Bryant DuraPac 558F Installation & Service Instructions Manual page 29

IX. REFRIGERANT CHARGE
Amount of refrigerant charge is listed on unit nameplate and
in Table 1. Refer to GTAC II; Module 5; Charging, Recovery,
Recycling, and Reclamation section for charging methods
and procedures. Unit panels must be in place when unit is
operating during charging procedure.
NOTE: Do not use recycled refrigerant as it may contain
contaminants.
A. No Charge
Use standard evacuating techniques. After evacuating system,
weigh in the specified amount of refrigerant (refer to Table 1).
B. Low Charge Cooling
Using cooling charging chart (see Fig. 37), add or remove
refrigerant until conditions of the chart are met. Note that
charging chart is different from those normally used. An
accurate pressure gage and temperature-sensing device is
required. Charging is accomplished by ensuring the proper
amount of liquid subcooling. Measure liquid line pressure at
the liquid line service valve using pressure gage. Connect
temperature sensing device to the liquid line near the liquid
line service valve and insulate it so that outdoor ambient
temperature does not affect reading.
C. To Use the Cooling Charging Chart
Use the above temperature and pressure readings, and find
the intersection point on the cooling charging chart. If inter-
section point on chart is above line, add refrigerant. If inter-
section point on chart is below line, carefully recover some of
the charge. Recheck suction pressure as charge is adjusted.
NOTE: Indoor-air CFM must be within normal operating
range of unit. All outdoor fans must be operating.
The TXV (thermostatic expansion valve) is set to maintain
between 15 and 20 degrees
compressors. The valves are factory set and should not
require re-adjustment.
D. Perfect Humidity™ System Charging
The system charge for units with the Perfect Humidity
option is greater than that of the standard unit alone. The
charge for units with this option is indicated on the unit
nameplate drawing. To charge systems using the Perfect
Humidity Dehumidification package, fully evacuate, recover,
and re-charge the system to the nameplate specified charge
level. To check or adjust refrigerant charge on systems using
BOTH CIRCUITS
ALL OUTDOOR FANS MUST BE OPERATING
140
120
ADD CHARGE IF ABOVE CURVE
100
80
REDUCE CHARGE IF BELOW CURVE
60
40
50 100 150
LIQUID PRESSURE AT LIQUID VALVE (PSIG)
Fig. 37 — Cooling Charging Chart
of superheat at
200 250 300 350
the Perfect Humidity Dehumidification package, charge per
the standard subcooling charts. The subcooler MUST be
deenergized to use the charging charts. The charts reference
a liquid pressure (psig) and temperature at a point between
the condenser coil and the subcooler coil. A tap is provided
on the unit to measure liquid pressure entering the sub-
cooler (leaving the condenser).
X. FILTER DRIER
Replace whenever refrigerant
atmosphere.
XI. PROTECTIVE DEVICES
A. Compressor Protection
Overcurrent
Each compressor has internal line break motor protection.
Crankcase Heater
All units are equipped with a 70-watt crankcase heater to
prevent absorption of liquid refrigerant by oil in the crank-
case when the compressor is idle. The crankcase heater is
energized whenever there is a main power to the unit and
the compressor is not energized.
IMPORTANT: After prolonged shutdown or servicing, ener-
gize the crankcase heaters for 24 hours before starting the
compressors.
Compressor Lockout
If any of the safeties (high-pressure, low-pressure, freeze
protection thermostat, compressor internal thermostat) trip,
or if there is loss of power to the compressors, the CLO (com-
pressor lockout) will lock the compressors off. To reset, man-
ually move the thermostat setting.
B. Evaporator Fan Motor Protection
the
A manual reset, calibrated trip, magnetic circuit breaker
protects against overcurrent. Do not bypass connections or
increase the size of the breaker to correct trouble. Determine
the cause and correct it before resetting the breaker.
C. Condenser-Fan Motor Protection
Each condenser-fan motor is internally protected against
overtemperature.
D. High- and Low-Pressure Switches
If either switch trips, or if the compressor overtemperature
switch activates, that refrigerant circuit will be automati-
cally locked out by the CLO. To reset, manually move the
thermostat setting.
E. Freeze Protection Thermostat (FPT)
An FPT is located on the top and bottom of the evaporator
coil. It detects frost build-up and turns off the compressor,
allowing the coil to clear. Once the frost has melted, the com-
pressor can be reenergized.
XII. RELIEF DEVICES
All units have relief devices to protect against damage from
excessive pressures (e.g., fire). These devices protect the high
and low side.
XIII. CONTROL CIRCUIT, 24-V
This control circuit is protected against overcurrent by a
3.2-amp circuit breaker. Breaker can be reset. If it trips, deter-
mine cause of trouble before resetting. See Fig. 38 and 39.
XIV. REPLACEMENT PARTS
400
A complete list of replacement parts may be obtained from
any Bryant distributor upon request.
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system is exposed to