Trane SCXG-SVX01B-EN manual general Operation information, PURGE sequence “D”

general

Operation information

PURGE sequence “D”

This sequence can purge the air out of a building before coming out of unoccupied mode of operation in aVAV system. Also, it can be used to purge smoke or stale air.

•Supply fan – on

•Supply fan VFD – on (60 hz)

•Inlet guide vanes/VAV boxes – open

•Outside air damper – open

•Heat – all stages – off, modulating heat output at 0 vdc

•Occupied/Unoccupied output – energized

•VO relay – energized

•Exhaust fan (field-installed) - on

•Exhaust damper (field-installed) - open

PURGE with duct pressure control “E” This sequence can be used when supply air control is required for smoke control.

•Supply fan – on

•Supply fan VFD – on (if equipped)

•Inlet guide vanes – controlled by supply air pressure control function with supply air pressure high limit disabled

•Outside air dampers – open

•Heat – all stages – off, hydronic heat output at 0 vdc

•Occupied/unoccupied output – energized

•VO relay – energized

•Exhaust fan (field-installed) - on

•Exhaust damper (field-installed) - open

Note: Each system (cooling, exhaust, supply air, etc.) within the unit can be redefined in the field for each of the five sequences, if required. Also the definitions of any or all of the five sequences may be locked into the software by simple key strokes at the human interface panel. Once locked into the software, the sequences cannot be changed.

Exhaust/Comparative Enthalpy (ECEM ) Module - Option used on units with comparative enthalpy option

The exhaust/comparative enthalpy module receives information from the return air humidity sensor, and the RTM outside air temperature sensor and outside air humidity sensor, the outside air humidity sensor and temperature sensor to utilize the lowest possible enthalpy level when considering economizer operation. In addition, it receives space pressure information to maintain the space pressure within the setpoint control band. Refer to the Figure O-GI-1 for humidity vs. voltage values.

Figure O-GI-1. ECEM relative humidity vs. voltage

Ventilation Control Module (VCM) - Available only with Traq™ Damper Option

The ventilation control module (VCM) is located in the airside economizer section of the unit and linked to the unit’s UCM network. Using a velocity pressure transducer/solenoid (pressure sensing ring) in the fresh air section allows the VCM to monitor and control fresh air entering the unit to a minimum airflow setpoint. See Figure O-GI-2 for a detail view of the velocity pressure transducer/ solenoid assembly.

An optional temperature sensor can be connected to the VCM to enable control of a field installed fresh air preheater.

Also, a field-provided CO2 sensor can be connected to the VCM to control CO2 reset. The reset function adjusts the minimum cfm upward as the CO2 concentrations increase. The maximum effective (reset) setpoint value for fresh air entering the unit is limited to the system’s operating cfm.Table O-GI-5 lists the minimum outside air cfm vs. input voltage.

Table O-GI-5. Minimum outside air setpoint w/VCM module and Traq™ sensing

Unit	InputVolts	CFM
SXWG 20	0.5 - 4.5 vdc	6,350-8,500
SXWG 25	0.5 - 4.5 vdc	7,250-10,625
SXWG 30	0.5 - 4.5 vdc	7,250-12,750
SXWG 35	0.5 - 4.5 vdc	7,250-14,875
SXRG 20	0.5 - 4.5 vdc	7,250-8,500
SXRG 25	0.5 - 4.5 vdc	7,250-10,625
SXRG 32	0.5 - 4.5 vdc	7,250-13,600

Trane IntelliPak Lon-Talk Communication Module (LCI-I Option used on units with Trane ICSTM or 3rd party Building AutomationSystems)

The LonTalk Communication Interface module expands communications from the unit UCM network to aTraneTracer SummitTM or a 3rd party building automation system, utilizing LonTalk, and allows external setpoint and configuration adjustment and monitoring of status and diagnostics.

Figure O-GI-2.Velocity pressure transducer/ solenoid assembly

74 SCXG-SVX01B-EN