somehow.
    I think I'm going to have to break down and call somebody.
  6. DonL

    DonL Jack of all trades Master of one

    Messages:
    4,517
    Location:
    Houston, TX
    You should check the thermostat programming, before calling some one.

    The Battery gives you a few seconds to change, then it needs to be reprogrammed.

    What model stat do you have ?


    Good Luck.
  7. jeff_bathroom

    jeff_bathroom Member

    Messages:
    202
    Location:
    Florida
    Love to if you can tell me how.
    I have a Bryant T2-NHP01
  8. jeff_bathroom

    jeff_bathroom Member

    Messages:
    202
    Location:
    Florida
    In case this tidbit helps...
    at lunchtime it was getting so cold in the house that I turned the thermostat to "off".
    After lunch I turned it back onto cool and the heat came on. So, I shut it off for awhile
    and the outside fan kept running non-stop.
    I finally just pulled out the breaker to stop it. It's clear that I need to do something.

    also, this Thermostat is called "non-programmable".
    Last edited: Jul 11, 2013
  9. DonL

    DonL Jack of all trades Master of one

    Messages:
    4,517
    Location:
    Houston, TX

    The manual is available online.

    You should download it and read it.

    And turn your system OFF, until you can verify proper operation.

    Just buy another thermostat if that is a option, Shotgun it.

    Sounds to me like your T-stat is not set for the type of system that you have. RTFM...

    Call the man, before you need a new system.


    Good Luck
  10. jeff_bathroom

    jeff_bathroom Member

    Messages:
    202
    Location:
    Florida
    Got a guy coming to look at it. I already have the manual. It doesn't say anything about programming
    for a particular type of system. But, it might not be the manual you're talking about.
    Hopefully this won't be too expensive. But, I talked to another outfit before this one and they
    said a basic t-stat was about $190. That sounds expensive to me. At least it would be for this
    manual thing that it would replace. I don't need a cadillac to replace it with. Actually I asked the
    lady what model it was because I wanted to price it. As soon as I asked that, she basically said she'd
    check and call me back. Never called back of course. But that seems like really a bad way to do business
    to me. I don't mind some normal markup, but these hvac outfits double and triple their cost. If they want
    to charge labor, I think that's what they should charge and keep the hardware costs normal.
  11. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,334
    Location:
    New England
    IF the price was to remove and replace the old thermostat, consider it's not uncommon to charge time from when they leave one place until they finish at yours - IOW, it often can include some travel time, not just the time they're there. Labor charges are all over the place, but over $100/hr is not uncommon.

    It sort of sounds like your a/c may be low on refrigerant and is icing up. Shutting it off allows that ice to melt, then it can try to work for awhile. Also, the thermostat might not be located in a proper location - it must not be in a position where the sun can shine on it, or on an outside wall where the exterior can affect it, plus, it must not be in direct line of any registers.
  12. jeff_bathroom

    jeff_bathroom Member

    Messages:
    202
    Location:
    Florida
    There was a switch on the outside unit that fuzed shut such that the outside unit stayed on all the time.
    The behavior of the thermostat was odd, but seems to have straightened out since he replaced that switch.
    All in all not too bad of a hit. Thanks for your suggestions.
  13. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,334
    Location:
    New England
    Running the compressor without air moving over the coils will freeze things up. Sounds hopeful now. Depending on how long that was running constantly, your next electric bill could be a real whopper.
  14. jeff_bathroom

    jeff_bathroom Member

    Messages:
    202
    Location:
    Florida
    Interesting thought about the electric bill. :)
    It's really hard to tell how long it was like that. It could have been two to three weeks.
  15. DonL

    DonL Jack of all trades Master of one

    Messages:
    4,517
    Location:
    Houston, TX


    That may have been what all of the Loud Dripping was about.

    Hopefully the compressor was not damaged. It may have been cycling on the overload.
  16. jeff_bathroom

    jeff_bathroom Member

    Messages:
    202
    Location:
    Florida
    It may have been more so as a result, but we've always heard the drip. It just wasn't until recently that I decided
    finally to address the noise.
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