Follett C33984, Руководство по эксплуатации и обслуживанию

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Refrigeration system
Condenser unit operation
The condensing unit is weatherproof and equipped to operate in ambient temperatures from -2 0 F to 120 F
(-29 C to 48.9 C). The condensing unit is controlled by a low pressure control, which works in concert with
a refrigerant solenoid valve on the evaporator module. On start-up, the refrigerant solenoid valve opens
and suction pressure rises above the “on” set point of the control. The compressor and fan turn on and the
refrigeration system operates. Upon shut down, the refrigerant solenoid closes. The compressor will pump down
the ice machine evaporator and suction line until the low “off” set point is reached, at which point the compressor
and fan will turn off.
Low ambient operation: Reliable operation at low outdoor ambient temperature is achieved with a pumpdown
cycle, a crankcase heater and a head pressure control valve. When the outdoor ambient falls, the condensing
pressure falls. This causes the discharge pressure to fall as well. When the discharge pressure falls below the
dome pressure, the valve modulates open to the discharge port which allows discharge gas to bypass the
condenser. Mixing the discharge gas with the liquid creates a high pressure at the condenser outlet, reducing
the fl ow and causing liquid to back up in the condenser. Flooding the condenser reduces the area available for
condensing. This reduction in effective condenser surface area results in a rise in condensing pressure. During
summer conditions, the discharge pressure is high, thus closing the discharge port of the valve. Hence, there is
full liquid fl ow from the condenser to the receiver.
A check valve is installed in the liquid line between the receiver and the condenser to prevent liquid migration
from the receiver to the condenser during the off cycle. The low pressure control will start the condensing unit
anytime the low side pressure rises above the set point and pump the refrigerant out until the pressure falls to
the set point. The crankcase heater, which is energized whenever the condensing unit has power, keeps the
compressor oil warmer than the coldest location in the system. This minimizes off cycle refrigerant migration. If
power to the condensing unit is interrupted after the system is charged, the compressor should not be started
unless the crankcase heater has been energized for at least 24 hours immediately prior to compressor startup.
However the compressor can safely be started during the refrigeration system charging process (without the
warm-up period) once sufficient refrigerant is in the system to maintain a positive pressure on the suction side of
the compressor.
Under normal ambient operating conditions the left side condenser fan motor, when viewing the outdoor
condensing unit from the compressor side, is not energized; therefore,the fan will pinwheel. During hot summer
days, at elevated temperatures, the left side condenser fan will be energized to maintain the BTU efficiency of the
condensing unit.
For additional information, please reference Horizon ice machine installation instructions for remote condensing
units.
Air-cooled condensers (air) 60 F/16 C 70 F/21 C 80 F/27 C 90 F/32 C 100 F/38 C
Pressure (psig)
discharge/suction
229/32 232/32 244/33 252/35 253/36
Refrigerant pressure data
R404A ice machine charge specifi cations
Model Line Run Charge
1400 0 – 50 ft (0 – 15.2m) 11 lbs (4.9kg)
50 – 75 ft (15.2 – 22.9m) 12 lbs (5.4kg)
75 – 100 ft (22.9 – 30.5m) 13 lbs (5.9kg)
100 ft+ (30.5m+) Consult factory
Refrigerant charges