Liebert 50 & 60Hz - Manual (Page 47)

Microprocessor Control
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3.10.7 CW Flush (For Systems With a Modulating Chilled-Water Valve)
This function shows the interval time at which the system will perform a modulating chilled-water
valve system flush cycle. The factory default is 24 (hours) and is programmable from 0 (hours) which
signifies to never flush, to 99 (hours) which signifies to flush after every 99 hours of valve non-use. If
the valve is called on by the control to open within the programmed interval time, the timer will be
reset to 0. The flush cycle is active even when the fan is turned off, but power is applied to the unit.
When the interval timer reaches the programmed time, the valve will be opened for 3 minutes to flush
any contaminates which may have collected in the system.
3.11 Change Passwords
The display will prompt the operator to enter a three digit password when attempting to make
changes. The system includes two (2) passwords, one for setpoints and one for setup. The system
allows the password to be changed by first entering the default password set at the factory (1-2-3) for
setpoints and (3-2-1) for setup. The password function provides system security, so that only autho-
rized personnel are allowed to make changes to the system. (If unauthorized changes are being made,
the passwords may be compromised and new ones should be selected). The password function can be
disabled by setting DIP switch 8 in the wallbox to OFF, then resetting power to the unit.
3.12 Calibrate Sensors
The temperature and humidity sensors can be calibrated by selecting the CALIBRATE SENSORS
menu item. The temperature sensor can be calibrated ±5°F, while the humidity sensor can be cali-
brated ±10% RH. When calibrating the humidity sensor, the value shown will always be % RH, even
though absolute humidity control may be selected. If absolute humidity control is selected, the Nor-
mal Status Display will display the adjusted reading. This reading may not agree with the relative
humidity reading displayed while in calibration.
If the sensors are subject to frequent wide temperature and humidity swings, it may be necessary to
shorten the cycling by increasing the sensor response time delay. If the sensors are located too close to
the air discharge, they will likely experience rapid swings in measurement. The factory default is 30
seconds. Another method in reducing compressor cycling is to increase the temperature and/or humid-
ity sensitivity.
3.13 Alarm Enable
Each alarm can be disabled or enabled. Use the UP/DOWN ARROW to select a particular alarm,
press Enter to select either enable or disable. Then press Enter again to store the change. When the
alarm is disabled it will NOT report to either the wallbox beeper or the common alarm relay. The high
water in condensate pan and high head alarms cannot be disabled.
Table 12 Setup functions, default values and allowable ranges
Function Default Range
Restart Time Delay 0.1
0 to 9.9 min
(0 = manual restart)
C/F Degrees ° F ° C or ° F
Humidity Control Rel Relative or Absolute
Valve Time 165 50 to 250 sec(s)
CW Flush 24 0 to 99 hours
NOTE
The high-water alarm will automatically shut the unit off.