Liebert iCOM Microprocessor TM-10098 - Manual (Page 23)

iCOM
Controls Training and Service Manual
of the heating proportional band. The third electric heating stage activates when
the return air temperature decreases to 100% of the heating proportional band.
The temperature controller deactivates the third heating stage when the return air
temperature increases to 66% of the heating proportional control band value. The
second heating is deactivated when the return air temperature increases to 33% of
the heating proportional control band value. The first heating stage is deactivated
when the return air temperature increases to the temperature set point value or
0% of the heating proportional control band value.
3 Stage Electric Reheat – No Dead Band
Temp Set Point: 70
°F
Proportional Band: 8
°F
65 66 67 68 69 70
Decreasing Temperature
Reheat 1 On
Temp Set Point - (1/2 Proportional Band)
Reheat 3 On
Reheat 2 On
Reheat
3 Off
Reheat
2 Off Reheat
1 Off
Note: in the above example that the control band begins at the 70
°F temperature
set point and has a length of 4
°F, which is ½ of the programmed temperature
proportional band value.
As the return air temperature decreases Reheat 1 is activated at 68.7
°F or 33% of
the heating control band. If the return air temperature continues to decrease
Reheat 2 will activate at 67.4
°F or 66% of the heating control band. If the return
air temperature continues to decrease Reheat 3 will activate at 66
°F or 100% of
the heating control band.
When the return air temperature starts to increase, Reheat 3 is deactivated at
67.4
°F or 66% of the heating control band, Reheat 2 is deactivated at 68.7°F or
33% of the heating control band and Reheat 1 is deactivated at the temperature
set point of 70
°F or 0% of the heating control band.
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