Trane RT-PRC007-EN manual Supply AirTempering, Auto Changeover, ConventionalThermostat Interface

Controls

the requirement, the UCP will energize the second stage electric heat contactor(s) if the appropriate limits are closed.The UCP will cycle second stage on and off as required while keeping stage one energized.

The supply fan is energized approximately 1 second before the electric heat contactors. When the space temperature rises above the heating setpoint, the UCP deenergizes the supply fan and all electric heat contactors.

Supply AirTempering

This feature is available only with TRACER® or with systems using programmable zone sensors (CV only with economizer). For gas and electric heat units in the Heat mode but not actively heating, if the supply air temperature drops to 10 F below the occupied zone heating temperature setpoint, one stage of heat will be brought on to maintain a minimum supply air temperature.The heat stage is dropped if the supply air temperature

rises to 10 F above the occupied zone heating temperature setpoint.

Auto Changeover

When the System Mode is “Auto,” the mode will change to cooling or heating as necessary to satisfy the zone cooling and heating setpoints.The zone cooling and heating setpoints can be as close as 2 F apart.

Unoccupied ZoneTemperature Control Cooling and Heating

Both cooling or heating modes can be selected to maintain Unoccupied zone temperature setpoints. For Unoccupied periods, heating or primary cooling operation can be selectively locked out at the remote panels orTRACER.

ConventionalThermostat Interface

An interface is required to use a conventional thermostat instead of a zone sensor module with the UCP.The ConventionalThermostat Interface (CTI) is connected between conventional thermostat and the UCP and will allow only two steps of heating or cooling.The

CTI provides zone temperature control only and is mutually exclusive of the Trane Communications Interface.

Control Sequences of Operation Common to Both VAV and CV Units

Ventilation override (VOM)

Ventilation override allows an external system to assume control of the unit for the purpose of exhaust or pressurization. There are two inputs associated with ventilation override, the initiate input and the select input. When the UCP senses a continuous closed condition on the initiate input at the low voltage terminal board the unit will begin ventilation override depending on the condition of the select input.The default condition of the select input is exhaust (input open). A closed select input will yield pressurization.The component state matrix for ventilation override is

as follows:

System Component Exhaust		Pressurization
Heat/Cool	off	off
IGV	closed	open
Supply Fan	off	on
Exhaust Fan	on	off
Outside Air Damper	closed	open
Return Air Damper	open	closed
VAV Boxes	n/a	open

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