548086-XIM-C-0814
6
Johnson Controls Unitary Products
If a calibrated charging cylinder or accurate weighing device is avail-
able, add refrigerant accordingly. Otherwise, model-specific charging
charts are provided on the access panel of the unit.
SUPERHEAT CHARGING METHOD -
PISTON INDOOR
1.
Set the system running in cooling mode by setting the thermostat
at least 6°F below the room temperature and operate system for at
least 10 – 15 minutes.
2.
Refer to the technical guide for the recommended airflow and ver-
ify indoor airflow (it should be about 400 SCFM per ton).
3.
Measure and record the outdoor ambient (DB) temperature and
the suction pressure at the suction service valve.
4.
Using the charging chart located on the unit, find the intersection
of the outdoor ambient dry bulb and the suction pressure obtained
in step 3. This is the recommended suction tube temperature at
the service valve.
5.
Measure and record the suction tube temperature at the service
valve and compare to the recommended temperature obtained in
step 4.
6.
Add charge if the measured suction temperature in step 5 is above
the recommended value. Remove / recover refrigerant if the mea-
sured suction temperature is below the recommended value.
SUBCOOLING CHARGING METHOD - TXV INDOOR
1.
Set the system running in cooling mode by setting the thermostat
at least 6°F below the room temperature and operate system for at
least 10 – 15 minutes.
2.
Refer to the technical guide for the recommended indoor airflow
and verify it is correct (it should be about 400 SCFM per ton).
3.
Measure and record the indoor wet bulb (WB) and the outdoor
ambient dry bulb (DB) temperature.
4.
Using the charging chart located on the unit, find the intersection
of the indoor wet bulb and the outdoor dry bulb. This is the recom-
mended liquid pressure (and subcooling value).
5.
Measure and record the pressure at the liquid valve pressure port
and compare to the value obtained in step 4.
6.
Add charge if the measured liquid pressure is lower than the rec-
ommended value. Remove / recover charge if the measured liquid
pressure is above the recommended value.
Condenser subcooling is obtained by calculating the difference of the
saturated refrigerant temperature of the pressure measured at the liquid
base valve and the liquid tube temperature as measured at the liquid
base valve.
Subcooling Temp. (TC) = Saturated Temp. (TS) – Liquid Temp. (T).
Compressor damage will occur if system is improperly charged. On
new system installations, charge system per tabular data sheet for
the matched coil and follow guidelines in this instruction.
Example: The suction tube temperature listed on the table at the
intersection of the outdoor DB and the suction pressure is 63°F.
Temperature of the suction tube at the service valve is 68°F. It would
be necessary to add refrigerant to drop the suction tube temperature
to 63°F.
Example: The liquid pressure listed at the intersection of the indoor
WB and the outdoor DB 320 psig. Pressure at the liquid valve is 305
psig. It would be necessary to add refrigerant to increase the liquid
pressure to 320 psig.
IT IS UNLAWFUL TO KNOWINGLY VENT, RELEASE OR DIS-
CHARGE REFRIGERANT INTO THE OPEN AIR DURING
REPAIR, SERVICE, MAINTENANCE OR THE FINAL DISPOSAL
OF THIS UNIT.
TABLE 2:
R-22 Saturation Properties
Press
Temp
Press
Temp
Press
Temp
Press
Temp
Press
Temp
Press
Temp
Press
Temp
psig
°F
psig
°F
psig
°F
psig
°F
psig
°F
psig
°F
psig
°F
70
41
100
59
130
74
160
87
190
98
220
108
250
117
72
42
102
60
132
75
162
88
192
99
222
109
252
118
74
44
104
61
134
76
164
88
194
99
224
109
254
118
76
45
106
62
136
77
166
89
196
100
226
110
256
119
78
46
108
63
138
78
168
90
198
101
228
111
258
119
80
48
110
64
140
78
170
91
200
101
230
111
260
120
82
49
112
65
142
79
172
91
202
102
232
112
262
121
84
50
114
66
144
80
174
92
204
103
234
112
264
121
86
51
116
67
146
81
176
93
206
103
236
113
266
122
88
52
118
68
148
82
178
94
208
104
238
114
268
122
90
54
120
69
150
83
180
94
210
105
240
114
270
123
92
55
122
70
152
84
182
95
212
105
242
115
272
123
94
56
124
71
154
84
184
96
214
106
244
115
274
124
96
57
126
72
156
85
186
97
216
107
246
116
276
125
98
58
128
73
158
86
188
97
218
107
248
117
278
125