Fan Mode Input - Trane Tracer ZN.520 Manual

The Rover service tool allows you to
monitor, configure, and test Tracer ZN.520
zone controller zone controllers via a
connection to the communication link,
directly to the controller (stand-alone) or
through communication connection on
standard Trane sensors.
If the Tracer ZN.520 zone controller does
not receive a hardwired or communicated
request for fan mode, the unit recognizes
the fan input as auto and the fan operates
according to the default fan configuration.
Table 27 Tracer ZN.520 zone controller fan modes
Fan modes Tracer ZN.520 zone controller operation
Off Fan Off
Auto In occupied mode, the fan runs continuously at the default speed if configured as Off, Low, Medium, or High
(defined in unit configuration). You can define different speeds for heating and cooling. If the default fan speed is
Auto, then the fan may switch speeds, depending on the temperature error. If the cool default is Auto, then when
cooling, the fan speed increases as space temperature increases above the active cooling setpoint. If the heat
default is Auto, then when heating, the fan speed increases as space temperature decreases below the active
heating setpoint. In unoccupied mode, the fan cycles Off when no heating or cooling is required and switches to
High when heating or cooling is delivered.
High In the occupied mode, the fan runs continuously in High speed. In the unoccupied mode, the fan cycles between Off
and High when heating or cooling is delivered.
Medium In the occupied mode, the fan runs continuously in Medium speed. In the unoccupied mode, the fan cycles between
Off and High when heating or cooling is delivered.
Low In the occupied mode, the fan runs continuously in Low speed. In the unoccupied mode, the fan cycles between Off
and High when heating or cooling is delivered.
32
Analog inputs
Once a valid fan mode is established through the hardwired input and that local
fan mode is no longer present, the controller generates a Local Fan Mode
Failure diagnostic.
When a Local Setpoint Failure diagnostic occurs, the controller operates using
the default heating and cooling setpoints. These setpoints are factory-
configured, but may be changed using Trane's Rover service tool.
The Tracer ZN.520 zone controller uses the following validation sequence for
the zone temperature setpoints:
1 Check for a communicated setpoint. If present, validate this setpoint.
2 Check for a hardwired setpoint. If present, validate this setpoint.
3 Use the default setpoints if neither the hardwired setpoint nor the
communicated setpoint is available.

Fan mode input

The fan mode analog input (Fan) operates only as a fan mode switch input with
Trane zone sensors. Typically, the fan mode switch on a Trane zone sensor
generates the fan mode signal.
The Tracer ZN.520 zone controller detects the unique resistance corresponding
to each position of the fan switch. By measuring this resistance, the controller
determines the requested fan mode.
Table 27 describes the controller operation for all fan modes.
CNT-SVX04A-EN