Trane RT-PRC031-EN manual Zone Temperature Control

Controls Variable Air Volume (VAV) Only

overheat. The supply air temperature setpoint is adjusted based on the temperature of the critical zone(s). This can have the effect of improving comfort and/or lowering energy usage. The user-defined parameters are the same as for outdoor air reset. See Figure 12, p. 12

Supply Air Tempering

Modulating gas, electric, hot water and steam heat units only—When supply air temperature falls below the supply air temperature deadband low end, the heat valve will be modulated to maintain the set minimum supply air temperature.

Zone Temperature

Control

Unoccupied Zone Heating and Cooling

During Unoccupied mode, the unit is operated as a CV unit. Inlet guide vanes are driven full open, VFDs operate at 100%, and VAV boxes are driven full open. The unit controls zone temperature within the Unoccupied zone cooling and heating (heating units only) setpoints.

Daytime warm-up

This feature is available on all types of heating units. During Occupied mode, if the zone temperature falls to a preset, user-defined zone low limit temperature setpoint, the unit is put into Unoccupied mode and Daytime Warm-up is initiated. The system changes over to CV heating (full unit airflow), the VAV boxes are fully opened and full heating capacity is provided until the Daytime Warm-up setpoint is reached. The unit is then returned to normal Occupied mode.

Fresh Air Measurement

Trane air quality (TRAQ™) fresh air measurement damper system utilizes velocity pressure sensing rings. Based on unit design CFM, the ventilation control module (VCM) monitors and controls the quantity of fresh outside air entering the unit. The outside airflow can be calibrated to accommodate for altitude.

a.An optional temperature sensor may be connected to the ventilation control module to enable it to control a field-installed pre-heater.

b.An optional CO2 sensor may be connected to the ventilation control module to control fresh air based on CO2 Demand Control Ventilation (DCV).

Outside Air CFM

Compensation

As the supply fan (IGV or VFD) modulates, this function proportionally adjusts the economizer minimum position to compensate for the change in total airflow, in order to maintain a constant percent of outside air. The modified economizer minimum position is computed as a linear function, based on IGV or VFD position, given the two endpoints,

a.Minimum Position with IGV/ VFD @ 0%

b.Minimum Position with IGV/ VFD @ 100%

which are user adjustable at the Human Interface Panel.

RT-PRC031-EN 13