Refrigeration System - Follett Horizon Elite HCF1412R Operation And Service Manual

Refrigeration system

The condensing unit is weatherproof and equipped to operate in ambient temperatures from –20 F to 120 F (–29 C
to 48.9 C). The condensing unit is controlled by contact closure within the ice machine control board of the 24 VAC
circuit of the condensing unit. This control circuit energizes the compressor and condenser fans of the refrigeration
system. After any system shutdown condensing and suction pressure are expected to slowly equalize to outdoor
ambient saturation pressure.
Low ambient operation:
Reliable operation at low outdoor ambient temperature is achieved with the crankcase heater and a head pressure
control valve. When the outdoor ambient falls, the condensing pressure falls. When the condensing pressure falls
below the head pressure control valve set pressure (180 psig), the valve modulates to allows discharge gas to
bypass the condenser. Mixing the discharge gas with receiver liquid maintains high pressure liquid at the receiver
outlet. A second check valve is installed in the discharge line of the compressor to reduce refrigerant migration into
the compressor during the off cycle. The system contains a crankcase heater that is thermostatically controlled (on
at 60 F and off at 80 F). The heater maintains the compressor sump oil temperature above suction gas temperature
to prevent liquid refrigerant from accumulating in the compressor sump.
Warm ambient operation:
During warm ambient conditions (above 180 psig saturation pressure), the discharge pressure is higher than the
head pressure control valve set point therefore the head pressure control valve is not bypassing and there is full
liquid flow from the condenser to the receiver.
HCF1412R, HCF1412K 29