Liebert 50 & 60Hz, 8 Tons user manual 3.11Change Passwords, 3.12Calibrate Sensors, 3.13Alarm Enable

Microprocessor Control

3.10.7CW 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.

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

3.11Change 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.

3.12Calibrate 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.

3.13Alarm 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.

NOTE

The high-water alarm will automatically shut the unit off.

39