Sequence Of Operation - Trane Tracer ZN.520 Manual

The Tracer ZN.520 zone controller does not
support a 2-position outdoor air damper.
By default, if no occupancy binary input or
communicated occupancy request exists,
the Tracer ZN.520 zone controller runs in
occupied mode.
CNT-SVX04A-EN

Sequence of operation

The Tracer ZN.520 zone controller is factory-configured in a variety of heating-
only units, cooling-only units, and heating and cooling terminal units. The
controller supports the following configuration options.
Fan: One-, two-, or three-speed fan (exhaust fan optional on one- or two-
speed units)
Cooling: Modulating hydronic, 2-position hydronic, economizer, DX (direct
expansion) compressor
Heating: Modulating hydronic, 2-position hydronic, baseboard heat, one or
two stages of electric heat, steam
The Tracer ZN.520 zone controller controls the space temperature according to
the active space temperature, the active heating/cooling setpoint, discharge air
temperature, and the control algorithm. The space temperature and active
heating/cooling setpoint determine the operating mode of the controller (heat
or cool).
The active heating and cooling setpoints are affected by the controller's
occupancy mode. Valid occupancy modes are:
I Occupied
I Unoccupied
I Occupied standby
I Occupied bypass
The controller's occupancy mode is determined by either a binary input to the
controller or a communicated request (from a system-level controller or
another peer controller).
The controller uses the measured space temperature, discharge air
temperature, and the control algorithm to maintain the space temperature at
the active cooling setpoint (in cooling mode) or the active heating setpoint (in
heating mode). This algorithm utilizes proportional/integral (PI) control for
maintaining the space temperature. The controller's heat/cool mode is
determined by either a communicated request or by the controller itself when
the heat/cool mode is auto.
If the Tracer ZN.520 zone controller determines its heat/cool mode
automatically, the controller changes to the requested mode based on the
heating and cooling capacity determined by the control algorithm. For 2-pipe
and 4-pipe changeover applications (valid entering water temperature is
required), the entering water temperature is provided with either a
communicated or hardwired connection to the controller.
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