Setup Operation; Restart Time Delay; C/F Degrees; Humidity Control Method - Liebert Mini-Mate2 MMD24E User Manual

6.9

Setup Operation

Selecting Setpoint/Setup from the Main Menu will display the following selections:

• RESTART TIME DELAY

• C/F DEGREES

• HUMIDITY CONTROL METHOD

Use the Up/Down Arrow to scroll through the submenu. Press Enter to select a particular function.
6.9.1 Restart Time Delay
This function delays unit restart after main power is restored to the unit. If several systems are
operating, the time delays should be set to different values to cause a sequential start. Delay can be
set from 0.1 to 9.9 minutes (6 to 594 seconds). Setting the value to zero (0) will prevent unit restart
when power is restored. In this case, the unit must be restarted manually by pressing the "ON/OFF"
button on the keypad.
6.9.2 C/F Degrees
The control may be selected to show readings and setpoints in either degrees Fahrenheit (°F) or
Celsius (°C). To change the value use Enter to select this function, then use the Up/Down Arrow to
change the value. Press Enter to store the value.
6.9.3 Humidity Control Method
The operator may select either relative (direct) or absolute (predictive) humidity control. If "relative"
is selected, the RH control is taken directly from the RH sensor. If "absolute" is selected, the RH
control is automatically adjusted whenever return air temperature deviates from the desired
temperature setpoint (i.e., predictive humidity control). The LCD will indicate percentage relative
humidity for both methods of control. If the "absolute" feature is selected, the adjusted humidity
reading will also be shown. When utilizing the predictive humidity control feature, the humidity level
is automatically adjusted ~2% RH for each degree difference between the return air temperature and
the temperature setpoint.
Unnecessary dehumidification can result when overcooling occurs during a dehumidification cycle.
This is due to a higher than normal RH reading caused by overcooling the room (about 2% RH for
each degree of overcooling). This drop in temperature extends the dehumidification cycle. Later, when
the dehumidification ends and the temperature rises to the setpoint, the RH reading falls. The final
RH reading will then be lower than actually desired. If the temperature drop was significant enough,
the percentage RH could be low enough to activate the humidifier.
If the absolute humidity control is selected, over-dehumidification may be avoided. When overcooling
occurs (i.e., causing an increase in the RH reading) the humidity control program estimates what the
RH will be when the dehumidification cycle ends and temperature returns to the setpoint. This allows
the dehumidification cycle to end at the proper time. The predictive humidity control can greatly
reduce energy consumption by minimizing compressor/reheat operation. Use the Up/Down Arrow key
to select the desired humidity control method.
Table 23 Setup functions, default values and allowable ranges
Function
Restart Time Delay
C/F Degrees
Humidity Control
6.10

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
authorized 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 wall box to ON, then resetting power to the unit.
® ™
Liebert Mini-Mate2
Default Range
0 to 9.9 min
0.1 minute
(0 = manual restart)
°F °C or °F
Rel Relative or Absolute
46
Microprocessor Control