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  1. #1
    Join Date
    Jul 2009
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    North GA
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    effects of altitude

    I live and work in georgia.
    vacationing in Denver colorado with family.
    his unit is freezing up, coils clean and filter unit is a 5 ton lennox with txv metering.

    with the change in altitude what difference should I expect to see with pt relationships and psig.
    water boils at 94f rather than 120f

  2. #2
    Join Date
    May 2000
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    Urbandale IA. USA
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    Altitude affects what is OUTSIDE the system, not what is inside.
    It will affect how fast moisture evaporates.
    Those who dance, appear insane to those who do not hear the music.
    Those who believe, appear ignorant to those who do not know God.

  3. #3
    Join Date
    Jun 2009
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    Florida
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    Quote Originally Posted by cehs View Post
    Altitude affects what is OUTSIDE the system, not what is inside.
    It will affect how fast moisture evaporates.
    And how much air the fans move with each rotation. Lesser air density.
    Low Pressure Forever!

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  4. #4
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    Mar 2009
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    Quote Originally Posted by ChillerWisperer View Post
    And how much air the fans move with each rotation. Lesser air density.
    Not to mention the fact that your gauge manifold guage PT scales are no longer accurate, you have to have an altitude compensated/corrected PT chart. Remember that at 5200' the atmospheric pressure is NOT 14.7 PSI it is in the range of 12.2 to 12.7 PSI, can't remember exactly.

    Fans and gas fired appliances have to be derated by 4%/1000' of elevation or roughly 16% in Denver.

    As stated what happens inside the system is not affected however without altitude compensation the equipment used to measure what is inside the system is not correct. An example would be a standard guage "Blanks off" at around 24" of Vacuum at this altitude where it will read down to about 28" of Vacuum at sea level.
    If sense were so common everyone would have it !

    All opinions expressed are my own. Any advice provided is based on personal experience, generally accepted fact or publicly available information. As such, it is worth exactly what you paid for it, not a penny more not a penny less !!

  5. #5
    Join Date
    Jan 2007
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    in my lumpy chair
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    RH is be lower so pressures are lower, check airflow, superheat and subcooling
    I dont warranty Tinkeritus

  6. #6
    Join Date
    Mar 2009
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    Quote Originally Posted by Robert Shumate View Post
    water boils at 94f rather than 120f
    I hope you ment 194* F and 212* F for the boiling point of water. Just an observation.
    If sense were so common everyone would have it !

    All opinions expressed are my own. Any advice provided is based on personal experience, generally accepted fact or publicly available information. As such, it is worth exactly what you paid for it, not a penny more not a penny less !!

  7. #7
    Join Date
    Feb 2004
    Location
    New Mexico
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    5,346
    Quote Originally Posted by ChillerWisperer View Post
    And how much air the fans move with each rotation. Lesser air density.
    Not really. A cubic foot at sae level is the same size at altitude just less dense. A fan rated at 2000 cfm will move the same 2000 at altitude only will require less hp and won't be as efficient with transfer of heat.

    About the pt ? an example of r22 at 30 degf at sea level would be 54.9# at 5000 feet 30 degf would be 58#.
    There are charts available from supply houses here.You might Google it too.

    Like CCIKelly said almost everything measured at altitude needs to be compensated.
    Tracers work both ways.

  8. #8
    Join Date
    Apr 2005
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    N. E. Missouri
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    Quote Originally Posted by CCIKelly View Post
    I hope you ment 194* F and 212* F for the boiling point of water. Just an observation.
    Yeah, my water heater is set at 120 and it's not boiling yet!
    Do not argue with an idiot. He will drag you down to his level and beat you with experience.

  9. #9
    Join Date
    Jan 2007
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    in my lumpy chair
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    Boiling point of water
    F C
    sea level 212 100
    2000' 208 98
    5000' 203 95
    7500' 198 92
    10'000' 194 90
    15'000' 185 85

    It don't line up like the message shows
    I dont warranty Tinkeritus

  10. #10
    Join Date
    Jan 2007
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    in my lumpy chair
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    Quote Originally Posted by mrs reb77 View Post
    Yeah, my water heater is set at 120 and it's not boiling yet!
    Good lord Mrs... recalibrate your PSIA
    I dont warranty Tinkeritus

  11. #11
    Join Date
    Jul 2009
    Location
    North GA
    Posts
    14

    thanks

    Quote Originally Posted by CCIKelly View Post
    I hope you ment 194* F and 212* F for the boiling point of water. Just an observation.
    Yes I did thank you. I meant 194 not 94

  12. #12
    Join Date
    Jul 2009
    Location
    North GA
    Posts
    14
    Thank you all. I get it now. No need to insult. Those that did not, thank you for your help. I understand the adjustments needed. I know that inside will not be affected its outside that will be affected.

  13. #13
    Join Date
    Jul 2009
    Location
    North GA
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    and yes I did mean 194f and 212f not 94 and 120. inebriated with family at the time of posting.

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