6074816-UIM-A-0421
Johnson Controls Ducted Systems 9
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.
SUBCOOLING CHARGING METHOD - TXV INDOOR
The outdoor unit comes equipped with subcooling charts optimized for
that particular unit. Follow the instructions on the unit. If those instruc-
tions are not readily available, follow the instructions below.
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 min to 15 min.
2. Refer to the Technical Guide for the recommended indoor airflow
and verify it is correct (it must be between 350 SCFM/ton and
400 SCFM/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 recom-
mended value. Remove or recover the charge if the measured liq-
uid 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 Saturated Liquid
Temperature (TC) = Temperature (TS) – Temperature (T)
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 the system for
at least 10 min to 15 min.
2. Refer to the Technical Guide for the recommended indoor airflow
and verify it is correct (it must be between 350 SCFM/ton and
400 SCFM/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 or recover the refrigerant if the
measured suction temperature is below the recommended value.
CAUTION
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 liquid pressure listed at the intersection of the indoor
WB and the outdoor DB is 320 psig. The pressure at the liquid valve
is 305 psig. It is necessary to add refrigerant to increase the liquid
pressure to 320 psig.
!
CAUTION
It is unlawful to knowingly vent, release, or discharge refrigerant into
the open air during repair, service, maintenance, or the final disposal
of this unit.
Example: The suction tube temperature listed in the table at the
intersection of the outdoor DB and the suction pressure is 63°F.
The temperature of the suction tube at the service valve is 68°F. It is
necessary to add refrigerant to drop the suction tube temperature to
63°F.
!
Table 2: R-410A Saturation Properties
Temperature
(°F)
Pressure
(psig)
Temperature
(°F)
Pressure
(psig)
Temperature
(°F)
Pressure
(psig)
Temperature
(°F)
Pressure
(psig)
Temperature
(°F)
Pressure
(psig)
45 130 60 170 75 217 90 274 105 341
46 132 61 173 76 221 91 278 106 345
47 135 62 176 77 224 92 282 107 350
48 137 63 179 78 228 93 287 108 355
49 140 64 182 79 232 94 291 109 360
50 142 65 185 80 235 95 295 110 365
51 145 66 188 81 239 96 299 111 370
52 147 67 191 82 243 97 304 112 375
53 150 68 194 83 247 98 308 113 380
54 153 69 197 84 250 99 313 114 385
55 156 70 201 85 254 100 317 115 391
56 158 71 204 86 258 101 322 116 396
57 161 72 207 87 262 102 326. 117 401
58 164 73 211 88 266 103 331 118 407
59 167 74 214 89 270 104 336 119 412
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