Trane UniTrane Fan Coil Installation, Operation And Maintenance Manual Download Page 108

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Startup

108

UNT-SVX07E-EN

modulating outputs open further and binary outputs are
energized longer. At 100 percent capacity, the heating
valve is fully open (3-wire modulating valves) or on
continuously (two-position valves).

The fan output(s) normally run continuously during the
occupied and occupied standby modes, but cycle between
high and off speeds with heating/cooling during the
unoccupied mode. When in the occupied mode or
occupied standby mode and the fan speed is set at the
high, medium, or low position, the fan runs continuously
at the selected speed. Refer to the Troubleshooting section
for more information on abnormal fan operation.

When the unit’s supply fan is set to auto, the controller’s
configuration determines the fan speed when in the
occupied mode or occupied standby mode. The fan runs
continuously at the configured heating fan speed or
cooling fan speed. For all fan speed selections except off,
the fan cycles off during unoccupied mode.

The economizer outdoor air damper is never used as a
source of heating. Instead, the economizer damper (when
present) is only used for ventilation; therefore, the damper
is at the occupied minimum position in the occupied
mode. The damper control is primarily associated with
occupied fan operation.

Fan Mode Operation

For multiple fan speed applications, the controller offers
additional fan configuration flexibility. Separate default
fan speeds for heating and cooling modes can be
configured. The fan runs continuously for requested
speeds (off, high, medium, or low). When the fan mode
switch is in the Auto position or a hard-wired fan mode
input does not exist, the fan operates at the default
configured speed. See

Table 49

for default fan

configuration for heat and cool mode. During unoccupied
mode, the fan cycles between high speed and off with
heating and cooling fan modes. If the requested speed is
off, the fan always remains off.

During dehumidification, when the fan is on Auto, the fan
speed can switch depending on the error. Fan speed
increases as the space temperature rises above the active
cooling setpoint.

Additional flexibility built into the controller allows you to
enable or disable the local fan switch input. The fan mode
request can be either hard-wired or communicated to the
controller. When both are present, the communicated
request has priority over the hard-wired input. See

Table 50

Table 51

, and

Table 52

Continuous Fan Operation

During occupied and occupied standby modes, the fan
normally is on. For multiple speed fan applications, the fan
normally operates at the selected or default speed (off,
high, medium, or low). When fan mode is auto, the fan
operates at the default fan speed.

During unoccupied mode, the controller controls the fan
off. While unoccupied, the controller heats and cools to
maintain the unoccupied heating and cooling setpoints. In
unoccupied mode, the fan is controlled on high speed only
with heating or cooling.

The unit fan is always off during occupied, occupied
standby, and unoccupied modes when the unit is off due
to a diagnostic or when the unit is in the off mode due to
the local zone sensor module, a communicated request, or
the default fan speed (off).

If both a zone sensor module and communicated request
exist, the communicated request has priority.

Table 49. Fan configuration for Tracer ZN520 units

Auto Fan Operation

Fan Speed Default

Heating

Continuous

Off

Low

Medium

High

Cooling

Continuous