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A solenoid valve in the hot gas bypass lines is wired in parallel with both circuit's
liquid line solenoid valves SV1 and SV2. The hot gas bypass is available whenever a
refrigerant circuit is operating and regulates the evaporator pressure. The pressure
regulating valve is factory set to begin opening at 58 psig (32°F for R-22).
VFD Low Ambient Control (Optional)
The optional VFD fan control is used for unit operation below 35°F (2°C) down to a
minimum of 0°F (-17°C). The control looks at the saturated discharge temperature and
varies the fan speed to hold the temperature (pressure) ) at the "target" temperature.
This temperature is established as an input to a setpoint screen labeled "Sat Condenser
Temp Target".
Filter-Driers
Each refrigerant circuit is furnished with a full flow filter drier (AGZ 026 – 070) or a
replaceable core type filter-drier (AGZ 075 – 130).
replaceable core drier consists of a filter core held tightly in the shell in a manner that
allows full flow without bypass.
Pressure drop across the filter drier at full load conditions must not exceed 10 psig at
full load. See page 98 for maximum pressure drop at other load points. Replace the
filter drier if the pressure drop exceeds maximum.
Pump out refrigerant before removing end flange for replacement of core(s) to remove
A condenser liquid line service valve is provided for isolating the charge in the
condenser, but also serves as the point from which the liquid line can be pumped out.
With the line free of refrigerant, the filter-drier core(s) can be easily replaced.
System Adjustment
To maintain peak performance at full load operation, the system superheat and liquid
subcooling may require adjustment.
determine if adjustment is required.
Liquid Line Sight Glass
The color of the moisture indicator is an indication of the dryness of the system and is
extremely important when the system has been serviced. Immediately after the system
has been opened for service, the element may indicate a wet condition.
recommended that the equipment operate for about 12 hours to allow the system to
reach equilibrium before deciding if the system requires a change of drier cores.
Bubbles in the sight glass at constant full load indicates a shortage of refrigerant, a
plugged filter-drier, or a restriction in the liquid line. However, it is not unusual to see
bubbles in the sight glass during changing load conditions.
94
The hot gas line may become hot enough to cause injury.
Be careful during valve checkout.
liquid refrigerant and lower pressure to prevent accidental blow off of cover. EPA
recovery regulations apply to this procedure.
AGZ 026B through 130B
WARNING
The core assembly of the
WARNING
Read the following subsections closely to
It is
IOMM AGZ-5
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