Maricopa Community Colleges  HVA140AD   19932-20086 
Official Course Description: MCCCD Approval: 07/22/08
HVA140AD 19932-20086 LEC 0.50 Credit(s) 0.50 Period(s)
Heat Pump Charging and Piping
Reviews common and most effective charging techniques for heat pumps. Emphasizes critical nature of charging. Includes considerations for designing refrigerant piping and diagnosis of problems caused by faulty piping design.
Prerequisites: None.
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MCCCD Official Course Competencies:
 
HVA140AD   19932-20086 Heat Pump Charging and Piping
1. Explain percentage of charge deviation from norm to affect system. (I)
2. Describe malfunctions created by undercharge. (I)
3. Describe malfunctions created by overcharge. (I)
4. Describe dynamics of refrigerant migration. (I)
5. Describe deficiencies of following charging techniques, including: ambient plus 30 degrees; 40 degrees evaporator; sight glass; sweat back; pressure charts; super heat, and sub cooling. (II)
6. Describe most effective way to charge cap tube system. (II)
7. Describe most effective way to charge TXV system. (II)
8. Describe how to charge cap tube system in low ambient. (III)
9. Describe how to charge TXV system in low ambient. (III)
10. Describe the most effective way to charge a heat pump in the heating mode. (IV)
11. Describe advantages for using weight method of charging. (V)
12. Describe how to correct for line lengths while charging remote systems. (V)
13. Describe how to calibrate gauges. (VI)
14. Define primary considerations for designing piping. (VII)
15. Calculate total pressure drop in liquid line. (VII)
16. Describe how to size liquid line. (VIII)
17. Calculate refrigerant velocity in liquid line. (VIII)
18. Calculate amount of refrigerant charge for over-sized liquid lines. (VIII)
19. Describe how to protect system against overcharge. (VIII)
20. Calculate refrigerant velocity of suction line. (IX)
21. Calculate pressure drop of suction line. (IX)
22. Describe how to size suction line. (IX)
23. Describe purpose of double suction riser. (IX)
24. Describe guidelines for hanging long lines. (X)
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MCCCD Official Course Outline:
 
HVA140AD   19932-20086 Heat Pump Charging and Piping
    I. Refrigerant Charge
        A. Deviation
          1. Norm
          2. Percentage
        B. Performance
          1. Undercharge
          2. Overcharge
        C. Reliability - undercharge
          1. Overheating of compressor
          2. Extended run time of heated compressor
        D. Reliability - overcharge
          1. Overcharge plus migration
          2. Migration equals floodback equals compressor failure
        E. Importance - slow degradation
      II. Common Charging Techniques
          A. Ambient plus 30 degrees
            1. Accuracy
            2. Inaccuracy
            3. Charging charts
            4. Effectiveness
          B. 40 degrees evaporator coil
            1. Accuracy
            2. Inaccuracy
            3. Charging charts
            4. Effectiveness
          C. Sight glass method
            1. Liquid seal/full charge
            2. Effectiveness
          D. Sweat back method
            1. Psychometric chart
            2. Dew point/humidity
            3. Effectiveness
          E. Pressure charts
            1. Freon deviation/pressure
            2. "Hidden freon"/load conditions
            3. Effectiveness
          F. Superheat
            1. TXV system
              a. Superheat - inadequate
              b. Liquid storage - condenser
            2. Cap tube system
              a. Affected by condenser conditions
              b. Superheat calculators
            3. Effectiveness
          G. Subcooling
            1. Subcooling - load
            2. Subcooling guidelines
              a. Medium efficiency machines
              b. High efficiency machines
            3. Effectiveness
        III. Low Ambient Charging
            A. "Hidden" freon
            B. Cap tube system
              1. Induce false load
              2. Pressure chart backwards
            C. TXV system
              1. Induce false load
              2. Achieve proper pressures
          IV. Heat Pump Charging - Heating Mode
            V. Weight Method
                A. Advantages
                  1. Increases productivity
                  2. Eliminates masking problems
                  3. Eliminates freon waste
                B. Remote system
                  1. Line length
                  2. Size
                C. Types of scales
                  1. Digital
                  2. Postal
                  3. Dialacharge
                D. Effectiveness
              VI. Tools
                  A. Calibrating gauges
                  B. "Quick connects"
                    1. Purpose
                    2. Use
                VII. Primary Considerations
                    A. Refrigerant charge
                    B. Pressure drop
                      1. Efficiency loss
                      2. Change of boiling temperature
                    C. Refrigerant velocity
                      1. Refrigerant hammer
                      2. Oil trapping
                  VIII. Liquid Lines
                      A. Subcooling
                        1. System design
                        2. Tolerated pressure drop
                      B. Pressure drop
                        1. Linear line length
                        2. Equivalent line length
                        3. Lift
                      C. Liquid velocity
                        1. Liquid hammer
                        2. How to use chart
                      D. Calculations
                      E. Overcharge
                        1. Purpose
                        2. Quantity
                      F. Protection against overcharge
                        1. Accumulator
                          a. Use
                          b. Size
                          c. Installation
                        2. Liquid line solenoid
                          a. Use
                          b. Where to install
                          c. Pump down cycle
                    IX. Suction Lines
                        A. Velocity
                          1. Oil trapping
                          2. Calculations
                        B. Pressure drop
                          1. Linear length
                          2. Equivalent length
                          3. Efficiency loss
                          4. Calculations
                        C. Size
                        D. Double suction risers
                          1. Variable capacity systems
                          2. Purpose
                      X. Special Considerations
                          A. Hanging long line
                          B. Trapping
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