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Microprocessor Control
Liebert
®
Mini-Mate2
™
42
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
• SHOW DIPSWITCH
• CW FLUSH
• VALVE TIME
Use the Up and Down arrows 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 minutes to 9.9 minutes (6 seconds to 594 seconds). Setting the value to zero (0) will
prevent the unit from restarting 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 and Down arrows
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 display 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. Predictive humidity control can greatly reduce
energy consumption by minimizing both compressor/reheat operation. Use the UP or DOWN arrow
key to select the desired humidity control method.
6.9.4 Show DIP Switch
This function shows the position of the DIP switches, which are located on the control board in the
unit; 1 = Switch is “ON” and 0 = Switch is “OFF.” For more information on the DIP switches and their
functions, see Table 20.