X. START-UP
CAUTION: To prevent compressor damage or personal
injury, observe the following:
• Do not overcharge system with refrigerant.
• Do not operate unit in a vacuum or at negative pressure.
• Do not disable low-pressure switch.
CAUTION: To prevent personal injury wear safety
glasses, protective clothing, and gloves when handling
refrigerant and observe the following:
• Back seating service valves are not equipped with
Schrader valves. Fully back seat (counter clockwise)
valve stem before removing gage port cap.
CAUTION: Do not vent refrigerant to atmosphere. Re-
cover during system repair or final unit disposal.
Follow these steps to properly start up the system:
1. The outdoor unit is equipped with a crankcase heater which
operates when the compressor is off. Energize crankcase
heater 24 hr. before starting unit. To energize heater only,
set indoor thermostat to OFF position and close power
disconnect to unit.
NOTE: Starting the compressor without a minimum of 12 hours
of crankcase heat prior to initial start-up may result in compressor
chattering noise and possible damage to the compressor.
2. Fully back seat (open) liquid and vapor tube service valves.
3. Unit is shipped with valve stem(s) front seated and caps
installed. Replace stem caps after system is opened to
refrigerant flow (back seated). Replace caps finger tight and
tighten additional 1/12 turn (20 ft-lb torque) with wrench.
4. Close electrical disconnects to energize system.
5. Set room thermostat at desired temperature. Be sure set
point is below indoor ambient and is set low enough to
energize desired speed.
NOTE: Bryant electronic thermostats are equipped with a 15
minute staging timer. This timer prevents the two-speed system
from operating at high speed until unit has been operating in low
speed for 15 minutes unless there is at least a 5°F difference
between room temperature and thermostat set point. To force high
speed (after a minimum of 2 minutes in low speed), adjust the set
point at least 5° below room ambient.
6. Set room thermostat to COOL and fan control to AUTO or
ON as desired. Wait for appropriate time delay(s) and 2
minute minimum low-speed run time. Operate unit for 15
minutes. Check refrigerant charge.
NOTE: If unit has not operated within the past 12 hours or
following a unit power-up, upon the next thermostat high- or
low-speed demand, unit operates for a minimum of 5 minutes in
high speed.
XI. CHECK CHARGE
WARNING: Service valve gage ports are not equipped
with Schrader valves. To prevent personal injury, make
sure gage manifold is connected to the valve gage ports
before moving valves off fully back seated position. Wear
safety glasses and gloves when handling refrigerant.
A. COOLING ONLY PROCEDURE
1. Operate unit a minimum of 15 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 Table 4 for required subcooling temperature.
5. Refer to Table 3. 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. UNIT CHARGE
Factory charge and charging method are shown on pink charging
label. Puron® refrigerant cylinders contain a dip tube which
allows liquid refrigerant to flow from cylinder in upright
position. Charge Puron units with cylinder in upright position and
a commercial type metering device in manifold hose. Charge
refrigerant into suction line.
NOTE: Unit is to be charged in high capacity only. Charging in
low capacity may cause compressor chattering and possible
damage to the compressor.
TABLE 3—REQUIRED LIQUID-LINE TEMPERATURE (°F)
LIQUID
PRESSURE AT
SERVICE VALVE
(PSIG)
REQUIRED SUBCOOLING
TEMPERATURE
(°F)
8 1012141618
189 58 56 54 52 50 48
195 60 58 56 54 52 50
202 62 60 58 56 54 52
208 64 62 60 58 56 54
215 66 64 62 60 58 56
222 68 66 64 62 60 58
229 70 68 66 64 62 60
236 72 70 68 66 64 62
243 74 72 70 68 66 64
251 76 74 72 70 68 66
259 78 76 74 72 70 68
266 80 78 76 74 72 70
274 82 80 78 76 74 72
283 84 82 80 78 76 74
291 86 84 82 80 78 76
299 88 86 84 82 80 78
308 90 88 86 84 82 80
317 92 90 88 86 84 82
326 94 92 90 88 86 84
335 96 94 92 90 88 86
345 98 96 94 92 90 88
354 100 98 96 94 92 90
364 102 100 98 96 94 92
374 104 102 100 98 96 94
384 106 104 102 100 98 96
395 108 106 104 102 100 98
406 110 108 106 104 102 100
416 112 110 108 106 104 102
427 114 112 110 108 106 104
439 116 114 112 110 108 106
450 118 116 114 112 110 108
462 120 118 116 114 112 110
474 122 120 118 116 114 112
486 124 122 120 118 116 114
499 126 124 122 120 118 116
511 128 126 124 122 120 118
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