XIV.
CHECK CHARGE
Factory charge is shown on unit rating plate. To check charge in
cooling mode, refer to Cooling Only Procedure. To check charge
in heating mode, refer to Heating Check Chart Procedure.
A.
Cooling Only Procedure
NOTE:
If subcooling charging conditions are not favorable,
charge must be weighed in accordance with unit rating plate
±
0.6
oz/ft of 3/8-in. liquid line above or below 15 ft respectively.
EXAMPLE:
To calculate additional charge required for a 25-ft line set:
25 ft - 15 ft = 10 ft X 0.6 oz/ft = 6 oz of additional charge
Units installed with cooling mode TXV require charging with the
subcooling method.
1. Operate unit a minimum of 10 minutes before checking
charge.
2. Measure liquid service valve pressure by attaching an
accurate gage to service port.
3. Measure liquid line temperature by attaching an accurate
thermistor type or electronic thermometer to liquid line near
outdoor coil.
4. Refer to unit rating plate for required subcooling tempera-
ture.
5. Refer to Table 4. Find the point where required subcooling
temperature intersects measured liquid service valve pres-
sure.
6. To obtain required subcooling temperature at a specific
liquid line pressure, add refrigerant if liquid line tempera-
ture is higher than indicated or reclaim refrigerant if
temperature is lower. Allow a tolerance of
±
3°F.
B.
Heating Check Chart Procedure
To check system operation during heating cycle, refer to the
Heating Check Chart on outdoor unit. This chart indicates whether
a correct relationship exists between system operating pressure and
air temperature entering indoor and outdoor units. If pressure and
temperature do not match on chart, system refrigerant charge may
not be correct. Do not use chart to adjust refrigerant charge.
NOTE:
When charging is necessary during heating season,
charge must be weighed in accordance with unit rating plate
±
0.6
oz/ft of 3/8-in. liquid line above or below 15 ft respectively.
EXAMPLE:
To calculate additional charge required for a 25-ft line set:
25 ft - 15 ft = 10 ft X 0.6 oz/ft = 6 oz of additional charge
XV.
FINAL CHECKS
IMPORTANT:
Before leaving job, be sure to do the following:
1. Securely fasten all panels and covers.
2. Tighten service valve stem caps to 1/12-turn past finger
tight.
3. Leave User’s Manual with owner. Explain system operation
and periodic maintenance requirements outlined in manual.
4. Fill out Dealer Installation Checklist and place in customer
file.
CARE AND MAINTENANCE
For continuing high performance and to minimize possible equip-
ment failure, periodic maintenance must be performed on this
equipment.
Frequency of maintenance may vary depending upon geographic
areas, such as coastal applications.
TABLE 3—DEFROST CONTROL SPEED-UP
TIMING SEQUENCE
PARAMETER
MINIMUM
(MINUTES)
MAXIMUM
(MINUTES)
SPEED-UP
(NOMINAL)
30-minute cycle
27
33
7 sec
50-minute cycle
45
55
12 sec
90-minute cycle
81
99
21 sec
10-minute cycle
9
11
2 sec
5 minutes
4.5
5.5
1 sec
Fig. 15—Defrost Control
A91444
OF1
OF2
O
R
T2
Y
TI DFT
C
TEST 30 50 90
W1
O
R
W2
Y
C
CES0110063,
CES0130024
TABLE 4—REQUIRED LIQUID-LINE TEMPERATURE (°F)
LIQUID
PRESSURE AT
SERVICE VALVE
(PSIG)
REQUIRED SUBCOOLING
TEMPERATURE
(°F)
5
10
15
20
134
71
66
61
56
141
74
69
64
59
148
77
72
67
62
156
80
75
70
65
163
83
78
73
68
171
86
81
76
71
179
89
84
79
74
187
92
87
82
77
196
95
90
85
80
205
98
93
88
83
214
101
96
91
86
223
104
99
94
89
233
107
102
97
92
243
110
105
100
95
253
113
108
103
98
264
116
111
106
101
274
119
114
109
104
285
122
117
112
107
297
125
120
115
110
309
128
123
118
113
321
131
126
121
116
331
134
129
124
119
346
137
132
127
122
359
140
135
130
125
© 1997 Bryant Heating & Cooling Systems 7310 W. Morris St. Indianapolis, IN 46231
—12—
Printed in U.S.A.
663c181
Catalog No. 5366-300
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