6
18-BC56D1-5
Installer’s Guide
SUBCOOLING CHARGING IN COOLING ABOVE 55°F OD AMBIENT
The manufacturer has always recommended installing
approved matched indoor and outdoor systems.
All 13 SEER split systems are AHRI rated with only TXV
indoor systems.
The benefits of installing approved indoor and outdoor split
systems are maximum efficiency, optimum performance and
the best overall system reliability.
The following charging methods are therefore prescribed for
systems with indoor TXVs.
1. Subcooling (in the cooling mode) is the only recommended
method of charging above 55°F ambient temperatures.
2. For best results - the indoor temperature should be kept
between 70°F to 80°F. Add system heat if needed.
3. At start-up, or whenever charge is removed or added, the
system must be operated for a minimum 20 minutes to
stabilize before accurate measurements can be made.
4. Measure Liquid Line Temperature and Refrigerant
Pressure at service valves.
5. Determine total refrigerant line length, and height (lift)
if indoor section is above the condenser.
6. Determine the Design Subcool Charging Temperature
from the unit nameplate.
7. Locate this value in the appropriate column of the
Subcooling Charging Table. Locate your liquid line
temperature in the left column of the table, and the
intersecting liquid line pressure under your nameplate
subcool value column. Add refrigerant to raise the pres-
sure to match the table, or remove refrigerant to lower
the pressure. Again, wait 20 minutes for the system
conditions to stabilize before adjusting charge again.
8. When system is correctly charged, you can refer to
System Pressure Curves (in Service Facts) to verify
typical performance.
Installer’s Guide
R-22 SUBCOOLING CHARGING TABLE
LIQUID
TEMP.
(°F)
DESIGN SUBCOOLING VALUES (°F)
8
10
12
14
LIQUID LINE PRESSURE (psi)
45
89
93
96
100
50
98
102
105
109
55
107
111
115
119
60
117
121
126
130
65
128
132
137
141
70
139
144
148
153
75
151
156
161
166
80
163
168
174
179
85
176
182
187
193
90
190
196
202
208
95
205
211
217
223
100
220
226
233
239
105
236
243
249
256
110
253
260
267
274
115
271
278
285
293
120
289
297
305
313
125
309
317
325
333
SUBCOOL CHARGING TABLE CORRECTIONS FOR LINE LENGTH AND RISE
60
50
40
30
25
Add 5 psig to Subcool Charging Table Pressure
20
15
Use Design Subcool Value from Table
10
0
Subtract 5 psig from S.C. Table Pressure
10
20
25
30
40
60
80
TOTAL REFRIGERANT LINE LENGTH (FEET)
REFRIGERANT
LINE LIFT (FEET)
