Scotsman FM1200R - Manual (Page 21)

OPERATION: Refrigeration
Low Condensing Temperature
The refrigeration system under low condenser
air temperatures is much the same as it is
under higher temperatures, with the exception
that the resulting low head pressures cause
the head pressure control to close off the
liquid line between ththe condenser and the
receiver. This forces more refrigerant into the condenser (with a small amount of discharge
gas going into the receiver to maintain
pressure until the head pressure is built back
up to the rated gauge pressure of 220 psig).
At that pressure the valve opens up the liquid
line from the condenser to the receiver.
LIQUID LINE
VALVE
THERMOSTATIC
EXPANSION
VALVE
SUCTION
LINE
KING
VALVE
Refrigeration Schematic
COMPRESSOR
RECEIVER
HEAD
PRESSURE
CONTROL
VALVE
LIQUID LINE
DISCHARGE
LINE
EVAPORATOR
DETAIL OF HEAD
PRESSURE CONTROL
VALVE
REMOTE CONDENSER
FM1200R
November, 1988
Page 21