User manual

Operation
55 Liebert
®
iCOM
®
Compensated—The actual return air humidity sensor reading is sent to the Temperature and
Humidity Control where the Humidity Setpoint is adjusted based on how much the return room air
temperature deviates from the desired temperature setpoint. The adjusted humidity setpoint is used
for humidification percent requirement determination. For every 1°C deviation from the temperature
setpoint, the humidity setpoint is changed by 3% RH, inversely proportional: if the temperature
increases, the humidity setpoint is decreased, and vice versa. The recalculated humidity setpoint is
shown as the Actual Humidity Setpoint (User Menu, Sensor Data). As the humidity setpoint is
automatically adjusted, the high and low humidity setpoints (User Menu, Set Alarms) are adjusted
accordingly. The unadjusted humidity sensor reading is displayed on the Status menu.
Predictive—The actual return air humidity sensor reading is adjusted before it is sent to the
Temperature and Humidity Control. The humidity sensor reading is adjusted based on how much the
return room air temperature deviates from the desired temperature setpoint. For every 1°C deviation
from the temperature setpoint, the humidity sensor reading is changed by 3% RH, directly
proportional: if the temperature increases, the humidity reading is increased and vice versa. The
adjusted humidity sensor reading is displayed on the Status menu. Units are shipped from the factory
with Predictive humidity control set as default.
If Compensated or Predictive humidity sensor control is selected, overdehumidification is avoided.
When overcooling occurs, causing an increase in the relative humidity sensor reading, the humidity
control program predicts what the RH will be when the dehumidification cycle ends and return air
temperature returns to the setpoint. This allows the dehumidification cycle to end at the proper time.
The Compensated and Predictive humidity sensor control can reduce energy consumption by
minimizing compressor and reheat operation, and eliminating unnecessary humidifier operation.
Figure 47 Placing temperature and temperature/humidity sensors
NOTE
The historical humidity sensor graphs will display the real (unadjusted) sensor readings, no
matter which Humidity Control Sensor Type is selected. The graphical sensor data is in the
User menu under Graphics.
Temperature
Sensor
5 to 15 feet
(1.5 to 4.5m)
Internal Temperature
and Humidity Sensor
Return
Air
Supply Air
Liebert
Cooling Unit