Ventilation Control - Trane Tracer VV550 Installation, Operation And Maintenance Manual

Sequence of Operations

Ventilation Control

Ventilation is in effect whenever the space temperature controller is in one of the
following modes:
•
•
•
•
Ventilation is allowed as long as the space temperature 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: Ventilation flow controllers and flow tracking controllers do not do ventilation flow
The Tracer Summit
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
Two methods of ventilation control are possible: the CO
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.Data required for each method of ventilation control
Variable
Communicated space
CO
2
Communicated
ventilation ratio limit
Communicated
ventilation setpoint
Reported airflow
52
Occupied heating;
Occupied cooling;
Occupied standby heating;
Occupied standby cooling.
control as described in this topic.
™
BAS uses the effective ventilation setpoint from all the VAV boxes
Methods of ventilation control;
Arbitration of ventilation requirements;
Ventilation control actions;
Active minimum flow setpoint selection arbitration.
Table 35 shows the data required for each method of ventilation control.
Description
Space CO concentration
2
Ventilation ratio limit: System limit on the amount of outdoor air
(OA) that can be present in the primary air stream.
Dynamic ventilation setpoint: Input sent to the controller to
schedule ventilation.
Measured primary airflow
-based demand controlled
2
Method
CO -based Prescribed
2
DCV ASHRAE
setpoint rate
Mandatory Do not care
Optional Optional
Optional Optional
Mandatory Mandatory
CNT-SVX17G-EN