Vertiv Liebert iCOM - 3.3.7 Reheat Control

SCR Control Type
Enables/disables SCR reheat. (May not be included on your cooling unit.) See Reheat Control below . Values are:
• None: SCR reheat disabled.
• Tight: Use tight control reheat mode.
• Standard:Use standard reheat mode.
Electric Heat Stages
Number of electric stages that may be activated during reheat.
• Depending on your cooling unit, the maximum setting may be 1, 2, or 3.
3.3.7 Reheat Control
If your cooling units are equipped with a heating option, reheat control is directly linked to temperature control in that the
heating requirement determined by the temperature proportional band determines reheat operation. See Temperature
Control—TemperatureSetpointsandCooling Operation on page27 .
Electric, Hot Gas, and Hot Water Reheat
Depending on the type of cooling unit, there may be one to three stages of electric and hot gas/hot water reheat. Table 3.4
below , shows the nine electric reheat options.
Type Stage 1 Stage 2 Stage 3
A Electric 1 — —
B Electric 1 Electric 2 —
C Electric 1 Electric 2 Electric 3
D Hot gas — —
E Hot gas Electric 1 —
F Hot gas Electric 1 Electric 2
G Hot water — —
H Hot water Electric 1 —
I Hot water Electric 1 Electric 2
Table 3.4 Electric, Hot Gas and Hot Water Reheat Configurations
NOTE: During dehumidification, hot gas/hot water are not influenced by the electric reheat setting. Hot gas is set only
when the selected compressor is operating. (See Enable Hot Gas Heat on the previous page .)
Reheat is controlled by dividing the “heating” half of the temperature proportional band (below the setpoint) by the number of
stages. Figure 3.14 on the next page , illustrates electric reheat operation with three stages as follows:
• 70° setpoint
• 8° proportional band
• 2° deadband
• Three stage reheat
3 Service Operation
61
Vertiv™ Liebert® iCOM™Installer/User Guide