Trane SCXG-SVX01B-EN manual sequence of, Operation operation, Control Sequences of Operation

sequence of

Operation operation

Control Sequences of

Operation

Occupied/Unoccupied Switching There are four ways to switch occupied/ unoccupied:

(1)Night setback zone sensor

(2)Field-supplied contact closure (hardwired binary input to RTM)

(3)Tracer Summit

(4)Factory-mounted time clock

Field Supplied Occupied/Unoccupied Input on the RTM

This input accepts a field supplied switch or contacts closure, such as a time clock, with a rating of 12 mA at 24 VDC minimum.

Tracer Summit System

TheTracer Summit system can control the occupied/unoccupied status of the self-contained unit.

Factory MountedTime Clock A time clock can control the occupied/unoccupied status of the self-contained unit.

Unoccupied Sequence of Operation

The unoccupied mode helps conserve energy during times when a building is usually unoccupied. When in unoccupied mode, the unit will control to the unoccupied setpoints (usually a lower

heating setpoint and higher cooling setpoint). Setpoints can be programmed at the HI,Tracer Summit, or the night setback zone sensor.

The unit enters the unoccupied mode when the RTM receives a closed signal on the unoccupied input for more than five seconds.

For units with supply air temperature control entering unoccupied mode, the following sequence will occur:

•Heating/cooling functions cease and the economizer option closes fully.The supply fan shuts down for proper cool- down time of the heat exchanger. However, the supply fan may remain on for a short period of time.

•After the supply fan shuts down, the occupied/unoccupied relay energizes and the IGV option fully opens. Also, the VAV box stroke time begins.TheVAV box stroke time is field adjustable to allow time forVAV boxes to go to the full open airflow position.

•After the maxVAV box stroke time expires and the IGV’s are fully open, the supply fan, economizer (if enabled), compressors, and heat are enabled to satisfy the unoccupied zone temperature setpoints.

Note: Unoccupied economizer operation

can be enabled or disabled at the HI or using Tracer Summit.

Figure O-SO-1.Typical cycling morning warmup cycle

84 SCXG-SVX01B-EN