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7. If an offset needs to be applied, press ENTER key
to scroll to Offset.
8. Press UP or DOWN keys to change the offset to
desired value.
9. Press ENTER key to save.
10. Press ESCAPE key several times to return to Main
Menu screen.
FIGURE 37
Adjusting Discharge/Liquid Temperature Input
Outdoor Temperature Sensor
The unit is equipped with a combination outdoor
temperature and humidity sensor. The temperature is
measured with a 10k ohm NTC thermistor. See page
33 for more information.
Condenser Fan Operation
Condenser Fan Speed Control
The fan will speed up or slow down to attempt to
maintain a discharge/liquid pressure setpoint. The
discharge/liquid pressure setpoint will vary based on
the outdoor ambient conditions (see Figure 38). If
the outdoor temperature sensor fails, or is disabled,
the discharge/liquid pressure setpoint will be set to
a nominal value of 415 psig. Because the control
is dependent on the discharge pressure sensor, the
controller will alter its operation if the sensor is not
enabled or failed. When the liquid pressure transducer
is not enabled or considered failed by the controller, a
nominal speed will be used during a compressor call
(see Table 10).
Unit
W180
TABLE 10
Condenser Fan Nominal Speed
Discharge
Outdoor
Pressure
Temperature
Setpoint
< 80°F
350 psig
80°F – 95°F
350 – 425 psig
> 95°F
425 psig
FIGURE 38
Condenser Fan Liquid/Discharge Pressure Setpoint
Compressor
Compressor Components
Compressor
Three Phase Scroll Compressor Start Up Information
Scroll compressors, like several other types of
compressors, will only compress in one rotational
direction. Direction of rotation is not an issue with
single phase compressors since they will always start
and run in the proper direction.
However, three phase compressors will rotate in either
direction depending upon phasing of the power.
Since there is a 50-50 chance of connecting power
in such a way as to cause rotation in the reverse
direction, verification of proper rotation must be made.
Verification of proper rotation direction is made by
observing that suction pressure drops and discharge
pressure rises when the compressor is energized.
Reverse rotation also results in an elevated sound level
over that with correct rotation, as well as substantially
reduced current draw compared to tabulated values.
Verification of proper rotation must be made at the time
the equipment is put into service. If improper rotation
is corrected at this time, there will be no negative
impact on the durability of the compressor. However,
reverse operation for over 1 hour may have a negative
impact on the bearing due to oil pump out.
Nominal
Discharge/Liquid
Pressure Setpoint
425 psig
Nominal
Condenser Fan
Speed
58%
Manual
2100-749
Page
25 of 68
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