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  1. #1
    Join Date
    May 2014
    Posts
    19

    Odd thermostat problem, or I'm finally senile!

    I live in the High Desert with low humidity. I set my a/c thermostat for a certain temperature and it runs and runs forever and freezes me out!

    Here's the weird concern I with which I need help.... HELP!
    As the AC runs, & runs & runs it feels colder and colder, but the AC doesn't shut off and the temp reading does not go down on either the thermostat read out or an independent wall thermometer!

    In other words the temp drops to say 72 degrees on both the AC thermostat and a wall stand alone thermometer and stays there as the AC runs on forever and on making it FEEL colder and colder!

    As a retired science teacher this makes no sense to me! Temperature is temperature!

    Is it the feeling of being cold related to "humidity" rather than actual measurable temperature since the AC and the wall thermometer both say it is not getting colder, but I am freezing....and why does it keep running with out the thermometer dropping?

    Any ideas?

    Confused ex science teacher

  2. #2
    Join Date
    Mar 2013
    Location
    Springville, NY
    Posts
    2,880
    apparently it keeps running because your load equals the output of the ac. but, as it runs, the humidity is being dropped and you feel colder.
    ~~
    Nest is poo...

  3. #3
    Join Date
    Oct 2003
    Location
    Michigan
    Posts
    726
    Turn the temperature UP! 72 is freaking cold in my opinion.
    Could be senile though or move north where we still use heat and have snow on the ground.
    Beware of the prophet trying to make a profit.

    There is less oxygen from knee level to the floor! Check it out next time you tie your boots.

  4. #4
    Join Date
    Mar 2013
    Location
    Springville, NY
    Posts
    2,880
    i keep mine at 66-68
    ~~
    Nest is poo...

  5. #5
    Join Date
    May 2014
    Posts
    19
    Quote Originally Posted by qtip View Post
    Turn the temperature UP! 72 is freaking cold in my opinion.
    Could be senile though or move north where we still use heat and have snow on the ground.
    72 degrees was just an example! More like 75, and it's 90 degrees In Apple Valley, CA Getting the swimming pool warmed up!

  6. #6
    Join Date
    May 2014
    Posts
    19
    Quote Originally Posted by HVAC_Marc View Post
    apparently it keeps running because your load equals the output of the ac. but, as it runs, the humidity is being dropped and you feel colder.
    Thanx for your reply!

    The issue is that I have the temperature set at 75. When the AC comes on it will run and run and run until it feels very cold in the house, because the temperature does not drop below 75 in a reasonable period of time! It seems you are saying the AC keeps running because it cannot reduce the temperature based on the size of the house and size/efficiency of the AC unit. If not, please explain term load. Do I have it right?

    Are you also saying that as humidity goes down most people feel colder at the same temperature? I would have thought higher humidity at a lower temperature would feel colder. I guess I have that wrong! It seems colder to me when it is damp outside than when dry.

  7. #7
    Join Date
    Mar 2013
    Location
    Springville, NY
    Posts
    2,880
    you have the first part right. there are other factors but you have it essentially correct. the load is the heat/humidity that you are trying to mitigate.

    as the humidity drops, and at higher temperatures, sweat evaporates readily from skin. you feel cooler from the evaporation process. when the humidity is high and the temperature is cool, the dew point is close enough that a cold clammy condition is felt on the skin.
    ~~
    Nest is poo...

  8. #8
    Join Date
    Nov 2006
    Location
    Athens, Ohio
    Posts
    1,809
    Buy a device to measure the humidity in the house. As the air conditioner runs it should be reducing the humidity. Humidity is latent heat and the thermometer measures sensible heat.

  9. #9
    Join Date
    May 2014
    Posts
    19
    The confusing issue for those who don't think about AC very much, is that the temperature is not dropping, but as the AC runs and runs it feels colder and colder at the same unchanging temperature! So, of course my wife increases the temperature setting on the AC control to shut off the system! 15 minutes later we feel hot again and the idiotic cycle repeats I'm 71, and never had a problem with an AC before! I suspected the key factor is related to humidity levels in the high desert!

    I've reduced the number of rooms the AC is dealing with to see if that helps!

  10. #10
    Join Date
    Sep 2008
    Location
    Cedar Rapids, IA
    Posts
    486
    http://www.energy.wsu.edu/Documents/10_spr_iaq_nl.pdf

    This article gives a good explanation of comfort vs temperature, humidity, wind, etc.

    When an AC unit starts running it begins to lower the humidity first and then will lower the temperature. One possible solution to your comfort problem is to have a thermostat installed that can sense humidity and can activate the AC to dehumidify. You would then set the temperature setting higher and the RH% setting to get your desired comfort level.

  11. #11
    Join Date
    Aug 2009
    Location
    Beatrice, NE
    Posts
    2,118
    Is this a digital or mechanical thermostat? I have seen where the mechanical thermostat will do this. It has to do with the cooling anticipator. This is especially common with the Honeywell T87F round thermostats.

  12. #12
    Join Date
    May 2014
    Posts
    19
    Quote Originally Posted by kls-ccc View Post
    Is this a digital or mechanical thermostat? I have seen where the mechanical thermostat will do this. It has to do with the cooling anticipator. This is especially common with the Honeywell T87F round thermostats.
    It's a RobertShaw Digital! Do you have a recommendation for the best thermostat!?

  13. #13
    Join Date
    May 2014
    Posts
    19
    Quote Originally Posted by bob_scheel View Post
    http://www.energy.wsu.edu/Documents/10_spr_iaq_nl.pdf

    This article gives a good explanation of comfort vs temperature, humidity, wind, etc.

    When an AC unit starts running it begins to lower the humidity first and then will lower the temperature. One possible solution to your comfort problem is to have a thermostat installed that can sense humidity and can activate the AC to dehumidify. You would then set the temperature setting higher and the RH% setting to get your desired comfort level.
    Thanx! I've got some studying to do! What do you recommend as the best thermostat? Incidentally I insulated the hole in the wall behind the thermostat to avoid drafts in wall affecting thermostat!

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