Introduction
SS-SVX006C-EN 9
When ambient temperature drops, the discharge pressure
drops also. When the discharge pressure drops, the head
pressure control valve diverts discharge gas away from
the condenser to the receiver. Liquid flow from the
condenser is restricted, causing liquid to back up in the
condenser.
Flooding the condenser reduces the area available for
condensing. The desired
result is to increase the pressure
into the condenser, maintaining a minimum discharge
pressure during low ambient operation thus ensuring
proper condensing temperature. The head pressure
control valve requires no adjustment.
This method of controlling head pressure allows the
con
denser fan to run continuously. While the fan is
running, the flooded head pressure control valve
modulates the amount of discharge gas entering the
receiver. As the pressure increases, the valve diverts more
discharge gas to the condenser, allowing more liquid to
flow from the condenser to the receiver.
When using this method of head pressure regulation there
must be enough refrigerant in the system to ensure an
adequate charge at the lowest expected ambient
temperature in which the system will be operating. A
receiver is used to store the extra refrigerant when the
condenser is not utilizing it.
Figure 3. Flooded head pressure control diagram
REMOTE AIR COOLED
CONDENSER
RECEIVER
HEAD PRESSURE
REFRIGERANT
RECLAIM VALVE
PRESSURE
RELIEF VALVE
DISCHARGE LINE
LIQUID LINE
CHECK
VALVE
CONTROL VALVE
(SEE NOTE)
NOTE: SEPARATE CHECK VALVE IS PROVIDED
ONLY ON SMALL A/C UNITS UP TO 3 TONS
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