Dehumidification Operation

iCOM Controls Training and Service Manual

Dehumidification Operation

The Relative Humidity control program is used to illustrate the dehumidification operation in the following examples. The basic dehumidification control band is established at the humidity set point with the length equal to ½ of the programmed humidity proportional band value.

The humidity controller activates dehumidification operation when the return air humidity level increases to 100% of the humidity proportional band. The humidity controller deactivates dehumidification operation when the return air humidity level decreases to 0% of the humidity proportional control band value.

1-Stage Dehumidification, Compressorized Direct Expansion (DX) Systems

The Liebert DS unit is supplied with two (2) compressors. Under normal operation, the lead compressor is used for sensible cooling and the lag compressor is used for either additional cooling or for dehumidification control. The optional hot gas bypass solenoid valve is de-energized during dehumidification.

If single compressor dehumidification is selected, the lag compressor is activated by the humidity controller when the return air humidity level increases to 100% of the humidity proportional band.

The humidity controller deactivates the lag compressor when the return air humidity level decreases to 50% of the humidity proportional control band value.

1 Stage Compressorized Dehumidification – No Dead Band

Humidity Set Point - (1/2 Proportional Band)

Humid Set Point: 50%

 

 

 

 

Proportional Band: 8%

 

 

 

 

 

 

 

Dehumidification On

50

51

52

53

54

55

 

Dehumidification Off

Increasing Humidity

 

 

 

 

 

 

30

 

 

 

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Liebert TM-10098 service manual Dehumidification Operation