Applications Guide Tracer Graphical Programming - Trane

®
Chapter 8 Constant-volume AHU with warm-up, pre-cool, and communications
adjustment knob, with the building automation system setpoint being
given first consideration.
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.
Determine the discharge air temperature setpoint through a comparison
of the space temperature and the space temperature setpoint. Reset the
discharge air temperature setpoint according to heating or cooling
demand.
Heat/Cool arbitration
Determine the heat/cool decision 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.
Communications
The air handler is part of a Tracer Summit building automation system.
The following items are communicated to the air handler from the building
automation system:
• Occupancy
• Space temperature setpoint
• Outdoor air temperature
• Outdoor air humidity
• Space relative humidity
• Economizer enable
If communication with the BAS is lost, program the air handler to use its
predetermined default setpoints and operate in the occupied mode.
The air handler must communicate the following items to the building
automation system so that the building operator can view the status of
the air-handling unit:
• Space temperature
• Discharge air temperature
• Mixed air temperature
• Effective setpoint
• Effective occupancy
• Supply fan status
• Cooling valve status
• Heating valve status
• Outdoor air damper status
• Alarm status
• Application mode
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