Siemens BACNET 125-5037 - Manual (Page 17)

Siemens BACnet VAV Actuator Owner’s Manual
Siemens Building Technologies, Inc. 7
Calibration
Air Velocity Sensor - Calibration of the controller's internal air velocity sensor is periodically
required to maintain accurate air velocity readings. Calibration may be set to take place
automatically or manually.
Autozero Module (AZM) – Used when damper cannot be closed and constant airflow is
needed.
• For a controller used with an AZM, calibration occurs without closing the damper.
Application 2560, 2561, 2562, 2563.
• For a controller used without an AZM, the damper is briefly commanded closed to get
a zero airflow reading and an accurate damper position during calibration.
Application 2560, 2561, 2562, 2563.
Hot Water Valve – Calibration of a hot water valve (if used) is done by briefly commanding
the valve closed. Application 2562, 2565, 2567.
Damper Status Operation
When using an AZM it is possible, after a period of operation, for the calculated damper
position to differ from the actual (physical) damper position.
If this occurs, the controller will automatically compensate for any difference by readjusting
the calculated damper position. This calculated position may not match the actual position.
Fail-safe Operation
If the air velocity sensor fails, the controller uses pressure dependent control. The
temperature loop controls the operation of the damper.
If the room temperature sensor fails, then the controller operates using the last known
temperature value.
Heating and Cooling Switchover
The heating/cooling switchover determines whether the controller is in heating or cooling
mode by monitoring the room temperature and the demand for heating and cooling (as
determined by the temperature control loops).
Modulate Damper During Heating Mode (optional)
Applications that have a heating source (valve/electric) can be configured to modulate the
flow setpoint in sequence with the heating source.
CAUTION:
If the damper is set to modulate in heating mode, make sure the controller is in the
appropriate mode for the current supply air temperature.