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
the 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
FM1202R
November 1992
Page 20