Vertiv Liebert iCOM - Page 71

SCR Reheat—Standard Mode
NOTE: Standard SCR Reheat when used in conjunction with variable cooling capacity (such as chilled water, variable
speed fans or digital scroll compressors) provides ultimate capacity control and energy efficiency gains.
In standard mode, SCR reheat responds to a 0% to 100% heating requirement based on the temperature proportional band.
Figure 3.15 below , illustrates SCR reheat in standard mode as follows:
• 70° setpoint
• 8° proportional band
• No deadband
The proportional band is divided evenly on each side of the setpoint. The deadband is divided evenly on each side of the
setpoint.
• At 70° air temperature (heating demand 0%), no heating occurs.
• When temperature decreases below the setpoint, SCR reheat activates, and increases output as the heating
demand increases from 0% to 100%.
• As air temperature rises and heating demand decreases, the SCR reduces output and stops operating when 70°
(0% heading demand) is reached.
Figure 3.15 Temperature Control for Reheat—SCR in Standard Mode
No. Description No. Description
1 SCR reheat operation. 5
SCR reheat stops/begins operating at the setpoint.
Compressor 1 begins/stops operation at the setpoint.
2 Compressor 1 operation. 6 Compressor 2 stops operating.
3 Compressor 2 operation. 7 Compressor 2 begins operating.
4 SCR reheat output is 100%. 8 ½ of proportional band.
3 Service Operation
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Vertiv™ Liebert® iCOM™Installer/User Guide