Lennox AC13 -018 Installation Instructions Manual page 20

START: Measure outdoor ambient temperature
USE WEIGH-IN METHOD
Weigh-in or remove refrigerant
based upon line length
If refrigerant is
REMOVED, retest to
confirm that unit is
properly charged.
If value is LESS than
shown, then REMOVE
refrigerant.
°F Psig °F
32 57.5 50
33 58.8 51
34 60.2 52
35 61.5 53
36 62.9 54
37 64.3 55
38 65.7 56
39 67.1 57
40 68.6 58
41 70.0 59
42 71.5 60
43 73.0 61
44 74.5 62
45 76.1 63
46 77.6 64
65
47 79.2
48 80.8 66
67
49 82.4
506109−01 10/08
ABOVE or
39ºF (3.8ºC)
and BELOW
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 12 14 17 20 23 27 30 33 36 38 40 42 44
60 7 10 12 15 18 21 24 27 30 33 35 38 40 43
65 - 6 10 13 16 19 21 24 27 30 33 36 38 41
70 - - 7 10 13 16 19 21 24 27 30 33 36 39
75 - - - 6 9 12 15 18 21 24 28 31 34 37
80 - - - - 5 8 12 15 18 21 25 28 31 35
85 - - - - - - 8 11 15 19 22 26 30 33
90 - - - - - - 5
95 - - - - - -
100 - - - - - -
105 - - - - - -
110 - - - - - -
115 - - - - - -
* Dry−bulb temperature (ºF) of entering outdoor ambient air.
MORE or
LESS
Figure 38. HCFC−22 Superheat RFC Method
Table 4. HCFC−22 Temperature (°F) − Pressure (Psig)
Psig °F Psig
84.1 68 117.3
85.7 69 119.4
87.4 70 121.4
89.1 71 123.5
90.8 72 125.7
92.6 73 127.8
94.4 74 130.0
96.1 75 132.2
98.0 76 134.5
99.8 77 136.7
101.6 78 139.0
103.5 79 141.3
105.4 80 143.6
107.3 81 146.0
109.3 82 148.4
111.2
83 150.8
113.2 84 153.2
115.3
85 155.7
40ºF (4ºC)
and
ABOVE
BELOW
9 13 16 20 24 27 31
- 6 10 14 18 22 25 29
- - 8 12 16 21 24 28
- - 5 9 13 17 22 26
- - - 6 11 15 20 25
- - - - 8 14 18 24
If value is MORE
than shown, then
ADD refrigerant.
°F Psig °F
86 158.2 104
87 160.7 105
88 163.2 106
89 165.8 107
90 168.4 108
91 171.0 109
92 173.7 110
93 176.4 111
94 179.1 112
95 181.8 113
96 184.6 114
97 187.4 115
98 190.2 116
99 193.0 117
100 195.9 118
198.8
101
119
102 201.8 120
103 204.7
121
Page 20
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.
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.
If refrigerant is
ADDED, retest to
confirm that unit is
properly charged.
Psig °F Psig
207.7 122 267.1
210.8 123 270.7
213.8 124 274.3
216.9 125 278.0
220.0 126 281.7
223.2 127 285.4
226.4 128 289.2
229.6 129 293.0
232.8 130 296.9
236.1 131 300.8
239.4 132 304.7
242.8 133 308.7
246.1 134 312.6
249.5 135 316.7
253.0 136 320.7
137 324.8
256.5
260.0 138 329.0
139 333.2
263.5
°F Psig
140 337.4
141 341.6
142 345.9
143 350.3
144 354.6
145 359.0
146 363.5
147 368.0
148 372.5
149 377.1
150 381.7