Trane Tracer VV550 User Manual

52 CNT-SVX17G-EN
Sequence of Operations
Ventilation Control
Ventilation is in effect whenever the space temperature controller is in one of the
following modes:
• Occupied heating;
• Occupied cooling;
• Occupied standby heating;
• Occupied standby cooling.
Ventilation is allowed as long as the space t
emperature remains in control. If the space
temperature gets too cold or too hot, limiting ventilation can help get the space
temperature back under control.
Note: Vent
ilation flow controllers and flow tracking controllers do not do ventilation flow
control as described in this topic.
The Tracer Summit
™ BAS uses the effective ventilation setpoint from all the VAV boxes
to calculate how much outdoor air (OA) the system needs. The Tracer Summit BAS uses
the communicated ventilation ratio limit to tell the controllers how much outdoor air is
in the primary air. However, the air handler may not be able to provide as much outdoor
air as the system requires due, for example, to a low outdoor air temperature. If the
communicated ventilation ratio limit is not sufficient, the controller can raise its
minimum airflow setpoint as long as the space temperature remains under control.
This topic provides information concerning:
• Methods of ventilation control;
• Arbitration of ventilation requirements;
• Ventilation control actions;
• Active minimum flow setpoint selection arbitration.
Methods of Ventilation Control
Two methods of ventilation control are possible: the CO
2
-based demand controlled
ventilation (DCV) procedure and the prescribed ASHRAE rate procedure. Both methods
achieve the same results, only the procedure is different. Each method calculates an
effective ventilation setpoint that can be used locally, or by the system, to maintain
ventilation. Table 35 shows the data required for each method of ventilation control.
Table 35.Data required for each method of ventilation control
Variable
Method
Description
CO
2
-based
DCV
setpoint
Prescribed
ASHRAE
rate
Communicated space
CO
2
Space CO
2
concentration Mandatory Do not care
Communicated
v
entilation ratio limit
Ventilation ratio limit: System limit on the amount of outdoor air
(OA) that can be present in the primary air stream.
Optional Optional
Communicated
v
entilation setpoint
Dynamic ventilation setpoint: Input sent to the controller to
schedule ventilation.
Optional Optional
Reported airflow Measured primary airflow Mandatory Mandatory

Trane Tracer VV550 Specifications

General

Brand	Trane
Model	Tracer VV550
Category	Controller
Language	English