33
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 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 make-up 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 make-up
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 make-
up water solenoid will remain activated until
water gets to the high water level.
The make-up water solenoid will deactivate until
water gets to the medium water level. In normal
operation, the water level will swing between the
medium and high water levels. The maximum
high water level is 1” below the overflow drain
which occurs after the make-up water valve shuts
off when the water level reaches the high level
probe.
Figure 7 - Water Level Sensor
Maintain make-up water supply pressure between
15 and 60 psig for proper operation of the valve.
Inspect the make-up water valve assembly
monthly and adjust as required. Replace the valve
seat if leakage occurs when the valve is in the
closed position.
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