Humidity Control; Humidity Control Program Types; Absolute (Predictive) Humidity Control - Emerson Liebert iCOM Training And Service Manual

iCOM
Controls Training and Service Manual
Humidification and/or Dehumidification in Percent (%)
The humidity control program for the iCOM microprocessor is based on a
calculated percent (%RH) requirement for humidification and/or dehumidification.
This percent (%RH) requirement is determined by the control type (algorithm)
selected by the user.
There three (3) user selectable humidity control programs are:
• Absolute Humidity, grains of moisture in the air
• Relative Humidity (%RH)
• Compensated

Humidity Control Program Types

Absolute (predictive) Humidity Control – Factory Default Setting
Absolute (predictive) humidity control is based on the moisture content in the
return air. The iCOM microprocessor control automatically adjusts the humidity
control as the return air temperature deviates from the programmed temperature
setpoint. This calculation converts the return temperature and humidity values to a
moisture content value defined as either grains per cubic foot or grains per pound.
This recalculated content value is compared to the content control band that is
determined by the:
• Programmed temperature setpoint
• Programmed humidity setpoint in %RH
• Programmed humidity proportional band in %RH
This automatic adjustment results in a predictive humidity control response. With
absolute humidity control, the humidity control program is automatically adjusted
by approximately 2% RH for each degree difference between the return air
temperature and the temperature set point. See the following example on the
next page.
Temperature
Set Point
70°F
70°F

Humidity Control

Humidity
Set Point Proportional Band = 6%
50%
50%
24
Humidity
+3%
-3%
Content Level
Grains per LB
59.2
52.5