Flooded Cooler Freeze Protection; Flooded Cooler Low Fluid Temperature - Carrier AQUAFORCE 30XA080-500 Controls, Start-Up, Operation, Service And Troubleshooting Instructions

HIGH
PRESSURE
TRANSDUCER
OIL
FILTER
OIL
PRESSURE
TRANSDUCER
OIL
SOLENOID
VALVE
Fig. 51A — Suction Service Valve Locking Device,
Closed and Unlocked (Flooded Cooler Units)
VALVE
LOCKED
Fig. 51B — Suction Service Valve Locking Device,
Open and Locked (Flooded Cooler Units)
CHECK
VALVE
Fig. 50 — Typical Oil System (All Units)
a30-5246
OPEN
a30-5247
80
OIL
SEPARATOR
HEATER
(BOTTOM)
OIL SHUT OFF
VALVE
FLOODED COOLER FREEZE PROTECTION — All
coolers are equipped with cooler heaters and are controlled by
the Main Base Board. The control logic uses the unit status,
outdoor air temperature, and the saturated suction temperatures
for all circuits to decide if the cooler heater should be ener-
gized. The cooler heaters can only be energized when the state
of the unit is OFF. The cooler heaters will be energized if the
outdoor-air temperature is less than the Cooler Heater Set Point
and the lowest circuit Saturated Suction Temperature is less
than the heater set point plus 6° F (3.3° C). See Table 51. The
cooler heater set point = freeze point + Cooler Heater DT Setp
(Cooler Heater Delta Spt, HTR). If the entering or leaving
water temperature is less than the Heater Set Point and the out-
door air temperature is less than the Heater Set Point –2° F
(1.1° C), then the heater will be turned on.
If the Entering or Leaving Water Temperature is less than
the Brine Freeze Setpoint (Brine Freeze Setpoint, LOSP)
+1.0° F (0.5° C), then the heater will be turned on along with
the pump.
The entire cooler is covered with closed-cell insulation
applied over the heater. The heater plus insulation protects
cooler against low ambient temperature freeze-up to 0° F
(–17.8 C).
IMPORTANT: If unit is installed in an area where
ambient temperatures fall below 32 F (0° C), a suitable
corrosion-inhibited antifreeze solution or cooler heater
must be used in the chilled water circuit.
FLOODED COOLER LOW FLUID TEMPERATURE —
Main Base Board is programmed to shut chiller down if leav-
ing fluid temperature drops below 34 F (1.1 C) for cooler fluid
type water or below Brine Freeze Setpoint (Brine Freeze Set-
point, LOSP) for cooler fluid type brine. The unit will shut
down without a pumpout. When fluid temperature rises to
6° F (3.3° C) above the leaving fluid set point, safety resets and
chiller restarts. Reset is automatic as long as this is the first
occurrence.
OIL LEVEL
SWITCH
(BOTTOM)
a30-4243