Trane SCXG-SVX01B-EN manual Cycling Capacity Morning Warmup MWU, Timed Override Activation ICS

sequence of

Operation operation

For units without volume control entering unoccupied mode, the following se- quence will occur:

•The occupied/unoccupied relay ener- gizes and the economizer option fully closes.

•The fan mode is set to auto and the unit will control to the unoccupied zone temperature setpoints.

With MWU enabled at the HI, if the zone temperature is below the MWU setpoint, the unit enters the MWU mode.

Morning Warmup

This feature can be enabled at the HI, and can be used with factory or field-installed heat. If MWU is not required disable the function in the setup menu at the HI. MWU transitions the zone from unoccupied to occupied. It will heat until the MWU setpoint is met. The unit is then released to occupied mode. Supply duct static pressure is maintained during this sequence. MWU can be set (at the HI) to function as either full or cycling capacity.

Full Capacity Morning Warmup (MWU) Full capacity morning warmup uses full heating capacity to heat the zone as quickly as possible. Full heating capacity is provided until the morning warmup setpoint is met. At this point, the unit is released to daytime mode.

Cycling Capacity Morning Warmup (MWU)

Cycling capacity morning warmup provides a more gradual heating to overcome “building sink” as the zone is heated. Normal zone temperature control with varying capacity is used to raise the zone temperature to the MWU zone temperature setpoint. This method of warmup is used to overcome the “building sink” effect.

Reference Figure O-SO-1 on page 73 for a pictorial explanation of the cycling MWU sequence. Cycling capacity MWU will heat until MWU temperature setpoint

is reached. Next a 60 minute timer begins. If the building load reaches the MWU ventilation setpoint, or the 60 minutes expire, whichever is first, the airside economizer will control to the minimum position. MWU will end when the zone temperature rises above the MWU terminate setpoint.

Timed Override Activation - ICS™

This function is operational whenever the unit’s RTM module is used as the zone temperature sensor source, which can be set at the HI panel. When this function is initiated by the push of the override button on the zone sensor, the unit will switch to the occupied mode. Unit operation (occupied mode) during timed override is terminated by a signal from Tracer.

Timed Override Activation - Non-ICS This function is active whenever the unit’s RTM module board is selected as the zone temperature source, which can be set at the human interface panel. When this function is initiated by the push of the override button on the zone sensor, the unit will switch to the occupied mode. Automatic cancellation of the timed override mode occurs after three hours of operation.

VAV Drive Max Output

This is a single-pole, double-throw relay rated at a maximum voltage of 24 vac, two amps max. The relay contacts of this relay switch when the unit goes from the occupied mode to the unoccupied mode by means of the unoccupied binary input, night setback zone sensor, orTracer Summit. The contacts will stay switched during the unoccupied and morning warmup mode. They will return to the position shown on the unit wiring diagram when the unit returns to the occupied mode. The intent of this binary output is to signal theVAV boxes or other terminal devices to go to a full open airflow position.

SCXG-SVX01B-EN 85