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Thread: Vision pro 8000 thermostat

  1. #1
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    Vision pro 8000 thermostat

    Hello, I leave my vision pro 8000 tstat on the same temp all day long. It is scheduled to turn down around midnight about 1 degree and then back around 9:00 am , so it stays the same temp from 9:00 am to midnight. During the day on a 91 degree day it will stay off for 15-20 minutes but at night between 8 pm and 11 pm it seems like it comes on every 10 minutes, this is when it is 75 degrees outside. It would seem that it should come on less often so is there something with this tstat that would cause it to run more often? I understand it is a learning tstat but I'm not sure what it could be learning to cause it to run more often in the evening.

    Does anyone know what the swing temp differential is for this tstat? Not sure if that would causing the issue considering it runs more when it not as hot outside in the evening.

    Thank you

  2. #2
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    Typicall the stat will maintain a temp within 1 degree of the set temp. If the equipment is running more often it just means the demand is higher, or the equipment may need some attention. It's a little hard to help without more info.

  3. #3
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    Thanks. When you say equipment do you mean the tstat? Im guessing the ac unit is not the issue as it just comes on when the stat calls for it. The cycles are not longer so I think unit is fine. The issue is that the stat is calling for the unit to come on at shorter intervals at night than during the day but seems like it should stay off longer

    What additional info can I provide?

  4. #4
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    Quote Originally Posted by James Colver View Post
    Typicall the stat will maintain a temp within 1 degree of the set temp. If the equipment is running more often it just means the demand is higher, or the equipment may need some attention. It's a little hard to help without more info.
    Agree and also if you have it set a degree cooler at night, all the walls and content has to be cooled to that. The attic holds a lot of heat for a period as well.

  5. #5
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    The problem is likely the attic temperature.
    What is the roof material?
    What color is the roof material?

    The cooling system cools the interior air - not the house. The house is cooled by the air.

    The typical shingle roof represents a massive thermal mass. 30-40 lbs per square foot. All day it absorbs and retains the sun's heat. The high attic temperature makes all the ceilings under it into radiant heating panels. Even after the outdoor ambiant drops - the massive amount of heat your roof has gathered and saved for you all day is available to continue heating your house.

    This is why you can often walk a neighborhood in the evening after dark and hear attic exhaust fans still running after a hot summer day.

    The cooling system cools the interior air to the thermostat's set point and switches off the cooling system.
    The large well-heated thermal mass of the structure immediately begins to re-heat the interior air.
    The thermostat then switches the cooling system back on.

    That's why what you describe isn't happening at 11:00A

    PHM
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    Quote Originally Posted by dorlando View Post
    Hello, I leave my vision pro 8000 tstat on the same temp all day long. It is scheduled to turn down around midnight about 1 degree and then back around 9:00 am , so it stays the same temp from 9:00 am to midnight. During the day on a 91 degree day it will stay off for 15-20 minutes but at night between 8 pm and 11 pm it seems like it comes on every 10 minutes, this is when it is 75 degrees outside. It would seem that it should come on less often so is there something with this tstat that would cause it to run more often? I understand it is a learning tstat but I'm not sure what it could be learning to cause it to run more often in the evening.

    Does anyone know what the swing temp differential is for this tstat? Not sure if that would causing the issue considering it runs more when it not as hot outside in the evening.

    Thank you
    PHM
    --------
    The conventional view serves to protect us from the painful job of Thinking

  6. #6
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    That does make a lot of sense about the attic. I have shingle roof, medium to dark brown color. I did have some insulation pumped into the attic a couple years ago but not sure how much it is helping. Do attic fans help? Is there a specific type I should look for? I have heard different things about them. Our house gets sun all day long, no trees covering the roof.

  7. #7
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    Insulation slows heat transfer - it does not stop it. And a hot attic results in hot insulation which results in hot ceilings.

    The average sun load is 440 BTU's per hour per square foot of area exposed to the sunlight. I think this is called the Solar Constant - or something like that. But even a small roof - say 2000 square feet - is exposed to quite a lot of heat during a sunny day. The best roof in this regard is highly reflective, highly emissive, with low mass. Shingle roofs are the opposite of all three. <g>

    Yes; attic fans are good as they exhaust superheated attic air and allow it to be replaced with outdoor ambient air. I dislike having holes in a roof so I like to use generous gable end vents and install the attic exhaust fan at the farthest end for the bedrooms. The inlet has to be generous and the house well sealed from the attic to avoid exhausting air from the conditioned space of the house.

    PHM
    --------


    Quote Originally Posted by dorlando View Post
    That does make a lot of sense about the attic. I have shingle roof, medium to dark brown color. I did have some insulation pumped into the attic a couple years ago but not sure how much it is helping. Do attic fans help? Is there a specific type I should look for? I have heard different things about them. Our house gets sun all day long, no trees covering the roof.
    PHM
    --------
    The conventional view serves to protect us from the painful job of Thinking

  8. #8
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    Thank you. I will look into that. I do have gable ends. Did you mean to type to install them at the farthest end "from" the bedrooms, so not near bedrooms?

  9. #9
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    From; yes.

    It's noting to do with performance - it's just that some people can find even slight sounds objectionable.

    PHM
    -------


    Quote Originally Posted by dorlando View Post
    Thank you. I will look into that. I do have gable ends. Did you mean to type to install them at the farthest end "from" the bedrooms, so not near bedrooms?
    PHM
    --------
    The conventional view serves to protect us from the painful job of Thinking

  10. #10
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    I would like to revisit my original thermostat question. I agree with what has been said about the attic retaining the heat and that heat transferring into the house into the evening which could cause the thermostat to kick on more often. Here is where I am a bit confused. At 4:00 when it is over 90 degrees outside the off cycle may be 15-17 minutes but come 7:30-10:30 the off cycle is only 10 minutes. It would seem the demand is higher during the peak of the day but yet when the sun has gone down and it is cooler outside the tstat comes on more often. Taking tonight for example, it is a very cool night in Orlando and at 10:30 the tstat is coming on but the room where the tstat is feels cooler than at times during the day.

    Is it possible that since this is a "learning" tstat that it has programmed itself to come on more often in the evening? I'm not sure why it would do that because we keep the same temp during the entire day. The only time it changes is around midnight, I have the schedule set to bring it down 1 degree then. Thank you.

  11. #11
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    Not sure if this is of help but the attic etc has been discussed but also if it is a brick home you can actually feel the heat from several inches away and it will hold the heat for awhile. Maybe others can offer more on that.

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