Trane IntelliPak SAHL Series Installation, Operation And Maintenance Manual page 94

Unit Start Up
1. 2-Stage DX Cooling - The minimum fan speed for units with 2 stages of DX Cooling will be 37%
2. 3-Stage DX Cooling - There are no IntelliPak applications with 3 stages of DX Cooling.
3. 4-Stage DX Cooling - The minimum fan speed for units with 4 stages of DX Cooling will be 37%
Rapid Restart
This feature will occur after every power cycle. Once power is restored (e.g., via a backup
generator), the RTM will maximize cooling capacity within 3-5 minutes. Once the space has
returned to its Zone Temperature Setpoint, the RTM controls the load using normal capacity control
algorithms. The supply fan will be turned on immediately after a power cycle, module initialization,
or after the Unit Start Delay has timed out. The supply fan proving switch input must be closed prior
to continuing with Rapid Restart.
Once the supply fan proving switch input has closed, the unit will consider the outside air
temperature to determine whether economizing or DX mechanical cooling will be utilized to
provide the necessary cooling. If the outside air temperature is less than 50°F and economizing is
enabled, the outside air damper will be utilized. If the outside air temperature is above 50°F , the
outside air damper will remain closed and DX mechanical cooling will occur for the duration of
Rapid Restart.
Supply Fan Operation – Speed Control:
•
•
•
Figure 42. Typical rapid restart timeline
Units without an Economizer
Upon entering an "occupied" mode of operation, the RTM receives input from the remote panel
to start the supply fan. For constant volume applications, the RTM supply fan contacts K2 close
which energizes the supply fan contactor 1K16. When the supply fan starts, the fan proving switch
(3S68) closes, signaling the RTM that airflow has been established. The VFD will begin to ramp the
fan, (if equipped).
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of the unit's full airflow capacity. At Stage 1 of DX Cooling the minimum Fan Speed will be 37%
and at Stage 2 of DX Cooling the Fan Speed will be at a minimum of 67%.
of the unit's total airflow. At Stage 1 the minimum Supply Fan Speed will be 37%, at Stage 2
the minimum Supply Fan Speed will be 58%, and at Stages 3 & 4 the minimum Supply Fan
Speed will be 67%.
VAV: The supply fan speed will ramp to 50%, then release to normal discharge static pressure
control, limited only by the high duct static limit functionality.
CV: The supply fan speed will turn on full airflow.
SZVAV: The supply fan speed will ramp to full airflow.
RT-SVX36G-EN