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347337-UIM-A-0408
Johnson Controls Unitary Products 5
SECTION V: INSTALLATIONS REQUIRING
AN ADD-ON TXV KIT
For installations requiring a TXV kit, refer to the Installation Instructions
accompanying the TXV kit.
SECTION VI: EVACUATION
It will be necessary to evacuate the system to 500 microns or less. If a
leak is suspected, leak test with dry nitrogen to locate the leak. Repair
the leak and test again.
To verify that the system has no leaks, simply close the valve to the vac-
uum pump suction to isolate the pump and hold the system under vac-
uum. Watch the micron gauge for a few minutes. If the micron gauge
indicates a steady and continuous rise, it’s an indication of a leak. If the
gauge shows a rise, then levels off after a few minutes and remains
fairly constant, it’s an indication that the system is leak free but still con-
tains moisture and may require further evacuation if the reading is
above 500 microns.
SECTION VII: SYSTEM CHARGE
The factory charge in the outdoor unit includes enough charge for the
unit, a 15 ft. line set, and the smallest indoor coil match-up. Some
indoor coil matches may require additional charge. See tabular data
sheet provided in unit literature packet for charge requirements.
The “TOTAL SYSTEM CHARGE” must be permanently stamped on the
unit data plate.
Total system charge is determined as follows:
1. Determine outdoor unit charge from tabular data sheet.
2. Determine indoor coil adjustment from tabular data sheet.
3. Calculate the line charge using the tabular data sheet if line length
is greater than 15 feet.
4. Total system charge = item 1 + item 2 + item 3.
5. Permanently stamp the unit data plate with the total amount of
refrigerant in the system.
Use the following charging method whenever additional refrigerant is
required for the system charge.
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. If mix matched TXV
indoor coils are used with these models, the following subcooling charg-
ing method must be used. Superheat charging charts are not valid with
TXV equipped systems.
SUBCOOLING CHARGING METHOD - MIXED MATCH
COILS
The recommended subcooling is 10°F
1. Set the system running in the cooling mode by setting the thermo-
stat at least 6°F below the room temperature.
2. Operate the system for a minimum of 15-20 minutes.
3. Refer to the tabular data sheet for the recommended airflow and
verify this indoor airflow (it should be about 400 SCFM per ton).
4. Measure the liquid refrigerant pressure P and temperature T at the
service valve.
5. Calculate the saturated liquid temperature ST from Table 2.
6. Subcooling temperature TC = Saturated Temperature (ST) - Liquid
Temp (T).
Add charge if the calculated subcooling temperature TC in Step 6 is
lower than the recommended level. Remove and recover the refrigerant
if the subcooling TC is higher than the recommended level. See Table
2.
Check flare caps on service ports to be sure they are leak tight. DO
NOT OVERTIGHTEN (between 40 and 60 inch - lbs. maximum).
Schrader valve core MUST NOT be installed with TXV installation.
Poor system performance or system failure could result.
Do not leave the system open to the atmosphere.
Refrigerant charging should only be carried out by a qualified air
conditioning contractor.
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 pressure P and temperature T measured at the liq-
uid service port is 196 psig and 90°F, respectlvely. From Table 2,
the saturated temperature for 196 psig is 100°F. The subcooling
temperature TC = 100°-90°=10°F
TABLE 2:
R-22 Saturated Properties
Pressure
PSIG
Temp °F
Pressure
PSIG
Temp °F
Pressure
PSIG
Temp °F
Pressure
PSIG
Temp °F
Pressure
PSIG
Temp °F
Pressure
PSIG
Temp °F
80 48 110 64 140 78 170 91 200 101 230 111
82 49 112 65 142 79 172 91 202 102 232 112
84 50 114 66 144 80 174 92 204 103 234 112
86 51 116 67 146 81 176 93 206 103 236 113
88 52 118 68 148 82 178 94 208 104 238 114
90 54 120 69 150 83 180 94 210 105 240 114
92 55 122 70 152 84 182 95 212 105 242 115
94 56 124 71 154 84 184 96 214 106 244 115
96 57 126 72 156 85 186 97 216 107 246 116
98 58 128 73 158 86 188 97 218 107 248 117
100 59 130 74 160 87 190 98 220 108 250 117
102 60 132 75 162 88 192 99 222 109 252 118
104 61 134 76 164 88 194 99 224 109 254 118
106 62 136 77 166 89 196 100 226 110 256 119
108 63 138 78 168 90 198 101 228 111 258 119