Trane RT-PRC010-EN Controls, VAV/CV Units, Occupied/Unoccupied Switching a, Night Setback Sensors

Controls (VAV/CV Units)

near theTXV bulb location to shut the cooling off when coil frosting conditions occur.The supply fans are not shut off and will de-ice the coil.Timers prevent the compressors from rapid cycling.

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Occupied/Unoccupied Switching

a

Description — 3 ways to switch Occupied/Unoccupied:

(1)NSB Panel

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

(3)TRACER

Night Setback Sensors

Trane’s night setback sensors are programmable with a time clock function that provides communication to the rooftop unit through a 2-wire communications link.The desired transition times are programmed at the night setback sensor and communicated to the rooftop.

Night setback (unoccupied mode) is operated through the time clock provided in the sensors with night setback. When the time clock switches to night setback operation, the outdoor air dampers close and heating/cooling can be enabled or disabled depending on set-up parameters. As the building load changes, the night setback sensor energizes the rooftop heating/cooling (if enabled) function and the evaporator fan.The rooftop unit will cycle through the evening as heating/cooling (if enabled) is required in the space.When the time clock switches from night setback to occupied mode, all heating/ cooling functions begin normal operation.

When using the night setback options with a VAV heating/cooling rooftop, airflow must be maintained through the rooftop unit.This can be accomplished by electrically tying the VAV boxes to the Unoccupied output relay contacts on the Rooftop Module (RTM) or by using changeover thermostats. Either of these methods will assure adequate airflow through the unit and satisfactory temperature control of the building.

Occupied/Unoccupied input on the RTM

This input accepts a field supplied switch or contacts closure such as a time clock.

TraneTracer® System

TheTraneTracer System can control the Occupied/Unoccupied status of

the rooftop.

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Timed Override Activation — ICS

This function is operational when the RTM is the zone temperature sensor source, which was set up at the Human Interface Panel. When this function is initiated by the push of a override button on the ICS sensor, theTracer will switch the unit 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 RTM is selected as the ZoneTemperature Sensor source, which was set up at the Human Interface Panel. When this function is initiated by the push of an override button on the zone sensor, the unit will switch to the Occupied mode. Automatic Cancellation of theTimed Override Mode occurs after three hours of operation.

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Low Ambient Compressor Lockout

This function will lock out the compressor if the outdoor air temperature is below the low ambient compressor lock out temperature set point.The factory setpoint is 50 F on standard units and 0 F on low ambient units.This setpoint is adjustable at the Human Interface Panel. Compressors will be locked out when outdoor air temperatures falls below that selected temperature and will be allowed to start again when the temperature rises 5 F above the setpoint.

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Comparative Enthalpy Control of Economizer

An optional Comparative Enthalpy system is used to control the operation of the economizer, and measures the temperature and humidity of both return

air and outside air to determine which source has lower enthalpy.This system allows true comparison of outdoor air and return air enthalpy by measurement of outdoor air and return air temperatures and humidities.

Reference Enthalpy Control of

Economizer

The optional reference enthalpy compares ambient temperature and humidity to the economizer enthalpy control setpoint. If ambient temperature and humidity are below the economizer enthalpy control setpoint the economizer will operate freely.This system provides more sophisticated control where outdoor air humidity levels may not be acceptable for building comfort and indoor air quality.

Dry BulbTemperature Control of Economizer

The optional dry bulb system measures ambient temperature comparing it to the economizer control temperature setpoint. If the ambient temperature is below the economizer dry bulb temperature control setpoint, the economizer will operate freely.This system is best suited for arid regions where the humidity levels of fresh air would not be detrimental to building comfort and indoor air quality.

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Compressor Lead/Lag

Compressor lead/lag is a user-selectable feature through the Human Interface Panel available on all units. After each request for compressor operation, the lead refrigeration circuit or compressor on 20-30 tons units switches, thereby causing a more equitable or balanced run time among compressors.

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Emergency Stop Input

A binary input is provided on the Rooftop Module (RTM) for installation of field provided switch or contacts for immediate shutdown of all unit functions.

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