The proportional band is divided evenly on each side of the setpoint. The deadband is divided evenly on each side of the
setpoint. The temperature proportional band below the setpoint is divided into thirds, one for each stage.
• From 70° to 69°, 0% heating is required.
• At 68.7° air temperature (heating demand 33%), stage 1 activates and continues operating until temperature
reaches 69°.
• When temperature decreases to 67.4° (heating demand 66%), stage 2 activates, and continues until temperature
reaches 68.7° (heating demand 33%).
• When temperature decreases to 67.4° (heating demand 100%), stage 2 activates, and continues until
temperature reaches 68.7° (heating demand 66%).
• When temperature decreases to 63° (heating demand 100%), stage 3 activates, and continues until temperature
reaches 67.4° (heating demand 33%).
Figure 3.14 Temperature Control for Reheat—Three Stage Electric Reheat
No. Description No. Description
1 Stage 1 reheat. 4 ½ of proportional band.
2 Stage 2 reheat. 5 Deadband.
3 Stage 3 reheat.
SCR Reheat
SCR reheat uses pulsed on/off operation to modulate heating capacity to control temperature more precisely than staged,
electric reheat. 100% heating capacity is constant operation of SCR reheat. As the temperature proportional band requires
more heat, the SCR output adjusts proportionally.
3 Service Operation
62
Vertiv™ Liebert® iCOM™Installer/User Guide
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