AAON LL-540 - Manual (Page 51)

51
ready to connect to the piping. Rotate the
shaft periodically (At least monthly) to keep
rotating element free and bearings fully
functional.
For long term storage, the pump must be
placed in a vertical position in a dry
environment. Internal rusting can be
prevented by removing the plugs at the top
and bottom of the casing and drain or air
blow out all water to prevent rust buildup or
the possibility of freezing. Be sure to
reinstall the plugs when the unit is made
operational. Rust-proofing or packing the
casing with moisture absorbing material and
covering the flanges is acceptable. When
returning to service be sure to remove the
drying agent from the pump.
Pump Operation
Before initial start of the pump, check as
follows:
1. Be sure that pump operates in the
direction indicated by the arrow on the
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 Make Up 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.