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Thread: psycrometer

  1. #27
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    Quote Originally Posted by Mr Bill View Post
    But they work great to get the grease right when cooking hot wings.
    They do have their place in the right application.

  2. #28
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    Mar 2011
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    Got a Fieldpiece pocket digital psychrometer from my supplier today for $60!

  3. #29
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    Quote Originally Posted by timberlinemd View Post
    Got a Fieldpiece pocket digital psychrometer from my supplier today for $60!
    I got mine for 52$.

  4. #30
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    I seen that one too but counter Guy was a little skeptical on its performance.

  5. #31
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    May 2004
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    Quote Originally Posted by andersonbe06 View Post
    Is a sling psycrometer required to acuaratly calculate superheat and subcooling as well as a temperature probe. All we have at work is a laser\infered thermometer . Thanks guys and gals
    The original posters question has distorted throughout the thread is a simple yes or no question as superheat is the temperature above the refrigerant saturation and subcooling is a temperature below refrigerants saturation at specific temperatures and pressures. So the answer is no you do not need a sling psychrometer to measure superheating or subcooling! As other posters have mentioned A gauge, temperature probe, and the pt chart is what is required to measure the units Superheat and subcooling. There are definitely some handy tips being offered and useful information,,
    I know the guy who know's the "Chiller Whisperer"

  6. #32
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    Quote Originally Posted by joegrind View Post
    So the answer is no you do not need a sling psychrometer to measure superheating or subcooling!


    Joe, the OP did not say measure, he said calculate. I (and others I imagine) think he is asking if the sling psychrometer (or other means of measuring WB) is needed to calculate the target SH or SC, not just to measure it. So, to measure, not required. To calculate the target, required. Agreed?

  7. #33
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    May 2004
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    Quote Originally Posted by DDC_Dan View Post
    Joe, the OP did not say measure, he said calculate. I (and others I imagine) think he is asking if the sling psychrometer (or other means of measuring WB) is needed to calculate the target SH or SC, not just to measure it. So, to measure, not required. To calculate the target, required. Agreed?
    Maybe you got me on a technicality, maybe I've been out of the residential arena for too long! I guess I don't understand how it can be calculated as it is a real-time measurement of the here and now I don't know of an application where you project what the superheat will be, Anyway my bad if I misunderstood it, I just asked simple questions in the past only not to get answered But was offered a whole slew of other opinions not related to the question Cheers
    I know the guy who know's the "Chiller Whisperer"

  8. #34
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    Jan 2006
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    Trane prefers the subcooling method for TXV's.

    However if you use their supplied chart on some systems with TXV's- you must know the wet bulb.

    I don't use the wet bulb chart much, so I'm not sure when they quit using them.

  9. #35
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    Quote Originally Posted by joegrind View Post
    Maybe you got me on a technicality, maybe I've been out of the residential arena for too long! I guess I don't understand how it can be calculated as it is a real-time measurement of the here and now I don't know of an application where you project what the superheat will be
    It the calculation isn't of what the superheat will be, but of what it should be, which varies with differences in the wet bulb temperature of the air entering the evaporator coil, and the dry bulb temperature of the air entering the condenser coil.
    Measuring the wet bulb temperature of the air entering the evaporator coil requires the use of a wet bulb thermometer, or a psychrometer.

    If you don't take the measurements, and do the calculation to determine what the superheat should be, what good is taking the measurements to know what it is?

    Quote Originally Posted by walterc View Post
    Trane prefers the subcooling method for TXV's.

    However if you use their supplied chart on some systems with TXV's- you must know the wet bulb.

    I don't use the wet bulb chart much, so I'm not sure when they quit using them.
    The chart you are speaking of is not for charging, it is for determining if the system is operating within its design parameters.
    On TXV systems, the wet bulb temperature is not needed for either of the 2 charging procedures AS/Trane have used.
    If more government is the answer, then it's a really stupid question.

  10. #36
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    Only one person has mentioned airflow so far though. There is no point in taking any of these measurements and using that formula (which doesn't have an air volume factor in it) if you can't determine the total amount of heat content in the air that you are conditioning. So how many cfm/ pounds of air is this formula based on? Would anyone even notice if they had a 15 degree SH and their designed SH was suppose to be 12 based on that formula? And would they add refrigerant to drop SH to design conditions rather than finding that the blower is moving a higher volume of air or a fresh air duct is present or ducts are not fully sealed in the attic? We are in a greatly technical field with constantly changing conditions, the only thing we tend to do is hang on to rule-of-thumbs and homemade formulas. In the end though that truly gets us close enough.

    My Jerry Springer final thoughts speech
    ## + years in the field never made you a know-it-all This industry is far more diverse than you are

  11. #37
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    Quote Originally Posted by git-r-dun View Post
    Only one person has mentioned airflow so far though. There is no point in taking any of these measurements and using that formula (which doesn't have an air volume factor in it) if you can't determine the total amount of heat content in the air that you are conditioning. So how many cfm/ pounds of air is this formula based on? Would anyone even notice if they had a 15 degree SH and their designed SH was suppose to be 12 based on that formula? And would they add refrigerant to drop SH to design conditions rather than finding that the blower is moving a higher volume of air or a fresh air duct is present or ducts are not fully sealed in the attic? We are in a greatly technical field with constantly changing conditions, the only thing we tend to do is hang on to rule-of-thumbs and homemade formulas. In the end though that truly gets us close enough.

    My Jerry Springer final thoughts speech
    That is why, whenever possible, I measure the return WB and DB temperature of the air as it actually enters the coil, and while I'm there, measure the supply air DB and do the TEET calculation.
    If more government is the answer, then it's a really stupid question.

  12. #38
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    Quote Originally Posted by andersonbe06 View Post
    Is a sling psycrometer required to acuaratly calculate superheat and subcooling as well as a temperature probe. All we have at work is a laser\infered thermometer . Thanks guys and gals
    To measure superheat/subcooling you do not need a psycrometer. All you need is the existing pressures vs. the PT chart settings based on your low side temperature and high side temperature (heat pump sensitive) respectively. To determine if you have the correct superheat you will need a psycrometer as a minimum to determine indoor WB as well as the R/A temperature entering the coil (keep in mind you may have a certain level of heat gain if you take your reading from inside the conditioned space. The closer to the evaporator the better) and your OAT. There are other methods and formulas that can be used as listed in this thread, but this would be the bare bones approach to measuring superheat/subcooling and calculating the required superheat/subcooling. I hope this helps

  13. #39
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    May 2004
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    Quote Originally Posted by mark beiser View Post
    It the calculation isn't of what the superheat will be, but of what it should be, which varies with differences in the wet bulb temperature of the air entering the evaporator coil, and the dry bulb temperature of the air entering the condenser coil.
    Measuring the wet bulb temperature of the air entering the evaporator coil requires the use of a wet bulb thermometer, or a psychrometer.

    If you don't take the measurements, and do the calculation to determine what the superheat should be, what good is taking the measurements to know what it is?



    The chart you are speaking of is not for charging, it is for determining if the system is operating within its design parameters.
    On TXV systems, the wet bulb temperature is not needed for either of the 2 charging procedures AS/Trane have used.
    the OP Originally asked a very simple question , Everybody is offering up opinions and charging procedures for equipment that he never asked for, All are valid and differ depending on the equipment On. Don't slag me for simply trying to answer his question and not offer opinions above and beyond
    I know the guy who know's the "Chiller Whisperer"

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