Applications Guide Tracer Graphical Programming - Trane

®
Reviewing the sequence of operation
occupied standby setpoints and maintain the outdoor air damper to its
minimum position.
Unoccupied mode (including night heat/cool)
When the air handler is in unoccupied mode, turn the supply fan off, close
the outside air damper fully, and close the cooling and heating valves
fully. Open the heating valve completely if the outdoor air temperature
falls below the freeze avoidance setpoint, 35°F (adjustable).
If the space temperature falls below the unoccupied heating setpoint,
start the supply fan and transition the air handler to heating and keep
the outdoor air damper closed to maintain the unoccupied heating setpoint.
When the space temperature rises above the unoccupied heating
setpoint, shut down the air handler.
If the space temperature rises above the unoccupied cooling setpoint,
start the supply fan and transition the air handler to cooling to maintain
the unoccupied cooling setpoint. Modulate the outside air damper if the
outside air temperature is less than the economizer changeover setpoint.
When the space temperature falls below the unoccupied cooling setpoint,
shut down the air handler.
Warm-up and pre-cool modes
During occupied and occupied standby modes, when there is a call for
heating and the space temperature is 3°F or more below the effective
occupied heating setpoint, initiate a warm-up sequence. During warm-up,
operate the supply fan continuously, close the outdoor air damper, and
opentheheatingvalveto100%.Whenthespacetemperaturecomes
within 2°F of the heating setpoint, open the outside air damper to the
occupied minimum position and transition the air handler to occupied
mode.
During occupied and occupied standby modes, when there is a call for
cooling and the space temperature is 3°F or more above the effective occupied
cooling setpoint, initiate a morning cool-down sequence. Operate the
supply fan continuously and the air handler in the economizing mode, if
possible. If economizing is not possible, open the cooling valve to 100%
and keep the outside air damper closed. When the space temperature
reaches the cooling setpoint, open the outside air damper to the occupied
minimum position and transition the air handler to occupied mode.
Setpoints
For occupied, occupied standby, and occupied bypass modes, calculate
effective cooling and heating setpoints based on a single space temperature
setpoint and the configured default occupied and occupied standby
setpoints. The space temperature setpoint source may be the building
automation system, the operator display, or a wired thumbwheel setpoint
CNT-APG001-EN 191