Applications Guide Tracer Graphical Programming - Trane

®
Reviewing the sequence of operation
scheduled occupancy period, set the space temperature control to follow
the occupied standby setpoints.
Unoccupied mode (including night heat/cool)
When the air handler is in unoccupied mode, turn the supply fan off and
fully close the outside air damper and the cooling and heating valves.
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. 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.
Space 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 operator display
or a wired thumbwheel setpoint adjustment knob.
Note:
Calculate the effective cooling and heating setpoints as in other
Comm5 devices. See “Calculating the effective space setpoints”
on page 135 for more information.
Discharge air setpoints
Compare the space temperature and space temperature setpoint to determine
the discharge air temperature setpoint. Reset the discharge air temperature
setpoint according to heating or cooling demand.
Heat/Cool arbitration
Determine the heat/cool mode of the air handler based on the effective
occupied or occupied standby cooling and heating setpoints. Transition
the air handler to cooling if the space temperature exceeds the cooling
setpoint plus 1°F. Transition the air handler to heating if the space temperature
falls below the heating setpoint minus 1°F.
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