System Readings (refrigeration)

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System Readings (refrigeration)
2015-02-24 18:53:24
superheat subcooling suction line temp

how to read gauges and convert to temperatures, subcooling, superheat, txvs,low pressure switch settings, fan cycling switch settings
Show Answers:

  1. Where do you get Ambient Air readings from.

                                 High Side
    2" from the condenser coil
  2. How can you get Liquid Line Temp.

                                 High side
    Condensing Temp - Subcooling
  3. How can you get High Side pressure.

                                 High Side
    Condensing temp converted.
  4. How do you get Condensing Temperature.( Design)

                                 High Side
    Ambient air + Condenser TD(Design)
  5. How Do you get Condensing Temperature(Actual)

                                High Side

    High side pressure, converted (Actual)
  6. How can you get Condenser TD ( Temperature Difference).
    • Condensing Temperature - Ambient
    • (Condenser Temperatures are):
    • Medium temp 30*
    • Mid Efficiency 25*
    • High Efficiency 20*
    • Remote 10*
  7. How can you get Subcooling.

                                 High Side
    Liquid Line Temp - Condensing temp
  8. How can you get Suction Line Temp.

                                  Low Side
    Superheat - Boiling Temp
  9. How can you get Low Side Pressure.

                                 Low Side
    Boiling Temp converted to a pressure.
  10. How can you get Superheat.

                                 Low Side
    Boiling Temp - Suction line Temp
  11. where is supply air
    back of evaporator coil = boiling temp. (coil temp)
  12. where do we get Return Air
    Temp in front of the fan = box temp
  13. How do we get Delta T
    Supply air - Return Air.
  14. What would happen to the
    subcooling/superheat if you open or
    turn the txv clockwise.
    your Superheat/subcooling would go up.⇧
  15. What would happen to your subcooling/superheat if you close or turn the txv counterclockwise.
    Your Superheat/Subcooling wil go down⇩
  16. What is considered to be low ambient temperature.
    60*F and below.
  17. How would you get the C/O Setting for a Low Pressure Switch
    • 5# for Low pressure refrigerant
    • 10# for high pressure refrigerant
  18. How would you get a C/I setting for a Low Pressure Switch
    Low side PSIG plus 10# (buffer)
  19. What is the formula to getting a fan cycling switch setting
    Low Ambient(60)+ condensing TD= X *F convert to pressure= X #PSIG= C/O + 40#= X = C/I
  20. Definition: Delta-T
    • Difference in temperature across a divider; 
    • often used to refer to the difference between 
    • indoor and outdoor temperatures.
  21. Definition:  superheat
    Sensible heat in a gas above the amount needed to maintain the gas phase.
  22. When fan is off in a from a fan cycling switch you can only measure what
  23. Evaporator temp is the same as  what
    Boiling temperature
  24. how do you get evaporator temp
    convert low side pressure to a temperature
  25. How do you get boiling temp(Design)
    Return air - evap TD(Design)
  26. how do you get boiling temp (Actual)
    convert low side pressure to a temp(Actual)
  27. How do you get Design evaporator TD
    Box temp - Evaporator TD
  28. Inside box temperature is the same as what
    Supply air temperature