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Thread: Lowest Safe Temperature

  1. #1
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    Lowest Safe Temperature

    I live in an area where power is cheap and I dont mind the system running all the time. What is the coldest temperature I can set the thermostat to without risking damage to equipment? Assuming no lower 55+ ambient outside (from the manual).

    New Equipment Installed:

    Trane XR13 4TTR3036H1000P and Trane 4MXCB004AC6HCA Coil

    I also had a new return duct added to cut the static which is now .6

  2. #2
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    Go by the manual.

  3. #3
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    Trane says 55 outside. Never seen a figure inside but problem would be freezing of the coil. We have a customer who likes it cold. We put a freezestat on the coil so if it gets down around 32, the unit cycles off.

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  5. #4
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    Txv nominal rating @ 200# dp, 55/68 = ~,100# dp. Any lower and probable high ssh & lp.

  6. #5
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    When the mold starts growing on the back side of the drywall it’s to low


    Sent from my iPhone using Tapatalk

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  8. #6
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    Quote Originally Posted by jbhenergy View Post
    When the mold starts growing on the back side of the drywall it’s to low


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    That about covers it

  9. #7
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    Quote Originally Posted by drichard989 View Post
    I live in an area where power is cheap and I dont mind the system running all the time. What is the coldest temperature I can set the thermostat to without risking damage to equipment? Assuming no lower 55+ ambient outside (from the manual).

    New Equipment Installed:

    Trane XR13 4TTR3036H1000P and Trane 4MXCB004AC6HCA Coil

    I also had a new return duct added to cut the static which is now .6
    Anything below 70° is considered refrigeration

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  11. #8
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    Quote Originally Posted by jbhenergy View Post
    When the mold starts growing on the back side of the drywall it’s to low


    Sent from my iPhone using Tapatalk
    .
    X2
    Pandora's box. If you're planning on keeping healthy 70°...were the installer's aware before?
    ..
    Do not attempt vast projects with
    half vast experience and ideas.
    ...

  12. #9
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    Quote Originally Posted by Sleuth View Post
    .
    X2
    Pandora's box. If you're planning on keeping healthy 70°...were the installer's aware before?
    ..

    I had mentioned it but they didn’t want to go bigger with the current ducting in place.

    I’m not worried about mold, it’s pretty dry here.

    So aside from added cost it doesn’t really matter?

    I had seen things about there not being enough “thermal load” or that the coil can freeze if the temp is too low. However since the airflow is within the envelope of my equipment i’m just not sure

  13. #10
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    68. Anything below that your freeze.

    Unless you can run extremely low humidity so you don’t condensate.

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  15. #11
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    my cousin keeps his 3,500 sq ft house at 60

    But ... we went nuts doing the insulation
    Tell your Cat I said "Psst Psst Psst"

  16. #12
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    So related to this. Someday when i build a house, what would i need to do to be able to keep cool at 65 degrees with ambient anywhere from 50 outside (laziness to open windows ) to 110 outside?

    Oversize ducting+equipment?

  17. #13
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    My cousin doubled everything wooden , and insulation

    Like the walls are Not your typical 2x4 .... they are 2x8

    Attic has double the amount of insulation as well

    The AC ... you just size it for the house
    Tell your Cat I said "Psst Psst Psst"

  18. #14
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    Quote Originally Posted by Snapperhead View Post
    My cousin doubled everything wooden , and insulation


    Like the walls are Not your typical 2x4 .... they are 2x8

    Attic has double the amount of insulation as well

    The AC ... you just size it for the house
    So then if he does this and has no issues with freezing, why shouldn’t I? while i may be undersized , all that should mean is a more expensive power bill and maybe a shorter total lifespan of the equipment

  19. #15
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    Quote Originally Posted by drichard989 View Post
    So related to this. Someday when i build a house, what would i need to do to be able to keep cool at 65 degrees with ambient anywhere from 50 outside (laziness to open windows ) to 110 outside?

    Oversize ducting+equipment?
    Buy a Walk - In cooler box!

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  21. #16
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    Get a full DOAS unit.

  22. #17
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    If you have enough moisture to condense on a glass of ice water you have enough for mold to grow.

    More importantly if you have humidity below 50% you don’t need to waste the energy to make it an ice box.

    If you have insist on extreme low temperature then build a walk-in cooler, put in refrigeration equipment and suffer from stress when you go from 65 inside to 110 outside.

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  24. #18
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    Quote Originally Posted by drichard989 View Post
    So related to this. Someday when i build a house, what would i need to do to be able to keep cool at 65 degrees with ambient anywhere from 50 outside (laziness to open windows ) to 110 outside?

    Oversize ducting+equipment?
    More about vapor barrier and infiltration at this point. When they say walk in cooler, what they mean is spray foam. A walk in cooler and freezer has foam filled panels.

    So you will want closed cell phone and then aerobarrier sprayed. And then you will need an erv or dehu with fresh air would be preferable


    Sent from my iPhone using Tapatalk

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  26. #19
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    Quote Originally Posted by pecmsg View Post
    Anything below 70° is considered refrigeration
    Im refrigerated at 67F and 47RH
    Nest is POO!!

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  28. #20
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    Quote Originally Posted by HVAC_Marc View Post
    Im refrigerated at 67F and 47RH
    How???
    It’s 73 52% rh in my house now and I’m a bit chilly lol


    Sent from my iPhone using Tapatalk

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