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506109−01 10/08
START: Measure outdoor ambient temperature
NOTE − Do not attempt to charge system where a
dash appears, system could be overcharged.
Superheat is taken at suction line service port.
Suction line superheat must never be less than 5ºF
at the suction line service port.
USE WEIGH-IN METHOD
Weigh-in or remove refrigerant
based upon line length
SHº (Superheat) Values (+/−5ºF)
Wet Bulb (air entering indoor coil)
ºF* 50 52 54 56 58 60 62 64 66 68 70 72 74 76
40 15 18 20 23 26 29 32 34 38 41 43 46 48 51
45 13 16 18 21 24 27 30 33 36 39 41 44 46 49
50 11 14 16 19 22 25 28 31 34 37 39 42 44 47
55 9 12141720232730333638404244
60 7 10121518212427303335384043
65 - 6 10 13 16 19 21 24 27 30 33 36 38 41
70 - - 7 1013161921242730333639
75 - - - 6 9 121518212428313437
80 - - - - 5 8 12 15 18 21 25 28 31 35
85 - - - - - - 8 11 15 19 22 26 30 33
90 - - - - - - 5 9 131620242731
95 - - - - - - - 6 101418222529
100 --------81216212428
105 --------5913172226
110 ---------611152025
115 ----------8141824
* Dry−bulb temperature (ºF) of entering outdoor ambient air.
1. Confirm proper airflow across coil using figure 32.
2. Compare unit pressures with Table 5, Normal
Operating Pressures.
3. Use SUPERHEAT to correctly charge unit or to
verify the charge is correct.
4. Set thermostat to call for heat (must have a cooling
load between 70-80ºF (21−26ºC)
5. Connect gauge set.
6. When heat demand is satisfied, set thermostat to
call for cooling.
7. Allow temperatures and pressures to stabilize.
8. Measure the suction line pressure and use the use
value to determine saturation temperature (table
4):
SATº =_________
9. Record suction line temperature:
VAPº =_________
10. Subtract to determine superheat (SHº):
VAPº − _____ SATº ______ = SHº______
11. Record the wet bulb temperature (air entering
indoor coil):
WB =_______
12. Record outdoor ambient temperature.
13. Compare results with table to the left.
If value is MORE
than shown, then
ADD refrigerant.
If value is LESS than
shown, then REMOVE
refrigerant.
If refrigerant is
REMOVED, retest to
confirm that unit is
properly charged.
MORE or
LESS
If refrigerant is
ADDED, retest to
confirm that unit is
properly charged.
ABOVE or
BELOW
39ºF (3.8ºC)
and BELOW
40ºF (4ºC)
and
ABOVE
Figure 38. HCFC−22 Superheat RFC Method
Table 4. HCFC−22 Temperature (°F) − Pressure (Psig)
°F Psig °F Psig °F Psig °F Psig °F Psig °F Psig °F Psig
32 57.5 50 84.1 68 117.3 86 158.2 104 207.7 122 267.1
140 337.4
33 58.8 51 85.7 69 119.4 87 160.7 105 210.8 123 270.7 141 341.6
34 60.2 52 87.4 70 121.4 88 163.2 106 213.8 124 274.3 142 345.9
35 61.5 53 89.1 71 123.5 89 165.8 107 216.9 125 278.0 143 350.3
36 62.9 54 90.8 72 125.7 90 168.4 108 220.0 126 281.7 144 354.6
37 64.3 55 92.6 73 127.8 91 171.0 109 223.2 127 285.4 145 359.0
38 65.7 56 94.4 74 130.0 92 173.7 110 226.4 128 289.2 146 363.5
39 67.1 57 96.1 75 132.2 93 176.4 111 229.6 129 293.0 147 368.0
40 68.6 58 98.0 76 134.5 94 179.1 112 232.8 130 296.9 148 372.5
41 70.0 59 99.8 77 136.7 95 181.8 113 236.1 131 300.8 149 377.1
42 71.5 60 101.6 78 139.0 96 184.6 114 239.4 132 304.7 150 381.7
43 73.0 61 103.5 79 141.3 97 187.4 115 242.8 133 308.7
44 74.5 62 105.4 80 143.6 98 190.2 116 246.1 134 312.6
45 76.1 63 107.3 81 146.0 99 193.0 117 249.5 135 316.7
46 77.6 64 109.3 82 148.4 100 195.9 118 253.0 136 320.7
47 79.2
65 111.2
83 150.8
101 198.8
119 256.5
137 324.8
48 80.8 66 113.2 84 153.2 102 201.8 120 260.0 138 329.0
49 82.4
67 115.3
85 155.7
103 204.7
121 263.5
139 333.2
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