Trane Tracer VV550 Installation, Operation And Maintenance Manual page 62

Sequence of Operations
Table 40.Space temperature controller active minimum airflow setpoint selection (continued)
a
PD STC mode
Unoccupied
cool
Unoccupied
heat
MWU
Pre-cool
Night purge
a. PD is the acronym for pressure dependent.
b. PAT is the acronym for primary air temperature.
Air Valve Control in Ventilation Flow Control Operation
The Tracer
cooling operation. Air delivered to the space is controlled with a three-wire floating-point
actuator that modulates the air valve. The controller positions the modulating air valve
to deliver the desired airflow (cooling or heating capacity). The desired airflow is called
the active flow setpoint.
The active flow setpoint is set to the communicated ventilation setpoint, if valid. If the
communicated ventilation setpoint is not valid, the configured ventilation setpoint is
used.
62
Effective Control
occupancy action 
b
mode (PAT)
Unoccupied Cooling
Heating
Don't care Cooling
Heating
®
VV550/VV551 controllers support one modulating air valve for heating and
Local
reheat Active minimum setpoint (the greatest of the
state following)
Off • Zero (air valve closed)
On • Configured minimum local heating airflow
• Configured minimum position setpoint
Off • Zero (air valve closed)
On • Configured minimum local heating airflow
• Configured minimum position setpoint
Off • Configured minimum airflow
• Configured minimum position setpoint
On • Configured minimum local heating airflow
• Configured minimum airflow
• Configured minimum position setpoint
Off • Configured minimum heating airflow
• Configured minimum position setpoint
On • Configured minimum local heating airflow
• Configured minimum heating airflow
• Configured minimum position setpoint
CNT-SVX17G-EN