AAON RL-240 - Manual (Page 59)

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pump casing. Check rotation each time
motor leads have been disconnected.
2. Check all connections of motor and
starting device with wiring diagram. Check
voltage, phase and frequency of line circuit
with motor name plate.
3. Check suction and discharge piping and
pressure gauges for proper operation.
4. Turn rotating element by hand to assure
that it rotates freely.
Running
Periodically inspect pump while running,
but especially after initial start-up and after
repairs.
1. Check pump and piping for leaks. Repair
immediately.
2. Record pressure gauge readings for future
reference.
3. Record voltage, amperage per phase, and
kW.
Condenser Fan Motors
The direct-drive condenser motors on
AAON evaporative-cooled condensers are
1200-rpm
premium efficiency motors
controlled by a VFD. These motors are
totally enclosed air over motors with weep
holes in the bottom end bell so that any
condensation can drain out of the motor.
The motors have a small electric resistance
heater installed inside the casing to keep the
motors warm when they are deactivated.
The heaters are designed to keep the interior
of the motor 10°F warmer than the
surrounding ambient temperature. This
prevents condensation from forming inside
the motor.
Ensure that fan is tightly mounted to the
motor shaft and the motor mounting bolts
are aligned and secure.
Water Makeup Valve
The sump water level is controlled by a set
of conductivity probes at different levels in
the sump. This water level controller is
located in the vestibule behind the condenser
pump. There are four conductivity probes in
this controller. There is a reference probe
(shown as “ref” on the wiring diagram). This
probe is one of the two longest probes. The
other long probe is the low water level probe
(shown as “lo” on the wiring diagram). The
medium length probe is for the medium
water level (shown as “med” on the wiring
diagram). The short probe is for the high
water level (shown as “hi” on the wiring
diagram). There is a solenoid valve in the
makeup water line that is activated by the
water level controller. The water level
controller determines the level of water in
the sump based on conductivity between two
probes. If the controller sees conductivity
between two probes, it knows that water is
at least at the level of that probe.
If the water in the sump is below the low
probe, it will not allow the condenser pump
or the sump heater to operate. It will activate
the makeup water solenoid to try to fill the
sump assuming water is flowing to the unit.
Once water is above the low probe, it will
allow the condenser pump and sump heater
(if ordered and the ambient temperature is
below 40°F) to operate. The makeup water
solenoid will remain activated until water
gets to the high water level. When the water
gets to the high water level, the makeup
water solenoid will deactivate until water
gets to the medium water level. In normal
operation, the water level should swing
between the medium and high water levels.
The maximum high water level should be 1”
below the overflow drain which occurs after
the makeup water valve shuts off when the
water level reaches the high level probe.